Dr Jacob Kloprogge
Honorary Senior Fellow
School of Earth and Environmental Sciences
Book
Kloprogge, J. Theo and Lavinsky, Robert Photo atlas of mineral pseudomorphism. Amsterdam, Netherlands: Elsevier, 2017. doi:10.1016/B978-0-12-803674-7.01001-X
Book Chapters
Kloprogge, J. Theo (2017). Infrared and Raman spectroscopy of minerals and inorganic materials. In John Lindon, George E. Tranter and David Koppenaal (Ed.), Encyclopedia of spectroscopy and spectrometry 3rd ed. (pp. 267-281) London, United Kingdom: Academic Press. doi:10.1016/B978-0-12-409547-2.12154-7
Kloprogge, J. T. (2016). Characterisation of halloysite by spectroscopy. In Peng Yuan, Antoine Thill and Faïza Bergaya (Ed.), Developments in clay science (pp. 115-136) Amsterdam: Elsevier. doi:10.1016/B978-0-08-100293-3.00006-6
Theo Kloprogge, J., Duong, Loc V., Martens, Wayde N., Eerden, Ad Van Der and Frost, Ray L. (2007). Mid- and near-infrared pectroscopy of hydrothermally synthesized 2:1 phyllosilicates in the system Na2O-Al2O3-SiO2-H2O. In Progress in Solid State Chemistry Research (pp. 285-299) : Nova Science Publishers, Inc..
Journal Articles
Kloprogge, J. Theo (2018) Infrared and raman microscopy of the arsenate double salt mineral tilasite, camg(AsO4)F, from Långban, Värmland, Sweden. Philippine Journal of Science, 147 4: 639-646.
Kloprogge, J. Theo and Wood, Barry J. (2018) X-ray photoelectron spectroscopy and Raman microscopy of a ferroan platinum crystal from the Kondyor Massif, Russian Far East. Spectroscopy Letters, 52 1: 43-48. doi:10.1080/00387010.2018.1546745
Kloprogge, J. Theo and Wood, Barry J. (2017) X-ray Photoelectron spectroscopic and Raman spectroscopic study of bayldonite from Wheal Carpenter, Cornwall, UK. Vacuum, 141 2: 49-56. doi:10.1016/j.vacuum.2017.03.018
Kloprogge, J. Theo and Wood, Barry J. (2017) X-ray photoelectron spectroscopic and Raman microscopic investigation of the variscite group minerals: variscite, strengite, scorodite and mansfieldite. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 185 163-172. doi:10.1016/j.saa.2017.05.042
Kloprogge, J. Theo and Wood, Barry J. (2016) Systematic XPS study of gallium-substituted boehmite. Journal of Materials Science, 51 11: 5436-5444. doi:10.1007/s10853-016-9847-1
Kloprogge, J. Theo and Wood, Barry J. (2015) Chemical bonding and electronic structures of microcline, orthoclase and the plagioclase series by X-ray photoelectron spectroscopy. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 137 711-716. doi:10.1016/j.saa.2014.08.120
Kloprogge, J. Theo (2015) Comment on “A spectroscopic comparison of selected Chinese kaolinite, coal bearing kaolinite and halloysite - A mid-infrared and near-infrared study“ and “Infrared and infrared emission spectroscopic study of typical Chinese kaolinite and halloysite. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 136 PB: 175-177. doi:10.1016/j.saa.2014.09.005
Webb, Gregory E., Northdurft, Luke D., Kamber, Balz S., Kloprogge, J.T. and Zhao, Jian-Xin (2009) Rare earth geochemistry of scleractinian coral skeleton during meteoric diagenesis: a sequence through neomorphism of aragonite to calcite. Sedimentology, 56 5: 1433-1463. doi:10.1111/j.1365-3091.2008.01041.x
Frost, Ray L. and Theo Kloprogge, J. (2008) Chapter 6 Heating stage spectroscopy: infrared, raman, energy dispersive x-ray and x-ray photoelectron spectroscopy. Handbook of Thermal Analysis and Calorimetry, 5 171-208. doi:10.1016/S1573-4374(08)80009-X
Reddy, B. Jagannadha, Frost, Ray L., Martens, Wayde N., Wain, Daria L. and Kloprogge, J. Theo (2007) Spectroscopic characterization of Mn-rich tourmalines. Vibrational Spectroscopy, 44 1: 42-49. doi:10.1016/j.vibspec.2006.07.010
Frost, Ray L., Weier, Matt L., Williams, Peter A., Leverett, Peter and Kloprogge, J. Theo (2007) Raman spectroscopy of the sampleite group of minerals. Journal of Raman Spectroscopy, 38 5: 574-583. doi:10.1002/jrs.1702
Duong, L. V., Kloprogge, J. T., Frost, R. L. and Van Veen, J. A R (2007) An improved route for the synthesis of Al13-pillared montmorillonite catalysts. Journal of Porous Materials, 14 1: 71-79. doi:10.1007/s10934-006-9010-5
He, H. P., Zhou, Q., Frost, R. L., Wood, B. J., Duong, L. V. and Kloprogge, J. T. (2007) A X-ray photoelectron spectroscopy study of HDTMAB distribution within organoclays. Spectrochimica Acta Part A-molecular And Biomolecular Spectroscopy, 66 4-5: 1180-1188. doi:10.1016/j.saa.2006.06.005
He, Hongping, Zhou, Qin, Martens, Wayde N., Kloprogge, Theo J., Yuan, Peng, Xi, Yunfei, Zhu, Jianxi and Frost, Ray L. (2006) Microstructure of HDTMA+-modified montmorillonite and its influence on sorption characteristics. Clays and Clay Minerals, 54 6: 689-696. doi:10.1346/CCMN.2006.0540604
Carmody, Onuma, Frost, Ray L., Kristóf, János, Kokot, Serge, Kloprogge, J. Theo and Mako, Eva (2006) Modification of kaolinite surfaces through mechanochemical activation with quartz: A diffuse reflectance infrared fourier transform and chemometrics study. Applied Spectroscopy, 60 12: 1414-1422. doi:10.1366/000370206779321472
Frost, R.L., Bouzaid, J.M., Musumeci, A.W., Kloprogge, J.T. and Martens, W.N. (2006) Thermal decomposition of the synthetic hydrotalcite iowaite. Journal of Thermal Analysis and Calorimetry, 86 2: 437-441. doi:10.1007/s10973-005-7290-7
Kloprogge, J. Theo, Broekmans, Maarten, Duong, Loc V., Martens, Wayde N., Hickey, Liesel and Frost, Ray L. (2006) Low temperature synthesis and characterisation of lecontite, (NH 4)Na(SO4)•2H20. Journal of Materials Science, 41 11: 3535-3539. doi:10.1007/s10853-005-5909-5
Kloprogge, J. Theo, Hickey, Liesel, Trujillano, Raquel, Holgado, Maria Jesús, San Román, M. S., Rives, V., Martens, Wayde N. and Frost, Ray L. (2006) Characterization of intercalated Ni/Al hydrotalcites prepared by the partial decomposition of urea. Crystal Growth and Design, 6 6: 1533-1536. doi:10.1021/cg0504612
Frost, Ray L., Čejka, Jiří, Weier, Matt L., Martens, Wayde and Kloprogge, J. Theo (2006) A Raman and infrared spectroscopic study of the uranyl silicates-Weeksite, soddyite and haiweeite. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 64 2: 308-315. doi:10.1016/j.saa.2005.07.028
Frost, Ray L., Weier, Matt L., Čejka, Jiří and Kloprogge, J. Theo (2006) Raman spectroscopy of walpurgite. Journal of Raman Spectroscopy, 37 5: 585-590. doi:10.1002/jrs.1483
Frost, Ray L., Wills, Rachael-Anne, Kloprogge, J. Theo and Martens, Wayde (2006) Thermal decomposition of ammonium jarosite (NH4)Fe 3(SO4)2(OH)6. Journal of Thermal Analysis and Calorimetry, 84 2: 489-496. doi:10.1007/s10973-005-6953-8
Kloprogge, J. Theo, Mahmutagic, Emir and Frost, Ray L. (2006) Mid-infrared and infrared emission spectroscopy of Cu-exchanged montmorillonite. Journal of Colloid and Interface Science, 296 2: 640-646. doi:10.1016/j.jcis.2005.09.055
Frost, Ray L., Wills, Rachael-Anne, Weier, Matt L., Martens, Wayde and Theo Kloprogge, J. (2006) A Raman spectroscopic study of alunites. Journal of Molecular Structure, 785 1-3: 123-132. doi:10.1016/j.molstruc.2005.10.003
He, Hongping, Frost, Ray L., Bostrom, Thor, Yuan, Peng, Duong, Loc, Yang, Dan, Xi, Yunfei and Kloprogge, J. Theo (2006) Changes in the morphology of organoclays with HDTMA+ surfactant loading. Applied Clay Science, 31 3-4: 262-271. doi:10.1016/j.clay.2005.10.011
