A theoretical study of the dielectric and magnetic responses of Fe-doped α-MnO2 based on quantum mechanical calculations

The microwave electromagnetic properties of Fe-doped alpha-MnO2 are studied theoretically using quantum mechanical calculations based on density functional theory. The calculations employ the Perdew-Burke-Ernzerhof model, a generalized gradient approximation, to deal with the exchange-correlation interaction. The possible role of Fe doping in modifying the electromagnetic performance is studied utilizing density of states (DOS) and the bond length between the metal and oxygen. Calculations of the bond length in the presence of Fe show a contracted bond length between the metal atoms and O with enhanced bond strength, resulting in increased storage of electric field energy. This explains the experimental observation of a reduced dielectric loss after Fe-doping. The DOS results demonstrate that Fe doping enhances the spin-polarization of MnO2. Therefore, the total magnetic moment is increased after doping, corresponding to the magnetic enhancement of MnO2. The theoretical predictions concluded from the quantum mechanical calculations agree well with the experimental observations. The results provide an early stage exploration of theoretical research on the microwave absorbing properties of doped MnO2.