Normal coordinate analysis for CaNb2O6 of columbite structure

Abstract

The Raman and infrared spectra of CaNb₂O₆ are assigned by normal coordinate analysis according to Shimanouchi’s method. The Raman spectroscopy results enabled us to refine the force field, which was then checked by the infrared spectroscopy results. The obtained force constants show that there are three different types of Nb–O bonds in the columbite structure and that the Ca–O bonds are of electrostatic nature. The potential energy distribution calculation gives us a precise assignment for all the observed frequencies.