Strong microwave absorption of Fe-deficient SrFe9.4Cu0.8Sn0.5O19-d with enhanced permittivity and ferromagnetic resonance by high annealing temperature
XRD patterns, the permittivity, the permeability, the dielectric tangent loss tande and the magnetic tangent loss tandm, and RL of SrFe9.4Cu0.8Sn0.5O19-d and SrFe11-2xCuxSnxO19-d (x = 0.6 and 0.7).