The atomic and electron structure of ZrO2

Abstract

The atomic structure of amorphous and crystalline zirconium dioxide (ZrO2) films is studied using X-ray diffraction and extended X-ray absorption fine structure techniques. The electron structure of ZrO2 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 ZrO2 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 ZrO2, as determined using the electron energy loss spectroscopy data, amounts to 4.7 eV. The electron band structure calculations performed for a cubic ZrO2 phase point to the existence of both light (0.3m 0) and heavy (3.5m 0) holes, where m 0 is the free electron mass. The effective masses of band electrons in ZrO2 fall within (0.6–2.0)m 0.