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Large magnetodielectric effect and negative magnetoresistance in NiO nanoparticles at room temperature
RSC Advances ( IF 3.9 ) Pub Date : 2020-4-3 , DOI: 10.1039/d0ra00188k Soumi Chatterjee 1 , Ramaprasad Maiti 2 , Dipankar Chakravorty 1
RSC Advances ( IF 3.9 ) Pub Date : 2020-4-3 , DOI: 10.1039/d0ra00188k Soumi Chatterjee 1 , Ramaprasad Maiti 2 , Dipankar Chakravorty 1
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Nickel oxide nanoparticles having a mean particle size of 19.5 nm were synthesized by a simple chemical method. Those nanoparticles exhibited a spin glass like behaviour at a temperature around 9 K. The samples showed electronic conduction arising out of small polaron hopping between the Ni2+ and Ni3+ species present in the material. A large magnetodielectric parameter with a maximum value of 52.2% was observed in the sample at room temperature which resulted from the Maxwell–Wagner polarization effect. This was explained as arising due to a large negative magnetoresistance caused by spin polarized electron hopping between Ni2+ and Ni3+ sites with the consequential formation of space charge polarization at the interfaces of the NiO nanoparticles. This was substantiated by direct measurement of magnetoresistance of the samples which gave identical results. It is believed that negative magnetoresistance after direct measurement occurred due to the interaction between ferromagnetic and antiferromagnetic phases and the value was 37%, the highest reported in the literature so far. As a result of the presence of Ni3+ ions, antiferromagnetic phase and ferromagnetic like behaviour of NiO nanoparticles gave higher magnetization than other reported nanoparticles. Such large values of magnetoresistance of the samples will make the material useful as an ideal magnetic sensor.
中文翻译：
室温下NiO纳米颗粒的大磁介电效应和负磁阻
通过简单的化学方法合成了平均粒径为19.5 nm的氧化镍纳米颗粒。这些纳米颗粒在 9 K 左右的温度下表现出类似自旋玻璃的行为。样品显示出材料中存在的Ni 2+和 Ni 3+物质之间的小极化子跳跃产生的电子传导。在室温下，由于麦克斯韦-瓦格纳极化效应，在样品中观察到了最大值为 52.2% 的大磁电介质参数。这被解释为由于 Ni 2+和 Ni 3+位点之间的自旋极化电子跳跃引起的大的负磁阻，从而在 NiO 纳米粒子的界面处形成空间电荷极化。这通过直接测量样品的磁阻得到了证实，得到了相同的结果。据认为，直接测量后的负磁阻是由于铁磁相和反铁磁相之间的相互作用而产生的，其值为37%，是迄今为止文献报道的最高值。由于 Ni 3+离子的存在，NiO 纳米颗粒的反铁磁相和类铁磁行为比其他报道的纳米颗粒具有更高的磁化强度。样品如此大的磁阻值将使该材料成为理想的磁传感器。
更新日期：2020-04-03
中文翻译：
室温下NiO纳米颗粒的大磁介电效应和负磁阻
通过简单的化学方法合成了平均粒径为19.5 nm的氧化镍纳米颗粒。这些纳米颗粒在 9 K 左右的温度下表现出类似自旋玻璃的行为。样品显示出材料中存在的Ni 2+和 Ni 3+物质之间的小极化子跳跃产生的电子传导。在室温下，由于麦克斯韦-瓦格纳极化效应，在样品中观察到了最大值为 52.2% 的大磁电介质参数。这被解释为由于 Ni 2+和 Ni 3+位点之间的自旋极化电子跳跃引起的大的负磁阻，从而在 NiO 纳米粒子的界面处形成空间电荷极化。这通过直接测量样品的磁阻得到了证实，得到了相同的结果。据认为，直接测量后的负磁阻是由于铁磁相和反铁磁相之间的相互作用而产生的，其值为37%，是迄今为止文献报道的最高值。由于 Ni 3+离子的存在，NiO 纳米颗粒的反铁磁相和类铁磁行为比其他报道的纳米颗粒具有更高的磁化强度。样品如此大的磁阻值将使该材料成为理想的磁传感器。
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