MnBi1-xCrx(x=0.04,0.08,0.12,0.16)合金的晶体结构与磁性能

Crystal Structure and Magnetic Properties of MnBi1-xCrx(x=0.04, 0.08, 0.12, 0.16)

关键词:  MnBi掺杂  Rietveld全谱拟合  晶体结构  磁性能

Key words:  MnBi doping  Rietveld  crystal structure  magnetic properties

摘要:

本研究采用真空电弧熔炼法制备了MnBi_1-xCr_x（x=0.04，0.08，0.12，0.16）系列合金，利用X射线衍射仪（XRD）、Rietveld全谱拟合和振动样品磁强计（VSM）研究和测定MnBi_1-xCr_x系列合金样品的晶体结构和磁性能。结果发现，退火后的样品主相是低温相（LTP）MnBi（空间群：P6₃/mmc（194））。Rietveld全谱拟合分析确定每个样品中各相的含量并解析出主相MnBi_1-xCr_x的晶体结构。M（M=Bi，Cr）原子之间的原子间距d_M-M随着掺杂量增大而增大。M原子与Mn原子的间距d_M-Mn随着掺杂量增大而减小。在400 K时趋于饱和，且在掺杂量小于x=0.12时，饱和磁化强度随着掺杂量的增加而增大，在掺杂量大于x=0.12时，饱和磁化强度已经达到饱和，为20.55 emμ/g，且不随掺杂含量的变化而变化。随着Cr含量的增加，矫顽力亦逐渐增加，并且在掺杂量为x=0.12时达到最大值。随着测试温度的上升，合金矫顽力均呈上升趋势。MnBi_1-xCr_x（x=0.04，0.08，0.12，0.16）的德拜温度分别为378.46 K，369.52 K，354.62 K和351.64 K。

Abstract:

MnBi_1-xCr_x(x=0.04, 0.08, 0.12, 0.16) series alloys were prepared by vacuum arc melting method. The crystal structure and magnetic properties of the series alloy samples were investigated and determined by X-ray diffraction (XRD), Rietveld full-spectrum fitting and vibrating sample magnetometer (VSM). The results show that main phase of the annealed sample is a low temperature phase (LTP) MnBi (space group:P63/mmc(194)). Rietveld method is used to determine the content of each phase in each sample and to analyze the crystal structure of the main phase MnBi_1-xCr_x.The atomic distance d_M-M between M (M=Bi, Cr) atoms increases with the increase of doping amount. The M atom and Mn atom distance d_M-Mn decreases with the increase of doping amount. At 400 K, it tends to be saturated, and when the doping amount is less than x=0.12, the saturation magnetization increases with the increase of doping amount. When the doping amount is greater than x=0.12, the saturation magnetization has reached saturation, which is 20.55 emμ/g, and does not vary with the change in doping content. As the test temperature increases, the coercivity of the alloy increases. The Debye temperatures of MnBi_1-xCr_x(x=0.04, 0.08, 0.12,0.16) are 378.46 K,369.52 K,354.62 K and 351.64 K, respectively.