Direct measurement of the magnetocaloric effect in MnZnSb intermetalic compound

摘要

The equiatomic intermetallic alloy MnZnSb with a tetragonal Cu2Sb-type crystal structure (space group P4mm) was melted in the resistance furnace in the evacuated quartz ampoule. The adiabatic temperature change (Delta T-ad) and the isothermal variation of the magnetic entropy (Delta S-M) of the MnZnSb compound near to the magnetic phase transition were studied. The.Tad in a magnetic field up to 1.25 T was studied by the direct method. It was found that temperature dependencies of both Delta T-ad and.SM show a sharp peak near room temperature with a maximum at Curie temperature TC = 317 K. It was shown that there is no temperature hysteresis of the Delta T-ad in MnZnSb, and the maximum of Delta T-ad when the compound is heated or cooled is detected at the same temperature. The estimated value of Delta T-ad in a field of 14 T is 4.5 K. It was shown that near the Curie temperature, the field dependence of the maximum of magnetic entropy change is adequately described by the thermodynamic Landau theory for magnetic second-order phase transitions.