Study on Molding and Performance for Nanometer La_(0.8)Sr_(0.2)MnO_3 Massive Material under High Pressure

The La0.8Sr0.2MnO3 massive samples were prepared with crystal grain size about 30nm under high pressure.The structure,grain size and morphology of the samples were characterized by X-ray diffraction(XRD) and field emission scanning electron microscope(FESEM).Raman spectra of the samples was carried out by micro-Raman spectrometer in the range of 100-3000cm-1 with the laser power of 400mW.The results showed that the grain evolution of La0.8Sr0.2MnO3 was influenced by temperature and pressure.When the agglomeration temperature was below 300℃,the grain growth rate increased with increasing pressure at the sintering pressure of 1-3GPa while it fell down as pressure rised continuously at the sintering pressure of 4-5GPa.The grain growth rate increased with increment of pressure when the agglomeration temperature was over 300℃.Physical properties of agglomeration samples synthesized under high pressure were studied.Experimental results indicated that the micro-hardness of samples increased obviously after high pressure agglomeration.When sintering temperature was 300℃,the resistivity of samples decreased firstly then increased with increment of pressure.The sample prepared under 5GPa at 300℃ had obviously ferromagnetic character at room temperature.