ABSTRACT

The heat capacities of powdered Ba2TiSi2O8 and Sr2TiSi2O8 have been measured over the temperature range from (2 to 300) K using a Quantum Design Physical Property Measurement System (PPMS). These two compounds have similar heat capacity values over the experimental temperature range because of their analogous structures. However, the heat capacities do display a crossover at T = 112.6 K, below which the heat capacity of Ba2TiSi2O8 becomes larger than that of Sr2TiSi2O8. The experimental data have been fitted to a series of theoretical functions from which the thermodynamic functions have been calculated. The standard molar entropies at T = 298.15 K have been determined to be (254.67 +- 2.55) and (252.61 +- 2.78) J K 1 mol 1 for Ba2TiSi2O8 and Sr2TiSi2O8, respectively.

Compounds

#	Formula	Name
1	Ba2O8Si2Ti	barium titanium silicate (Ba2Si2TiO8)
2	O8Si2Sr2Ti	strontium titanium silicate (Sr2TiSi2O8)

Datasets

The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type	Compound-#	Property	Variable	Constraint	Phase	Method	#Points
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Relaxation calorimetry, quantum design PPMS	59
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Relaxation calorimetry, quantum design PPMS	58
POMD	1	Molar entropy, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Relaxation calorimetry, quantum design PPMS	58
POMD	1	Molar enthalpy, kJ/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Relaxation calorimetry, quantum design PPMS	58
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Relaxation calorimetry, quantum design PPMS	59
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Relaxation calorimetry, quantum design PPMS	58
POMD	2	Molar entropy, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Relaxation calorimetry, quantum design PPMS	58
POMD	2	Molar enthalpy, kJ/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Relaxation calorimetry, quantum design PPMS	58

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Low temperature heat capacity study of Ba2TiSi2O8 and Sr2TiSi2O8

Shi, Q.[Quan], Park, T.-J.[Tae-Jin], Schliesser, J.[Jacob], Navrotsky, A.[Alexandra], Woodfield, B. F.[Brian F.]

ABSTRACT