锶位掺钠对La0.67Sr0.33MnO3体系晶格结构和磁电特性的影响

通过红外光谱和Raman光谱分析了锶(Sr)位掺钠(Na)对La0.67Sr0.3333MnO3体系晶格结构的影响.结果表明:由于Na 的半径小于Sr2 的,Na对Sr位替代后使A位平均离子半径减小,导致Mn-O-Mn键长、键角变化,出现了Jahn-Teller效应.另外,通过实验和计算得到了体系的磁化强度-温度(magnetization-temperature,M-T)曲线,电阻率-温度(resistivity-temperature,p-T)曲线和磁电阻-温度(magnetoresistance-temperature,MR-T)曲线,研究了晶格畸变和双交换作用,发现通过调节Sr位掺Na的摩尔分数获得了室温区的庞磁电阻效应.

INFLUENCE OF NATRIUM DOPING AT STRONTIUM SITE ON CRYSTAL STRUCTURE AND MAGNETOELECTRIC PROPERTIES OF La0.67Sr0.33MnO3 SYSTEM

Influences of natrium (Na) doping at strontium (Sr) site on crystal structure of an La0.67Sr0.33MnO3 system were analyzed through infrared (IR) spectra and Raman spectra. It is found that, as the radius of the Na+ is smaller than that of Sr2+, the substitution of Na for Sr causes the average ion radius of the A-site to decrease and leads to the change of the bond length and bond angle of Mn-O-Mn, and thus the Jahn-Teller effect appears. In addition, magnetization-temperature (M-T) curves, resistivity-temperature (p-T)curves and magnetoresistance-temperature (MR-T) curves of the system were obtained through experiments and calculation. The lattice distortion and double-exchange function were studied, and it was found that a colossal magnetoresistance effect on the room temperature range can be obtained by adjustment of the Na doping molar fraction at the Sr site.