منابع مشابه
Negative thermal expansion of diamond and zinc-blende semiconductors.
Experimentally it is well known that diamond and zinc-blend semiconductors show an "unusual" (i.e. , negative) thermal expansion at about 100 K. We performed density-functional-theory calculations of thermodynamic potentials (i.e. , total energies and entropies) for perfect crystals, to study the temperature dependence of the lattice parameter. The origin of the negative expansion eff'ect is tr...
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A major problem challenging specialists in present-day materials sciences is the development of compact, cheap to fabricate heat sinks for electronic devices, primarily for computer processors, semiconductor lasers, high-power microchips, and electronics components. The materials currently used for heat sinks of such devices are aluminum and copper, with thermal conductivities of about 250 W/(m...
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A numerical model was used to examine experimental data in which a gas chromatograph measured the composition of gas sampled through a 70-pn orifice in the growth substrate during atmospheric-pressure RF plasma diamond CVD. Substantial discrepancies were found between the measurements and the predicted species mole fractions at the surface, but the data were in much better accord with predicted...
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I n t r o d u c t i o n THE structures of the cancrinite-group minerals are character ized by parallel s ix-membered rings consisting of alternating A104 and SiO4 tetrahedra. The hexagonal symmetry is the result of the stacking of such six-membered rings in an AB... sequence. This stacking leads to large continuous channels that are formed by twelve-membered rings of alternating A1Oa and SiO4 t...
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Thermal expansion is an important property of substances. Its theoretical prediction has been challenging, particularly in cases the volume decreases with temperature, i.e., thermal contraction or negative thermal expansion at high temperatures. In this paper, a new theory recently developed by the authors has been reviewed and further examined in the framework of fundamental thermodynamics and...
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ژورنال
عنوان ژورنال: Nature
سال: 1894
ISSN: 0028-0836,1476-4687
DOI: 10.1038/049480d0