(Ca0.96D0.04)MnO3(D=Ca, Sr, Rb, Sm)氧化物的制备和热电性能研究

Preparation and thermoelectric properties of (Ca0.96D0.04)MnO3(D=Ca, Sr, Rb, Sm)

摘要:

利用溶胶凝胶法制备出(Ca_0.96D_0.04)MnO₃(D=Ca, Sr, Rb, Sm)氧化物粉末后,先分别采用氩气气氛的放电等离子烧结和空气气氛的常压烧结制备出CaMnO₃(CMO)块体,并对其相组成进行分析,选择出更为优异的CaMnO₃块体制备方法。再进一步制备出(Ca_0.96D_0.04)MnO₃(D=Sr, Rb, Sm)氧化物块体,最后对(Ca_0.96D_0.04)MnO₃(D=Ca, Sr, Rb, Sm)块体的物相组成、显微组织和热电性能进行测试分析。实验结果表明：氩气气氛放电等离子烧结制备的CaMnO₃块体发生物相分解,原因是放电等离子烧结的烧结环境贫氧；空气气氛的常压烧结可以得到物相较纯净的(Ca_0.96D_0.04)MnO₃(D=Ca, Sr, Rb, Sm)块体；在整个测试温度范围内,(Ca_0.96D_0.04)MnO₃(D= Sr, Rb, Sm)的ZT值在873K时达到最大,分别为0.11、0.08和0.07,相比于未掺杂试样提高了约1.3~2.2倍。

Abstract:

The (Ca_0.96D_0.04)MnO₃(D=Ca, Sr, Rb, Sm) oxide powders were prepared by sol-gel method firstly, and the CaMnO₃(CMO) bulk samples were prepared thereafter by spark plasma sintering in argon atmosphere and air atmospheric sintering at ordinary pressure respectively. After analyzing their phase compositions, the better preparation method of CaMnO₃ bulk samples are selected and then the (Ca_0.96D_0.04) MnO₃ (D=Sr, Rb, Sm) oxide bulks were prepared. Finally, the phase composition, microstructure and thermoelectric properties of (Ca_0.96D_0.04) MnO₃ (D=Ca, Sr, Rb, Sm) bulk samples are measured and analyzed. The results show that the CaMnO₃(CMO) bulk samples prepared by spark plasma sintering in argon atmosphere have occurred phase decomposition, which is due to the SPS poor oxygen sintering environment. High quality (Ca_0.96D_0.04)MnO₃(D=Ca, Sr, Rb, Sm) bulk samples with single phase can be prepared by atmospheric sintering at ordinary pressure. The dimensionless figure of merit ZT is improved with peak values of 0.11,0.08,0.07 at 873K for (Ca_0.96D_0.04)MnO₃(D= Sr, Rb, Sm) bulk samples respectively, which are about 1.3~2.2 times higher than that of the un-doped samples.