高温对钙钛矿La_(0.65)Ca_(0.18)Sr_(0.17)MnO_3形貌及磁热效应的影响

Effect of high-temperature on shape and magneto-caloric effect of La_(0.65)Ca_(0.18)Sr_(0.17)MnO_3 perovskite

采用水热合成法制取了La0.65Ca0.18Sr0.17MnO3钙钛矿粉末.通过X射线衍射仪(XRD)测量与扫描电镜(SEM)观测,发现高温不改变纯的La0.65Ca0.18Sr0.17MnO3的晶体结构,但对立方相的La0.65Ca0.18Sr0.17MnO3的形貌有一定影响.在1.4 T的磁场下,利用自制的ΔTad-T曲线测量仪测得La0.65Ca0.18Sr0.17MnO3样品的磁热效应,结合其在0.01 T下的M-T曲线图,得出高温影响钙钛矿样品磁热效应测量的实质是:高温改变了钙钛矿粉末的致密度从而影响对其磁热效应测量的准确性.

La0.65Ca0.18Sr0.17MnO3 perovskite powder was prepared by hydrothermal method. The experiment shows that high-temperature can not change the crystal structure of pure La0.65Ca0.18Sr0.17MnO3 powder proved by X-ray diffraction（XRD） but has an effect on the shape of La0.65Ca0.18Sr0.17MnO3（cubic phase） powder according to SEM. The magneto-caloric effect of the perovskite powder was measured by directly using the self-made △Tad- T curve measurement device at the magnetic field of 1.4 T and its M-T curve was measured at the magnetic field of 0.01 T. The high-temperature affects the accurate measurement of magneto-caloric effect of perevskite because it changes the dense degree of the perevskite powder.