Structure, Properties Of La_0.4Nd_0.1Sr_0.5MnO₃ Thin Film And La_0.5-xNd_xSr_0.5MnO₃

In recent years, the colossal magneto-resistance effect in rare-earth manganite perovskites La1-xTxMnO3(where T was alkali metal Sr, Ca, Ba, Pb) have attracted considerable attention in scientific studies due to its potential application. 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 (La1-xREx)1-yTyMnO3 double rare earth structure(where RE was second kind of rare earth ions) were still not many, Doping Nd3+ film research is still blank. In this article, the systemic research and analysis about structures and properties for La0.5-xNdxSr0.5MnO3(x=0.0,0.1,0.2,0.3, 0.4) bulk material and La0.4Nd0.1Sr0.5MnO3 thin film have been investigated.Manganite perovskite polycrystalline samples of La0.5-xNdxSr0.5Mn03(x=0.0,0.1, 0.2,0.3,0.4) were prepared by solid phase reaction method. The samples was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), infrared absorption spectrum microwave absorption and four probe method. An orthorhombic perovskite structure forming when x is less than 0.3; the samples is composed of La0.1Nd0.4Sr0.5MnO3 and Nd2O3 when x is equal to 0.4. The grain shape is inerratic cube and grain size is not uniform. It shows that the particles is becoming smaller, and 615 cm-1 nearby the absorption peak of infrared absorption spectra moves from a lower frequency to a higher frequency with the increase of Nd doping content x. The concentration of doping Nd 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 La0.4Nd0.1Sr0.5MnO3 (LNSMO) films have been grown on (100) LaAl03 single 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 results show the LNSMO films annealed in range of 700～900℃have a single-phase with a pseudo-cubic perovskite structure. The different annealing temperature lead to oxygen content and grain size changing in thin film. Magneto-resistance of the thin film which are annealed at 850℃arrive at about 24.9% when the temperature is at 300K and the magnetic field is at 1.5T.