Formation and structure of 3:29-type Gd3(Fe1-xCox)29-yCry compounds

Based on a study of the phase relation in the Fe- and Co-rich region of the equi-gadolinium content section with the Gd content corresponding to the chemical formula Gd-3 Fe, Co, Cr) (29) in the Gd-Fe-Co-Cr quaternary system, formation, structure and magnetic properties of the 3 : 29-type Gd-3 (Fe1-xCox)(29-y)Cr-y compounds have been investigated. It has been found that the composition range of formation of the single phase Gd-3 (Fe1-xCox)(29-y)Cr-y Compounds is 0 less than or equal tox less than or equal to0.7 for y = 5.0, 0.7 less than or equal tox less than or equal to 0.8 for y = 5.5, and 0.8 less than or equal to x less than or equal to 1.0 for y = 6.0. A pure Co-based Gd3Co29-xCrx compound series have been synthesized. The solubility limit of the Cr atoms in the Gd3Co29-xCrx compounds was found to be from x = 6.5 to x = 7.3. The results indicate that all the synthesized Gd-3 (Fe1-xCox)(29-y)Cr-y compounds crystallize in Nd-3 (Fe, Ti)(29)-type structure of the monoclinic system and the space group A2/m. The solubility limit of Co atoms in the Gd-3 (Fe1-xCox)(29-y)Cr-y compounds increases with increasing the stabilizing element Cr. It is noteworthy that substitution of Co for Fe leads to a remarkable change of the magnetocrystalline anisotropy of the Gd-3 (Fe1-xCox)(29-y)Cr-y compounds. When x greater than or equal to0.4 the anisotropy changes from the easy plane type to the uni-, axial type, which is important for permanent magnet application.