摘要
利用溶胶凝胶法制备出(Ca_(0.96)D_(0.04))MnO_3(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CaMnO_3(CMO)块体,并对其进行相组成分析,选择出更为优异的CaMnO3块体制备方法。再进一步制备出(Ca_(0.96)D_(0.04))MnO_3(D=Sr, Rb, Sm)氧化物块体,最后对(Ca_(0.96)D_(0.04))MnO_3(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CaMnO_3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_(0.96)D_(0.04))MnO_3(D=Ca, Sr,Rb, Sm)块体;在整个测试温度范围内,(Ca_(0.96)D_(0.04))MnO_3(D=Sr, Rb, Sm)的ZT值在873 K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1.3~2.2倍。
The(Ca_(0.96)D_(0.04))MnO_3(D=Ca, Sr, Rb, Sm) oxide powders were prepared by a sol-gel method firstly, and the CaMnO_3(CMO)bulk samples were prepared thereafter by spark plasma sintering in an argon atmosphere and air atmospheric sintering at ordinary pressure.After analyzing their phase composition, a better preparation method for CaMnO_3 bulk samples were selected and then the(Ca_(0.96)D_(0.04))MnO_3(D=Sr, Rb, Sm) oxide bulks were prepared. Finally, the phase composition, microstructure and thermoelectric properties of(Ca_(0.96)D_(0.04))MnO_3(D=Ca, Sr, Rb, Sm) bulk samples were measured and analyzed. The results show that the CaMnO_3(CMO) bulk samples prepared by spark plasma sintering in argon atmosphere have undergone phase decomposition, which is due to the poor oxygen sintering environment of SPS. High quality(Ca_(0.96)D_(0.04))MnO_3(D=Ca, Sr, Rb, Sm) bulk samples with single phase can be prepared by air atmospheric sintering at ordinary pressure. For(Ca_(0.96)D_(0.04))MnO_3(D= Sr, Rb, Sm) bulk samples, the dimensionless figure of merit ZT is improved with peak values of 0.11, 0.08 and 0.07 at 873 K, which are 1.3~2.2 times higher than that of the un-doped samples.
引文
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