There are ternary oxides containing bismuth for example, BiFeO The stability region of CBO gives rise to high stability even under strongly oxidizing conditions (∆µ O = 0) and therefore ambient conditions, as reported in literature as well. While lower temperatures create smaller particles and poorly crystallized products, higher temperatures of 1200 K facilitate larger grain growth. The narrow stability region complicates the synthesis of a pure CBO phase, leading to grains with different Cu:Bi ratios. Moreover, the binary and non-stoichiometric oxides are photoelectrochemically active, providing different electronic and optical properties. Thus, the position of the valence and conduction bands, hence the band gap value, can easily differ, depending on the Cu:Bi ratio. 86