The Preparation And Properties Of Multiferroelectric Magnetoelectric LCMTO

Multiferroelectric magnetoelectri materials have a spontaneous polarization that can be reoriented by an applied electric field, a spontaneous magnetization that can be reoriented by an applied magnetic field. These materials have been exploited as transducer, waveguides, switches, phase inverters, modulators, etc. Which also find a lot of technological applications in radioelectronics, optoelectronics, microwave electronics in instrumentation. However few existed in nature. Many of the multiferroelectric magnetoelectric material have been synthesized by two phases for the purpose, and many of the research have always been concentrated on the substitution between the A-site cation Ln and other metallic ions effect on the properties. The substitution of A-site cation Ln can induce significant effect on the magnetization and polarization, nevertheless B-site cation can induce more effect on the polarization of perovskite structure. As a result, the doping of titanate which had typical high dielectric behavior would have significant effect on the research and development of novel multiferroelectric magnetoelectric material. This paper investigated the preparation and properties of multiferroelectric magnetoelectric LCMTO bulk and film which keeps substitution each other between La and Ca as well as Mn and Ti.The development research on multiferroism was intensively reviewed in this paper. The application of radio frequency magneto-controlled sputtering was introduced briefly.In this research, multiferroelectric magnetoelectric LCMTO with excellect crystal and electric properties which keeps substitution each other between La and Ca as well as Mn and Ti were prepared by traditional ceramic process, and the film was prepared by radiofrequency magneto-controlled sputtering.The results showed that in La0.5Ca0.5MnxTi1-xO3 two dielectric peaks appeared at the temperature of 50-300 and 400-450 . The former was related to Mn doping,both of p-carries supplied by La3+ or oxygen hole and n-carries induced by changing Mn4+ into Mn3+ can be locally displaced and simultaneously response with external electric field., furthermore due to the overlaps between positive and negative carries. The latter was due to the phase transformation between orthorhombic and cubic, which was in fact the Curie point.In the system, more hole deficiency was supplied by excessive La ions. This increased the concentrations of p-carries, and decreased the bound of crystal lattice field to the carries on the other hand. As a result, the dielectric peak move to lower temperature due to the carries.It is approved that the deficiency level keeps relatively the lowest and the dielectric constant however shows the highest, if the contents of Mn3+ and La3+ are comparatively the same. On the contrary, the dielectric constant decreases with increasing the contents difference of Mn3+ and La3+ ions. The effect of overlap appeared when the dielectric loss was aroused due to the activation of positive and negative carries at certain temperature, which brought abnormally high dielectric loss. The 3d electrons increased with the content of Mn doping increasing, and the electrical property increased accordingly as the electron transport path improved.It is confirmed that all the orthorhombic perovskite phase which is formed initially at the heat treatment temperature of about 600C and thoroughly above 850C are observed in the LCMTO thin film deposited on Si (100) substrate by rf magneto-controlled sputtering. The contents of the perovskite phase in the thin film increases with increasing heat treatment temperature up to 850 . As the heat treatment temperature increasing, the lattice constant in La0.55Ca0.45Mn0.27Ti0.73O3 and La0.56Ca0.44Mn0.38Tio.62O3 thin film deposited on Si (100) increases due to the existence of strain between thin film and silicon substrate, and the the lattice constant in La0.69Ca0.31Mno.37Ti0.63O3 thin film deposited on Ag/Si(100) decreases due to the stress between thin film and silicon substrate.