Phase transition-enabled MnFe2O4 nanoparticles modulated by high-pressure with enhanced electrical transport properties
Phase transition-enabled MnFe2O4 nanoparticles modulated by high-pressure with enhanced electrical transport properties
复制标题
高压调制的相变 MnFe2O4 纳米粒子具有增强的电传输性能
DOI：
10.1016/j.apsusc.2021.150532
复制
发表时间：
2021-07-14
影响因子：
6.7
通讯作者：
Wang, Jingshu
中科院分区：
文献类型：
--
作者：
Gong, Lei;Chen, Guangbo;Wang, Jingshu
通过XRD、拉曼光谱和阻抗谱测量的平均值，首次建立了MnFe2O4纳米颗粒的压力调谐结构-功能关系。施加外部压力导致MnFe2O4晶格连续收缩。在17.1 ~ 26.3 GPa的压力范围内，MnFe2O4发生了立方-正交结构相变。同时，随着压力从环境态增加到37.1 GPa，样品的电导率持续提高。进一步分析表明，Fe-3d和O-2p轨道的杂化增强和压缩后带隙的减小是影响MnFe2O4电导率的主要因素。随着压力的释放，样品恢复到立方尖晶石结构，但晶界电阻和介电常数仍比压缩前降低了近3个数量级。通过对回收样品的霍尔效应和电子显微镜分析，界面密度的增加和载流子浓度的增加是MnFe2O4纳米粒子电性能明显改善的原因。在本工作中，压力循环退火导致的电导率的高提高为设计具有优异电学和电化学性能的铁氧体材料提供了新的可行途径，并扩大了其在电子器件和微波工业等方面的应用前景。
Pressure tuned structure-function relationship of MnFe2O4 nanoparticles is established for the first time by the mean of XRD, Raman and impedance spectra measurements. The application of external pressure results in a continuous lattice contraction of MnFe2O4. In the pressure range of 17.1-26.3 GPa, MnFe2O4 undergoes a cubicto-orthorhombic structural phase transition. Meanwhile, increasing pressure from ambient state to 37.1 GPa leads to the continued improvement of conductivity of the sample. Further analysis shows that the hybridized enhancement between Fe-3d and O-2p orbits and the decrease in band gap upon compression are the major factors to affect the conductivity of MnFe2O4. With the release of pressure, the sample recovers to the cubic spinel structure, but the grain boundary resistance and dielectric constant are still decreased by nearly 3 orders of magnitude compared with the counterpart before compression. By analysis of Hall-effect and electron microscope on the recovered sample, the increased interfaces density and accordingly the enlarged carrier concentration account for the obvious improvement of electrical properties in MnFe2O4 nanoparticles. In this work, such a high enhancement in conductivity due to the annealing of pressure-cycle provides a newly feasible pathway to design ferrite materials with excellent electrical and electrochemical properties, and expands their application prospects in electronic devices and microwave industries, etc.