利用溶胶-凝胶法（sol-gel）制备了多晶类钙钛矿型稀土锰氧化物La0.60Sr0.40-xKxMnO3（x=0.00,0.15,0.20,0.30）。发现K＋取代部分Sr2＋后,可使样品的居里温度降至室温附近,并且使样品的室温磁电阻比替代前明显增大。在1.8T的磁场下,x=0.30的样品磁电阻峰值为21%,相应的峰值温度为304K。而母体La0.60Sr0.40MnO3的磁电阻峰值仅为6.4%,峰值温度为373K。可见K＋离子替代使室温附近样品的庞磁电阻效应有了明显的改善。
Polycrystalline perovskite rare-earth manganites La0.60Sr0.40-xKxMnO3（x=0.00,0.15,0.20,0.30） were synthesized by sol-gel method.It is found that when Sr2＋ ions are partly substituted by K＋ ions,the Curie temperature of substituted samples can decrease to room temperature and the room temperature magnetoresistance（MR） increases obviously comparing with un-substituted La0.60Sr0.40MnO3.Under an applied filed of 1.8T,there is a maximum MR with 21% at 304 K for the sample La0.60Sr0.1K0.3MnO3.However,under the same applied field,there is only a maximum MR with 6.4% at 373 K for the un-substituted sample La0.60Sr0.40MnO3.Therefore,K＋ ion substitution can remarkably improve the MR of this kind of material.
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