The structural geometry, vibrations and deformation density Ap for lithium niobate, LiNbO3, and lithium tantalate, LiTaO3, are derived from synchrotron radiation diffraction measurements. Electron density is transferred from the Nb (

The deformation density (Ap) for Y2BaCuOs, barium diyttrium cuprate, determined by single-crystal X-ray diffraction with synchrotron radiation, is affected to only a limited degree by the bonding interactions involving the O anions. Electron density is strongly depleted along the cation-cation contacts within the mirror plane in the structure and is transferred to regions between mirror planes that do not lie along short cation-cation vectors. The structural geometry for the CuO5 moiety, with the Cu atom in the +2 state, closely resembles that of the Cu205 group in YBa2Cu307_ 6, for which the +3 state involvement for Cu has been suggested. Space group Pnma, orthorhombic, Mr = 458.68, a = 12.1793 (7)

We have investigated the effect of postgrowth thermal annealing on the electron emission from InAs quantum dots ͑QDs͒ containing a misfit-related defect state induced by strain relaxation. Additional carrier depletion in the GaAs bottom layer near the QD, caused by the defect state, can effectively suppress electron tunneling from the QD, leading to the observation of a thermal emission from the QD electron ground state to the GaAs conduction band with a large emission energy of 213 meV, in contrast to defect-free nonrelaxed QDs in which an emission of 58 meV from the QD electron ground state to first excited state is observed. The emission energy is reduced to 193 meV and to 164 meV after annealing at 650 and 700°C for 1 min, respectively. This emission energy reduction is correlated with the photoluminescence blueshift which is attributed to the interdiffusion of atoms across the QD interface. The electron emission from the QD first excited and ground states is found to be a thermal emission at high temperatures and a tunneling emission at low temperatures. The tunneling energy barrier is found to be comparable to the thermal emission energy, supporting a thermal emission to the GaAs conduction band. This study illustrates a significant effect of a defect state on the electron-emission process in the QDs, suggesting the possibility of modifying the electron emission time of the QDs by purposely introducing a deep defect state.