Aligned high magnetization Nd(Fe,Co,Mo)12 films nitrided by N ion implantation

Abstract

Ion implantation has been used to nitride highly aligned ThMn12-type structure Nd(Fe,Co,Mo)12 film samples. The initial 1–12-type films were made by sputtering with the crystallite c axes aligned perpendicular to the film plane. The films were then nitrided to produce fully nitrided 1–12 films, but only for a limited range of N ion doses. Much of the 1–12 phase was made amorphous before full nitriding was observed. It was not possible to thermally anneal the N implanted samples to lower the α-Fe concentration resulting from the N ion bombardment. This is only consistent with the Nd(Fe,Co,Mo)12N phase being metastable. Low temperature heat treatments of the N implanted films at temperatures less than 270 °C produced evidence for Fe16N2 formation, but little restoration of the 1–12 phase. For heat treatments at temperatures of 270 °C and above no evidence of Fe16N2 was detected. These results indicate that it is not possible to produce nitrided ThMn12 films with Fe16N2 inclusions by ion implantation.

Metastable phases in rare-earth permanent-magnet materials

“…Nitride films with same structure were obtained by annealing the films in nitrogen atmosphere at an elevated temperature. Nd(Fe, Co, Mo) 12 N x , Nd(Fe, T) 12 N x and disordered Nd(Fe, Ti) 7 and Pr(Fe,Co,Mo) 12 N films grown by sputtering have also been studied (Qian et al 1996, Rani et al 1994. High coercivity film samples of the ordered Sm 2 Fe 17 N x phase have been grown by sputtering (Rani et al 1993).…”