TY - JOUR
T1 - Heat capacities and thermodynamic properties of antimony substituted lanthanum orthoniobates
AU - Mielewczyk-Gryn, Aleksandra
AU - Wachowski, Sebastian
AU - Strychalska, Judyta
AU - Zagórski, Krzysztof
AU - Klimczuk, Tomasz
AU - Navrotsky, Alexandra
AU - Gazda, Maria
N1 - Funding Information:
The research performed at Gdansk University of Technology was financially supported by the National Science Center (Poland) Grant no. DEC-2012/07/E/ST3/00584 . Sample preparation and other work at UC Davis was supported by the U.S. National Science Foundation (grant EAR 13–21410 ).
Publisher Copyright:
© 2016 Elsevier Ltd and Techna Group S.r.l.
PY - 2016/5/1
Y1 - 2016/5/1
N2 - The results of heat capacity measurements for the lanthanum orthoniobate substituted with 10, 20 and 30 mol% of antimony (LaNb0.9Sb0.1O4, LaNb0.8Sb0.2O4 and LaNb0.7Sb0.3O4) are presented and discussed. Temperature dependence of low temperature heat capacity was analyzed within the Debye and Einstein models. The Debye temperature decreased, whereas the Einstein temperature increased with antimony content. The decrease of the Debye temperature with increasing antimony content was correlated with decreasing scheelite-fergusonite transition temperature. The increase of the Einstein temperature of LaSbxNb1-xO4 with increasing antimony content may indicate increasing frequency of optical vibrations of Nb(Sb)-O4-2 polyhedra relative to La3+ cations. Using the heat capacity data, standard entropies of the phases were calculated and combined with previously measured enthalpies of formation to obtain Gibbs energies of formation. Standard thermodynamic properties were tabulated.
AB - The results of heat capacity measurements for the lanthanum orthoniobate substituted with 10, 20 and 30 mol% of antimony (LaNb0.9Sb0.1O4, LaNb0.8Sb0.2O4 and LaNb0.7Sb0.3O4) are presented and discussed. Temperature dependence of low temperature heat capacity was analyzed within the Debye and Einstein models. The Debye temperature decreased, whereas the Einstein temperature increased with antimony content. The decrease of the Debye temperature with increasing antimony content was correlated with decreasing scheelite-fergusonite transition temperature. The increase of the Einstein temperature of LaSbxNb1-xO4 with increasing antimony content may indicate increasing frequency of optical vibrations of Nb(Sb)-O4-2 polyhedra relative to La3+ cations. Using the heat capacity data, standard entropies of the phases were calculated and combined with previously measured enthalpies of formation to obtain Gibbs energies of formation. Standard thermodynamic properties were tabulated.
KW - Debye temperature
KW - Entropy
KW - Gibbs energy
KW - Heat capacity
KW - Lanthanum orthoniobate
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U2 - 10.1016/j.ceramint.2016.01.093
DO - 10.1016/j.ceramint.2016.01.093
M3 - Article
AN - SCOPUS:84959919441
SN - 0272-8842
VL - 42
SP - 7054
EP - 7059
JO - Ceramics International
JF - Ceramics International
IS - 6
ER -