TY - JOUR
T1 - Thermochemistry of Fluoride Perovskites
T2 - Heat Capacity, Enthalpy of Formation, and Phase Transition of NaMgF3
AU - Topor, L.
AU - Navrotsky, A.
AU - Zhao, Y.
AU - Weidner, D. J.
N1 - Funding Information:
This research was supported by the Center for High Pressure Research, (CHiPR), an NSF Science and Technology Center.
Copyright:
Copyright 2004 Elsevier Science B.V., Amsterdam. All rights reserved.
PY - 1997/8
Y1 - 1997/8
N2 - The enthalpies of formation, heat content, heat capacity, and transition of NaMgF3perovskite have been determined. A new high temperature calorimetric methodology has been applied for the enthalpy of formation measurements. The heat content and heat of formation measurements were done using a "hybrid calorimeter" built recently in our laboratory. For the heat capacity measurements, a Netzsch 404 high-temperature differential scanning calorimeter (DSC) has been used. The enthalpy of formation from the binary fluorides at 298 K is -15.76±2.46 kJ/mol, and that from the elements is -1716.51±2.8 kJ/mol. The measured heat capacities between 313 and 1153 K show aλ-anomaly with a transition at 1051 K. The presence of one peak supports a recent X-ray study which concluded that the crystal structure transforms from the orthorhombicPbnmphase directly to the cubicPm3mphase. The enthalpy of transformation is 2.3±0.03 kJ/mol. The heat content values measured by transposed temperature drop calorimetry are in agreement with those calculated by graphical integration of the experimental heat capacity data obtained by DSC.
AB - The enthalpies of formation, heat content, heat capacity, and transition of NaMgF3perovskite have been determined. A new high temperature calorimetric methodology has been applied for the enthalpy of formation measurements. The heat content and heat of formation measurements were done using a "hybrid calorimeter" built recently in our laboratory. For the heat capacity measurements, a Netzsch 404 high-temperature differential scanning calorimeter (DSC) has been used. The enthalpy of formation from the binary fluorides at 298 K is -15.76±2.46 kJ/mol, and that from the elements is -1716.51±2.8 kJ/mol. The measured heat capacities between 313 and 1153 K show aλ-anomaly with a transition at 1051 K. The presence of one peak supports a recent X-ray study which concluded that the crystal structure transforms from the orthorhombicPbnmphase directly to the cubicPm3mphase. The enthalpy of transformation is 2.3±0.03 kJ/mol. The heat content values measured by transposed temperature drop calorimetry are in agreement with those calculated by graphical integration of the experimental heat capacity data obtained by DSC.
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U2 - 10.1006/jssc.1997.7431
DO - 10.1006/jssc.1997.7431
M3 - Article
AN - SCOPUS:0038085629
SN - 0022-4596
VL - 132
SP - 131
EP - 138
JO - Journal of Solid State Chemistry
JF - Journal of Solid State Chemistry
IS - 1
ER -