Preparation And Thermoelectric Properties Of Layered CaMnO₃

In this paper,CaO?CaMnO₃?m?m=1,2,3?powders with lamellar structure were prepared by sol-gel method.X-ray diffraction?XRD?,scanning electron microscopy?SEM?,Fourier transform infrared spectroscopy?FTIR?and laser thermal conductivity tester were used to study the relationship between the composition of the powder phase,the thermoelectric properties and the thermal conductivity and electrical conductivity.It was found that single-phase Ca₂MnO₄ powder was obtained under the condition that the ratio of citric acid and total amount of citric acid was 1,1.5 and 2,respectively,and the calcination temperature was higher than 700°C.The The ratio of citric acid to the total amount of metal ions is 1: 1.After calcination at 900°C,the average grain size of Ca₂MnO₄ powder is about 16 nm,and the dispersibility is better.Calcium nitrate and manganese nitrate as the reactants,calcium ions and manganese ions in the amount of the ratio of 3:2 and 4:3,citric acid and the total amount of metal ions in the ratio of 1.5:1,by 1200°C After calcination,single-phase Ca₃Mn₂O₇ powder and Ca₄Mn₃O₁₀ powder were obtained respectively,and the average grain size was about 23 nm and 24 nm.At the same time,it was found that the thermal conductivity of the typical Ca₂MnO₄,Ca₃Mn₂O₇ and the typical Ca₄Mn₃O₁₀ powders was 0.072 Wm-1K-1,0.129Wm-1K-1 and 0.142Wm-1K-1 at 300 K.At 600 K,in the order of 0.075 Wm-1K-1,0.113 Wm-1K-1 and 0.134Wm-1K-1.