I googled it
Single crystals of ?-PbO2 are formed when an intermediate oxide of lead represented by the generic formula, PbOx wherein x denotes a value falling in the range of 1.4 to 1.7, is heated in an aqueous alkali hydroxide solution under a pressure exerted by use of oxygen or an oxygen-containing gas. The single crystals are in the shape of slender rods, have a black color and have a metallic gloss.
and
he mechanochemical processes, including mechanochemical synthesis of mixed-valence lead oxides, in mixtures of PbO, Pb3O4, and PbO2were studied by x-ray diffraction. The results demonstrate that the reduction of Pb4+is accompanied by the formation of Pb2O3, Pb3O4, and possibly PbO1.37. Phases of variable composition close in structure to minium, Pb3O4, are shown to coexist during mechanical processing. The structure of the metastable oxide Pb3O4 – x with Pb2+: Pb4+> 2 (@O4 – 2x ) is tentatively determined. The sequence of the observed transformations is interpreted in terms of the model for the reaction zone, with consideration for primary and secondary interactions.
But I can't really figure it out..... confirm with your teacher