Kloprogge, J. T., Duong, L. V., Weier, M. and Martens, W. N. (2006) Nondestructive identification of arsenic and cobalt minerals from Cobalt City, Ontario, Canada: Arsenolite, erythrite, and spherocobaltite on pararammelsbergite. Applied Spectroscopy, 60 11: 1293-1296. doi:10.1366/000370206778999148
Lin, YH, Adebajo, MO, Kloprogge, JT, Martens, WN and Frost, RL (2006) X-ray diffraction and Raman spectroscopic studies of Zn-substituted carrboydite-like compounds. Materials Chemistry And Physics, 100 1: 174-186. doi:10.1016/j.matchemphys.2005.12.028
Kloprogge, J. Theo, Duong, Loc V., Martens, Wayde N., Frost, Ray L. and Visser, Diederik (2006) Near- and mid infrared spectroscopy of the lithium-bearing amphibole holmquistite from Barraute, Canada. Journal of Near Infrared Spectroscopy, 14 3: 209-212. doi:10.1255/jnirs.616
Kloprogge, J. Theo (2006) Spectroscopic studies of synthetic and natural beidellites: A review. Applied Clay Science, 31 3-4: 165-179. doi:10.1016/j.clay.2005.10.003
Frost, RL, Musumeci, AW, Kloprogge, JT, Adebajo, MO and Martens, WN (2006) Raman spectroscopy of hydrotalcites with phosphate in the interlayer: implications for the removal of phosphate from water. Journal of Raman Spectroscopy, 37 7: 733-741. doi:10.1002/jrs.1500
Adebajo, MO, Frost, RL, Kloprogge, JT and Kokot, S (2006) Raman spectroscopic investigation of acetylation of raw cotton. Spectrochimica Acta Part A-molecular And Biomolecular Spectroscopy, 64 2: 448-453. doi:10.1016/j.saa.2005.07.045
Frost, Ray L., Wills, Rachael-Anne, Kloprogge, J. Theo and Martens, Wayde N. (2006) Thermal decomposition of hydronium jarosite (H3O)Fe 3(SO4)2(OH)6 . Journal of Thermal Analysis and Calorimetry, 83 1: 213-218. doi:10.1007/s10973-005-6908-0
Mills, Stuart J., Frost, Ray L., Kloprogge, J. Theo and Weier, Matt L. (2005) Raman spectroscopy of the mineral rhodonite. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 62 1-3: 171-175. doi:10.1016/j.saa.2004.12.022
Frost, Ray L., Weier, Matt L., Kloprogge, J. Theo, Rull, Fernando and Martinez-Frias, Jesus (2005) Raman spectroscopy of halotrichite from Jaroso, Spain. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 62 1-3: 176-180. doi:10.1016/j.saa.2004.12.023
Frost, Ray L., Erickson, Kristy L. and Kloprogge, Theo J. (2005) Vibrational spectroscopic study of the nitrate containing hydrotalcite mbobomkulite. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 61 13-14: 2919-2925. doi:10.1016/j.saa.2004.11.002
Xi, Yunfei, Frost, Ray L., He, Hongping, Kloprogge, Theo and Bostrom, Thor (2005) Modification of Wyoming montmorillonite surfaces using a cationic surfactant. Langmuir, 21 19: 8675-8680. doi:10.1021/la051454i
Frost, Ray L., Weier, Matt L., Martens, Wayde N., Kloprogge, J. Theo and Kristóf, János (2005) Thermo-Raman spectroscopic study of the uranium mineral sabugalite. Journal of Raman Spectroscopy, 36 8: 797-805. doi:10.1002/jrs.1366
Duong, Loc, Bostrom, Thor, Kloprogge, Theo and Frost, Ray (2005) The distribution of Ga in Ga-pillared montmorillonites: A transmission electron microscopy and microanalysis study. Microporous and Mesoporous Materials, 82 1-2: 165-172. doi:10.1016/j.micromeso.2005.03.006
Carmody, Onuma, Kristóf, János, Frost, Ray L., Makó, Éva, Kloprogge, J. Theo and Kokot, Serge (2005) A spectroscopic study of mechanochemically activated kaolinite with the aid of chemometrics. Journal of Colloid and Interface Science, 287 1: 43-56. doi:10.1016/j.jcis.2005.01.060
Kloprogge, J. Theo (2005) Infrared and Raman spectroscopy of naturally occurring hydrotalcites and their synthetic equivalents. CMS Workshop Lectures, 13 204-238.
Kloprogge, J. Theo and Frost, Ray L. (2005) Infrared emission spectroscopy of clay minerals. CMS Workshop Lectures, 13 100-124.
Kloprogge, J. Theo (2005) Short introduction to infrared and Raman spectroscopy. CMS Workshop Lectures, 13 2-7.
Kloprogge, J. Theo (2005) Preface. CMS Workshop Lectures, 13 .
Duong, Loc V., Wood, Barry J. and Kloprogge, J. Theo (2005) XPS study of basic aluminum sulphate and basic aluminium nitrate. Materials Letters, 59 14-15: 1932-1936. doi:10.1016/j.matlet.2005.02.029
Kloprogge, J. Theo, Duong, Loc V. and Frost, Ray L. (2005) A review of the synthesis and characterisation of pillared clays and related porous materials for cracking of vegetable oils to produce biofuels. Environmental Geology, 47 7: 967-981. doi:10.1007/s00254-005-1226-1
Vogels, R. J M J, Kloprogge, J. T., Geus, J. W. and Beers, A. W F (2005) Synthesis and characterization of saponite clays: Part 2. Thermal stability. American Mineralogist, 90 5-6: 945-953. doi:10.2138/am.2005.1617
Vogels, R. J.M.J., Kloprogge, J. T. and Geus, J. W. (2005) Homogeneous forced hydrolysis of aluminum through the thermal decomposition of urea. Journal of Colloid and Interface Science, 285 1: 86-93. doi:10.1016/j.jcis.2004.11.045
Vogels, R. J.M.J., Kloprogge, J. T. and Geus, J. W. (2005) Synthesis and characterization of saponite clays. American Mineralogist, 90 5-6: 931-944. doi:10.2138/am.2005.1616
Vogels, R. J.M.J., Kloprogge, J. T. and Geus, J. W. (2005) Catalytic activity of synthetic saponite clays: Effects of tetrahedral and octahedral composition. Journal of Catalysis, 231 2: 443-452. doi:10.1016/j.jcat.2005.02.004
Nothdurft, Luke D., Webb, Gregory E., Buster, Noreen A., Holmes, Charles W., Sorauf, James E. and Kloprogge, J. T. (2005) Brucite microbialites in living coral skeletons: Indicators of extreme microenvironments in shallow-marine settings. Geology, 33 3: 169-172. doi:10.1130/G20932.1
Vogels, R. J.M.J., Kloprogge, J. T. and Geus, J. W. (2005) Synthesis and characterisation of boron and gallium substituted saponite clays below 100°C at one atmosphere. Microporous and Mesoporous Materials, 77 2-3: 159-165. doi:10.1016/j.micromeso.2004.08.027
Kloprogge, J. Theo, Hickey, Leisel and Frost, Ray L. (2005) The effect of varying synthesis conditions on zinc chromium hydrotalcite: A spectroscopic study. Materials Chemistry and Physics, 89 1: 99-109. doi:10.1016/j.matchemphys.2004.08.035
Lin, YH, Adebajo, MO, Frost, RL and Kloprogge, JT (2005) Thermogravimetric analysis of hydrotalcites based on the takovite formula NixZn6-xAl2(OH)(16)(CO3)center dot 4H(2)O. Journal of Thermal Analysis And Calorimetry, 81 1: 83-89. doi:10.1007/s10973-005-0749-8
Frost, RL, Musumeci, AW, Bouzaid, J, Adebajo, MO, Martens, WN and Kloprogge, JT (2005) Intercalation of hydrotalcites with hexacyanoferrate(II) and (III) - a thermoRaman spectroscopic study. Journal of Solid State Chemistry, 178 6: 1940-1948. doi:10.1016/j.jssc.2005.03.045
Martens, Wayde N., Kloprogge, J. Theo, Frost, Ray L. and Rintoul, Llew (2005) Site occupancy of Co and Ni in erythrite-annabergite solid solutions deduced by vibrational spectroscopy. Canadian Mineralogist, 43 3: 1065-1075. doi:10.2113/gscanmin.43.3.1065
Kloprogge, J. Theo, Weier, Matt L., Duong, Loc V. and Frost, Ray L. (2004) Microwave-assisted synthesis and characterisation of divalent metal tungstate nanocrystalline minerals: Ferberite, hübnerite, sanmartinite, scheelite and stolzite. Materials Chemistry and Physics, 88 2-3: 438-443. doi:10.1016/j.matchemphys.2004.08.013
