NIST Standard Reference Database 30
Last Update to Data Content: 2002
"Enthalpy and Specific Heat of Strontium and Barium Zirconates at High Temperatures," V.A. Levitskii, D.S. Tsagareishvili, and G.G. Gvelesiani, High Temperature, Vol. 14 [1], pp. 69-72 (1976).
"The barium and strontium zirconates were synthesized by the ceramic method. The initial substances were BaCO3 ("chemically pure"), SrCO3 ("very pure"), and ZrO2 ("very pure"). The ... impurity content of the carbonates was: N - 0.001%, S - 0.002%, Cl - 0.001%, Fe - 0.0005%, K - 0.05%, Na - 0.05%, Ca - ≤0.3%, Pb - 0.0005%. Tablets of stoichiometric MeCO3 + ZrO2 mixtures were fired in air and in vacuum at 1200 °C to 1300 °C for 50 h to 200 h and cooled slowly, or quenched in liquid nitrogen."
"The single-phase nature of the obtained specimens was verified by x-ray diffraction. The x-ray diagrams were obtained in a focusing camera with a bent germanium single crystal as a monochromator... The unit cell parameters were determined from x-ray diagrams obtained in a RKU-86 camera (Cu Kα emission) by extrapolation to an angle of reflection of 90°... Barium zirconate had a perovskite structure... Strontium zirconate was indexed in a tetragonal system..."Calorimetry
"The enthalpy of the zirconates was measured by the method of mixtures in a massive calorimeter with an isothermic jacket (298 ± 0.01 K). ... The calorimeter was calibrated with an error of ± 0.1% against the high-temperature enthalpy of a conventional standard - very pure corundum. A briquet prepared from a powder of the investigated zirconate was put into an unsealed platinum ampul (weight 24.4357 g). The amount of zirconate used in the experiments was 7.8123 g, and that of barium zirconate was 9.7891 g. ... The total error (including the error of the calibration factor of the calorimeter) of enthalpy measurement in this work did not exceed 1 %."
| Axis |
Temperature ( K ) |
Axis Length ( Å ) |
|---|---|---|
| a | 298.15 | 5.797(1) |
| c | 298.15 | 8.198(2) |
| Phase |
Temperature ( K ) |
Molar Heat Capacity ( J mol-1 K-1 ) |
Specific Heat ( J kg-1 K-1 ) |
|---|---|---|---|
| tetragonal | 298.15 | 103.4 | 455.8 |
| tetragonal | 400 | 114.2 | 503.4 |
| tetragonal | 500 | 119.4 | 526.2 |
| tetragonal | 600 | 122.5 | 539.9 |
| tetragonal | 700 | 124.6 | 549.1 |
| tetragonal | 800 | 126.1 | 556.1 |
| tetragonal | 900 | 127.4 | 561.6 |
| tetragonal | 1000 | 128.4 | 566.3 |
| tetragonal | 1100 | 129.4 | 570.5 |
| tetragonal | 1200 | 130.2 | 574.2 |
| tetragonal | 1300 | 131.0 | 577.7 |
| tetragonal | 1400 | 131.8 | 581.0 |
| tetragonal | 1500 | 132.5 | 584.2 |
| tetragonal | 1600 | 133.2 | 587.3 |
| Axis |
Temperature ( K ) |
Axis Length ( Å ) |
|---|---|---|
| a | 298.15 | 4.193(1) |
| Phase |
Temperature ( K ) |
Molar Heat Capacity ( J mol-1 K-1 ) |
Specific Heat ( J kg-1 K-1 ) |
|---|---|---|---|
| alpha | 298.15 | 101.7 | 367.8 |
| alpha | 400 | 110.3 | 398.8 |
| alpha | 500 | 115.6 | 417.9 |
| alpha | 600 | 119.6 | 432.5 |
| alpha | 700 | 123.1 | 445.1 |
| alpha | 758 | 125.0 | 451.9 |
| beta | 758 | 115.6 | 418.0 |
| beta | 800 | 115.6 | 418.0 |
| beta | 900 | 115.5 | 417.7 |
| beta | 1000 | 115.4 | 417.4 |
| beta | 1100 | 115.4 | 417.1 |
| beta | 1175 | 115.3 | 417.0 |
| gamma | 1175 | 125.3 | 453.0 |
| gamma | 1200 | 125.7 | 454.6 |
| gamma | 1300 | 127.6 | 461.4 |
| gamma | 1400 | 129.5 | 468.1 |
| gamma | 1500 | 131.3 | 474.7 |
| gamma | 1600 | 133.1 | 481.4 |
"...polymorphic transitions alpha-BaZrO3 to beta-BaZrO3 and beta-BaZrO3 to gamma-BaZrO3 occurred at 758±1 K and 1175±1 K, respectively."