Original paper
Changes in the domain structure of anorthites induced by heating
Müller, W. F.; Wenk, H. R.
Neues Jahrbuch für Mineralogie - Monatshefte Jg. 1973 Heft 1 (1973), p. 17 - 26
19 references
published: Mar 27, 1973
DOI: 10.1127/njmm/1973/1973/17
ArtNo. ESP156197301002, Price: 19.00 €
Abstract
The effects of heat-treatment on domains in natural anorthites was studied by means of high voltage (650 kV) transmission electron microscopy. No significant change in texture and diffraction contrast of the c-domains was observed in anorthite (An94.5) heated at 500 and 600 °C for 7 days and then quenched or slowly cooled down, but c-domains could not be observed in samples heated at 1200 °C for 7 days or at 1430 °C for V2 hour and subsequently quenched. Heating of anorthite specimens (An97 and An100) inside of the electron microscope with a hot stage up to about 575 °C showed that the diffraction contrast of the c-antiphase domain boundaries disappears at temperatures above 200—250 °C. It reappears, however, after cooling and there is no change in, position, shape and size of the antiphase domain boundaries. These observations strongly suggest that the antiphase domain structure as observed at room temperature is not affected by the processes at 200—250 °C but controlled by the pattern of structural disorder formed at much higher temperatures. Electron irradiation of heated anorthite caused structural disorder.
Keywords
Electron microscopy • high temperature • antiphase domains • anorthite