Tridymite

About: Tridymite is a research topic. Over the lifetime, 840 publications have been published within this topic receiving 14831 citations.

X-Ray Investigation of Tridymite-glass

Abstract: THERE has been a lengthy controversy between G W Morey1 and A Dietzel2 concerning the nature of the crystallites in devitrified glass in region B of the phase diagram of the system: SiO2 Na2O CaO (see2) Morey, from microscopic investigations, thought that tridymite was present in this devitrified glass, whereas Dietzel, with the further help of expansion curves, decided in favour of cristobalite Microscopic work on such a problem is very difficult, especially when dealing with crystallites in crusted in a vitreous mass On the other hand, expansion curves are quite useless There are three anomalies in the expansion of pure tridymite The first occurs about 120° C, the second around 165° C and the last at 420° C A solid rod of 36 mm of glass B does not give any appreciable anomaly of expansion A rod of the same dimensions made from a powder of this devitrified glass also gives a negative result X-ray powder analysis on the contrary gives a definite solution of the problem A devitrified glass of the initial percentage composition: SiO2 78, CaO 12, and Na2O 10 (glass B) gives an unmistakable pattern of tridymite (Co-K-50 mah)

Devitrification characteristics of alkali‐lead oxide‐dolomite lime‐silica glasses*

Abstract: The devitrification characteristics of the field of compositions, which includes the commercial lime crystal glasses, were investigated. Tridymite was found to crystallize from glasses containing as low as 62% of SiO2. Tridymite, devitrite, diopside, sodium disilicate, and an unidentified compound were found to be primary phases. Potassium oxide (K2O), in general, lowers the liquidus temperature when it replaces Na2O.

Electric Anisotropy of Tridymite as Revealed by Electron Diffraction

Abstract: An electron beam served to charge the specimen and simultaneously was diffracted by this specimen. Analysis of the diffraction pattern obtained permits one to see that the easy polarization direction of tridymite lies parallel to the c axis of a hexagonal lattice. This diffraction pattern has been registered with the wavelength fluctuating between 0.0295 and 0.0333 A. The inner field induced within the specimen was about 0.6 V/A along the c axis.

Thermal decomposition of K 1 − x Cs x BSi 2 O 6 borosilicates

Abstract: Thermal decomposition of mixed K1 − x Cs x BSi2O6 borosilicates by the methods of thermal analysis, annealing, and quenching, with the following refining of the structure by the Rietveld method on the example of solid solutions with x = 0.3 and 0.7 crystallizing in the space groups $$I4\bar 3d$$ and $$Ia\bar 3d$$ , respectively, is studied. It is shown that the solid-phase decomposition of borosilicates proceeds with the release of the gas- eous phase and formation of cristobalite and/or tridymite of SiO2 at the final stage. In this case the solid solutions enriched by potassium decompose in one stage with the formation of SiO2, while the solutions enriched by cesium decompose with the formation of the intermediate zeolite-like CsBSi5O12 borosilicate, which also decomposes during further thermal treatment. According to the data of the structure, the refining of K1 − x Cs x BSi2O6 solid solutions obtained by thermal treatment at 1000°C for 20, 65, 80, and 100 h, it is detected that for the samples with x = 0.3 and 0.7 the parameter of the cubic cell of the leucite-like phase decreases and the vacancies in the position of alkaline cation appear. During the solid-phase decomposition of K1 − x Cs x BSi2O6 solid solutions the structure degrades.