Kazuo Kanematsu

Magnetism and Crystal Structure of Zirconium Compound with Laves Structure

Magnetic studies were performed on intermetallic compounds with Laves‐type structure, (Zr, Nb)Fe2, (Zr, Mo)Fe2, Zr(Fe, Mn)2, Zr(Fe, V)2, and Zr(Fe, Co)2. The crystal structure of all the compounds except Zr(Fe, Co)2 changes from the MgCu2 type to MgZn2 type with decreasing ZrFe2 content. The magnetism changes from ferromagnetism to paramagnetism with change from MgCu2 type to MgZn2 type, and it is concluded that the MgCu2 structure favors ferromagnetism and MgZn2 structure does not. Zr(Fe, Co)2 has a MgCu2 structure over the entire composition range and the magnetism changes from ferromagnetism to paramagnetism with decreasing ZrFe2 content.

Ferromagnetism of YFe2Hx

Isothermal hydrogen absorption of YFe2 at several temperatures forms four types of hydrides: δ, γ, β1, and β2. The δ hydrides with an orthorhombic MgCu2‐type structure, YFe2H4.1, are ferromagnets of 3.8μB/f.u. (YFe2H4.1) and Tc=310 K. The Mossbauer spectrum is analyzed with the direction of magnetization along [111]. The γ hydride YFe2H2.4 is a rhombohedral‐type ferromagnet of 3.5μB/f.u. and Tc=500 K. The spectrum is analyzed with the direction of magnetization along the c axis. Both β1 hydride YFe2H1.9 and β2 hydrides YFe2H1.3 are rhombohedral‐type ferromagnets of 3.5μB/f.u. and Tc=570 K. The β1 hydride shows a smooth decrease of magnetization but the β2 hydride shows a large decrease of magnetization between 200 and 400 K. The Mossbauer spectra of both hydrides are analyzed with the direction of magnetization in the c plane. The magnetization decrease in the β2 hydride is discussed, assuming high‐ and low‐magnetization phases.

Structural and magnetic properties of Ni2In type (Mn1 − xNix)65Ga35 compounds

Abstract New intermetallic compounds (Mn 1 − x Ni x ) 65 Ga 35 of Ni 2 In type structure are found in the range of 0.15 ⩽ x ⩽ 0.45. In the higher x range, the magnetization—temperature curves show Curie—Weiss type behaviors, but those with x ⩽ 0.35 suggest another type ferromagnet. The magnetic ordering temperature T c decreases for x ⩽ 0.2 and then increases with increasing x . The curves of 0.25 ⩽ x ⩽ 0.3 show a hump and then slightly decrease with decreasing temperature. In the neutron diffraction experiment for x = 0.275, the (0 0 1) reflection appears for 165 K ⩽ T T C to 8.47 C with temperature.

Crystal structure and magnetic properties of Y1−xZrxFe2.9

Crystal structure of Y 1- x Zr x Fe 2.9 system were ascertained by X-ray diffraction to be classified in four types, PuNi 3 type in x <0.3, orthorhombic type in 0.3< x <0.7, C14 like hexagonal type in 0.7< x <0.85 and C15 type in 0.85< x <0.95. The Mossbauer spectra of the compounds were explained to be two superimposed hyperfine patterns. It is concluded that a direction of hyperfine field lies in the c plane for the compounds in 0< x <0.3 and lies along the c axis for the compounds in 0.4< x <0.95.

Magnetic and crystallographic properties of deuterides YFe2Dx

The isothermal deuterium absorption and desorption experiments, X-ray and magnetization measurements revealed four types of deuterides in YFe 2 D x , γ 1 of 3.8< x , γ 2 of x <3.4, and β and amorphous of x <2.1 at room temperature. The crystal structure of all deuterides are rhombohedral. The magnetization of all deuterides are about 3.8 µ B /YFe 2 D x and the Curie temperatures are 120 K for the γ 1 -deuteride and 300 K for the γ 2 -deuteride. The β-deuteride is always a mixture with the amorphous deuteride, and the Curie temperature of amorphous deuteride is 570 K and that of β-deuteride varies from 290 K to 400 K with increasing deuterium concentration. Mossbauer mesurements were performed and hyperfine fields of Fe were estimated for every deuterides.

Formation and magnetic properties of crystalline and amorphous SmCo2 hydrides

Ferromagnetic C15-type compounds SmCox are found for 1.74 ⩽ x ⩽ 2.04. The values of the magnetizations vary from 1.21 μB(SmCo1.74)−1to 1.34 μB(SmCo2.04)−1. The Curie temperatures are 230 K, independent of x. The initial hydrogenation of SmCox leads to a C14-type hydride which contains about four hydrogen atoms per SmCOx. Below 373 K, the C14-type hydride changes into a PuNi3-type hydride having four hydrogen atoms per SmCo2. Above 453 K, the C14-type hydride transforms into an amorphous hydride having fewer than three hydrogen atoms per SmCo2, which in turn decomposes into SmH2 and cobalt above 573 K. The C14-type and the PuNi3-type hydrides are considered to be paramagnetic. The amorphous hydride is ferromagnetic up to the decomposition with 2.2 μB(SmCo2)−1.

Magnetic and X-Ray Studies on (Fe1-xVx)3Ge

The ternary system (Fe1-xVx)3Ge has three types of structure, hcp(D019), bcc(A2 or L21), and A15, which are stable 0x0.10, 0.17x0.28, and 0.55<x1.0 respectively. The magnetization of the ferromagnetic hcp and bcc alloys decreases linearly with x. The paramagnetism of the A15 alloy varies with substitution of Fe from the Pauli type to the Curie-Weiss type. The magnetic properties and the phase boundaries of the bcc alloy suggest that the structure is of the L21 type.

Effect of beryllium on magnetism of R2Co17Be

Abstract X-ray and magnetization measurements were performed for R 2 Co 17 and R 2 Co 17 Be in order to investigate the effect of beryllium on the magnetic properties. Addition of beryllium makes Th 2 Zn 17 structure more stable than Th 2 Ni 17 structure and decreases the magnetization and Curie temperature.

Effect of Interstitial Beryllium Atoms for the Magnetic Properties of R2Fe17Be

Magnetic Properties R2Fe17Be have been studied in order to detect the effect of interstitial beryllium atom for the magnetic properties of R2Fe17. Experimental results show that the lattice constants, magnetization and Curie temperature of R2Fe17 decrease by adding beryllium. The effect of beryllium for the magnetic properties was discussed.

Magnetic properties of (Ni1-xMnx)1.9Ge Alloys

Abstract The high-temperature phase of (Ni 1 - x Mn) 1.9 Ge is found to be a hexagonal Ni 2 In type structure in the range 0 ⩽ x ⩽ 0.7. In the lower values of x , spin glass and re-entrant spin-glass phase was found. In the range 0.55 ⩽ x ⩽ 0.7, the alloys are ferromagnetic and the Curie temperature decreases with increasing x . A phase transition of Ni 2 In type ⇔TiNiSi type occurs at 0.45 ⩽ x ⩽ 0.55, below 270K. Magnetic and crystallographic phase diagram is proposed.