Contribution à l'étude de l'ionicité des liaisons dans le rutile

Knowledge of both ionic dielectric susceptibility and ionic displacements induced by an electric field allows one to evaluate the effective charges on the ions. To determine the ionic displacements a method involving differential photometry of X-rays and anomalous scattering has been used. The dielectric susceptibility is well known but its ionic part has not been measured, so that one can give only the maximum possible value (f = 0.78) of the ionicity factor. In addition, it is shown that the effect of the local electric fields upon the atomic scattering factors is not significant.