A photoelectrochemical study of the hexagonal ferrite PbFe12O19

Several techniques have been used in order to characterize the photoelectronic properties of a magnetoplumbite single crystal of composition Pb_1.19Fe_11.88O_18.91. Measurements of electrical resistivity and thermoelectric power have shown between 77 and 300 K the compound to have n-type semiconducting properties. The I–V characteristics (in the dark and under illumination), the spectral response and the flat band potential have also been determined.The density of donors derived from Mott-Schottky plots (3.2 × 10¹⁹) is in good agreement with the value of the Fe²⁺ concentration (2.9 × 10¹⁹) obtained by chemical analysis. Electron affinity was found to be equal to 4.5 ± 0.2 eV. The photocurrent corresponding to the photoelectrolysis of water is due to indirect electronic transitions at 1.75, 2.1 and 2.4 eV. Evidence is given suggesting that these transitions correspond to lead-iron and/or iron-iron charge transfers.