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          Institute: MPI für Festkörperforschung     Collection: FKF Publikationen 2006     Display Documents

ID: 273527.0, MPI für Festkörperforschung / FKF Publikationen 2006
Thermodynamic properties of BaCeO3 and BaZrO3 at low temperatures
Authors:Ahrens, M.; Maier, J.
Date of Publication (YYYY-MM-DD):2006
Title of Journal:Thermochimica Acta
Issue / Number:2
Start Page:189
End Page:196
Review Status:Peer-review
Audience:Not Specified
Abstract / Description:Specific heat capacities (C-p) of polycrystalline samples of BaCeO3 and
BaZrO3 have been measured from about 1.6 K up to room temperature by
means of adiabatic calorimetry. We provide corrected experimental data
for the heat capacity of BaCeO3 in the range T < 10 K and, for the
first time, contribute experimental data below 53 K for BaZrO3.
Applying Debye's T-3-law for T -> 0 K, thermodynamic functions as molar
entropy and enthalpy are derived by integration. We obtain C-p = 114.8
(+/- 1.0) J mol(-1) K-1, S degrees = 145.8 (+/- 0.7) J mol(-1) K-1 for
BaCeO3 and C-p = 107.0 ( +/- 1.0) J mol(-1) K-1, S degrees = 125.5 (+/-
0.6) J mol(-1) K-1 for BaZrO3 at 298.15 K. These results are in overall
agreement with previously reported studies but slightly deviating, in
both cases. Evaluations of C-p(T) yield Debye temperatures and identify
deviations from the simple Debye-theory due to extra vibrational modes
as well as anharmonicity. The anharmonicity turns out to be more
pronounced at elevated temperatures for BaCeO3. The characteristic
Debye temperatures determined at T= 0 K are Theta(0) = 365 (+/- 6) K
for BaCeO3 and Theta(0) = 402 (+/- 9) K for BaZrO3. (c) 2006 Elsevier
B.V. All rights reserved.
Free Keywords:heat capacity; thermal analysis; adiabatic calorimetry; perovskites
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Festkörperforschung
External Affiliations:Max Planck Inst Festkorperforsch, D-70569 Stuttgart, Germany.
Identifiers:ISI:000236576100008 [ID No:1]
ISSN:0040-6031 [ID No:2]
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