Single-crystal X-ray diffraction study of α-quartz-type Al1-xGaxPO4

Single crystals in the AlPO4-GaPO4 system prepared by hydrothermal methods were investigated by electron microprobe analysis and X-ray diffraction. The fine details of the crystal structures, and, in particular, the intertetrahedral bridging angle and the tetrahedral tilt angle, were found to vary in an essentially linear manner with gallium content. The piezoelectric properties of a-quartz homeotypes are known to be correlated to these angles. The present results thus open the possibility to tune the piezoelectric properties of these materials by varying the chemical composition.