XRD and 29Si MAS-NMR spectroscopy across the β-Lu2Si2O7–β-Y2Si2O7 solid solution

Samples in the system Lu2−xYxSi2O7 (0⩽x⩽2) have been synthesized following the sol–gel method and calcined to 1300 °C, a temperature at which the image-polymorph is known to be the stable phase for the end-members Lu2Si2O7 and Y2Si2O7. The XRD patterns of all the compositions studied are compatible with the structure of the image-polymorph. Unit cell parameters are calculated as a function of composition from XRD patterns. They show a linear change with increasing Y content, which indicates a solid solubility of image-Y2Si2O7 in β-Lu2Si2O7 at 1300 °C. 29Si MAS NMR spectra of the different members of the system agree with the XRD results, showing a linear decrease of the 29Si chemical shift with increasing Y content. Finally, a correlation reported in the literature to predict 29Si chemical shifts in silicates is applied here to obtain the theoretical variation in 29Si chemical shift values in the system Lu2Si2O7–Y2Si2O7 and the results compare favorably with the values obtained experimentally.