Kloprogge, J. Theo, Hickey, Leisel and Frost, Ray L. (2004) FT-Raman and FT-IR spectroscopic study of synthetic Mg/Zn/Al-hydrotalcites. Journal of Raman Spectroscopy, 35 11: 967-974. doi:10.1002/jrs.1244
Kloprogge, J. Theo, Hickey, Leisel and Frost, Ray L. (2004) The effects of synthesis pH and hydrothermal treatment on the formation of zinc aluminum hydrotalcites. Journal of Solid State Chemistry, 177 11: 4047-4057. doi:10.1016/j.jssc.2004.07.010
Kloprogge, J. Theo, Ding, Zhe, Martens, Wayde N., Schuiling, Roelof D., Duong, Loc V. and Frost, Ray L. (2004) Thermal decomposition of syngenite, K2Ca(SO4) 2·H2O. Thermochimica Acta, 417 1: 143-155. doi:10.1016/j.tca.2003.12.001
Kloprogge, J. Theo, Weier, Matt, Crespo, Inmaculada, Ulibarri, Maria A., Barriga, Cristobalina, Rives, V., Martens, Wayde N. and Frost, Ray L. (2004) Intercalation of iron hexacyano complexes in Zn,Al hydrotalcite. Part 2. A mid-infrared and Raman spectroscopic study. Journal of Solid State Chemistry, 177 4-5: 1382-1387. doi:10.1016/j.jssc.2003.11.034
Frost, Ray L., Martens, Wayde and Kloprogge, J. Theo (2004) Synthetic deuterated erythrite - A vibrational spectroscopic study. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 60 1-2: 343-349. doi:10.1016/S1386-1425(03)00232-4
Frost, Ray L., Williams, Peter A., Martens, Wayde, Leverett, Peter and Kloprogge, J. Theo (2004) Raman spectroscopy of basic copper(II) and some complex copper(II) sulfate minerals: Implications for hydrogen bonding. American Mineralogist, 89 7: 1130-1137. doi:10.2138/am-2004-0726
Frost, Ray L., Kloprogge, J. Theo and Martens, Wayde N. (2004) Raman spectroscopy of the arsenates and sulphates of the tsumcorite mineral group. Journal of Raman Spectroscopy, 35 1: 28-35. doi:10.1002/jrs.1076
Martens, Wayde N., Kloprogge, J. Theo, Frost, Ray L. and Rintoul, Llew (2004) Single-crystal Raman study of erythrite, Co3(AsO 4)2·8H2O. Journal of Raman Spectroscopy, 35 3: 208-216. doi:10.1002/jrs.1136
Martens, Wayde N., Rintoul, Llew, Kloprogge, J. Theo and Frost, Ray L. (2004) Single crystal raman spectroscopy of cerussite. American Mineralogist, 89 2-3: 352-358. doi:10.2138/am-2004-2-314
Kloprogge, J. Theo, Boström, Thor E. and Weier, Matt L. (2004) In situ observation of the thermal decomposition of weddelite by heating stage environmental scanning electron microscopy. American Mineralogist, 89 1: 245-248. doi:10.2138/am-2004-0129
Frost, Ray L., Weier, Matt L., Clissold, Meagan E., Williams, Peter A. and Kloprogge, J. Theo (2003) Thermal decomposition of the natural hydrotalcites carrboydite and hydrohonessite. Thermochimica Acta, 407 1-2: 1-9. doi:10.1016/S0040-6031(03)00262-4
Frost, Ray L. and Kloprogge, J. Theo (2003) Raman spectroscopy of some complex arsenate minerals - Implications for soil remediation. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 59 12: 2797-2804. doi:10.1016/S1386-1425(03)00103-3
Frost, Ray L., Martens, Wayde, Kloprogge, J. Theo and Ding, Zhe (2003) Raman spectroscopy of selected lead minerals of environmental significance. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 59 12: 2705-2711. doi:10.1016/S1386-1425(03)00054-4
Frost, Ray L., Martens, Wayde, Williams, Peter A. and Kloprogge, J. Theo (2003) Raman spectroscopic study of the vivianite arsenate minerals. Journal of Raman Spectroscopy, 34 10: 751-759. doi:10.1002/jrs.1049
Frost, Ray L., Weier, Matt L. and Kloprogge, J. Theo (2003) Raman spectroscopy of some natural hydrotalcites with sulphate and carbonate in the interlayer. Journal of Raman Spectroscopy, 34 10: 760-768. doi:10.1002/jrs.1050
Frost, Ray L., Weier, Matt L., Martens, Wayde, Kloprogge, J. Theo and Ding, Zhe (2003) Thermal decomposition of the vivianite arsenates - Implications for soil remediation. Thermochimica Acta, 403 2: 237-249. doi:10.1016/S0040-6031(03)00046-7
Kloprogge, J. T., Visser, D., Martens, W. N., Duong, L. V. and Frost, R. L. (2003) Identification by RAMAN microscopy of magnesian vivianite formed from Fe2+, Mg, Mn2+ and PO43- in a Roman camp near fort Vechten, Utrecht, the Netherlands. Geologie en Mijnbouw/Netherlands Journal of Geosciences, 82 2: 209-214.
Frost, Ray L., Weier, Matt L., Martens, Wayde, Kloprogge, J. Theo and Ding, Zhe (2003) Dehydration of synthetic and natural vivianite. Thermochimica Acta, 401 2: 121-130. doi:10.1016/S0040-6031(02)00505-1
Frost, Ray L., Crane, Martin, Williams, Peter A. and Kloprogge, J. Theo (2003) Isomorphic substitution in vanadinite [Pb5(VO4)3Cl] - A Raman spectroscopic study. Journal of Raman Spectroscopy, 34 3: 214-220. doi:10.1002/jrs.978
Martens, Wayde, Frost, Ray L., Kloprogge, J. Theo and Williams, Peter A. (2003) Raman spectroscopic study of the basic copper sulphates - Implications for copper corrosion and 'bronze disease'. Journal of Raman Spectroscopy, 34 2: 145-151. doi:10.1002/jrs.969
Frost, Ray L., Kloprogge, J. Theo and Williams, Peter A. (2003) Raman spectroscopy of lead sulphate-carbonate minerals - Implications for hydrogen bonding. Neues Jahrbuch fur Mineralogie, Monatshefte, 12: 529-542. doi:10.1127/0028-3649/2003/2003-0529
Martens, Wayde, Frost, Ray L. and Kloprogge, J. Theo (2003) Raman spectroscopy of synthetic erythrite, partially dehydrated erythrite and hydrothermally synthesized dehydrated erythrite. Journal of Raman Spectroscopy, 34 1: 90-95. doi:10.1002/jrs.958
Martens, Wayde N., Frost, Ray L., Kloprogge, J. Theo and Williams, Peter A. (2003) The basic copper arsenate minerals olivenite, cornubite, cornwarlite, and clinoclase: An infrared emission and Raman spectroscopic study. American Mineralogist, 88 4: 501-508. doi:10.2138/am-2003-0404
Frost, R. L., Martens, W., Ding, Z. and Kloprogge, J. T. (2003) DSC and high-resolution TG of synthesized hydrotalcites of Mg and Zn. Journal of Thermal Analysis and Calorimetry, 71 2: 429-438.
Frost, Ray L., Williams, Peter A., Kloprogge, J. Theo and Martens, Wayde (2003) Raman spectroscopy of the copper chloride minerals nantokite, eriochalcite and claringbullite - Implications for copper corrosion. Neues Jahrbuch fur Mineralogie, Monatshefte, 10: 433-445. doi:10.1127/0028-3649/2003/2003-0433
Martens, W. N., Ding, Z., Frost, R. L. and Kloprogge, J. T. (2002) Raman spectroscopy of the basic copper carbonates: Azurite and malachite. Acta Universitatis Carolinae, Geologica, 46 1: 53-54.
Frost, R. L., Ding, Z. and Kloprogge, J. T. (2002) Does life exist on Mars? Do nontronites hold the key to life on Mars?. Acta Universitatis Carolinae, Geologica, 46 1: 28-29.
Frost, R. L., Martens, W. N., Kloprogge, J. T., Williams, P. A. and Edwards, H. G M (2002) Raman spectroscopy of the basic copper arsenates and phosphates. Acta Universitatis Carolinae, Geologica, 46 1: 30-31.
Martens, W. N., Frost, R. L., Kloprogge, J. T. and Edwards, H. G.M. (2002) Where did the cinnabar from Herod's palace originate?. Acta Universitatis Carolinae, Geologica, 46 1: 55-56.
Kloprogge, J. T., Frost, R. L. and Schuiling, R. D. (2002) Raman and FT-IR spectroscopy of syngenite formed during the treatment of liquid manure with H2SO4. Acta Universitatis Carolinae, Geologica, 46 1: 46-47.
Kloprogge, J. T. and Frost, R. L. (2002) Raman and FT-IR study of celestine from middle triassic limestone (Muschelkalk), Winterswijk, The Netherlands. Acta Universitatis Carolinae, Geologica, 46 1: 44-45.
