作　　者： ; ; ;

机构地区： 福建农林大学机电工程学院

出　　处： 《福建农林大学学报（自然科学版）》 2007年第3期331-336,共6页

摘　　要： 用溶胶凝胶法制备Cu低掺杂La0.7Ca0.3Mn1-xCuxO3(x=0%,1%,2%,3%,4%,5%)系列单相多晶巨磁电阻材料.在77-350 K下测量了样品的电阻率随温度的变化关系,结果表明,样品电阻率与温度的关系均具有明显的电阻率峰结构.采用小极化子绝热跃迁模型对系列样品的ρ-T曲线进行ρ=0ρTexp(E/kT)关系拟合,结果表明,电阻率的转变峰对应于绝缘体—金属相(I-M)转变,且系列样品的电阻率随温度的变化在相转变峰以上温区很好地符合小极化子绝热跃迁模型,从而确定了样品的高温区,为相转变温度以上温区;在此基础上采用小极化子绝热跃迁模型电阻率与温度的关系式对系列样品的高温区电阻率—温度关系曲线进行拟合,分别得到系列样品的电导活化能(激活能).拟合结果表明,Cu离子的掺入较大地改变了系统的电导活化能,随掺杂浓度的增高,系列样品的活化能依次递增. A series of polycrystal bulk low Cu doping samples of La0.7Ca0.3Mn1-xCuxO3 （x =0% ,1% ,2% ,3% ,4% ,5% ） have been prepared by Sol-Gel process. The temperature dependences of resistance Of all the samples were measured from 77 K up to 350 K. The measurement results indicated that obvious peaks existed in the resistivity-temperature curves. Basing on nonadiabatic small polaron hopping model, we used the function of ρ=ρo Texp（E/kT） to fit the p-T curves. The fitting results showed that the resistivity peaks corresponded to the transition of the phase from mater to insulator （M-I）. Under this condition, using function of ρ =ρo Texp（E/kT） deduced from nonadiabatic small polaron hopping model, we fitted the resistivity of all the samples in high temperature region （ the temperature region higher than transition temperature of the phase）, and the conductance activation energies of all the samples were gained respectively. The fitting results indicated that the doping of Cu ion influenced the activation energies obviously, activation energies increased gradually with the increasing of substitution contents.

关 键 词： 低掺杂 电阻率 高温区 电导活化能

领　　域： [理学] [理学]