Magnetic properties of nanostructured TbMn/sub 6/Sn/sub 6/ melt-spun ribbons

The effect of cooling rate on the magnetic properties of nanostructured TbMn/sub 6/Sn/sub 6/ melt-spun ribbons has been investigated intensively. The coercivity of TbMn/sub 6/Sn/sub 6/ ribbons enhances with increasing the wheel speed (V/sub s/) from 25 to 40 m/s. In this study, the optimal magnetic properties of (sigma)/sub r/ = 12.3 emu/g, /sub i/H/sub c/ = 4.7 kOe at room temperature, and (sigma)/sub r/ = 9.7 emu/g, /sub i/H/sub c/ = 57.2 kOe at 5 K are obtained in TbMn/sub 6/Sn/sub 6/ ribbons quenched at Vs=35 m/s. The average grain size of optimized TbMn/sub 6/Sn/sub 6/ ribbons (V/sub s/ = 35 m/s) is about 30-40 nm, according to transmission electron microscopy investigation. Based on X-ray diffraction patterns, the TbMn/sub 6/Sn/sub 6/ ribbons mainly consist of 1 : 6 : 6-type phase. Besides, from thermal magnetic analysis, it is evidenced that only one magnetic phase having a Curie temperature of about 140(degree)C is present in the ribbon. Exchange coupling effect is found, as evidenced by Henkel plot, to exist in all the ribbons at room temperature.