钇掺杂钨酸铅晶体中的极化子和导纳谱

Polaron and admittance spectroscopy of yttrium-doped lead tungstate single crystal

在室温至 16 0℃范围内测量了掺钇钨酸铅 (PWO∶Y)晶体的直流电导率 ,证明此时的载流子为极化子 .观察到极化子由能带导电到跳跃导电转变引起的电导率极小 .在此温区的交流导纳分析给出的交流电导率比直流电导率大三个数量级 ,说明此时的交流电导率主要是复介电常数的贡献 .当样品的电导率和介电常数均随频率而变化时 ,从交流测量只能得到样品的总的导纳谱 ,而不能将其中的电导谱和介电谱分开 .

Both DC and AC conductance of,Y-doped PbWO4 single crystal have been studied over a temperature range from ambient temperature to 160 degreesC. Results of DC conductivity indicate that the carriers in PbWO4 in such a temperature range are polarons other than ions, for a transition of polarons from energy band conduction to hopping conduction which characterized by a minimum of conductivity has been observed. AC conductivity obtained from admittance analysis is almost 3-orders higher than that of DC analysis, it ought to be mainly ascribed to the effect of dielectric. If conductivity and dielectric constant of a given system change together with frequency, AC measurement can only yield a total admittance spectrum, but is unable to separate conductivity spectrum from dielectric spectrum.