355. Studies of the crystallisation of gallium hydroxide precipitated from hydrochloric acid solu…

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Taichi Sato, et al, J. Chem. Tech. Biotechnol. 32,469 (1982)
https://doi.org/10.1002/jctb.5030320306

(1) The precipitate, separated immediately from the mother liquor after preparation for a given period of time in the water bath, exists in an amorphous type and transforms to a gallium oxyhydroxide during aging independent of pH.
(2) Although gallium is amphoteric, -GaOOH (not Ga(OH)3), having a diaspore structure, has been known as a crystalline gallium hydroxide only.
(3) The intensity of the diffraction lines becomes intense with increasing aging time, suggesting that freshly precipitated amorphous Ga(OH)3 transforms to crystalline -GaOOH during aging.
(4) The process of aging, the crystallisation of the original precipitate accompanied by the nucleation of crystalline gallium hydroxide is more predominant than the recrystallisation due to the dissolution of gallium hydroxide gel.
(5) The transformation from amorphous to -GaOOH is caused by the crystallisation of the original precipitates by the nucleation of crystalline Ga(OH)3.