Patent ID: 7371458

Claim:
A high-weatherability iron nitride-based magnetic powder comprising iron nitride-based magnetic particles constituted primarily of Fe 16 N 2 with an average grain size of 20 nm or less, wherein a substance containing one or more of the elements Si and P are adhered to the surface of the Fe 16 N 2 particles after the particles have been formed, the total content of Si and P in the magnetic powder after adhesion is 0.1% or greater as an atomic ratio with respect to Fe, and the value ΔH c as defined by Equation (1) below is 5% or less: Δ H c =( H c0 —H c1 )/ H c0 ×100 (1) where, H c0 is the coercivity (kA/m) of the iron nitride-based magnetic powder after adhesion, and H c1 is the coercivity (kA/m) of the iron nitride-based magnetic powder after adhesion and after being kept for one week in a constant-temperature, constant-humidity vessel at 60° C. and 90% RH.