无机材料学报

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Al掺杂对La0.8Sr0.2Mn1-xAlxO3电输运性能的影响

张爱梅1, 朱佳佳1, 方天诚2, 潘茜茜1   

  1. 1. 河海大学 理学院,南京210093;
    2. 中国科学技术大学 物理学院, 合肥 230026
  • 收稿日期:2022-07-14 修回日期:2022-09-05
  • 作者简介:张爱梅(1978-), 女, 教授. E-mail: amzhang2009@hhu.edu.cn.
  • 基金资助:
    国家自然科学基金(11404091); 江苏省自然科学基金(BK20140839);

Effects of Al Doping on the Structure and Electrical Transport Property of La0.8Sr0.2Mn1-xAlxO3

ZHANG Aimei1, ZHU Jiajia1, FANG Tiancheng2, PAN Xixi1   

  1. 1. College of Science, Hohai University, Nanjing 210093, China;
    2. College of Physics, University of Science and Technology of China, Hefei 230026, China
  • Received:2022-07-14 Revised:2022-09-05
  • About author:ZHANG Aimei (1978-), female, professor. E-mail: amzhang2009@hhu.edu.cn
  • Supported by:
    National Natural Science Foundation of China (11404091); Natural Science Foundation of Jiangsu Province (BK20140839)

摘要: 钙钛矿锰氧化物La1-xSrxMnO3作为一种代表性庞磁阻材料,在磁传感器等领域具有广阔的应用前景。在低磁场和室温下很难获得显著的庞磁阻效应,为提高其磁电阻效应和转变温度,本研究采用传统固相反应法制备了La0.8Sr0.2Mn1-xAlxO3 (0≤x≤0.25)(LSMAO)多晶样品,并系统分析了Al掺杂对LSMO电输运性质和磁电阻效应的影响。X射线衍射(XRD)图谱表明LSMAO样品为单一的菱方结构,属于R3̅C空间群。电输运性质研究发现,样品的电阻率随Al的掺杂呈指数型上升,且外加磁场使金属-绝缘体转变温度有所提高。这可能是由于Al3+稀释了Mn3+/Mn4+离子网络,在减少载流子数量的同时增加了磁无序。此外,LSMAO陶瓷的导电机理随Al3+的掺杂从小极化子模型(Small polaron hopping model, SPH)转变成变程跳跃模型(Variable range hopping model, VRH),反映出非磁性的Al3+抑制了铁磁团簇间的载流子交换,使得小极化子热激活近邻跃迁过程被抑制。LSMAO的磁电阻值显示从x=0时的21.03%增加到x=0.25时的59.71%,证明Al3+的掺杂可有效增强LSMAO的磁电阻效应。

关键词: 电输运, 小极化子模型, 变程跳跃模型, 磁电阻

Abstract: As a colossal magnetoresistance material, the perovskite manganese oxide La1-xSrxMnO3 has broad application prospects in magnetic sensors and other fields. However, it is difficult to obtain a significant colossal magnetoresistance effect at a low magnetic field and room temperature. In order to improve its magnetoresistance effect and transition temperature, La0.8Sr0.2Mn1-xAlxO3 (0≤x≤0.25) (LSMAO) polycrystalline samples were prepared by the traditional solid-state reaction method in this study. The effects of Al doping on the electrical transport property and magnetoresistance effects of LSMO were systematically analyzed. The X-ray diffraction (XRD) results indicate that all the samples crystallize in a single rhombohedral structure with the space group of R3̅C. The study of electrical transport property shows that the resistivity of the samples increases exponentially with the doping of Al3+, and the metal-insulator transition temperature is increased by an external magnetic field. This may be due to the dilution of the Mn3+/Mn4+ ions network by Al3+, which increases the magnetic disorder while reducing the number of carriers. In addition, the conduction mechanism of LSMAO ceramics changes from the small polaron hopping model (SPH) to the variable range hopping model (VRH) with the doping of Al3+, reflecting that the non-magnetic Al3+ suppress the carrier exchange between the ferromagnetic clusters. As a result, the thermally activated neighbor transition process of small polarons is suppressed. The magnetoresistance value of LSMAO is enhanced from 21.03% to 59.71% with x increasing from 0 to 0.25, which proves that the doping of Al3+ can effectively enhance the magnetoresistance effect of LSMAO.

Key words: electrical transport, small polaron hopping model, variable range hopping model, magnetoresistance

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