Inorganic Materials

, Volume 54, Issue 4, pp 361–365 | Cite as

Synthesis and High-Temperature Heat Capacity of Dy2Ge2O7 and Ho2Ge2O7

  • L. T. Denisova
  • L. A. Irtyugo
  • Yu. F. Kargin
  • N. V. Belousova
  • V. V. Beletskii
  • V. M. Denisov
Article
  • 16 Downloads

Abstract

The Dy2Ge2O7 and Ho2Ge2O7 pyrogermanates have been prepared by solid-state reactions in several sequential firing steps in the temperature range 1237–1473 K using stoichiometric mixtures of Dy2O3 (or Ho2O3) and GeO2. The heat capacity of the synthesized germanates has been determined as a function of temperature by differential scanning calorimetry in the range 350–1000 K. The experimentally determined C p (T) curves of the dysprosium and holmium germanates have no anomalies and are well represented by the Maier–Kelley equation. The experimental C p (T) data have been used to evaluate the thermodynamic functions of the Dy2Ge2O7 and Ho2Ge2O7 pyrogermanates: enthalpy increment H°(T)–H°(350 K), entropy change S°(T)–S°(350 K), and reduced Gibbs energy Ф°(T).

Keywords

solid-state synthesis dysprosium and holmium germanates differential scanning calorimetry heat capacity thermodynamic properties 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Bondar’, I.A., Vinogradova, N.V., Dem’yanets, L.N., et al., Soedineniya redkozemel’nykh elementov. Silikaty, germanaty, fosfaty, arsenaty, vanadaty (Rare-Earth Compounds: Silicates, Germanates, Phosphates, Arsenates, and Vanadates), Moscow: Nauka, 1983.Google Scholar
  2. 2.
    Dem’yanets, L.N., Lobachev, A.N., and Emel’-chenko, G.A., Germanaty redkozemel’nykh elementov (Rare-Earth Germanates), Moscow: Nauka, 1980.Google Scholar
  3. 3.
    Portnoi, K.I. and Timofeeva, N.I., Kislorodnye soedineniya redkozemel’nykh elementov (Rare-Earth Oxide Compounds), Moscow: Metallurgiya, 1986.Google Scholar
  4. 4.
    Wang, H., Chroneos, A., Dimoulas, A., et al., Interaction of oxygen vacancies in yttrium germanates, Phys. Chem. Chem. Phys., 2012, vol. 14, pp. 14630–14634.CrossRefGoogle Scholar
  5. 5.
    Leskelä, M. and Ninistö, L., Inorganic complex compounds I, Handb. Phys. Chem. Rare Earths, 1986, vol. 8, pp. 203–334.CrossRefGoogle Scholar
  6. 6.
    Subramanian, M.A. and Sleight, A.W., Rare earth pyrochlores, Handb. Phys. Chem. Rare Earths, 1993, vol. 16, pp. 225–248.CrossRefGoogle Scholar
  7. 7.
    Becker, U.W. and Felsche, J., Phases and structural relations of the rare earth germanates RE2Ge2O7, RE = La–Lu, J. Less-Common Met., 1987, vol. 128, pp. 269–280.CrossRefGoogle Scholar
  8. 8.
    Li, X., Cai, Y.Q., Cui, Q., et al., Long-range magnetic order in Heisenberg pyrochlore antiferromagnets Gd2Ge2O7 and Gd2Pt2O7 synthesized under high pres-sure, Phys. Rev. B: Condens. Matter Mater. Phys., 2016, vol. 94, paper 214429.Google Scholar
  9. 9.
    Morosan, E., Fleitman, J.A., Huang, Q., et al., Structure and magnetic properties of the Ho2Ge2O7 pyrogermanate, Phys. Rev. B: Condens. Matter Mater. Phys., 2008, vol. 77, paper 224423.Google Scholar
  10. 10.
