Papers by Author: Shi Qing Yang

Abstract: MnZn soft ferrite materials with NiO-CoO dopant are prepared by conventional oxide technique.The influences of CoO and NiO addition on the microstructure and magnetic properties of low-loss and high Bs MnZn ferrites are investigated. The present results show that MnZn soft ferrite materials with CoO addition of 0.1wt% and NiO addition of 1.28wt% possess both homogeneous grains and high saturation magnetic flux density. The lowest loss point is located at 100°C. The valley point of power loss shifts to higher temperature with increasing of NiO dopant. The power losses decrease and sintering density increases with increase of CoO addition. The sintered MnZn ferrite materials based upon a specific sinter curve possesss excellent comprehensive properties: μi=2198 , Pcv=319 kw/m3 , Bs=540mT (T=25°C), Bs=451mT (T=100°C).

Abstract: In this paper, the influences of depositing angles on TbFe film magnetic and magnetostrictive characteristics were discussed. TbFe films were deposited by DC magnetron sputtering. With the decrease of depositing angles from 900 to 150, TbFe film in-plane magnetization measured at 1600kA.m-1 external field is greatly increased. With the decrease of depositing angles from 900 to 150, the magnetostrictive saturation field is decreased. TbFe film in-plane magnetostriction is improved when depositing angles are changed from 900 to 150. Magnetic domain structures detected by MFM indicates that film easy magnetization direction is gradually changed from perpendicular to parallel with the decrease of depositing angles. The variation of film magnetic and magnetostrictive performances can be explained by the oblique anisotropy associated with columnar grain morphology of the films.

Abstract: In this paper, the influences of annealing temperature on TbFe magnetostrictive film magnetic and magnetostrictive characteristics were discussed. TbFe films were prepared by RF magnetron sputtering. XRD patterns indicate that polycrystalline films consisting mainly of a-Fe and TbFe2 Laves phase could be obtained through rapid cycle annealing process (RCAP) at higher annealing temperature. Grain sizes could be controlled through varying annealing temperature. From film hysteresis loops measured by VSM, it has been found that the annealing treatment can improve TbFe film in-plane magnetization at 1600 kA.m-1 external field, and decrease in-plane coercivity. Magnetostriction of annealed TbFe films measured by optical cantilever deflectometer is better than as-deposited films at 40 kA.m-1 external magnetic field.