MAGNETIC-PROPERTIES OF SM-FE-TI-AL SPUTTERED FILMS WITH IHC GREATER THAN 30-KOE

Recently the synthesis of a new high intrinsic coercive force, iHc=38.5 kOe at 293 K, Sm-Fe-Ti phase in film form was reported. Films with Al additions have now been made, and the preparation conditions are better defined. The addition of 2.3-4.5 at. % Al helped to sharpen the x-ray patterns of the high iHc samples. The iHc values for Al concentrations less than 4 at. % did not fall below 30 kOe for proper preparation conditions. The nominal composition for the high iHc phase samples spanned from 17 to 22 at. % Sm, and Ti/Fe ratios from 0.09 to 0.14 when related to Sm-Ti-Fe. The high iHc samples are reported to be composed of two Ti-substituted phases. The high iHc phase is found to be a SmCo5-related hexagonal structure with a nominal formula of Sm 7(Fe,Ti)30. The Ti addition allows Ti to form dumbbell pairs in replacing Sm atoms. The semihard phase component is reported as a cubic Sm(Fe,Ti)2 phase. The iHc values were most sensitive to the Ti/(Ti+Fe) atomic ratio and rose at the rate of +6 kOe/%[Ti/(Ti+Fe)] as the nominal composition of 19 at. % Sm was approached and starts to decrease for higher ratios. Initial magnetization studies have been used to show the influence of the magnetic field that was applied during sputter depositions and crystallization.