In this investigation, we have used the thermal treatment method for the preparation of nickel and manganese ferrite nanoparticles. All the samples were calcined at different temperatures from 420 to 570 °C. The results of XRD demonstrated the variation of average nanocrystallite size as a function of calcination temperature. Mossbauer spectra of calcined NiFe2O4 nanoparticles at 570 °C exhibit two sextets, indicating the samples are ferromagnetic, while calcined MnFe2O4 nanoparticles at 420 °C reveal simultaneous presence of two paramagnetic doublets with a central magnetic sextet. The Mossbauer spectroscopy is also applied here for investigating the magnetic hyperfine characteristics and cation distribution of the above-mentioned ferrite nanoparticles. Mossbauer results demonstrate that higher calcination temperature assistances M2+ ions enter into the octahedral sites, while simultaneously Fe3+ ions transfer from the octahedral (B) sites to the tetrahedral (A) sites. As the results indicate, magnetic properties of the samples can be attributed to the hyperfine parameters such as hyperfine field and cation distribution. The results of Mossbauer showed the change in hyperfine parameters along with changing temperature and nanocrystallite size.

中文翻译：

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热处理法制备的 NiFe2O4 和 MnFe2O4 铁氧体纳米粒子的 57Fe Mossbauer 光谱研究

在本研究中，我们使用热处理方法制备镍锰铁氧体纳米颗粒。所有样品均在 420 至 570 °C 的不同温度下煅烧。XRD 结果表明平均纳米微晶尺寸随煅烧温度而变化。在 570 °C 下煅烧的 NiFe2O4 纳米颗粒的穆斯堡尔光谱显示出两个六重峰，表明样品是铁磁性的，而在 420 °C 下煅烧的 MnFe2O4 纳米颗粒显示出同时存在两个具有中心磁性六重峰的顺磁性双峰。穆斯堡尔光谱也用于研究上述铁氧体纳米粒子的磁性超精细特性和阳离子分布。Mossbauer 结果表明，较高的煅烧温度有助于 M2+ 离子进入八面​​体位点，同时 Fe3+ 离子从八面体 (B) 位点转移到四面体 (A) 位点。结果表明，样品的磁性可归因于超精细场和阳离子分布等超精细参数。Mossbauer 的结果显示超精细参数随着温度和纳米微晶尺寸的变化而变化。