Frost, R. L., Martens, W., Williams, P. A. and Kloprogge, J. T. (2002) Raman and infrared spectroscopic study of the vivianite-group phosphates vivianite, baricite and bobierrite. Mineralogical Magazine, 66 6: 1063-1073. doi:10.1180/0026461026660077
Frost, R. L., Makó, É, Kristóf, J. and Kloprogge, J. T. (2002) Modification of kaolinite surfaces through mechanochemical treatment - A mid-IR and near-IR spectroscopic study. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 58 13: 2849-2859. doi:10.1016/S1386-1425(02)00033-1
Frost, Ray L., Kloprogge, Theo, Williams, Peter A., Martens, Wayde, Johnson, Therese E. and Leverett, Peter (2002) Vibrational spectroscopy of the basic copper phosphate minerals: Pseudomalachite, ludjibaite and reichenbachite. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 58 13: 2861-2868. doi:10.1016/S1386-1425(02)00034-3
Frost, Ray L., Martens, Wayde, Theo Kloprogge, J. and Williams, Peter A. (2002) Raman spectroscopy of the basic copper chloride minerals atacamite and paratacamite: Implications for the study of copper, brass and bronze objects of archaeological significance. Journal of Raman Spectroscopy, 33 10: 801-806. doi:10.1002/jrs.921
Frost, Ray L., Williams, Peter A., Martens, Wayde and Theo Kloprogge, J. (2002) Raman spectroscopy of the polyanionic copper(II) minerals buttgenbachite and connellite: Implications for studies of ancient copper objects and bronzes. Journal of Raman Spectroscopy, 33 9: 752-757. doi:10.1002/jrs.917
Kristóf, J., Frost, R. L., Kloprogge, J. T., Horváth, E. and Makó, É (2002) Detection of four different OH-groups in ground kaolinite with controlled-rate thermal analysis. Journal of Thermal Analysis and Calorimetry, 69 1: 77-83. doi:10.1023/A:1019981505712
Frost, R. L., Martens, W. N., Duong, L. and Kloprogge, J. T. (2002) Evidence for molecular assembly in hydrotalcites. Journal of Materials Science Letters, 21 16: 1237-1239. doi:10.1023/A:1016542700574
Frost, R. L., Ding, Z., Kloprogge, J. T. and Martens, W. N. (2002) Thermal stability of azurite and malachite in relation to the formation of mediaeval glass and glazes. Thermochimica Acta, 390 1-2: 133-144. doi:10.1016/S0040-6031(02)00127-2
Frost, Ray L., Williams, Peter A., Martens, Wayde, Theo Kloprogge, J. and Leverett, Peter (2002) Raman spectroscopy of the basic copper phosphate minerals cornetite, libethenite, pseudomalachite, reichenbachite and ludjibaite. Journal of Raman Spectroscopy, 33 4: 260-263. doi:10.1002/jrs.850
Frost, R. L., Martens, W. N., Rintoul, L., Mahmutagic, E. and Kloprogge, J. T. (2002) Raman spectroscopic study of azurite and malachite at 298 and 77 K. Journal of Raman Spectroscopy, 33 4: 252-259. doi:10.1002/jrs.848
Martens, Wayde N., Frost, Ray L., Kristof, János and Theo Kloprogge, J. (2002) Raman spectroscopy of dimethyl sulphoxide and deuterated dimethyl sulphoxide at 298 and 77 K. Journal of Raman Spectroscopy, 33 2: 84-91. doi:10.1002/jrs.827
Ding, Z., Frost, R. L. and Kloprogge, J. T. (2002) Thermal activation of copper carbonate. Journal of Materials Science Letters, 21 13: 981-983. doi:10.1023/A:1016046320098
Frost, Ray L., Kloprogge, J. Theo and Ding, Zhe (2002) The Garfield and Uley nontronites - An infrared spectroscopic comparison. Spectrochimica Acta - Part A Molecular and Biomolecular Spectroscopy, 58 9: 1881-1894. doi:10.1016/S1386-1425(01)00638-2
Frost, Ray L., Kloprogge, J. Theo and Ding, Zhe (2002) Near-infrared spectroscopic study of nontronites and ferruginous smectite. Spectrochimica Acta - Part A Molecular and Biomolecular Spectroscopy, 58 8: 1657-1668. doi:10.1016/S1386-1425(01)00637-0
Kloprogge, J. T., Hammond, M., Hickey, L. and Frost, R. L. (2002) Low temperature synthesis of cobalt clays. Journal of Materials Science Letters, 21 12: 931-933. doi:10.1023/A:1016069505772
Kloprogge, J. Theo, Schuiling, Roelof D., Ding, Zhe, Hickey, Leisel, Wharton, David and Frost, Ray L. (2002) Vibrational spectroscopic study of syngenite formed during the treatment of liquid manure with sulphuric acid. Vibrational Spectroscopy, 28 2: 209-221. doi:10.1016/S0924-2031(01)00139-4
Kloprogge, J. T., Hickey, L. and Frost, R. L. (2002) Synthesis and spectroscopic characterization of deuterated hydrotalcite. Journal of Materials Science Letters, 21 8: 603-605. doi:10.1023/A:1015655018529
Ruan, H. D., Frost, R. L., Kloprogge, J. T. and Duong, L. (2002) Infrared spectroscopy of goethite dehydroxylation: III. FT-IR microscopy of in situ study of the thermal transformation of goethite to hematite. Spectrochimica Acta - Part A Molecular and Biomolecular Spectroscopy, 58 5: 967-981. doi:10.1016/S1386-1425(01)00574-1
Kloprogge, J. T., Ruan, H. D. and Frost, R. L. (2002) Thermal decomposition of bauxite minerals: Infrared emission spectroscopy of gibbsite, boehmite and diaspore. Journal of Materials Science, 37 6: 1121-1129. doi:10.1023/A:1014303119055
Martens, Wayde N., Ding, Zhe, Frost, Ray L., Kristof, János and Kloprogge, J. Theo (2002) Raman spectroscopy of hydrazine-intercalated kaolinite at 77, 298, 323, 343 and 358 K. Journal of Raman Spectroscopy, 33 1: 31-36. doi:10.1002/jrs.812
Crane, Martin, Frost, Ray L., Williams, Peter A. and Kloprogge, J. Theo (2002) Raman spectroscopy of the molybdate minerals chillagite (tungsteinian wulfenite-I4), stolzite, scheelite, wolframite and wulfenite. Journal of Raman Spectroscopy, 33 1: 62-66. doi:10.1002/jrs.820
Ruan, H. D., Frost, R. L., Kloprogge, J. T. and Duong, L. (2002) Far-infrared spectroscopy of alumina phases. Spectrochimica Acta - Part A Molecular and Biomolecular Spectroscopy, 58 2: 265-272. doi:10.1016/S1386-1425(01)00532-7
Frost, R. L., Van Der Gaast, S. J., Zbik, Marek, Kloprogge, J. T. and Paroz, G. N. (2002) Birdwood kaolinite: A highly ordered kaolinite that is difficult to intercalate-An XRD, SEM and Raman spectroscopic study. Applied Clay Science, 20 4-5: 177-187. doi:10.1016/S0169-1317(01)00071-0
Ruan, H. D., Frost, R. L., Kloprogge, J. T. and Duong, L. (2002) Infrared spectroscopy of goethite dehydroxylation. II. Effect of aluminium substitution on the behaviour of hydroxyl units. Spectrochimica Acta - Part A Molecular and Biomolecular Spectroscopy, 58 3: 479-491. doi:10.1016/S1386-1425(01)00556-X
Frost, Ray L., Edwards, Howell G. M., Duong, Loc, Kloprogge, J. Theo and Martens, Wayde N. (2002) Raman spectroscopic and SEM study of cinnabar from Herod's palace and its likely origin. Analyst, 127 2: 293-296. doi:10.1039/b109368c
Frost, Ray L., Kristof, János, Kloprogge, J.Theo and Horvath, Erzsébet (2002) Deintercalation of hydrazine-intercalated kaolinite in dry and moist air. Journal of Colloid and Interface Science, 246 1: 164-174. doi:10.1006/jcis.2001.8011
de Oliveira, Luiz F.C., Edwards, Howell G. M., Frost, Ray L., Kloprogge, J. Theo and Middleton, Paul S. (2002) Caput mortuum: Spectroscopic and structural studies of an ancient pigment. Analyst, 127 4: 536-541. doi:10.1039/b111473p
Martens, Wayde N., Kloprogge, J. Theo, Frost, Ray L. and Bartlett, John R. (2002) A crystallite packing model for pseudoboehmite formed during the hydrolysis of trisecbutoxyaluminium to explain the peptizability. Journal of Colloid and Interface Science, 247 1: 132-137. doi:10.1006/jcis.2001.8079
Kloprogge, J.Theo, Evans, Rhys, Hickey, Leisel and Frost, Ray L (2002) Characterisation and Al-pillaring of smectites from Miles, Queensland (Australia). Applied Clay Science, 20 4-5: 157-163. doi:10.1016/S0169-1317(01)00069-2
Kloprogge, J. Theo, Wharton, David, Hickey, Leisel and Frost, Ray L. (2002) Infrared and Raman study of interlayer anions CO2 3 -, NO- 3, SO2 4 - and ClO- 4 in Mg/Al-hydrotalcite. American Mineralogist, 87 5-6: 623-629. doi:10.2138/am-2002-5-604
Frost, Ray L., Kristof, János, Horvath, Erzsébet, Martens, Wayde N. and Kloprogge, J. T. (2002) Complexity of intercalation of hydrazine into kaolinite - A controlled rate thermal analysis and DRIFT spectroscopic study. Journal of Colloid and Interface Science, 251 2: 350-359. doi:10.1006/jcis.2002.8384
Kloprogge, J. T., Case, M. H. and Frost, R. L. (2001) Raman microscopic study of the Li amphibole holmquistite, from the Martin Marietta Quarry, Bessemer City, NC, USA. Mineralogical Magazine, 65 6: 775-785. doi:10.1180/0026461016560008
Frost, Ray L. and Kloprogge, J. Theo (2001) Raman microscopy study of kalinite, tschermigite and lonecreekite at 298 and 77K. Neues Jahrbuch fur Mineralogie, Monatshefte, 1 27-40.
