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X-ray powder diffraction investigation of new high temperature polymorphs of CaTeO3 and CaTe2O5

  • S. N. Tripathi (a1), R. Mishra (a1), M. D. Mathews (a1) and P. N. Namboodiri (a1)


X-ray powder diffraction investigation of the new high temperature polymorphs beta- and gamma-CaTeO3 and gamma- and delta-CaTe2O5 and picnometric measurements of the room temperature phases of the two compounds have been carried out. The study led to the elucidation of their unit cell structures and assignment of entirely new lattice types and parameters to the room temperature phases of CaTeO3 and CaTe2O5 in contrast and supersession to the existing structural information. The results are as follows: CaTeO3 has only one stable phase at room temperature and temperatures up to 882 °C, i.e., α- and has a triclinic unit cell with a=4.132±0.003 Å, b=6.120±0.006 Å, c=12.836±0.013 Å, α=121.80°, β=99.72°, γ=97.26°. The first high temperature phase stable between 882 and 894 °C, i.e., β-CaTeO3, has a monoclinic lattice: a=20.577±0.007 Å, b=21.857±0.009 Å, c=4.111±0.002 Å, β=96.15°, while the next phase stable above 894 °C, i.e., γ-CaTeO3, has a hexagonal unit cell with parameters: a=14.015±0.0001 Å, c=9.783±0.001 Å, c/a=0.698. CaTe2O5 has one stable phase at temperatures up to 802 °C, i.e., α-CaTe2O5 with a monoclinic lattice and parameters: a=9.069±0.002 Å, b=25.175±0.007 Å, c=3.366±0.001 Å, β=98.29 °. The first high temperature phase stable in the range 802–845°, i.e., β-CaTe2O5, is monoclinic with unit cell parameters: a=4.146±0.001 Å, b=5.334±0.002 Å, c=6.105±0.002 Å, β=98.362 °; the next higher temperature phase stable over 845–857 °C, i.e., γ-CaTe2O5, has an orthorhombic unit cell with: a=8.638±0.001 Å, b=9.291±0.001 Å, c=7.862±0.001 Å and the highest temperature solid phase stable above 857 °C, i.e., δ-CaTe2O5 has a tetragonal unit cell with a=5.764±0.000 Å, c=32.074±0.020 Å, c/a=5.5637.


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JCPDS, Powder Diffraction File, International Centre for Diffraction Data, Newtown Square, PA, USA.
Knyazeva, R. N., and Guschina, A. S. (1968). “Preparation and thermal decomposition of calcium tellurate (VI),” Russ. J. Inorg. Chem. RJICAQ 13, 791. rji, RJICAQ
Lynch, J. F., Ruderer, C. G., and Duckworth, W. H. (1966). Engineering Properties of Selected Materials (The American Ceramic Society, Columbus, OH), pp. 5.4.4-4, 5.5.1-9.
Mishra, R., Namboodiri, P. N., Tripathi, S. N., and Dharwadkar, S. R. (1998). “Partial phase diagram of CaO-TeO2 system,” J. Alloys Compd. JALCEU 200, 5664. jal, JALCEU
Mishra, R., Bharadwaj, S. R., Kerkar, A. S., and Dharwadkar, S. R. (1997). “Determination of the Gibb’s energy of formation of CaTeO3 and CaTe2O5 by the transpiration technique,” J. Alloys Compd. JALCEU 248, 8085. jal, JALCEU
Morey, G. W. (1938). Properties of Glass (Reinhold, New York), p. 273.
Von Tromel, M., and Zeithen-Reichnac, H. (1970). “Formation of calcium tellurate by solid state reactions,” Z. Anorg. Allg. Chem. ZAACAB 378, 232237. zaa, ZAACAB
Wroblewska, J. J., Dobrowolski, A. E., and Freundlich, W. (1979). “Crystallochemical study of tellurates of divalent elements Ca, Ba, Zn and Cd,” Rev. Chim. Miner. RVCMA8 16, 112. rvm, RVCMA8


X-ray powder diffraction investigation of new high temperature polymorphs of CaTeO3 and CaTe2O5

  • S. N. Tripathi (a1), R. Mishra (a1), M. D. Mathews (a1) and P. N. Namboodiri (a1)


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