摘要
用传统的固相反应法合成了Fe位掺杂Al的双钙钛矿型氧化物Sr2 Fe1 -xAlxMoO6 (x =0 0 ,0 0 5 ,0 10 ,0 15 ,0 3)多晶材料 .x射线衍射和扫描电子显微分析显示 ,在Fe位掺杂Al既没有引入杂相 ,也没有明显改变Sr2 FeMoO6 多晶材料的晶粒尺寸和晶界状态 .非磁性Al离子的掺杂使晶粒内部磁有序区细化成更小的区域 ,同时使反铁磁区内的磁耦合作用变弱 .这一方面提高了亚铁磁区磁化方向的磁场灵敏度 ;另一方面也降低了反铁磁区对自旋相关电子的散射 ;两方面的共同作用使Sr2 FeMoO6 的低场磁电阻效应明显增强 ,但这种尺寸效应也使材料的磁电阻在高温下下降得更快 .
Polycrystalline powders of the family of compounds Sr-2 Fe1-x Al-x MoO6 ( x = 0, 0.05, 0.10, 0.15, 0.30) were prepared according to the standard solid-state reaction. XRD patterns and SEM images show that the structure and the grain size of these compounds were not changed and no impurity was observed by doping with Al in Sr2FeMoO6. In the cationic ordered segregation, a large ferrimagnetic patch can be separated into some smaller ones by the Al doping. So the chain of the ferrimagnetic exchange path will be shortened and the strength of exchange will be weakened. Therefore I their moments become more sensitive to external field. Furthermore, when the Al ion replaces the Fe ion in the disordered segregation, the antiferromagnetic coupling becomes weaker. As a result, the low-field magnetoresistance is enhanced. But the smaller ferrimagnetic segregates become more sensitive to thermal agitation at high temperatures. The weakness of the Al-doped SFMO lies in its stronger temperature dependence of the saturated moments and the low-field magnetoresistance.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2005年第2期907-911,共5页
Acta Physica Sinica
基金
国家自然科学基金 (批准号 :10 3 0 40 0 4)
哈尔滨工业大学校基金 (批准号 :HIT .2 0 0 2 46)资助的课题~~
