【摘要】 本文主要介绍用溶胶 凝胶法制备的Ba离子掺杂的双层钙钛矿锰基氧化物La4 /3(Sr1-xBax) 5/3Mn2 O7(0 <x <1)在液氮温区的电输运性质 .在Ba离子掺杂x≤ 0 .2时 ,金属 绝缘体的转变温度 (Tp)随着掺杂量的增加向低温移动 ,低温电阻增加 ;当x≥ 0 .2时 ,随掺杂量的增加Tp 反而逐渐升高而低温电阻减小 .对于不同烧结温度的样品 ,在x <0 .4范围内 ,低温电阻值随烧结温度增加而增加 ;在x >0 .4范围内 ,低温电阻值随烧结温度增加而减小 .出现这种反常行为的结果可能是由于随着Sr逐步被Ba离子取代而引起的失配效应造成结构相分离所致更多还原

【Abstract】 A series of layered manganites of La-{4/3}(Sr-{1-x}Ba-x)-{5/3}Mn-2O-7(0≤x≤1) were prepared by Sol-Gel. The electrical transport properties were measured in a temperature range of 77～300K. Experimental results show that, with increasing of x for the level of x≤0.2, metal-insulator transition temperature T-p decreases and low-temperature resistance increases; with increasing of x for the level of x≥0.2, T-p increases and low-temperature resistance decreases. For the samples with different sintering temperatures, with increasing of the sintering temperature, the low-temperature resistance increases in the doping level of x<0.4. However, the low-temperature resistance decreases in the doping level of x>0.4. The observation of abnormal behaviors of Ba doped La-{4/3}(Sr-{1-x}Ba-x)-{5/3}Mn-2O-7 may result from the coexistence of La-{1/3}Sr(Ba)-{2/3}MnO-3 and (Sr,Ba)O.更多还原