【摘要】 在2—390K温度之间研究了La0.8Ba0.2MnO3的磁矩、磁电阻与温度的关系.发现以不同价态的Mn元素引入得到的La0.8Ba0.2MnO3,性能虽然都存在金属—绝缘体转变,以及在磁场作用下居里温度附近电阻率变化非常显著的特点,但是价态对磁性转变温度TC,金属—绝缘体转变温度Tmi,以及磁电阻极大值温度TMR的影响都非常显著.三种价态相比较,使用二价Mn的电阻率最低以及磁性转变温度更接近室温.认为影响材料性能的主要因素是材料制备时引进的Mn元素的价态,由于原料价态的不同而形成的氧空位浓度变化,进而影响了Mn4+Mn3+的比.更多还原

【Abstract】 The influence of temperature (in the range of 2—390K) on the magnetic moment, and magnetoresistance has been investigated in this paper. It is found that the magnetoelectric properties, particularly the Curie temperature T-C, the metal-insulator transition temperature, T- mi , and the maximum magnetoresistance T- MR , of La-{0.8}Ba-{0.2}MnO-3 are closely related to the valence of Mn in the oxides. La- 0.8 Ba- 0.2 MnO-3 synthesized with 2+ Mn oxides exhibited the lower resistivity, and a Curie temperature closer to room temperature (290K) compared with that synthesized with 3+ Mn oxides. It can be concluded that the magnetoelectric properties of La-{0.8}Ba-{0.2}MnO-3 are dependent on the Mn valence of oxides. This could be attributed to the influence of oxygen vacancy concentration variation on the Mn 4+ /Mn 3+ ratio in the resultant compounds during solid sintering reaction, which results from the valence difference of oxide precursors.更多还原