【摘要】 通过将样品放置在石墨粉旁 ,在高温下氮气氛中退火来改变La0 .35Ca0 .65MnOy 的氧含量 .脱氧初期氧含量的改变对样品的电输运特性有显著的影响 ,而磁性质的变化不大 .氧含量y =2 .90 2 ,2 .86 1,2 .85 2的样品电阻率随氧含量的减少而增大 .但随氧含量的进一步减小(y =2 .816 ) ,样品的电阻率反而减小 ,但样品在进一步脱氧时 (y <2 .810 )发生分解 .本工作表明在La0 .35Ca0 .65MnOy 体系中可以通过改变氧含量使Mn3+/Mn4+比与La1 -xCaxMnO3中出现巨磁阻效应的Mn3+/Mn4+比相近 ,但并不能使La0 .35Ca0 .65MnOy 出现巨磁阻效应更多还原

【Abstract】 The oxygen content of La-{0.35}Ca-{0.65}MnO-y was tuned by annealing the samples at high temperatures in flowing nitrogen with graphite powder nearby. The slight reduction of oxygen contents (y=2.902,2.861,2.852) enlarged samples′ resistivity, while keeping the magnetic properties unchanged. With further reduction of oxygen contents (y=2.816) sample′s resistivity decreases. When oxygen contents reduced to 2.810, La-{0.35}Ca-{0.65}MnO-y samples are destructed. This work shows that though oxygen content of La-{0.35}Ca-{0.65}MnO-y can be tuned so that the ratio Mn+{3+}/Mn+{4+} in La-{0.35}Ca-{0.65}MnO-y is comparable with the ratio Mn+{3+}/Mn+{4+} in La-{1-x}Ca-xMnO-3 showing CMR effect, La-{0.35}Ca-{0.65}MnO-y can not display CMR effect.更多还原