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Tridymite
About: Tridymite is a research topic. Over the lifetime, 840 publications have been published within this topic receiving 14831 citations.
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TL;DR: In this article, it was found that the thermal expansion is controllable by the amount of silica polymorphs, particularly tbat of tridymite, in silica/glass composites.
Abstract: Sintered composites of silica-containing Na2WO4 as a phase transformation agent and sodium borosilicate glass were prepared, and silica polymorphs in silica/glass sintered composites were identified and quantitatively analyzed by means of XRD. The amount of tridymite increased with the addition of Na2WO4. It was found that the thermal expansion is controllable by the amount of silica polymorphs, particularly tbat of tridymite, in silica/glass composites. Addition of Na2WO4 to the composites increased the dielectric constant, which may be attributed to the increase in the amounts of sodium and tungsten ions which have high polarizabilty.
3 citations
TL;DR: In this article, a self-resonance method was used to obtain the piezoelectric properties of quartz SiO2 at 150-200 kHz over a range from room temperature to 960°C.
Abstract: Piezoelectric properties of quartz SiO2 were obtained using a self-resonance method at 150–200 kHz over a range from room temperature to 960°C, and in detail particularly in the incommensurate phase. Their large elastic anomalies were observed. Piezoelectricity was found to be preserved up to 960°C. The "tridymite phase" was not detected.
3 citations
TL;DR: Under certain limits of oxygen fugacity and temperature in the system Mg-Fe-Si-O the crystalline assemblage of olivine, tridymite, and metallic iron will produce liquid with cooling.
Abstract: Under certain limits of oxygen fugacity and temperature in the system Mg-Fe-Si-O the crystalline assemblage of olivine, tridymite, and metallic iron will produce liquid with cooling. Changes in composition, accompanying changes in temperature, of the olivine phase cause exothermic oxidation of the metallic iron, providing enough heat to produce liquid.
3 citations
TL;DR: Tridymite occurs in the vicinity of Kusatsu Spa as extremely fine crys tals in opaline silica which has replaced two pyroxene andesite as mentioned in this paper.
Abstract: Tridymite occurs in the vicinity of Kusatsu Spa as extremely fine crys tals in opaline silica which has replaced two pyroxene andesite. Specific gravity: 2.2•}0.1, optical properties: n1•†1.478, n2•...1.480, 2V ?? 0, elongation negative, showing straight but wavy extinction. Chemical composition: SiO2 96.89, TiO2 0.86, A12O3 0.71, Fe203 tr., FeO none, MnO none, MgO none, CaO none, Na20 0.72, K20 0.16, H20(+) 0.12, H20(-) 0.08, P2O5 tr., total 99.54%. The d. t. a. curve shows two endothermic peaks, one at 128•Ž. and the other at 155•Ž.; they are attributed to the transition from the low to the middle form and from the middle to the high form respectively. Many sharp X-ray powder diffraction lines were confirmed, most of which have not been reported in previous papers. Under the microscope, noticeable tex ture of the silicified andesite was observed, suggesting that the tridymite has gradually crystallized out of opaline silica: some of its crystals are extremely small and appear to grade into opaline silica. Introduction Along the river Yugawa running through Kusatsu Spa, silicified rocks are distributed over considerable area. The writer discovered that some of them are largely composed of opaline silica and tridy mite. Any report concerning such a mode of occurrence of tridymite has not yet been published*). The purpose of this paper is to pro* Just after this paper had been completed , H. Minato reported the similar occurrence of tridymite associated with hydrated halloysite at the Joshin Mine, Gumma Prefecture (Advances in Clay Science, 3, 264 (1961), in Japanese.)
3 citations
3 citations