采用溶胶-凝胶法(sol-gel)制备了名义组分为La0.60Sr0.40-Na工MnO3(x=0.00,0.10,0.15,0.20,0.30,0.33,0.35)的类钙钛矿型稀土锰氧化物多晶样品.发现用Na+替代部分Sr+2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的磁场作用下,样品La0.60 Sr0.07Na0.33MnO3在292K时磁电阻为24.4％,比不含Na的La0.60 Sr0.40MnO3增大了2.8倍；样品La0.60Sr0.25Na0.15MnO3在285K～345K温区内磁电阻保持在3.9％(±0.2％)左右,受温度影响不大,因此显著提高了样品的室温磁电阻和其温度稳定性.迄今为止还未见这类材料在室温附近具有如此宽范围和高温度上限的MR温度稳定性报道.这对于该类磁电阻材料的应用有很大意义.%Perovskite rare-earth manganites polycrystalline samples formulated as La0.60Sr0.40-xNaxMnO3 (x = 0. 00, 0. 10, 0. 15, 0. 20, 0. 30, 0. 33, 0. 35) were synthesized by sol-gel method. It is found that when Sr+2 ions were partly substituted by Na+1 ions, the Curie temperature of the substituted samples decreased to room temperature and the room temperature magnetoresistance (MR) increased obviously than un-substituted La0.60Sr0.40MnO3. Under an applied filed of 1. 8T, the maximum MR for the sample La0.60Sr0.07 Na0.33 MnO3 at 292 K was 24. 4% , 2. 8 times more than La0.60Sr0.40MnO3; and there was a stable MR of 3. 9%(±0. 2%) in the temperature range of 285K to 345K for the sample La0.60Sr0.25 Na0.15MnO3. Therefore, the room temperature magnetoresistance and the temperature stability of MR were obviously improved. Up to now, no similar reports have been found concerning so good temperature stability of MR in so wide temperature range around room temperature. These are prpbably significant to magnetoresistance materials application.
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