Sintering temperature effect on electrical and thermal properties of Zn_(1-x)Al_xO as thermoelectric material candidate

摘要

Thermoelectric is a device to convert residual heat energy into electricity. Electrical and thermal properties of constituent material determine thermoelectric efficiency. One of metal oxides, namely zinc oxide (ZnO), is highly stable in a large temperature range, non-toxic, low cost and eco-friendly, has potential application as thermoelectric at high temperature. The aims of this study are to synthesize Zn_(0.98)Al_(0.02)O by coprecipitation method using ZnO and Al_2O_3 powders as raw materials, and to investigate the effect of sintering temperatures (at 700, 800, 900, and 950°C) on the electrical and thermal properties of the material. The sample products were analyzed by x-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive x-ray (EDX) measurements to identify phase content, to observe particle morphology and to analyze distribution of elements in the sample, respectively. LCR meter was conducted to study electrical measurements of the samples. Further, thermal properties of the samples were analyzed by TGA measurements. The data show that Al~(3+) ions have been successfully doped into ZnO crystal lattice and they tend to increase the electrical conductivity of the samples. The sintered Zn_(0.98)Al_(0.02)O sample at 900°C has the highest conductivity value (4.53 × 10~(-4) S/m) compared to the others. It is relatively stable at high temperature, and thus, it can be used as one promising candidate for thermoelectric material at high temperature.