Synthesis of Fe16N2 Compound Films by Reactive Sputtering

Fe16N2 films (of thickness 3000Ã…) were fabricated on MgO (001) substrates by the conventional dc facing target sputtering method using a controlled reactive plasma, at an electron temperature of Te=0.3 eV, an electron density of Ne=1×10¹⁰ cm^¿3, a deposition rate of 200Ã…/min and an N2 flow ratio ranging from 10% to 20%. In the as-deposited state, single ¿\´ phases with various nitrogen contents were formed. After annealing at 150°C for two hours, an ¿" phase (¿11 at% N) and an ¿\´ phase (11.1 at% N and 1 to 2 at% N) were formed. The Ms value was nearly the same as for ¿-Fe (2.2 T), despite the existence of the ¿" phase. The lattice constant c of the ¿" phase in these films agreed well with the value reported by Jack, but lattice constant a values were about 1 to 3% smaller than Jack\´s value. The unit cell volumes of the ¿" phase in these films were between 192.5 and 202.6Ã…³, from 1.4 to 6.3% less than Jack\´s value of 205.5Ã…³.