Pyroelectric Li₂Si₂O₅glass-ceramics

Abstract

Highly oriented surface layers of lithium disilicate crystals were grown by crystallizing glasses of the composition Li:O: SiOr. The thickness of the oriented layer was a function of the thermal treatment. The ctystallites in these layers were oriented with their c-axes perpendicular to the sample surface. These layers were found to be pyroelectric as determined by the Chynoweth technique. The pyroelectric responses of the glass-ceramics crystallized in a thermal gradient were approximately tour times larger than that of a tourmaline crystal of similar dimensions.

Crystallization, texture and second-harmonic generation in TiO2–BaO–B2O3 glasses

“…It is also known that spontaneous preferential growth of certain crystallographic planes may occur in certain situations from the external glass surfaces towards the glass interior, leading to textured microstructures and yielding properties that are peculiar to some oriented glass-ceramics [19,20].…”

Crystals and composites

“…For texture symmetry groups which do not belong to the 32 crystallographic point groups, one of the Curie groups oo oo m, oo oo, oo/mm, oo m, oo/m, oo 2 or oo is more appropriate. This can be illustrated by considering polar glass ceramics with conical symmetry (Gardopee, Newnham & Bhalla, 1981). A glass can be crystallized under a strong temperature gradient such that polar crystals grow like icicles into the interior from the surface.…”

Ferroic Shape Memory Materials & Piezo:Pyro-Electric Oriented Recrystallized Glasses.

“…•er~ a'i~ed that glasses with suitably selected composition can b recrystallized into a polar glass-ceramic form, which can then be used as a thermal or a pressure sensing element (Gardopee et al 1980(Gardopee et al , 1981.…”

“…If the glass-ceramic shows both crystallographic and polar orientation, but the individual crystallites are not bonded together by the glass matrix as in the case of Li 2 Si 2 O 5 (Gardopee et al 1981) again the system is not of much use for practical devices. This is particularly true in the present study since the objective of the work was to prepare large area glass-ceramics with uniform properties.…”