The investigation under study deals with the combustion synthesis of nanocrystalline Mg substituted nickel zinc ferrites i.e., Mg_xNi_0.6−xZn_0.4Fe₂O₄ (x = 0.0 to 0.6) using malic acid dihydrazide as a novel fuel and the effect of magnesium substitution on the structural and magnetic properties. The nanocrystalline monophasic nature of “as prepared” Mg_xNi_0.6−xZn_0.4Fe₂O₄ (x = 0.0 to 0.6) has been confirmed from XRD and Raman spectroscopic studies and the crystallite sizes were found to be in the range of 19–25 nm which nearly matches with TEM. The RT and low temperature magnetization studies indicate a continuous decrease in magnetization with increase in Mg substitution. In contrast, the hysteretic behaviour diminished and the emergence of superparamagnetism is observed in all the samples as the Mg content increases. The decrease in M_S with increase in Mg concentration is attributed to the replacement of magnetic Ni²⁺ ions with non-magnetic Mg²⁺ ions and also to the enhancement of the Y–K angle by cation redistribution. The variation of AC susceptibility with temperature exhibits broad maxima, indicating a distribution of particle sizes in the sample with the existence of single domain and superparamagnetic type domain structures. The susceptibility decreases continuously beyond x = 0.4 until 0.6, and the samples exhibit only superparamagnetism. The AC susceptibility studies also show a decrease in Curie temperature (T_C) with an increase in x for Mg_xNi_0.6−xZn_0.4Fe₂O₄ (x = 0.0 to 0.6) resulting from weakening of A–B interaction. The ZFC–FC studies along with the Mössbauer studies were also corroborated by the proposed existence of dominant superparamagnetism with an increase in Mg concentration.

中文翻译：

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磁性稀释的镍锌铁氧体中的纳米级驱动的结构变化和相关的超顺磁性†

研究中的研究涉及使用苹果酸二酰肼作为新型燃料燃烧Mg取代的纳米晶Mg取代的镍锌铁氧体，即Mg _x Ni _{0.6− x} Zn _0.4 Fe ₂ O ₄（x = 0.0至0.6）以及镁的作用在结构和磁性能上的替代。Mg _x Ni _{0.6− x} Zn _0.4 Fe ₂ O ₄（xX射线衍射和拉曼光谱研究已确认= 0.0至0.6），并且发现微晶尺寸在19–25 nm范围内，与TEM几乎匹配。RT和低温磁化研究表明，随着Mg替代量的增加，磁化强度持续下降。相反，随着Mg含量的增加，在所有样品中都观察到磁滞行为减弱，并且出现了超顺磁性现象。在下降中号_小号随着Mg浓度的增加归因于更换磁性的Ni ²⁺与非磁性Mg离子²⁺离子和还向的增强ÿ - ķ阳离子再分布的角度。AC磁化率随温度的变化表现出极大的最大值，表明存在单畴和超顺磁性型畴结构的样品中粒径分布。磁化率持续下降，超过x = 0.4直到0.6，并且样品仅表现出超顺磁性。该交流磁化率的研究还表明在居里温度（下降Ť _Ç与增加）X镁_X的Ni _0.6〜X锌_0.4的Fe ₂ ø ₄（X= 0.0到0.6）是由于A–B相互作用减弱所致。ZFC-FC研究以及Mössbauer研究也被证实存在，随着Mg浓度的增加，超顺磁性占主导地位。