Heyan Liu

New quarternary half metallic material CoFeMnSi

A good field to develop new materials with half metallicity is the quaternary Heusler alloys. The preferred route is to combine the compounds that have been already grown in Heusler structure. As a typical example, the quaternary LiMgPdSb-type CoFeMnSi have been investigated in detail. For the quaternary LiMgPdSb-type compounds, three nonequivalent structures exist. From the calculated density of state (DOS) results, it can be seen that one superstructure shows half metallicity. The second superstructure has a pseudogap at the Fermi level. The third superstructure shows metallic behavior. Based on the analysis of the measured XRD pattern and magnetization curve, we can deduce that the CoFeMnSi compound is crystallized in the structure where half metallicity occurs.

Half-metallic ferromagnetism in zinc-blende CrBi and the stability of the half-metallicity of zinc-blende CrM (M = P, As, Sb, Bi)

First-principles calculations within density-functional theory are used to investigate zinc-blende-structured CrBi. Our calculation predicts ZB-type CrBi to be a true half-metallic ferromagnet with a magnetic moment of 3 μB per formula. Its half-metallicity can be maintained over a relatively wide range of lattice constant (from −8 to 8%). The trends with varying lattice constant for the ZB-type half-metallic system CrM (M = P, As, Sb, Bi) are also studied.

Synthesis of Iron-Based Laves Phase Containing Praseodymium Magnetostrictive Materials

Abstract The synthesis and magnetostriction of Pr x Tb 1-x Fe 2 , Pr x Tb 1-x Fe 2 B 0.2 and Pr x Tb 1-x (Fe 0.6 Co 0.4 ) 2 alloys were investigated in this study. The addition of boron or cobalt atom in Pr x Tb 1-x Fe 2 could effectively prevent the formation of non-cubic phases, and Pr concentration limit was successfully increased from 0.2 to 0.4. X-ray step scanning for the Pr x Tb 1-x Fe 2 B 0.2 and Pr x Tb 1-x (Fe 0.6 Co 0.4 ) 2 alloys showed that PrFe 2 possessed a large spontaneous magnetostriction λlD III .

The magnetic properties of closely spaced three-dimensional nanomagnet array

With Monte Carlo method, we investigate the magnetic ground state, magnetic specific heat, and magnetic hysteresis loop for three types of closely spaced nanomagnet arrays in three-dimensional (3D) space. It is found that the magnetic ground state of three nanomagnet arrays exhibits the vortex order, caused by the long-range dipolar interactions. Three types of nanomagnet arrays have almost the same magnetic transition temperature even if their array formation in 3D triangular lattice is different. Some slight jump occurs in the hysteresis loop of the face-centered cubic nanomagnet array, while for the simple hexagonal nanomagnet and close-packed hexagonal nanomagnet arrays no jump is found.

Study on the sintering method of Terfenol-D

A sintering method, which is called low-temperature instantaneous liquid-phase sintering with addition of Sn, is exploited to fabricate Terfenol-D sintered compacts. In this work, the influences of powder size, Sn content, compaction pressure, and sintering technique on the magnetic and mechanical properties have been investigated. A large magnetostriction (λ‖) of 546ppm at 12kOe is obtained for the sintered compact fabricated at the following conditions: a powder size <75μm, a Sn content of 8:100, a compaction pressure of 1.0GPa, and sintering at 250°C for 150s in the rapid thermal processor. In addition, the sintered compact fabricated by this means possesses higher oxidation resistance and its hard brittleness improves.