Premium
Silica Structure Studies: V, The Variable Inversion in Cristobalite
Author(s) -
HILL V. G.,
ROY RUSTUM
Publication year - 1958
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.1151-2916.1958.tb12911.x
Subject(s) - cristobalite , tridymite , stacking , atmospheric temperature range , materials science , mineralogy , impurity , crystallography , chemistry , thermodynamics , metallurgy , physics , organic chemistry , quartz
It is demonstrated experimentally that even in the purest laboratory silicas available the temperature of the α‐β inversion in cristobalite is variable and depends on the structure of the starting material and on the temperature and length of heat‐treatment. It is shown that this variability is an index of the order achieved in the cristobalite structure quite independent of impurities. There is no specific order characteristic of a particular temperature; the completely ordered 3 C stacking of cristobalite is the most stable cristobalite throughout the temperature range and has an α‐β inversion temperature of 267°± 2°C. All disordered cristobalites will tend toward the 3C 267° cristobalite with time. The conversion of cristobalite to tridymite involving the 3 C → 2 H stacking change does not alter the cristobalite inversion temperature, nor have any regular polytypes other than those recognized as tridymite been encountered.