Powder X-ray diffraction (PXRD) patterns of the physical mixtures (i.e., ball-milled powders of each glass prior to pelletisation and heating) display the expected amorphous behaviour of the starting materials (Figure ). The weak, sharp peak at 2θ ~ 27° in the inorganic glass is also evident in the 1:1 Zn:P physical mixture, in addition to two additional peaks. However, these small peaks are minor and likely correspond to an unidentified crystalline impurity.