Optical and magnetic properties of silica implanted with N⁺ and Fe⁺

Silica platelets (Corning 7940) were implanted sequentially with N⁺ at 52 keV to different doses ranging from 0 to 1.2×10¹⁷ ions cm^-2 and then with Fe⁺ at 160 keV to a dose of 6×10¹⁶ ions cm^-2. The optical absorption decreased with increasing N¹ dose at photon energies ranging from 1.4 eV to 6.5 eV. The relative intensity, S(0°), of the ferromagnetic resonance absorption and its resonance field, H_s(0°), at θ = 0° were larger than S(90°) and H_s(90°) at θ = 90°, where θ is the angle between the applied magnetic field and the normal to the implanted surface. The maximum values of S(0°) and S(90°) were observed near the N/Fe atomic ratio of 0.2. At the similar atomic ratio, the differential relative intensity, S(0°)- S(90°), and the differential resonance field, H_s(0°)- H_s(90°), associated with the degree of magnetic interaction between the produced compounds, also showed maxima. We conclude that sequential ion-implantation of N¹ and Fe¹ into silica causes a chemical interaction to produce iron nitrides.