Parasitic amorphous on single-domain crystal: structural observations of silicate glass-ceramics.
Glass-ceramics (GCs) are materials obtained from the crystallisation of functional phases in glass, and have a structure that the crystallised phase embedded in the glass matrix. Glass-forming oxides are commonly added to the functional phases to improve the stability of precursor glass; however, the issue of glass-ceramics permitting the presence of residual phases resulting from addition is required to be clarified. To elucidate this issue, we prepared 'perfectly surface-crystallised' GC consisting of fresnoite-type Sr(2)TiSi(2)O(8) from a non-stoichiometric glass and performed texture/morphology observations. Numerous SiO(2)-rich binodal-like nanospheres (~10 nm) were parasitic on the fresnoite single-crystal domains. The parasitic texture is considered to form via the following process: (i) binodal-type phase separation into stoichiometric fresnoite (crystalline matrix) and SiO(2)-rich phases (amorphous nanoparticles) and (ii) single-domain formation by surface crystallisation in the matrix. Furthermore, in terms of texture, the resulting GC differs from the GCs reported to date, i.e., inverse GC.
Department of Applied Physics, Tohoku University , 6-6-05 Aoba, Aoba-ku, Sendai 980-8579, Japan. takahashi@laser.apph.tohoku.ac.jp
Yoshihiro
Y
Takahashi
Yoshiki
Y
Yamazaki
Rie
R
Ihara
Takumi
T
Fujiwara