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Structural Control of Phase Formation in Low‐Tem perature AIPO 4 —Sio 2 Reactions
Author(s) -
Takahashi Tatsuhito,
Agrawal D. K.,
Roy R.
Publication year - 1989
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1989.tb06163.x
Subject(s) - tridymite , cristobalite , boehmite , crystallography , quartz , phase (matter) , mineralogy , nucleation , materials science , chemistry , organic chemistry , aluminium , composite material
The phase relation along the binary join of AIPO 4 ‐SiO 2 were investigated up to 400°C using starting materials made by a solution route. Precursor structures used were boehmite (AIOOH), H 3 PO 4 , noncrystalline silica, and quartz. The silica precursors acted as structural seeds for the epitaxial growth of AIPO 4 . Studies showed that SiO 2 and AIPO 4 were the only crystalline and noncrystalline phases present along the binary join, and no substantial crystalline solution or any ternary phase was observed. Three polymorphic forms of AIPO 4 , i.e., berlinite, tridymite, and cristobalite, coexisted as low as 200°C. The nature of the silica precursor greatly influenced the development of the polymorphic phases of AIPO 4 . The low‐quartz precursor suppressed the formation of the cristobalite form of AIPO 4 and favored berlinite (AIPO 4 quartz) production. On the other hand, noncrystallin silica with a cristobalite‐like broad XRD peak suppressed the formation of berlinite and enhaned that of the cristobalite form of AIPO 4 . These precursor effects indicate that heteroepitaxy is very significant during the nucleation and growth of AIPO 4 phases on the surface of SiO 2 particles even in these low‐temperature reactions.