Heat capacity, enthalpy and entropy of strontium niobate Sr2Nb2O7 and calcium niobate Ca2Nb2O7

被引：20

作者：

Leitner, J. ^{[1
]}

Hampl, M. ^{[1
]}

Ruzicka, K. ^{[2
]}

Straka, M. ^{[2
]}

Sedmidubsky, D. ^{[3
,4
]}

Svoboda, P.

机构：

[1] Prague Inst Chem Technol, Dept Solid State Engn, CR-16628 Prague 6, Czech Republic

[2] Prague Inst Chem Technol, Dept Phys Chem, CR-16628 Prague, Czech Republic

[3] Prague Inst Chem Technol, Dept Inorgan Chem, CR-16628 Prague 6, Czech Republic

[4] Charles Univ Prague, Fac Math & Phys, Dept Condensed Matter Phys, Prague 12000 2, Czech Republic

来源：

THERMOCHIMICA ACTA | 2008年 / 475卷 / 1-2期

关键词：

enthalpy increments; heat capacity; entropy; calorimetry; strontium niobate; calcium niobate;

D O I：

10.1016/j.tca.2008.06.010

中图分类号：

O414.1 [热力学];

学科分类号：

摘要：

The heat capacity and the enthalpy increments of strontium niobate Sr2Nb2O7 and calcium niobate Ca2Nb2O7 were measured by the relaxation time method (2-300K), DSC (260-360K) and drop calorimetry (720-1370K). Temperature dependencies of the molar heat capacity in the form C-pm = 248.0 + 0.04350T - 3.948 x 10(6)/T-2 JK(-1) for Sr2Nb2O7 and C-pm = 257.2 + 0.03621T - 4.434 x 10(6)/T-2 J K-1 mol(-1) for Ca2Nb2O7 were derived by the least-square method from the experimental data. The molar entropies at 298.15 K, S-m degrees (298.15 K) = 238.5 +/- 1.3 JK(-1) mol(-1) for Sr2Nb2O7 and S-m degrees(298.15 K) = 212.4 +/- 1.2 JK(-1) mol(-1) for Ca2Nb2O7, were evaluated from the low-temperature heat capacity measurements. (C) 2008 Elsevier B.V. All rights reserved.

引用

页码：33 / 38

页数：6

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