A careful electron diffraction study has been made of the incommensurately modulated room-temperature phases of the fresnoites Ba2TiGe2O8 (BTG) and Ba2TiSi2O8 (BTS) and used to determine their (3+1)- and (3+2)-dimensional ...
Beryllian sapphirine Mg4−xAl4+x[Al4+x−2yBeySi2−x+yO18]O2 has been synthesized from starting compositions with y ≤ 1 at x = 0 and y ≤ 0.5 at x = 0.5, P = 0.1–1.3 GPa, T = 700–1350 °C. Electron diffraction shows the sapphirines ...