Crystallographic and magnetic properties of NdFe10.7TiM0.3(M=B, Ti)

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Abstract
NdFe10.7TiM0.3(M=B, Ti) has been studied with x‐ray diffraction, Mössbauer spectroscopy, and a vibrating sample magnetometer. The alloys were prepared by arc‐melting under an argon atmosphere. The NdFe10.7TiB0.3 exhibits a pure single phase, whereas the NdFe10.7Ti1.3 contains some α‐Fe, from x‐ray and Mössbauer measurements. The NdFe10.7TiB0.3 has the ThMn12‐type tetragonal structure with a0=8.587 Å and c0=4.788 Å. The Curie temperature (TC) is 570 K from Mössbauer spectroscopy performed at various temperatures ranging from 13 to 770 K. Each spectrum below TC was fitted with five subspectra of Fe sites in the structure (8i1, 8i2, 8j1, 8j2, and 8f ). The area fraction of the subspectra at room temperature are 16.4%, 8.2%, 14.8%, 21.3%, and 39.3%, respectively. Magnetic hyperfine fields for the Fe sites decrease on the order of Hhf(8i)≳Hhf(8j)≳Hhf(8f ). The average hyperfine field Hhf(T) of the NdFe10.7TiB0.3 shows a temperature dependence of [Hhf(T)−Hhf(O)]/Hhf(O)=−0.39(T/TC)3/2 & −0.17(T/TC)5/2 for T/TCTC for 60 min resulted in a two phase microstructure consisting of a ThMn12‐type structure and α‐Fe.