ИСТИНА

In this work, the equiatomic intermetallic alloy MnZnSb with tetragonal Cu 2 Sb-type crystal structure (space group P4/nmm) was melted in the resistance furnace in evacuated quartz ampule. The crystalline structure was examined by the methods of X-ray diffraction, using Cu Kα radiation. The adiabatic MCE in magnetic field up to 1.2 T in wide temperature range was studied by the direct method with T-type thermocouple attached inside the sample. The field and temperature dependencies of magnetization were investigated by vibration magnetometer in magnetic field up to 14 T, and isothermal change of magnetic contribution of entropy was calculated by Maxwell relation. The magnetic and magnetocaloric properties of MnZnSb were investigated. It was found that temperature dependence of MCE shows a sharp peak near room temperature with the maximum at Curie temperature T C = 317 K. The maximum magnitude of MCE is 0.45K in field of 1.2 T. It was shown that there is no the temperature hysteresis of the MCE in MnZnSb, and maximum of MCE at heating and cooling is detected at the same temperature. The MCE in fields more than 2T was estimated by calculation from the magnetization curves. The maximum value of MCE in field of 14 T is 4.5 K. It was found that in fields more than 4 T the temperature dependence of MCE demonstrates a wide maximum near Curie temperature. It was established that at temperature less than T C (in ferromagnetic phase) the MCE depends linear on field; at the same time at temperature above T C (in paramagnetic phase) the MCE is linear function of square magnetization. The exchange parameter was calculated in frame of mean-field approach from the dependence of MCE on the magnetization. It was concluded that MnZnSb is the intermetallic compound with significant MCE value about 0.4 K per 1 T at temperatures close to room temperature and the MCE hysteresis is absence. It is known that small hysteresis of MCE is important for technical applications. The main magnetocaloric characteristics of the intermetallic alloy MnZnSb: isothermal variation of the magnetic entropy under the magnetic phase transition, the magnitude of the magnetocaloric effect, and the cooling capacity were determined. It was found that the alloy investigated is of interest from the point of view of practical applications (magnetic cooling).