Tsugio Shibata

Magnetic properties of some gadolinium—Cobalt intermetallic compounds

Abstract Crystallographic and magnetic properties of the single crystals having the compositions of GdCo 3 , Gd 2 Co 7 , GdCo 5 , Gd 2.2 Co 16.6 and Gd 2 Co 17 were studied in order to contribute to the investigation of the magnetic anisotropy in the Gd–Co system. The single crystal used were prepared by means of the Bridgman method using BN-coated alumina crucibles. The room-temperature magnetocrystalline anisotropy constants K 1 of GdCo 3 , Gd 2 Co 7 , GdCo 5 , Gd 2.2 Co 16.6 and Gd 2 Co 17 are determined as 8.1 × 10 6 , 1.3 × 10 7 , 4.1 × 10 7 , 3.0 × 10 6 and -2.7 × 10 6 erg/cm 3 , respectively. it is also found that the magnetocrystalline anisotropy of Gd–Co phases in the stable region of the Th 2 Zn 17 -type structure changes very sensitively from negative to positive as the ratio Gd/Co increases above the stoichiometric ratio of 2/17.

Single crystal preparation of rare earth-cobalt intermetallic compounds by a BN-coated crucible

Abstract A preparation method for single crystals of RCo 5 and R 2 (Fe x Co 1− x ) 17 by a Bridgman technique using a BN-coated crucible is presented, where R denotes Y, Pr, Nd, Sm, and Gd. The grown single crystals are about 13 mm in diameter and 50 mm long. The single crystals of RCo 5 and R 2 (Fe x Co 1− x ) 17 where R has a low vapor pressure at high temperatures such as Y, Nd, and Gd tend grow more easily. The growth of single crystals such as SmCo 5 and Sm 2 Co 17 is more difficult because of the high vapor pressure of Sm. Some magnetic properties are described for the Y 2 (Fe x Co 1− x ) 17 ( x = 0−0.5) system as an example.

Magnetization reversal in GdCo5 single crystals

The magnetic properties and the process of magnetization reversal in a bulk single‐crystal sphere of GdCo5 were studied between 80 and 300 K. Numerous rectangular hysteresis loops were observed similar to observations made in small‐particle experiments, and they are discussed in terms of the nucleation model and the pinning model.

Magnetic Properties of RCo5 Permanent Magnets Prepared by Liquid Phase Sintering

Results of the experiments on the effects of liquid phase sintering for YCo5, LaCo5, SmCo5, PrCo5 and Sm-Pr-Co series are reported. It is observed that the crystals of an optimum sintering change into a single phase of CaCu5 type. The lattice parameters of RCo5 magnets prepared by the liquid phase sintering process give different unit cell volumes from the base materials. The optimum amount of Co in the sintered Sm-Co alloys was found to be 64.3 wt%. We obtained the best magnetic properties in Sm-Pr-Co series when Sm0.3Pr0.7Co5 was used as a base material.