Glass Studied by Neutron and X-Ray Diffraction

The short-range order of K P 0 3 glass has been studied by diffraction methods in order to make evident the different behaviour of the P-O bonds within the P 0 4 tetrahedron. The oxygen sites are devided into bridging and terminal (non-bridging) oxygen sites, corresponding to two P 0 bond lengths, the difference of which amounts to 14.5 pm. Previous conclusions about the changes of the P 0 bond lengths under the influence of modifier cations of different electric field strength are corroborated. The K-O environments reveal two apparently different distances rKO with equal contributions to the total K 0 coordination number of about 6.7. To explain this phenomenon, the K + cations are suggested to be located in non-spherical cavities.