Inorganic Materials

, Volume 36, Issue 6, pp 625–628 | Cite as

High-pressure polymorph of LaNbO4

  • Yu. A. Titov
  • A. M. Sych
  • A. N. Sokolov
  • A. A. Kapshuk
  • V. P. Yashchuk


A new polymorph of LaNbO4 with a BaMnF4-type structure(a = 0.3938(2) nm,b = 1.442(1) nm,c = 0.5682(3) nm,Z = 4) and octahedral oxygen coordination of Nb was prepared at high pressures and temperatures (8 GPa, 1570 K). At normal pressure, the reverse transformation, from high-pressure LaNbO4 to theM-fergusonite form, occurs at temperatures above 870 K and is close to a second-order phase transition. The spontaneous polarization in high-pressure LaNbO4, evaluated from the second-order nonlinear optical response, is about 2 ώC/cm2.


Second Harmonic Generation Scheelite Spontaneous Polarization Layered Perovskite LaNbO4 
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  1. 1.
    Rooksby, H.P. and White, E.A.D., The Structures of 1: 1 Compounds of Rare Earth Oxides with Niobia and Tantala,Acta Crystallogr., 1963, vol. 16, no. 9, pp. 888–890.CrossRefGoogle Scholar
  2. 2.
    Stubican, V.S., High Temperature Transitions in Rare Earth Niobates and Tantalates,J. Am. Ceram. Soc., 1964, vol. 47, no. 2, pp. 55–58.CrossRefGoogle Scholar
  3. 3.
    Keller, S., Über ternare Oxide des Niobs und Tantals vom Typ ABO4,Z. Anorg. Allg. Chem, 1962, vol. 318, no. 1/2, pp. 89–106.CrossRefGoogle Scholar
  4. 4.
    Wolten, G.M. and Chase, A.B., Synthetic Fergusonites and a New Polymorph of Yttrium Tantalate,Am. Mineral., 1967, vol. 52, no. 9/10, pp. 1536–1541.Google Scholar
  5. 5.
    Wolten, G.M., The Structure of the M1-Phase of YTaO4, a Third Fergusonite Polymorph,Acta Crystallogr., 1967, vol. 23, no. 6, pp. 939–944.CrossRefGoogle Scholar
  6. 6.
    Kurova, T.A. and Aleksandrov, V.B., Crystal Structure of LaTaO4,Dokl. Akad. Nauk SSSR, 1971, vol. 201, no. 5, pp. 1095–1098.Google Scholar
  7. 7.
    Cava, R.J. and Roth, R.S., The Structure of LaTaO4 at 300°C by Neutron Powder Profile Analysis,J. Solid State Chem., 1981, vol. 36, no. 2, pp. 139–147.CrossRefGoogle Scholar
  8. 8.
    Roth, R.S., Negas T., Parker, H.S.,et al., Crystal Chemistry of Cerium Titanates, Tantalates, and Niobates,Mater. Res. Bull., 1977, vol. 12, no. 12, pp. 1173–1182.CrossRefGoogle Scholar
  9. 9.
    Titov, Yu.A., Sych, A.M., Sokolov, A.N.,et al., Polymorphism of NdTaO4,Neorg. Mater., 1997, vol. 33, no. 1, pp. 67–71 [Inorg. Mater. (Engl. Transl.), vol. 33, no. 1, pp. 60–63].Google Scholar
  10. 10.
    Leonov, A.P., Stefanovich, S.Yu., and Venevtsev, Yu.N., SHG Characterization of Noncentrosymmetric Phases in Polycrystalline Materials, inPoluchenie i primenenie segnetomaterialov v narodnom khozyaistve (Preparation and Applications of Ferroelectrics), Moscow: Mosk. Dom Nauchno-Tekh. Propagandy, 1984, pp. 21–26.Google Scholar
  11. 11.
    Stefanovich, S.Yu., Zakharov, N.A., and Venevtsev, Yu.N.,Segnetoelektriki A2B2O7 so sloistoi perovskitopodobnoi strukturoi (Layered Perovskite-like Ferroelectrics A2B2O7), Moscow: Nauchno-Issled. Inst. Tekhniko-Ekonomicheskikh Issledovanii, 1978.Google Scholar
  12. 12.
    Titov, Yu.A., Sych, A.M., and Nedil’ko, L.F., Polymorphism of Chemically Prepared LnTaO4 (Ln = La, Pr),XIV Ukrainskaya konferentsiya po neorganicheskoi khimii (XIV All-Ukraine Conf. on Inorganic Chemistry), Kiev, 1996, p. 153.Google Scholar
  13. 13.
    Titov, Yu.A., Sych, A.M., Mel’nik, V.M., and Bondarenko, T.N., New A2B2O7 Layered Perovskites,Zh. Neorg. Khim., 1987, vol. 32, no. 1, pp. 3–6.Google Scholar
  14. 14.
    Sych, A.M., Stefanovich, S.Yu., Titov, Yu.A.,et al., High-Pressure Phase of Eu2Ti2O7 and Its Ferroelectric Properties,Neorg. Mater., 1991, vol. 27, no. 12, pp. 2597–2599.Google Scholar
  15. 15.
    Sych, A.M., Titov, Yu.A., and Maksakova, R.V., Stability Field of Layered Perovskites in the La2Ti2O7-LaNbO4- LaGaO3 System,Ukr. Khim. Zh. (Russ. Ed.), 1989, vol. 55, no. 6, pp. 563–566.Google Scholar

Copyright information

© MAIK “Nauka/Interperiodica” 2000

Authors and Affiliations

  • Yu. A. Titov
    • 1
  • A. M. Sych
    • 1
  • A. N. Sokolov
    • 2
  • A. A. Kapshuk
    • 1
    • 2
  • V. P. Yashchuk
    • 1
  1. 1.Shevchenko National UniversityKievUkraine
  2. 2.Bakul’ Institute of Superhard MaterialsNational Academy of Sciences of UkraineKievUkraine

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