Department of Physics, The University of Burdwan, Burdwan - 713104, India.
Phys Chem Chem Phys. 2019 Jan 30;21(5):2628-2638. doi: 10.1039/c8cp06222f.
This article deals with the magnetic and thermal expansion properties of Pr2Fe16Si. This compound has been well characterized from the structural point of view by analysing X-ray diffraction (XRD) patterns. The temperature dependent behaviour of magnetization (M) and the structural parameters (lattice parameters, unit cell volume) suggest that the compound undergoes a second order phase transition from a paramagnetic to a ferromagnetic state at TC = 390 K, driven by an increase in bond length between iron atoms at 6c sites. The field-dependent behaviour of M below TC, and comparatively lower value of coercivity (Hc) have been explained by the role of Si atoms as pinning centres. In the ferromagnetic phase, the system is found to behave like an inhomogenous mean field system. The study of thermal expansion properties establishes that the compound is a zero thermal expansion material (αv = 5.3 × 10-6 K-1) operative in the temperature range T = 200-340 K. As a magnetocaloric material, Pr2Fe16Si possesses high RCP (87 J kg-1 at μ0H = 1.5 T), high operating temperature (390 K) and moderate |ΔSM|max.
本文研究了 Pr2Fe16Si 的磁热膨胀性能。通过分析 X 射线衍射 (XRD) 图谱，从结构角度对该化合物进行了很好的表征。磁化率 (M) 和结构参数（晶格参数、晶胞体积）随温度的变化表明，该化合物在 TC = 390 K 时经历了从顺磁态到铁磁态的二级相变，这是由 6c 位铁原子之间键长的增加引起的。低于 TC 时 M 的场依赖性以及相对较低的矫顽力 (Hc) 可以通过 Si 原子作为钉扎中心的作用来解释。在铁磁相中，该系统被发现表现为非均匀的平均场系统。热膨胀性能的研究表明，该化合物在 T = 200-340 K 的温度范围内是一种零热膨胀材料（αv = 5.3×10-6 K-1）。作为磁热材料，Pr2Fe16Si 具有高 RCP（在 μ0H = 1.5 T 时为 87 J kg-1）、高工作温度 (390 K) 和适中的 |ΔSM|max。
