4 . magnetism study on we presented a detailed study of dy - doping effect on magnetism
Moreover , the diffraction peak shifts toward high angle as sr content increases . it is ascribed to the substitution of la3 + by sr2 + in lscf increases the average radius of a ions and causes a charge imbalance
The investigation of structure by x - ray diffraction shows that crystal parameters changes clearly when percenting ca and la into pbtio _ 3 , it was caused by the ca ion and la ion replaced the pb ion of a position in perovskite compound , that bring lattice mismatch and asymmetrical replace
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
The future work will be concentrated as following : ( 1 ) the mechanism of the effect of doping in a site on 2pr should be clarified by the research on the rule of 2pr of sbti doped by the lanthanide serials having different ions radii ; ( 2 ) the properties bit - sbti doped in the b site should be studied ; ( 3 ) the thin films of these materials should be prepared and their properties should be studied
The difference between the magnetic moments for the samples with respective doping level can be ascribed to the variation of the competition between thermal effect and the magnetic coupling . based on the spin orientation rotation of dy sublattice as well as the antiferomagnetic coupling between dy sublattice and mn sublattice , we successfully elucidate the changes of magnetic structure in perovskite compounds s . electron spin resonance ( esr ) study on perovskite compounds on the basis of chapter 4 , we give further study on micromagneticism of dy - doping perovskite compounds la0 . 67 - xdyxsr0 . 33mno3
According to the sample prepared by hydrothermal method , the doping cations can enter the spinel lattice . rare earth cations mostly occupy position b because of their big radius . cerium are oxidized to ce4 + , whose radius is relatively small , and ce4 + mostly occupies position a . as a whole , the coercivity of cobalt ferrite doped with rare earth element is bigger than that of pure cobalt ferrite
This viewpoint is concided with the 2pr of sr2bi4ti5o18 ferroelectrics doped by la . the curie temperatures of sblt and blt - sblt decrease with the increase of la content . for sblt , when la content excesses 0 . 75 , the samples exhibit typical characteristics of relaxor type ferroelectrics . blt - sblt with 1 . 50 la exhibits characteristics of relaxor type ferroelectrics as well
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