منابع مشابه
The High Pressure Behavior of Cristobalite
The most abundant rock-forming minerals in the eanh's crust are framework silicates with complex crystal structures. These materials displaya remarkable chemical and structUral diversity. In addition,~structUral phase transitions involving displacive distonions are panicularly common, leading to yet more structural variation. There have been suggestions that the distonive behavior of the framew...
متن کاملsurvey on the rule of the due & hindering relying on the sheikh ansaris ideas
قاعده مقتضی و مانع در متون فقهی کم و بیش مستند احکام قرار گرفته و مورد مناقشه فقهاء و اصولیین می باشد و مشهور معتقند مقتضی و مانع، قاعده نیست بلکه یکی از مسائل ذیل استصحاب است لذا نگارنده بر آن شد تا پیرامون این قاعده پژوهش جامعی انجام دهد. به عقیده ما مقتضی دارای حیثیت مستقلی است و هر گاه می گوییم مقتضی احراز شد یعنی با ماهیت مستقل خودش محرز گشته و قطعا اقتضاء خود را خواهد داشت مانند نکاح که ...
15 صفحه اولThe pressure behavior of a cristobalite
Structural and volume compressibility data for two a cristobalite samples were determined by single-crystal X-ray diffraction methods at pressures up to -1.6 GPa. As with the other silica polymorphs that have been studied at high pressure, the change of the SiO-Si angle is correlated with the volume compressibility. The Si-O bond lengths and the O-Si-O angles remain essentially unchanged. The b...
متن کاملPressure-induced transformations of cristobalite
X-ray in situ studies in electrically and laser-heated diamond anvil cells (DACs) at pressures over 80 GPa and temperatures above 2500 K were used to determine stable silica phase at extreme conditions. We demonstrate that so far unidenti®ed phases obtained on the compression of a-cristobalite, new dense silica polymorph in the Martian Shergotty meteorite, and controversial post-stishovite phas...
متن کاملEffect of impurities on cathodoluminescence of tridymite and cristobalite
Cristobalite and tridymite in andesite and obsidian exhibit bright blue emissions in color cathodoluminescence (CL) images. CL spectra of cristobalite and tridymite show emission bands at 400 and 430 nm, respectively. Their CL intensity decreases with an increase in the electron irradiation time, similar to the short-lived blue luminescence reported in hydrothermal quartz. The reduction rate of...
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ژورنال
عنوان ژورنال: Journal of the Mineralogical Society of Japan
سال: 1958
ISSN: 1883-7018,0454-1146
DOI: 10.2465/gkk1952.3.603