STABILITY RANGE, STRUCTURE AND MAGNETIC-PROPERTIES OF YFE12-XMOX (0.5-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-2.0) ALLOYS

Intermetallic compounds with the general formula YFe12-xMox (0.5 less-than-or-equal-to x less-than-or-equal-to 2.0) were prepared by arc Crystal structure determination by X-ray powder diffractometry and Rietveld refinement techniques has shown that a tetragonal ThMn12 is formed with small admixture of alpha-Fe only for x < 1.0. Extrapolation of the linear dependence of the lattice parameters to x = 0 gives a = 8.4727 angstrom, c = 4.7682 angstrom and a unit cell volume V = 342.3 angstrom3. Curie temperatures increase with decreasing x but deviate from linear behavior below x = 1.0 leading to an estimate of T(c) = 480 K for the limiting case of x = 0. A more linear dependence on x is observed for the saturation magnetization. The extrapolated value for YFe12 is approximately 26 mu(B)/f.u. Anisotropy fields at 4.2 K increase from 5 T for x = 0.5 to 7.5 T for x = 1.0. Irreversible phenomena in the temperature dependence of magnetization are observed in the x = 2 sample. Hyperfine fields have been determined for the i,j and f sites at room temperature from Mossbauer spectra.