Thermal properties of [Cr(NH3)6](BF4)3 studied by adiabatic and relaxation calorimetry

• Published in: The Journal of chemical thermodynamics Vol. 89; pp. 223 - 227
• Main Authors: Górska, Natalia, Pełka, Robert, Inaba, Akira, Mikuli, Edward, Mihalik, Marian
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-10-2015
• Subjects: [Cr(NH3)6](BF4)3; Adiabatic and relaxation calorimetry; Heat capacity; Phase transitions; Schottky anomaly; Heat capacity; [Cr(NH3)6](BF4)3; Phase transitions; Adiabatic and relaxation calorimetry; Schottky anomaly
• ISSN: 0021-9614; 1096-3626
• DOI: 10.1016/j.jct.2015.05.012

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•Four solid phase transitions are observed between T=(9 and 300)K for [Cr(NH3)6](BF4)3.•Low temperature properties were investigated with relaxation calorimetry below T=20K.•For nonzero values of applied magnetic field well-defined Schottky anomaly appears.•Isothermal magnetization curve recorded up to 5T was measured at T=1.8K.
Four (solid–solid) phase transitions were detected in the temperature range of (9 to 300)K in polycrystalline [Cr(NH3)6](BF4)3 at TC1=240.7K, TC2=108.0K, TC3=91.9K, and TC4=61.3K by adiabatic calorimetry. The measurements by relaxation calorimetry were followed on lowering temperature from 20K down to 0.35K under six different external magnetic field values (9, 7, 5, 3, 1 and 0)T. For non-zero values of applied magnetic field well-defined Schottky anomaly appears. Magnetic heat capacity was calculated assuming the zero-field splitting for the decoupled Cr(III) ions. There is no discrepancy between the observed and calculated values. Isothermal magnetization curve recorded up to 5T was measured at temperature of 1.8K.