    Jana, S., Ghosh, D., and Wanklyn, B.M., Magnetic susceptibilities and anisotropy studies of holmium pyrogermanate Ho2Ge2O7 crystal, J. Magn. Magn. Mater., 1998, vol. 183, pp. 135–142.CrossRefGoogle Scholar
  11. 11.
    Ke, X., Dahlberg, M.L., Morosan, E., et al., Magnetothermodynamics of the Ising antiferromagnet Dy2Ge2O7, Phys. Rev. B: Condens. Matter Mater. Phys., 2008, vol. 78, paper 104411.Google Scholar
  12. 12.
    Moran, D.M. and Richardson, F.S., Chiroptical activity of holmium pyrogermanate: tetragonal Ho2Ge2O7, J. Alloys. Compd., 1992, vol. 180, pp. 171–175.CrossRefGoogle Scholar
  13. 13.
    Jouhet-Vetter, G. and Queyroux, F., Etude de quelques composes Ln2Ge2O7 (Ln = La, Nd, Sm, Eu, Gd), Mater. Res. Bull., 1975, vol. 10, pp. 1201–1204.CrossRefGoogle Scholar
  14. 14.
    Solovyov, L.A., Full-profile refinement by derivative difference minimization, J. Appl. Crystallogr., 2004, vol. 37, pp. 743–749.CrossRefGoogle Scholar
  15. 15.
    Denisov, V.M., Denisova, L.T., Irtyugo, L.A., and Biront, V.S., Thermal physical properties of Bi4Ge3O12 single crystals, Phys. Solid State, 2010, vol. 52, no. 7, pp. 1362–1365.CrossRefGoogle Scholar
  16. 16.
    Denisova, L.T., Irtyugo, L.A., Kargin, Yu.F., et al., High-temperature heat capacity and thermodynamic properties of Tb2Sn2O7, Inorg. Mater., 2017, vol. 53, no. 1, pp. 67–69.CrossRefGoogle Scholar
  17. 17.
    Pet'kov, V.I., Markin, A.V., and Smirnova, N.N., Thermodynamic properties of LiZr2(PO4)3 crystal phosphate, Russ. J. Phys. Chem. A, 2013, vol. 87, no. 8, pp. 1266–1271.CrossRefGoogle Scholar
  18. 18.
    Skuratov, S.M., Kolesov, V.P., and Vorob’ev, A.F., Termokhimiya (Thermochemistry), Moscow: Mosk. Gos. Univ., 1966, part II.Google Scholar
  19. 19.
    Prekul, A.F., Kazantsev, V.A., Shchegolikhina, N.M., et al., High-temperature heat capacity of the Al63Cu25Fe12 quasicrystal, Phys. Solid State, 2008, vol. 50, no. 11, pp. 2013–2015.CrossRefGoogle Scholar
  20. 20.
    Denisova, L.T., Izotov, A.D., Chumilina, L.G., et al., Heat capacity and thermodynamic properties of bismuth orthovanadate in the temperature range 356–980 K, Dokl. Phys. Chem., 2016, vol. 467, no. 1, pp. 41–44.CrossRefGoogle Scholar
  21. 21.
    Denisova, L.T., Irtyugo, L.A., Kargin, Yu.F., et al., High-temperature heat capacity of the oxide compounds in the Bi2O3–V2O5 system, Inorg. Mater., 2017, vol. 53, no. 3, pp. 300–306.CrossRefGoogle Scholar
  22. 22.
    Leitner, J., Chuchvalec, P., Sedmidubský, D., et al., Estimation of heat capacities of solid mixed oxides, Thermochim. Acta, 2003, vol. 395, pp. 27–46.CrossRefGoogle Scholar

Copyright information

© Pleiades Publishing, Ltd. 2018

Authors and Affiliations

  • L. T. Denisova
    • 1
  • L. A. Irtyugo
    • 1
  • Yu. F. Kargin
    • 2
  • N. V. Belousova
    • 1
  • V. V. Beletskii
    • 1
  • V. M. Denisov
    • 1
  1. 1.Institute of Nonferrous Metals and Materials ScienceSiberian Federal UniversityKrasnoyarskRussia
  2. 2.Baikov Institute of Metallurgy and Materials ScienceRussian Academy of SciencesMoscowRussia

Personalised recommendations