Kloprogge, J. Theo, Visser, Diederik, Case, Mark H. and Frost, Ray L. (2001) Raman microscopic study of holmquistite, a Li-bearing orthorhombic amphibole. Neues Jahrbuch fur Mineralogie, Monatshefte, 1 1-17.
Crane, Martin J., Leverett, Peter, Shaddick, Lindsay R., Williams, Peter A., Kloprogge, J. Theo and Frost, Ray L. (2001) The PbCrO 4-PbSO 4 system and its mineralogical significance. Neues Jahrbuch fur Mineralogie, Monatshefte, 11 505-519.
Kloprogge, J. Theo and Frost, Ray L. (2001) Infrared emission spectroscopic study of the dehydroxylation of some natural and synthetic saponites. Neues Jahrbuch fur Mineralogie, Monatshefte, 10 446-463.
Frost, Ray L., Williams, Peter A., Theo Kloprogge, J. and Leverett, P. (2001) Raman spectroscopy of descloizite and mottramite at 298 and 77 K. Journal of Raman Spectroscopy, 32 11: 906-911. doi:10.1002/jrs.758
Frost, Ray L., Locos, Oliver B., Kristof, Janos and Kloprogge, J. Theo (2001) Infrared spectroscopic study of potassium and cesium acetate-intercalated kaolinites. Vibrational Spectroscopy, 26 1: 33-42. doi:10.1016/S0924-2031(01)00108-4
Frost, R. L., Locos, O. B., Ruan, H. and Kloprogge, J. T. (2001) Near-infrared and mid-infrared spectroscopic study of sepiolites and palygorskites. Vibrational Spectroscopy, 27 1: 1-13. doi:10.1016/S0924-2031(01)00110-2
Frost, Ray L., Kristóf, János, Horváth, Erzsébet and Kloprogge, J. Theo (2001) Raman phonons and Raman Jahn-Teller bands in perovskite-like manganites. Journal of Raman Spectroscopy, 32 10: 805-811. doi:10.1002/jrs.770
Ruan, H. D., Frost, R. L. and Kloprogge, J. T. (2001) The behavior of hydroxyl units of synthetic goethite and its dehydroxylated product hematite. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 57 13: 2575-2586. doi:10.1016/S1386-1425(01)00445-0
Ruan, H. D., Frost, R. L. and Kloprogge, J. T. (2001) Comparison of Raman spectra in characterizing gibbsite, bayerite, diaspore and boehmite. Journal of Raman Spectroscopy, 32 9: 745-750. doi:10.1002/jrs.736
Kloprogge, J. Theo, Ruan, Huada and Frost, Ray L. (2001) Near-infrared spectroscopic study of basic aluminum sulfate and nitrate. Journal of Materials Science, 36 3: 603-607. doi:10.1023/A:1004860118470
Frost, Ray L., Fredericks, Peter M., Theo Kloprogge, J. and Hope, Greg A. (2001) Raman spectroscopy of kaolinites using different excitation wavelengths. Journal of Raman Spectroscopy, 32 8: 657-663. doi:10.1002/jrs.722
Kloprogge, J. T., Visser, D., Ruan, H. and Frost, R. L. (2001) Infrared and Raman spectroscopy of holmquistite, Li2(Mg,Fe2+)3(Al,Fe3+) 2(Si,Al)8O22(OH)2. Journal of Materials Science Letters, 20 16: 1497-1499. doi:10.1023/A:1017926529980
Frost, Ray L., Makó, Éva, Kristóf, János, Horváth, Erzsébet and Kloprogge, J. Theo (2001) Modification of kaolinite surfaces by mechanochemical treatment. Langmuir, 17 16: 4731-4738. doi:10.1021/la001453k
Frost, R. L. and Kloprogge, J. T. (2001) Towards a single crystal Raman spectrum of kaolinite at 77 K. Spectrochimica Acta - Part A Molecular and Biomolecular Spectroscopy, 57 1: 163-175. doi:10.1016/S1386-1425(00)00345-0
Frost, Ray L., Makó, Éva, Kristóf, János, Horváth, Erzsébet and Kloprogge, J. Theo (2001) Mechanochemical treatment of kaolinite. Journal of Colloid and Interface Science, 239 2: 458-466. doi:10.1006/jcis.2001.7591
Frost, Ray L., Kristóf, János, Horváth, Erzsébet and Kloprogge, J.Theo (2001) The modification of hydroxyl surfaces of formamide-intercalated kaolinites synthesized by controlled rate thermal analysis. Journal of Colloid and Interface Science, 239 1: 126-133. doi:10.1006/jcis.2001.7542
Martens, W. N., Frost, R. L., Bartlett, J. and Kloprogge, J. T. (2001) The ageing of alumina hydrolysates synthesized from sec-butoxyaluminium(III). Journal of Materials Chemistry, 11 6: 1681-1686. doi:10.1039/b010119m
Frost, Ray L., Kristof, János, Kloprogge, J. Theo and Horvath, Erzsébet (2001) Modification of the hydroxyl surface in cesium acetate intercalated kaolinite. Langmuir, 17 13: 4067-4073.
Martens, W. N., Frost, R. L., Bartlett, J. and Kloprogge, J. T. (2001) Thermal transformation of alumina hydrolysates and gels synthesized from secbutoxyaluminium(III) modified with short-chain aliphatic acids dissolved in butyl ether. Thermochimica Acta, 374 1: 31-43. doi:10.1016/S0040-6031(01)00487-7
Mendelovici, Efraim, Frost, Ray L. and Kloprogge, J.Theo (2001) Modification of chrysotile surface by organosilanes: An IR - Photoacoustic spectroscopy study. Journal of Colloid and Interface Science, 238 2: 273-278. doi:10.1006/jcis.2001.7524
Frost, Ray L., Kristóf, János, Horváth, Erzsébet and Kloprogge, J. Theo (2001) Separation of adsorbed formamide and intercalated formamide using controlled rate thermal analysis methodology. Langmuir, 17 11: 3216-3222. doi:10.1021/la001686b
Kloprogge, J.Theo, Hickey, Leisel and Frost, Ray L (2001) Heating stage Raman and infrared emission spectroscopic study of the dehydroxylation of synthetic Mg-hydrotalcite. Applied Clay Science, 18 1-2: 37-49. doi:10.1016/S0169-1317(00)00028-4
Frost, Ray L., Kristof, Janos, Schmidt, Jolene M. and Kloprogge, J. Theo (2001) Raman spectroscopy of potassium acetate-intercalated kaolinites at liquid nitrogen temperature. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 57 3: 603-609. doi:10.1016/S1386-1425(00)00382-6
Kloprogge, J. Theo, Hammond, Mayra, Hickey, Leisel and Frost, Ray L. (2001) A new low temperature synthesis route of fraipontite (Zn,Al)3(Si,Al)2O5(OH)4. Materials Research Bulletin, 36 5-6: 1091-1098. doi:10.1016/S0025-5408(01)00561-X
Ruan, H. D., Frost, R. L. and Kloprogge, J. T. (2001) Application of near-infrared spectroscopy to the study of alumina phases. Applied Spectroscopy, 55 2: 190-196. doi:10.1366/0003702011951498
Kloprogge, J. T., Ruan, H., Duong, L. V. and Frost, R. L. (2001) FT-IR and Raman microscopic study at 293 K and 77 K celestine, SrSO4, from the middle triassic limestone (Muschelkalk) in Winterswijk, The Netherlands. Geologie en Mijnbouw/Netherlands Journal of Geosciences, 80 2: 41-47.
Kristóf, J., Horváth, E., Frost, R. L. and Kloprogge, J. T. (2001) Thermoanalytical investigation of formamide intercalated kaolinites under quasi-isothermal conditions. Journal of Thermal Analysis and Calorimetry, 63 1: 279-289. doi:10.1023/A:1010117326869
Frost, Ray L. and Kloprogge, J. Theo (2000) Raman spectroscopy of kaolinite hydroxyls between 25°C and 500°C. Journal of Raman Spectroscopy, 31 5: 415-420. doi:10.1002/1097-4555(200005)31:5<415::AID-JRS531>3.0.CO;2-#
Kloprogge, J. Theo, Hammond, Mayra and Frost, Ray L. (2000) Low temperature synthesis and characterisation of pecoraite, a nickel containing phyllosilicate. Neues Jahrbuch fur Mineralogie, Monatshefte, 5 193-206.
Kloprogge, J. T., Ruan, H. and Frost, R. L. (2000) Near-infrared spectroscopic study of synthetic and natural pyrophyllite. Neues Jahrbuch fur Mineralogie, Monatshefte, 8 337-347.
Frost, Ray L., Ding, Zhe and Kloprogge, J. Theo (2000) The application of near-infrared spectroscopy to the study of brucite and hydrotalcite structure. Canadian Journal of Analytical Sciences and Spectroscopy, 45 4: 96-101.
