STRUCTURE, PROPERTIES OF La_0.8Zr_0.2MnO₃THIN FILM AND La_0.67Ca_0.33Mn_1-xZn_xO₃（0.03≤x≤0.2）

Since the giant magneto-resistance (GMR) effect in Fe/Cr was found, the structure and colossal magneto-resistance effect of the rare earth perovskite LaRxMnO3(R=Ca, Sr, Ba) was paid more attention. However, there were also many difficulties for this kind of magnetoresistance material in practical applications, such as:CMR effect occurred in a strong magnetic field (usually several Teslas) and low temperature area. These factors become a big limit in the applications of this kind of materials. At present, the researches mainly focused on A-site alkali metal doping, the reports about doping Zr4+were still not many. Therefore, doped Zr4+in the A-site La0.8Zr0.2MnO3thin film was prepared. An interesting way to modify the crucial Mn4+/Mn3+Proportion is to dope at the Mn site. In this article, the systemic research and analysis about structures and properties for La0.67Ca0.33Mn1-xZnxO3(x=0.03,0.05,0.1,0.15,0.2) bulk material and La0.8Zr0.2MnO3thin film have been investigated.Manganite perovskite polycrystalline samples of La0.67Ca0.33Mn1-xZnxO3(x=0.03,0.05,0.1,0.15,0.2) were prepared by solid phase reaction method. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), infrared absorption spectrum、microwave absorption and four probe method. An orthorhombic perovskite structure when Zn x is less than0.2; the samples is composed of Lao.67Cao.33Mn1-xZnxO3and ZnO when x is equal to0.2. The grain shape is inerratic cube and grain size is not uniform. It shows that the particles are becoming bigger, and615cm-1nearby the absorption peak of infrared absorption spectra moves from a lower frequency to a higher frequency with the increase of Zn doping content x. The concentration of doping Zn ions has an important effect on magnetoresistance (MR) and microwave absorbing properties of samples.Using RF magnetron sputtering and annealed at different temperatures, a series of La0.8Zr0.2MnO3films have been grown on (100) LaAlO3single crystal substrates. The thin film was characterized by X-ray diffraction (XRD), atomic force microscope (AFM), X-ray Photoelectron spectroscopy (XPS) and four probe method. The XRD analyses of these samples indicate that the La0.8Zr0.2MnO3films annealed at temperature range of700～900℃had a single-phase with a pseudo-cubic perovskite structure. The valence state of zirconium(doped element) was confirmed by XPS measurements. The results show that Zr mainly exists Zr4+valence state forms. The magneto-resistance of the thin film, which was annealed at850℃reached about26.7%when the temperature was300K and the magnetic field was1.5T.