Liu J Y, Zheng Z G, Lei L, Qiu Z G, Zeng D C
School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, People's Republic of China.
Rev Sci Instrum. 2020 Jun 1;91(6):065102. doi: 10.1063/1.5128949.
Direct measurements of the adiabatic temperature change (ΔT) in Gd and MnFePSiC are made using a homemade adiabatic magnetocalorimeter at 260-360 K and 0-7 T. The system uses a servo motor to drive the samples into and out of the magnetic field under a vacuum environment provided by the Physical Property Measurement System (PPMS). The peak values of ΔT for Gd and MnFePSiC at 7 T are 8.71 K and 6.41 K at ambient temperatures of 303 K and 317 K, respectively. Based on the theory model, it is found that ΔT of Gd depends on the 2/3 exponential function of magnetic field H (ΔT ∝ H), whereas the MnFePSiC compound follows the power law of ΔT ∝ H due to the first order magnetic transitions. Furthermore, using the constructed experimental instrument, the adiabatic temperature change in different magnetic materials, including materials with first/second order magnetic transition and blocks, flakes, or powders, can be directly measured under large magnetic fields and wide temperature spans.
使用自制的绝热磁热计在260 - 360 K和0 - 7 T的条件下，对钆（Gd）和锰铁磷硅碳化物（MnFePSiC）的绝热温度变化（ΔT）进行了直接测量。该系统在物理性能测量系统（PPMS）提供的真空环境下，使用伺服电机将样品驱动进出磁场。在7 T时，钆和锰铁磷硅碳化物在303 K和317 K的环境温度下，ΔT的峰值分别为8.71 K和6.41 K。基于理论模型发现，钆的ΔT取决于磁场H的2/3指数函数（ΔT ∝ H），而由于一级磁转变，锰铁磷硅碳化物遵循ΔT ∝ H的幂律。此外，使用所构建的实验仪器，可以在大磁场和宽温度范围内直接测量不同磁性材料（包括具有一级/二级磁转变的材料以及块状、片状或粉末状材料）的绝热温度变化。
