Synthesis and High-Temperature Heat Capacity of Dy{sub 2}Ge{sub 2}O{sub 7} and Ho{sub 2}Ge{sub 2}O{sub 7}

Journal Article · Sun Apr 15 04:00:00 EDT 2018 · Inorganic Materials

DOI:https://doi.org/10.1134/S0020168518040039· OSTI ID:22788154

Irtyugo, L. A. ^[1]; Kargin, Yu. F. ^[2]; Belousova, N. V.; Beletskii, V. V.; Denisov, V. M. ^[1]

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1. Siberian Federal University, Institute of Nonferrous Metals and Materials Science (Russian Federation)
2. Russian Academy of Sciences, Baikov Institute of Metallurgy and Materials Science (Russian Federation)

The Dy{sub 2}Ge{sub 2}O{sub 7} and Ho{sub 2}Ge{sub 2}O{sub 7} pyrogermanates have been prepared by solid-state reactions in several sequential firing steps in the temperature range 1237–1473 K using stoichiometric mixtures of Dy{sub 2}O{sub 3} (or Ho{sub 2}O{sub 3}) and GeO{sub 2}. 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{sub p}(T) curves of the dysprosium and holmium germanates have no anomalies and are well represented by the Maier–Kelley equation. The experimental C{sub p}(T) data have been used to evaluate the thermodynamic functions of the Dy{sub 2}Ge{sub 2}O{sub 7} and Ho{sub 2}Ge{sub 2}O{sub 7} pyrogermanates: enthalpy increment H°(T)–H°(350 K), entropy change S°(T)–S°(350 K), and reduced Gibbs energy Ф°(T).

• OSTI ID: 22788154
• Journal Information: Inorganic Materials, Journal Name: Inorganic Materials Journal Issue: 4 Vol. 54; ISSN INOMAF; ISSN 0020-1685
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CALORIMETRY
DYSPROSIUM OXIDES
ENTHALPY
ENTROPY
EQUATIONS
FREE ENTHALPY
GERMANATES
HOLMIUM OXIDES
MIXTURES
SOLIDS
SPECIFIC HEAT
STOICHIOMETRY
SYNTHESIS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K
THERMODYNAMICS