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首页> 外文期刊>Materials Science and Engineering. B, Solid-State Materials for Advanced Technology >Transport properties of ZnO substituted lead vanadate glass system at eutectic composition
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Transport properties of ZnO substituted lead vanadate glass system at eutectic composition

机译：共晶组成下ZnO取代的钒酸铅玻璃体系的输运性质

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摘要

Glasses of the system x(ZnO)(50 - x)PbO:50V_2O_5 were prepared by melt-quench process in the range x = 0-15 mol%. Measurements are reported for dc electrical conductivity as well as thermoelectrical power for the above compositions in the temperature range 27-227℃. The experimental results are analyzed with reference to various theoretical models proposed for dc electrical conduction in amorphous semi-conductors. The analysis shows that at high-temperatures the temperature dependence of dc conductivity is consistent with Mott's model of phonon-assisted hopping conduction, variable range hopping mechanism and Schnakenberg's model mechanism. The high-temperature thermoelectric power (TEP) was satisfactorily explained by Heikes' relation and the data also showed evidence of small polaron formation in these glasses. Thermo EMF measurements indicate that all the glass samples including unsubstituted lead metavanadate are n-type at room temperature. As temperature is increased ZnO substituted samples change from n-type to p-type. When Heikes' formula is applied to all the systems at room temperature the amount of disorder was found to be the same in all the systems. When Emin's formula is used for the estimation of W_D, the activation energy due to disorder, in ZnO substituted samples, unusually large values of W_D (～0.6 eV) are obtained. The present results indicate that the Emin's formula cannot be directly used to estimate the disorder energy in ZnO substituted lead vanadates. The temperature dependent change of sign of the thermoelectric power S, in these systems may arise due to change in V~(4+)/V~(5+) ratio with the change of temperature or due to the onset of band type of conduction as in MnO or other extrinsic compensated semi-conductors.
机译：通过熔融淬火法在x ＝ 0-15mol％的范围内制备系统x（ZnO）（50-x）PbO：50V_2O_5的玻璃。报告了在27-227℃的温度范围内上述组合物的直流电导率和热电功率的测量值。参考针对非晶半导体中直流电传导提出的各种理论模型，对实验结果进行了分析。分析表明，在高温下，直流电导率的温度依赖性与声子辅助跳变的Mott模型，变程跳变机制和Schnakenberg模型机制一致。 Heikes的关系令人满意地解释了高温热电功率（TEP），并且数据还显示了在这些玻璃中形成小的极化子的证据。热电动势测量表明，所有玻璃样品（包括未取代的偏钒酸铅）在室温下均为n型。随着温度升高，ZnO取代的样品从n型变为p型。当将Heikes公式在室温下应用于所有系统时，发现所有系统中的无序量相同。当使用Emin公式估算W_D时，在用ZnO取代的样品中，由于无序引起的活化能会获得异常大的W_D值（〜0.6 eV）。目前的结果表明，Emin公式不能直接用于估算ZnO取代的钒酸铅中的无序能。在这些系统中，热电势S的符号随温度的变化可能是由于V〜（4 +）/ V〜（5+）比随温度的变化而变化，或者是由于导带类型的开始如MnO或其他非本征补偿的半导体。

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