XPS of lanthanoide orthoniobates

Abstract

Abstract Using the XPS method, orthoniobate lanthanoids LnNbO 4 , where Ln=lanthanoids except Pm and Tm, representing a new number of ferroelectrics were studied in the range of electron binding energies from 0 up to 1350 eV. It is noted that the fine structure in the range of electron binding energies from 15 to 50 eV is generally caused by the electrons of inner valence molecular orbitals. The experimental values of relative intensities for Ln4f-electron spectra lines in orthoniobate lanthanoids LnNbO 4 were found and compared with the analogous values for oxides Ln 2 O 3 , and obtained on the basis of calculated photoionization cross-sections. The spectral characteristics of Ln4f-electrons in orthoniobates and oxides are very similar; and the data obtained do not contradict the assumption concerning the possible participation of Ln4f atomic orbitals in molecular orbital formation in lanthanoid compounds. The decreasing of the relative shake-up of satellite intensity with the decreasing of the electron binding energy of various subshells of the lanthanum ion was confirmed. The parameters of splitting of Ln5s-, Ln4s-electron lines connected with multiplet splitting, and the parameters of the fine structure of the Ln4p-electron spectra line occurring as a result of dynamic effect were obtained.