Frost, Ray L., Kloprogge, J. Theo, Williams, Peter A. and Leverett, Peter (2000) Raman microscopy of some natural pseudo-alums: Halotrichite, apjohnite and wupatkiite, at 298 and 77 K. Journal of Raman Spectroscopy, 31 12: 1083-1087. doi:10.1002/1097-4555(200012)31:12<1083::AID-JRS647>3.0.CO;2-#
Mendelovici, Efraim, Frost, Ray L. and Kloprogge, Theo (2000) Cryogenic Raman spectroscopy of glycerol. Journal of Raman Spectroscopy, 31 12: 1121-1126. doi:10.1002/1097-4555(200012)31:12<1121::AID-JRS654>3.0.CO;2-G
Kloprogge, J. Theo and Frost, Ray L. (2000) Study of the thermal behaviour of rectorite by in-situ infrared emission spectroscopy. Neues Jahrbuch fur Mineralogie, Monatshefte, 4 145-157.
Szetu, J. L., Frost, R. L., Kloprogge, J. T., Russell, S. C. and Martens, W. (2000) Dehydration and dehydroxylation of alumina gels prepared from tri-sec-butoxyaluminium modified with short chain aliphatic acids. Thermochimica Acta, 362 1-2: 37-48. doi:10.1016/S0040-6031(00)00572-4
Kloprogge, J. Theo, Ruan, Huada and Frost, Ray L. (2000) Near-infrared spectroscopic study of [AlO4Al12(OH)23(H2O)12]7+-O-Si(OH)3 nitrate crystals formed by forced hydrolysis of Al3+ in the presence of TEOS. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 56 12: 2405-2411. doi:10.1016/S1386-1425(00)00297-3
Frost, Ray L. and Kloprogge, J. Theo (2000) Vibrational spectroscopy of ferruginous smectite and nontronite. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 56 11: 2177-2189. doi:10.1016/S1386-1425(00)00279-1
Frost, R. L. and Kloprogge, J. T. (2000) Raman spectroscopy of the acetates of sodium, potassium and magnesium at liquid nitrogen temperature. Journal of Molecular Structure, 526 1-3: 131-141. doi:10.1016/S0022-2860(00)00460-9
Frost, Ray L., Kristof, Janos, Horvath, Erzbeth and Kloprogge, J. Theo (2000) Rehydration and phase changes of potassium acetate-intercalated halloysite at 298 K. Journal of Colloid and Interface Science, 226 2: 318-327. doi:10.1006/jcis.2000.6807
Frost, Ray L., Kristof, Janos, Kloprogge, J. Theo and Horvath, E. (2000) Rehydration of potassium acetate-intercalated kaolinite at 298 K. Langmuir, 16 12: 5402-5408. doi:10.1021/la9915522
Venz, P. A., Kloprogge, J. T. and Frost, R. L. (2000) Chemically modified titania hydrolysates: physical properties. Langmuir, 16 11: 4962-4968. doi:10.1021/la990830u
Kloprogge, J. T. and Frost, R. L. (2000) The effect of synthesis temperature on the FT-Raman and FT-IR spectra of saponites. Vibrational Spectroscopy, 23 1: 119-127.
Frost, Ray L., Ruan, Huada, Theo Kloprogge, J. and Gates, W. P. (2000) Dehydration and dehydroxylation of nontronites and ferruginous smectite. Thermochimica Acta, 346 1-2: 63-72.
Venz, P. A., Frost, R. L., Bartlett, J. R., Woolfrey, J. L. and Kloprogge, J. T. (2000) Thermal transformations of titania hydrolysates prepared from tetraisopropoxytitanium(iv). Thermochimica Acta, 346 1-2: 73-82.
Kloprogge, J. T., Frost, R. L. and Hickey, L. (2000) Infrared emission spectroscopic study of the dehydroxylation of some hectorites. Thermochimica Acta, 345 2: 145-156. doi:10.1016/S0040-6031(99)00359-7
Kloprogge, J. Theo and Frost, Ray L. (2000) Raman microscopic study at 300 and 77 K of some pegmatite minerals from the Iveland-Evje area, Aust-Agder, Southern Norway. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 56 3: 501-513. doi:10.1016/S1386-1425(99)00141-9
Frost, R. L., Kristof, J., Horvath, E. and Kloprogge, J. T. (2000) Vibrational spectroscopy of formamide-intercalated kaolinites. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 56 6: 1191-1204. doi:10.1016/S1386-1425(99)00221-8
Venz, P. A., Frost, R. L. and Kloprogge, J. T. (2000) Chemical properties of modified titania hydrolysates. Journal of Non-Crystalline Solids, 276 1: 95-112. doi:10.1016/S0022-3093(00)00267-2
Kloprogge, J. T. and Frost, R. L. (2000) Raman microscopy at 77 K of natural gypsum CaSO4·2H2O. Journal of Materials Science Letters, 19 3: 229-231. doi:10.1023/A:1006762825557
Frost, Ray L. and Kloprogge, J. Theo (2000) Raman spectroscopy of nacrite single crystals at 298 and 77 K. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 56 5: 931-939. doi:10.1016/S1386-1425(99)00183-3
Kloprogge, J. T. and Frost, R. L. (2000) Thermal decomposition of Ferrian chamosite: An infrared emission spectroscopic study. Contributions to Mineralogy and Petrology, 138 1: 59-67. doi:10.1007/PL00007663
Frost, R. L., Kristof, J., Horvath, E. and Kloprogge, J. T. (2000) Kaolinite hydroxyls in dimethylsulphoxide-intercalated kaolinites at 77 K - a raman spectroscopic study. Clay Minerals, 35 2: 443-454. doi:10.1180/000985500546792
Hickey, L., Kloprogge, J. T. and Frost, R. L. (2000) Effects of various hydrothermal treatments on magnesium-aluminum hydrotalcites. Journal of Materials Science, 35 17: 4347-4355. doi:10.1023/A:1004800822319
Frost, Ray L. and Kloprogge, J. Theo (2000) Raman spectroscopy of nontronites. Applied Spectroscopy, 54 3: 402-405. doi:10.1366/0003702001949483
Kloprogge, J. Theo and Frost, Ray L. (2000) Raman microscopy study of tyrolite: A multi-anion arsenate mineral. Applied Spectroscopy, 54 4: 517-521. doi:10.1366/0003702001949681
Kloprogge, J. T., Hickey, L. and Frost, R. L. (2000) Effect of increasing layer charge on the infrared absorption spectra of synthetic beidellites. Journal of Materials Science Letters, 19 13: 1131-1134. doi:10.1023/A:1006794707140
Frost, Ray L., Kristof, Janos, Rintoul, Llewellyn and Kloprogge, J. Theo (2000) Raman spectroscopy of urea and urea-intercalated kaolinites at 77 K. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 56 9: 1681-1691. doi:10.1016/S1386-1425(00)00223-7
Frost, Ray L., Kristof, Janos, Horvath, Erzsebet and Kloprogge, J. Theo (2000) Effect of water on the formamide-intercalation of kaolinite. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 56 9: 1711-1729. doi:10.1016/S1386-1425(00)00224-9
Frost, Ray L., Kristof, Janos, Horvath, Erzsebet and Kloprogge, J. Theo (1999) Modification of kaolinite surfaces with cesium acetate at 25, 120, and 220 °C. Langmuir, 15 26: 8787-8794. doi:10.1021/la981755a
Frost, Ray L., Kristof, Janos, Horvath, Erzsebet and Theo Kloprogge, J. (1999) Molecular structure of dimethyl sulfoxide in DMSO-intercalated kaolinites at 298 and 77. Journal of Physical Chemistry A, 103 48: 9654-9660.
Kloprogge, J. T., Frost, R. L. and Hickey, L. (1999) Infrared absorption and emission study of synthetic mica-montmorillonite in comparison to rectorite, beidellite and paragonite. Journal of Materials Science Letters, 18 23: 1921-1923. doi:10.1023/A:1006672913161
Kloprogge, J. Theo and Frost, Ray L. (1999) A Raman microscopic study of tungstate and molybdate minerals: Scheelite, wolframite and wulfenite. Neues Jahrbuch fur Mineralogie, Monatshefte, 5 193-211.
Kloprogge, J. T., Frost, R. L. and Kristof, J. (1999) Complex expansion of kaolinite with hydrazine; some preliminary observations. Neues Jahrbuch fur Mineralogie, Monatshefte, 2 49-61.
Kloprogge, J. T. and Frost, R. L. (1999) Infrared emission spectroscopy of Al-pillared beidellite. Applied Clay Science, 15 5-6: 431-445. doi:10.1016/S0169-1317(99)00025-3
Kloprogge, J. Theo, Frost, Ray L. and Kristof, Janos (1999) Application of infrared emission spectroscopy for the study of the dehydroxylation of synthetic paragonite. Canadian Journal of Analytical Sciences and Spectroscopy, 44 1: 33-36.
Kloprogge, J. Theo and Frost, Ray L. (1999) Raman microprobe spectroscopy of hydrated halloysite from a neogene cryptokarst from Southern Belgium. Journal of Raman Spectroscopy, 30 12: 1079-1085.
Kloprogge, J. T. and Frost, R. L. (1999) An infrared emission spectroscopic study of synthetic and natural pyrophyllite. Neues Jahrbuch fur Mineralogie, Monatshefte, 2 62-74.
