Combined study of KNbO3 and KTaO3 by different techniques of photoelectron and X-ray emission spectroscopy

The new results are presented of the experimental study of KNbO3 and KTaO3 by means of X-ray photoelectron spectroscopy, soft X-ray emission and X-ray fluorescence spectroscopy. In particular, Nb M(4,5) spectra have been measured over a range of near-threshold excitation energies 206.5 - 240.6 eV, and Ta N(3) spectra over 399.4 - 420.4 eV at the Advance Light Source in Berkeley. These spectra were found to be strongly dependent on the excitation energy. Moreover, the O K(alpha) X-ray emission spectra in both compounds as well as the valence-band photoelectron spectra are brought to the binding energy scale and discussed in combination. The trends in the spectra are explained on the basis of first-principles band-structure calculations, with the dipole transition matrix elements taken into account.