Microwave permittivity, permeability, and penetration depth of pyrite

The microwave permittivity and permeability of pyrite at frequencies of 915 and 2450 MHz were characterized from room temperature to approximately 500 °C using the cavity perturbation technique. The real and imaginary parts of the complex relative permittivity of pyrite slightly increase with temperature up to 450 °C, above which both parameters reveal a significant increasing trend associated with the decomposition of pyrite. The real part of the complex relative permeability of pyrite decreases from 1 to nearly 0.3 at both frequencies in the temperature range of interest, whereas the imaginary part of the complex relative permeability varies between 0.1 and 0.45. The increase in dielectric loss of pyrite upon heating primarily contributes to the decrease in the microwave penetration depth, indicating the strong microwave absorption in pyrite