TY - JOUR

T1 - Model-free temperature scaling for heat capacity

AU - Drebushchak, V. A.

PY - 2017/10/1

Y1 - 2017/10/1

N2 - In treating the experimental data on the heat capacity of solids, the essence of any model application is in the searching for the scaling factors (ki or 1/Θi) which transform a set of independent functions CP,i(T) for every substance into a function CP(T·ki) universal for the particular set of substances. DSC heat capacities of I–III–VI2 compounds at elevated temperatures exceed the upper limit of 12R (3R per mole of atoms) and make impossible application of any model. Nevertheless, the temperature scaling of heat capacity can be solved as a pure mathematical problem without any physical model (theory). The benefits of the model-free scaling are illustrated with the case of four isostructural chalcogenides (LiInS2, LiInSe2, LiGaS2, and LiGaSe2) measured recently with DSC in a temperature range from 180 to 460 K. The upper limit of CP(T·ki) functions was expanded up to 635 K. Low-temperature heat capacity of LiInSe2 published in 1995 made it possible to derive the thermodynamic functions (enthalpy and entropy) for LiInS2 (0–590 K), LiGaS2 (0–640 K), and LiGaSe2 (0–490 K) and expand those data for LiInSe2 from 300 to 460 K.

AB - In treating the experimental data on the heat capacity of solids, the essence of any model application is in the searching for the scaling factors (ki or 1/Θi) which transform a set of independent functions CP,i(T) for every substance into a function CP(T·ki) universal for the particular set of substances. DSC heat capacities of I–III–VI2 compounds at elevated temperatures exceed the upper limit of 12R (3R per mole of atoms) and make impossible application of any model. Nevertheless, the temperature scaling of heat capacity can be solved as a pure mathematical problem without any physical model (theory). The benefits of the model-free scaling are illustrated with the case of four isostructural chalcogenides (LiInS2, LiInSe2, LiGaS2, and LiGaSe2) measured recently with DSC in a temperature range from 180 to 460 K. The upper limit of CP(T·ki) functions was expanded up to 635 K. Low-temperature heat capacity of LiInSe2 published in 1995 made it possible to derive the thermodynamic functions (enthalpy and entropy) for LiInS2 (0–590 K), LiGaS2 (0–640 K), and LiGaSe2 (0–490 K) and expand those data for LiInSe2 from 300 to 460 K.

KW - Chalcogenides

KW - Characteristic temperature

KW - Enthalpy

KW - Entropy

KW - Heat capacity

KW - THERMODYNAMIC PROPERTIES

KW - CALORIMETRY

KW - LIINSE2

UR - http://www.scopus.com/inward/record.url?scp=85019838172&partnerID=8YFLogxK

U2 - 10.1007/s10973-017-6447-5

DO - 10.1007/s10973-017-6447-5

M3 - Article

AN - SCOPUS:85019838172

VL - 130

SP - 5

EP - 13

JO - Journal of Thermal Analysis and Calorimetry

JF - Journal of Thermal Analysis and Calorimetry

SN - 1388-6150

IS - 1

ER -