Frost, Ray L. and Kloprogge, J. Theo (1999) Infrared emission spectroscopic study of brucite. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 55 11: 2195-2205. doi:10.1016/S1386-1425(99)00016-5
Kloprogge, J. T., Hickey, L. and Frost, R. L. (1999) Infrared study of some synthetic saponites: effect of NH4/Al and H2O/(Si+Al) ratios during the crystallization. Journal of Materials Science Letters, 18 17: 1401-1403. doi:10.1023/A:1006615206037
Kloprogge, J. Theo and Frost, Ray L. (1999) Infrared emission spectroscopic study of some natural and synthetic paragonites. Applied Spectroscopy, 53 9: 1071-1077. doi:10.1366/0003702991948071
Kloprogge, J. T. and Frost, R. L. (1999) Raman microscopy study of basic aluminum sulfate. Part II. Raman microscopy at 77 K. Journal of Materials Science, 34 18: 4367-4374. doi:10.1023/A:1004604332114
Kloprogge, J. Theo and Frost, Ray L. (1999) Infrared emission spectroscopic study of the thermal transformation of Mg-, Ni- and Co-hydrotalcite catalysts. Applied Catalysis A: General, 184 1: 61-71.
Frost, Ray L., Kristof, Janos, Horvath, Elisabeth and Kloprogge, J. Theo (1999) Modification of the kaolinite hydroxyl surfaces through the application of pressure and temperature, Part III. Journal of Colloid and Interface Science, 214 2: 380-388. doi:10.1006/jcis.1999.6209
Frost, Ray L., Kristof, Janos, Horvath, Elisabeth and Kloprogge, J. Theo (1999) Modification of kaolinite surfaces through intercalation with potassium acetate, II. Journal of Colloid and Interface Science, 214 1: 109-117. doi:10.1006/jcis.1999.6177
Kloprogge, J. T., Frost, R. L. and Rintoul, L. (1999) Single crystal Raman microscopic study of the asbestos mineral chrysotile. Physical Chemistry Chemical Physics, 1 10: 2559-2564. doi:10.1039/a809238i
Kloprogge, J. Theo, Komarneni, Sridhar, Yanagisawa, Kazumichi, Fry, Robin and Frost, Ray L. (1999) Infrared emission spectroscopic study of the dehydroxylation via surface silanol groups of synthetic and natural beidellite. Journal of Colloid and Interface Science, 212 2: 562-569. doi:10.1006/jcis.1998.6082
Frost, R. L., Kloprogge, J., Russell, S. C. and Szetu, J. L. (1999) Dehydroxylation and structure of alumina gels prepared from trisecbutoxyaluminium. Thermochimica Acta, 329 1: 47-56. doi:10.1016/S0040-6031(98)00663-7
Theo Kloprogge, J. and Frost, Ray L. (1999) Infrared emission spectroscopic study of the dehydroxylation of synthetic Mg/Al and Mg/Zn/Al-hydrotalcites. Physical Chemistry Chemical Physics, 1 7: 1641-1647. doi:10.1039/a808496c
Frost, R. L., Kristof, J., Horvath, E. and Kloprogge, J. T. (1999) Deintercalation of dimethylsulphoxide intercalated kaolinites - a DTA/TGA and Raman spectroscopic study. Thermochimica Acta, 327 1-2: 155-166.
Frost, R. L., Kristof, J., Paroz, G. N. and Kloprogge, J. T. (1999) Intercalation of kaolinite with acetamide. Physics and Chemistry of Minerals, 26 3: 257-263. doi:10.1007/s002690050185
Frost, Ray L. and Kloprogge, J. Theo (1999) Raman spectroscopy of the low-frequency region of kaolinite at 298 and 77 K. Applied Spectroscopy, 53 12: 1610-1616. doi:10.1366/0003702991946073
Frost, Ray L., Kloprogge, J. Theo, Russell, Shane C. and Szetu, Jennifer (1999) Dehydroxylation and the vibrational spectroscopy of aluminum (oxo)hydroxides using infrared emission spectroscopy. Part III: diaspore. Applied Spectroscopy, 53 7: 829-835. doi:10.1366/0003702991947405
Kloprogge, J. T. and Frost, R. L. (1999) Raman and infrared microscopy study of zunyite, a natural Al13 silicate. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 55 7-8: 1505-1513. doi:10.1016/S1386-1425(98)00341-2
Kloprogge, J. Theo and Frost, Ray L. (1999) Raman microscopy study of cafarsite. Applied Spectroscopy, 53 7: 874-880. doi:10.1366/0003702991947478
Kloprogge, J. Theo and Frost, Ray L. (1999) Raman microscopic study of some borate minerals: ulexite, kernite, and inderite. Applied Spectroscopy, 53 3: 356-364. doi:10.1366/0003702991946587
Kloprogge, J. Theo, Frost, Ray L. and Fry, Robyn (1999) Infrared emission study of the thermal transformation mechanism of Al13-pillared clay. Analyst, 124 3: 381-384. doi:10.1039/a809240k
Kloprogge, J. T. and Frost, R. L. (1999) Raman microscopy study of basic aluminum sulfate. Journal of Materials Science, 34 17: 4199-4202. doi:10.1023/A:1004686315759
Frost, Ray L., Kloprogge, J. Theo, Russell, Shane C. and Szetu, Jennifer L. (1999) Vibrational spectroscopy and dehydroxylation of aluminum (oxo)hydroxides: gibbsite. Applied Spectroscopy, 53 4: 423-434. doi:10.1366/0003702991946884
Kloprogge, J. T. and Frost, R. L. (1999) Raman and infrared spectroscopic investigation of the neutralisation of aluminium in the presence of monomeric orthosilicic acid. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 55 7-8: 1359-1369. doi:10.1016/S1386-1425(98)00324-2
Kloprogge, J. Theo, Fry, Robyn and Frost, Ray L. (1999) An infrared emission spectroscopic study of the thermal transformation mechanims in Al13-pillared clay catalysts with and without tetrahedral substitutions. Journal of Catalysis, 184 1: 157-171. doi:10.1006/jcat.1999.2444
Frost, Ray L., Kloprogge, J. Theo, Kristof, Janos and Horvath, Erzsebet (1999) Deintercalation of hydrazine-intercalated low-defect kaolinite. Clays and Clay Minerals, 47 6: 732-741. doi:10.1346/CCMN.1999.0470607
Kristóf, J., Frost, R. L., Kloprogge, J. T., Horváth, E. and Gábor, M. (1999) Thermal behaviour of kaolinite intercalated with formamide, dimethyl sulphoxide and hydrazine. Journal of Thermal Analysis and Calorimetry, 56 2: 885-891.
Kloprogge, J. Theo and Frost, Ray L. (1999) Fourier transform infrared and Raman spectroscopic study of the local structure of Mg-, Ni-, and Co-hydrotalcites. Journal of Solid State Chemistry, 146 2: 506-515. doi:10.1006/jssc.1999.8413
Frost, Ray L., Kristof, Janos, Paroz, Gina N. and Theo Kloprogge, J. (1998) Modification of the kaolinite hydroxyl surfaces through intercalation with potassium acetate under pressure. Journal of Colloid and Interface Science, 208 2: 478-486. doi:10.1006/jcis.1998.5855
Kloprogge, J. T. and Frost, R. L. (1998) Raman microscopy study of basic aluminium nitrate. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 55 1: 163-169. doi:10.1016/S1386-1425(98)00178-4
Frost, Ray L., Kristof, Janos, Paroz, Gina N. and Kloprogge, J. T. (1998) Role of water in the intercalation of kaolinite with hydrazine. Journal of Colloid and Interface Science, 208 1: 216-225. doi:10.1006/jcis.1998.5780
Kloprogge, J. T. and Frost, R. L. (1998) The dehydroxylation of basic aluminum sulfate: An infrared emission spectroscopic study. Thermochimica Acta, 320 1-2: 245-252.
Frost, Ray L., Kristof, Janos, Paroz, Gina N. and Kloprogge, J. Theo (1998) Molecular structure of dimethyl sulfoxide intercalated kaolinites. Journal of Physical Chemistry B, 102 43: 8519-8532.
