【摘要】 用渗银和银胶接触两种方法分别在多晶Nd0.7Sr0.3MnO3陶瓷样品上制作电极,用两线和四线模式对两种接触界面的直、交流特性进行测量.结果发现:渗银电极与陶瓷样品之间具有很好的欧姆接触特性,两线、四线模式下的电阻测量值相近,并且没有电脉冲诱导电阻转变(EPIR)效应;而用银胶接触作电极时,V-I曲线表现出关于原点对称的非线性特征,并出现稳定的室温EPIR效应.两种不同方法制备的电极在交流电场下的输运也有很大差异:渗银电极阻抗实部随频率增大而增大,表现为趋肤效应;而银胶电极阻抗实部随频率增大而减小,当频率超过7kHz时,阻抗实部-温度曲线峰值出现分化.结合扫描电镜的结果,对两者在电输运特性差异上的原因进行了探讨.更多还原

【Abstract】 The transport properties of interface between metal electrode and Nd0. 7Sr0. 3MnO3 bulk have been investigated under 2-wire measuring mode using permeating Ag and Ag-glue contact,respectively. The results show that,for the permeating Ag contact,the measured results are similar to that of 4-wire measurement,and an ohmic character is obtained without EPIR effect. However,a strongly nonlinear V-I curve appears and exhibits a stable EPIR effect for the Ag-glue contact. Besides,It also shows remarkable difference when loaded with alternating current for the two different kinds of contacts. For the former,the real part of impedance R′ increases with increasing frequency which is attributable to the skin effect; for the latter,however,the R′ is of about megohm order of magnitude and the R′ peak decreases with increasing frequency. Moreover,the R′ peak splits into two peaks which respectively move to high and low temperature when further increasing the frequency. In combination with the data of scanning electron microscopy,the differences of electrical transport are discussed.更多还原