Synthesis and Properties of Gallium-Bearing Cordierite, Mg₂(Al_4-xGa_xSi₅0₁₈) Available to Purchase

On the join Mg₂Al₄Si₅O₁₈—“Mg₂Ga₄Si₅O₁₈” Ga-bearing cordierites could be synthesized from glasses at 1 atm as well as hydrothermally. The limit of stable solid solubility lies at about 12 mole percent of the theoretical Ga-end member at 750°C/3kb, 900°C/lkb 1000°C/lkb. The most Ga-rich cordierite, Mg2(Al_{3 2}Ga₀₈Si₅O₁₈), synthesized in the dry system at 1050°C/15 hrs was metastable. Ga-cordierites prepared at about 1000°C/latm are hexagonal. Lattice constants and mean refractive index increase with increasing sub-stitution of Ga for Al. At 13S0°C a hexagonal cordierite of the composition Mg₂(Al_3.6Ga_0.4Si₅O₁₈) could be transformed into a “low”-cordierite. The structural distortion of hydrothermally synthesized samples increased with raising Ga-contents.