Frost, Ray L., Kristof, Janos, Paroz, Gina N., Tran, Thu Ha and Kloprogge, J. Theo (1998) The role of water in the intercalation of kaolinite with potassium acetate. Journal of Colloid and Interface Science, 204 2: 227-236. doi:10.1006/jcis.1998.5604
Frost, Ray L., Cash, Greg A. and Kloprogge, J. Theo (1998) 'Rocky Mountain leather', sepiolite and attapulgite - An infrared emission spectroscopic study. Vibrational Spectroscopy, 16 2: 173-184. doi:10.1016/S0924-2031(98)00014-9
Johansson, Ursula, Frost, Ray L., Forsling, Willis and Kloprogge, J. Theo (1998) Raman spectroscopy of the kaolinite hydroxyls at 77 K. Applied Spectroscopy, 52 10: 1277-1282. doi:10.1366/0003702981942780
Kloprogge, J. T., Komarneni, S., Yanagisawa, K., Frost, R. L. and Fry, R. (1998) Infrared study of some synthetic and natural beidellites. Journal of Materials Science Letters, 17 21: 1853-1855. doi:10.1023/A:1006694629015
Frost, Ray L., Forsling, Willis, Holmgren, Allan, Kloprogge, J. Theo and Kristof, Janos (1998) Raman Spectroscopy at Temperatures between 298 and 423 K and at 77 K of Kaolinites Intercalated with Formamide. Journal of Raman Spectroscopy, 29 12: 1065-1069. doi:10.1002/(SICI)1097-4555(199812)29:12<1065::AID-JRS318>3.0.CO;2-E
Kloprogge, J. T. (1998) Synthesis of smectites and porous pillared clay catalysts: a review. Journal of Porous Materials, 5 1: 5-41. doi:10.1023/A:1009625913781
Frost, Ray L., Kloprogge, J. Theo, Tran, Thu Ha Thi and Kristof, Janos (1998) The effect of pressure on the intercalation of an ordered kaolinite. American Mineralogist, 83 11-12 PART 1: 1182-1187. doi:10.2138/am-1998-11-1206
Kloprogge, J. T., Korbijn, L. and Koster, T. P.M. (1997) Head-space gaschromatography, a quick and simple method to screen adsorption capabilities of porous materials: Adsorption of chlorobenzene on modified montmorillonite. Applied Clay Science, 12 1-2: 85-91. doi:10.1016/S0169-1317(96)00042-7
Vogels, Roland J.M.J., Breukelaar, Johan, Kloprogge, J. Theo, Jansen, J. Ben H. and Geus, John W. (1997) Hydrothermal crystallization of ammonium-saponite at 200°C and autogenous water pressure. Clays and Clay Minerals, 45 1: 1-7. doi:10.1346/CCMN.1997.0450101
Kloprogge, J. T., Vogels, R. J M J and Van Der Eerden, A. M J (1996) Hydrothermal synthesis of pyrophyllite from Si-Al gels and salt solutions: Some implications for the formation of pyrophyllite in low-grade metamorphic rocks rich in aluminous smectites. Neues Jahrbuch fur Mineralogie, Monatshefte, 3: 135-144.
Booij, Ernst, Kloprogge, J. Theo and Van Veen, J. A. Rob (1996) Large pore REE/Al pillared bentonites: Preparation, structural aspects and catalytic properties. Applied Clay Science, 11 2-4: 155-162. doi:10.1016/S0169-1317(96)00019-1
Booij, Ernst, Kloprogge, J. Theo and Rob van Veen, J. A. (1996) Preparation, structural characteristics and catalytic properties of large-pore rare earth element (Ce, La)/Al-pillared smectites. Clays and Clay Minerals, 44 6: 774-782. doi:10.1346/CCMN.1996.0440608
Kloprogge, J. T., Dirken, P. J., Jansen, J. B.H. and Geus, J. W. (1995) One- and two-dimensional 27Al MAS-NMR study of basic aluminum sulfate. Journal of Non-Crystalline Solids, 181 1-2: 151-156. doi:10.1016/0022-3093(94)00492-7
J.M.J. Vogels, Roland, Kloprogge, J. Theo, Buining, Paul A., Seykens, Don, Jansen, J. Ben H. and Geus, John W. (1995) The tridecameric aluminum complex as an appropriate precursor for fibrous boehmite: A 27Al NMR study on the partial hydrolysis of aluminum sec-butoxide. Journal of Non-Crystalline Solids, 191 1-2: 38-44. doi:10.1016/0022-3093(95)00304-5
Kloprogge, J. T., Booy, E., Jansen, J. B H and Geus, J. W. (1994) Synthesis of Al-pillared beidellite and its catalytic activity in the hydroconversion of n-heptane. Catalysis Letters, 29 3-4: 293-297. doi:10.1007/BF00807108
Kloprogge, J. T., Breukelaar, J., Wilson, A. E., Geus, J. W. and Jansen, J. B.H. (1994) Solid-state nuclear magnetic resonance spectroscopy on synthetic ammonium/aluminum-saponites. Clays and Clay Minerals, 42 4: 416-420. doi:10.1346/CCMN.1994.0420406
Theo Kloprogge, J., Breukelaar, Johan, Geus, John W. and Ben Jansen, J. H. (1994) Characterization of Mg-saponites synthesized from gels containing amounts of Na+, K+, Rb+, Ca2+, Ba2+, or Ce4+ Equivalent to the CEC of the Saponite. Clays and Clay Minerals, 42 1: 18-22. doi:10.1346/CCMN.1994.0420103
Visser, D., Kloprogge, J. T. and Maijer, C. (1994) An infrared spectroscopic (IR) and light element (Li, Be, Na) study of cordierites from the Bamble Sector, south Norway. LITHOS, 32 1-2: 95-107. doi:10.1016/0024-4937(94)90023-X
Kloprogge, J. T., Booy, E., Jansen, J. B.H. and Geus, J. W. (1994) The effect of thermal treatment on the properties of hydroxy-Al and hydroxy-Ga pillared montmorillonite and beidellite. Clay Minerals, 29 2: 153-167. doi:10.1180/claymin.1994.029.2.02
Theo Kloprogge, J., Seykens, Don, Geus, John W. and Jansen, J.Ben H. (1993) The effects of concentration and hydrolysis on the oligomerization and polymerization of Al(III) as evident from the 27Al NMR chemical shifts and linewidths. Journal of Non-Crystalline Solids, 160 1-2: 144-151. doi:10.1016/0022-3093(93)90294-8
Kloprogge, J. T., Welters, W. J.J., Booy, E., de Beer, V. H.J., van Santen, R. A., Geus, J. W. and Jansen, J. B.H. (1993) Catalytic activity of nickel sulfide catalysts supported on Al-pillared montmorillonite for thiophene hydrodesulfurization. Applied Catalysis A, General, 97 1: 77-85. doi:10.1016/0926-860X(93)80068-2
Theo Kloprogge, J., Seykens, Don, Jansen, J.Ben H. and Geus, John W. (1993) Aluminum monomer line-broadening as evidence for the existence of [AlOH]2+ and [Al(OH)2]+ during forced hydrolysis: a 27Al nuclear magnetic resonance study. Journal of Non-Crystalline Solids, 152 2-3: 207-211. doi:10.1016/0022-3093(93)90253-T
Kloprogge, J. Theo, Breukelaar, Johan, Jansen, J. Ben H. and Geus, John W. (1993) Development of ammonium-saponites from gels with variable ammonium concentration and water content at low temperatures. Clays and Clay Minerals, 41 1: 103-110. doi:10.1346/CCMN.1993.0410111
Kloprogge, J. Theo, van der Eerden, A. M.J., Jansen, J. Ben H., Geus, John W. and Schuiling, Roelof D. (1993) Synthesis and paragenesis of Na-beidellite as a function of temperature, water pressure, and sodium activity. Clays and Clay Minerals, 41 4: 423-430. doi:10.1346/CCMN.1993.0410403
Kloprogge, J. T., Geus, J. W., Jansen, J. B.H. and Seykens, D. (1992) Thermal stability of basic aluminum sulfate. Thermochimica Acta, 209 C: 265-276. doi:10.1016/0040-6031(92)80204-A
Theo Kloprogge, J., Jansen, J. Ben H., Schuiling, Roelof D. and Geus, John W. (1992) The interlayer collapse during dehydration of synthetic Na0.7-Beidellite: A 23Na solid-state magic-angle spinning NMR study. Clays and Clay Minerals, 40 5: 561-566. doi:10.1346/CCMN.1992.0400510
Kloprogge, J. T., Seykens, D., Geus, J. W. and Jansen, J. B.H. (1992) Temperature influence on the Al13 complex in partially neutralized aluminum solutions: a 27Al nuclear magnetic resonance study. Journal of Non-Crystalline Solids, 142 C: 87-93. doi:10.1016/S0022-3093(05)80010-9
Kloprogge, J. T., Seykens, D., Jansen, J. B.H. and Geus, J. W. (1992) A 27Al nuclear magnetic resonance study on the optimalization of the development of the Al13 polymer. Journal of Non-Crystalline Solids, 142 C: 94-102. doi:10.1016/S0022-3093(05)80011-0
Kloprogge, J. T., Van Der Eerden, A. M.J., Jansen, J. B.H. and Geus, J. W. (1990) Hydrothermal synthesis of Na-beidellite. Geologie en Mijnbouw, 69 4: 351-357.
Kloprogge, J. T., Jansen, J. B.H. and Geus, J. W. (1990) Characterization of synthetic Na-beidellite. Clays & Clay Minerals, 38 4: 409-414. doi:10.1346/CCMN.1990.0380410
Kloprogge, J. T., Van Roermund, H. L.M. and Maijer, C. (1989) Complex exsolution microstructures in inverted pigeonites from the Sjelset Igneous Complex, Rogaland, SW Norway. Norsk Geologisk Tidsskrift, 69 4: 239-249.
Conference Papers
Frost, R. L., Musumeci, A. W., Kloprogge, J. Theo, Weier, M. L., Adebajo, M. O. and Martens, W. (2006) Thermal decomposition of hydrotalcite with hexacyanoferrate(II) and hexacyanoferrate(III) anions in the interlayer. Journal of Thermal Analysis and Calorimetry, 86 1: 205-209. doi:10.1007/s10973-005-6933-z
Frost, Ray L., Kloprogge, Theo, Weier, Matthew L., Martens, Wayde N., Ding, Z. and Edwards, Howell G.H. (2003). Raman spectroscopy of selected arsenates - Implications for soil remediation. In: , , (2241-2246). . doi:10.1016/S1386-1425(03)00068-4