Spivakov Aleksandr, Lin Chun-Rong, Tsai Chang-Yen, Chen Ying-Zhen
Department of Applied Physics, National Pingtung University, No. 4-18 Minsheng Rd., Pingtung County, 90003, Taiwan.
Nanoscale Res Lett. 2022 Aug 4;17(1):70. doi: 10.1186/s11671-022-03709-0.
Bi-doped yttrium iron garnet nanopowders were successfully synthesized by a combustion method at different synthesis conditions, and the evolution of their structural, magnetic, and magneto-optical properties has been studied by various methods. X-ray diffraction analysis revealed that crystallite size increases with increase as in annealing time (t) well as in annealing temperature (T) and varied from 15.2 nm (T = 650 °C, t = 0.5 h) to 44.5 nm (T = 800 °C, t = 12 h). The magnetic hysteresis loops exhibit behavior characteristic of soft magnetic materials; herewith, the saturation magnetization demonstrates a growing trend with increasing crystallite size (D). The behavior of the coercivity indicates that, at room temperature, the transition between single-domain and multidomain states occurs at D = 35.3 nm. It was found that the size effect in the MCD spectra is clearly observed for the samples with crystallite sizes less than 42.2 nm for an intersublattice charge-transfer transition and a crystal-field tetrahedral transition. The influence of cation redistribution on the observed changes has been discussed.
通过燃烧法在不同合成条件下成功合成了铋掺杂钇铁石榴石纳米粉末，并采用多种方法研究了其结构、磁性和磁光性质的演变。X射线衍射分析表明，微晶尺寸随退火时间（t）和退火温度（T）的增加而增大，范围从15.2纳米（T = 650°C，t = 0.5小时）到44.5纳米（T = 800°C，t = 12小时）。磁滞回线表现出软磁材料的特征行为；据此，饱和磁化强度随微晶尺寸（D）的增加呈现出增长趋势。矫顽力的行为表明，在室温下，单畴和多畴状态之间的转变发生在D = 35.3纳米处。研究发现，对于微晶尺寸小于42.2纳米的样品，在亚晶格间电荷转移跃迁和晶体场四面体跃迁中，在磁圆二色光谱中能清楚地观察到尺寸效应。讨论了阳离子再分布对观察到的变化的影响。
