MAGNETIC-PROPERTIES OF ER2FE15GA2CX LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-3.0) COMPOUNDS

Er2Fe15Ga2Cx compounds with x = 0, 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 ar e prepared by are melting and heat treating at 1400 K for two days. X- ray diffraction of Er2Fe15Ga2Cx shows that the prepared samples are ap proximately single phase, having the hexagonal Th2Ni17-type or the rho mbohedral Th2Zn17-type structure. For x greater than or equal to 2.5, the samples contain a few percent of alpha-Fe. Both substitutional gal lium and interstitial carbon in Er2Fe17 lead to an increase of the uni t cell volume. The Curie temperature is found to rise with x from 478 K for x = 0 to 611 K for x = 2.5, and decreases to 585 K at x = 3.0. T he saturation magnetization mu(s) at 1.5 K is almost independent of ca rbon concentration. The thermomagnetic measurements demonstrate that a ll samples studied here exhibit a spin reorientation transition. The s pin reorientation temperature is found to increase strongly with the c arbon concentration for x < 1.5, and it is essentially constant at abo ut 230 K for x greater than or equal to 1.5.