Abstract The article reports the influence of particle size variation on microstructural, optical and magnetic properties of nanocrystalline Gd doped Ni-Zn ferrites with a generic formula Zn0.2Ni0.8Gd0.05Fe1.95O4. The nanoparticles were synthesized using chemical co-precipitation technique and the average crystallite sizes were found in the range of 4 nm–29 nm as estimated from Scherrer’s relation. Raman spectra confirmed the lowering of symmetry of the octahedral sites of the cubic spinel structure with rare earth doping. A blue shift was observed in the absorption profile of the nanoparticles due to the size effect. The 7 T field cooled M-H plots recorded at 5 K exhibited exchange bias for the sample with the smallest particle size which was attributed to the high anisotropy of the canted surface spins compared to the core spins.

中文翻译：

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纳米晶 Zn0.2Ni0.8Gd0.05Fe1.95O4 铁氧体的尺寸变化：交换偏置效应及其与无序表面自旋的相关性

摘要 本文报道了粒径变化对纳米晶 Gd 掺杂 Ni-Zn 铁氧体的微观结构、光学和磁性能的影响，其通式为 Zn0.2Ni0.8Gd0.05Fe1.95O4。纳米颗粒是使用化学共沉淀技术合成的，平均晶粒尺寸在 4 nm-29 nm 范围内，根据 Scherrer 关系估计。拉曼光谱证实了掺杂稀土的立方尖晶石结构八面体位点的对称性降低。由于尺寸效应，在纳米颗粒的吸收曲线中观察到蓝移。在 5 K 记录的 7 T 场冷却 MH 图显示出最小粒径样品的交换偏差，这归因于与核心自旋相比倾斜表面自旋的高各向异性。