Synthesis and High-Temperature Heat Capacity of Dy2Ge2O7 and Ho2Ge2O7


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).

This is a preview of subscription content, log in to check access.


  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.

    CAS  Article  Google Scholar 

  5. 5.

    Leskelä, M. and Ninistö, L., Inorganic complex compounds I, Handb. Phys. Chem. Rare Earths, 1986, vol. 8, pp. 203–334.

    Article  Google Scholar 

  6. 6.

    Subramanian, M.A. and Sleight, A.W., Rare earth pyrochlores, Handb. Phys. Chem. Rare Earths, 1993, vol. 16, pp. 225–248.

    Article  Google 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.

    CAS  Article  Google 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.

  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.

  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.

    CAS  Article  Google 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.

  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.

    CAS  Article  Google 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.

    CAS  Article  Google Scholar 

  14. 14.

    Solovyov, L.A., Full-profile refinement by derivative difference minimization, J. Appl. Crystallogr., 2004, vol. 37, pp. 743–749.

    CAS  Article  Google 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.

    CAS  Article  Google 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.

    Article  Google 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.

    Article  Google 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.

    CAS  Article  Google 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.

    CAS  Article  Google 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.

    CAS  Article  Google 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.

    CAS  Article  Google Scholar 

Download references

Author information



Corresponding author

Correspondence to L. T. Denisova.

Additional information

Original Russian Text © L.T. Denisova, L.A. Irtyugo, Yu.F. Kargin, N.V. Belousova, V.V. Beletskii, V.M. Denisov, 2018, published in Neorganicheskie Materialy, 2018, Vol. 54, No. 4, pp. 382–386.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Denisova, L.T., Irtyugo, L.A., Kargin, Y.F. et al. Synthesis and High-Temperature Heat Capacity of Dy2Ge2O7 and Ho2Ge2O7. Inorg Mater 54, 361–365 (2018).

Download citation


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