The atomic and electron structure of ZrO{sub 2}

The atomic structure of amorphous and crystalline zirconium dioxide (ZrO{sub 2}) films is studied using X-ray diffraction and extended X-ray absorption fine structure techniques. The electron structure of ZrO{sub 2} is experimentally determined using X-ray and UV photoelectron spectroscopy, and the electron energy band structure is theoretically calculated using electron density functional method. According to these data, the valence band of ZrO{sub 2} consists of three subbands separated by an ionic gap. The upper subband is formed by the O2p states and Zr4d states; the medium subband is formed by the O2s states; and the narrow lower subband is formed predominantly by the Zr4p states. The bandgap width in amorphous ZrO{sub 2}, as determined using the electron energy loss spectroscopy data, amounts to 4.7 eV. The electron band structure calculations performed for a cubic ZrO{sub 2} phase point to the existence of both light (0.3m{sub 0}) and heavy (3.5m{sub 0}) holes, where m{sub 0} is the free electron mass. The effective masses of band electrons in ZrO{sub 2} fall within (0.6-2.0)m{sub 0}.