Si/C相図における異常と予想されるもの
Guoying Gao1, N W Ashcroft, Roald Hoffmann
1Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA.
Journal of the American Chemical Society
|July 12, 2013
まとめ
研究者は,シリコンカーバイド (SiC) 構造を計算的に調査しました. 彼らは,崩壊したグラファイトのような構造と金属的潜在力を含むユニークな層状の配置を持つ新しい転移性SiC3相を発見しました.
科学分野:
- マテリアルサイエンス 材料科学
- コンピューティング・ケミストリー
- 固体物理 固体物理学
背景:
- 1 atmのシリコン-炭素 (Si/C) 段階図は,主に安定したシリコンカーバイド (SiC) ポリタイプを示しています.
- 運動的要因により持続する,転移性Si/C相は,様々な組成にわたって存在することができます.
- 以前の仮定では,元安定相はダイアモンド形構造に限定され,特にSi3Cのようなシリコンに富んだ組成物には限定されると示唆されていた.
研究 の 目的:
- Si/C相図の炭素豊富な側面のメタステーブル相を計算的に調査する.
- 既知の安定形態を超えて,新しい,運動的に持続的なシリコンカーバイド構造を特定し,特徴づけること.
- 未知のSiCステキオメトリーの構造的多様性と潜在的な性質を調査する.
主な方法:
- SiC3ステキオメトリーの計算による探査.
- 潜在エネルギー表面の分析により,メタステーブルな構造を特定する.
- 新しいSiC3相における原子配列と結合の特徴.
主要な成果:
- 異常な転移安定したSiC3構造を発見し,以前の仮定に異議を唱えました.
- ベンゼノイドC6ユニットとSi-Siブリッジを特徴とするグラファイトのような構造が崩壊した.
- ポリエネおよびポリフェニレン層を持つ他の転移性構造の観察,一部の金属特性を示す.
結論:
- Si/Cシステムの炭素に富んだ側面は,予期せぬメタステーブルな相を宿している.
- サイクロファンの関連形態を含む特定されたSiC3構造は,カルビドシリコンの既知の構造的景観を拡張します.
- いくつかの新種の超安定SiC3相は,金属性などの潜在的に貴重な電子特性を有しています.
さらに関連する動画
04:09Demonstrating the Simplicity and In Situ Temperature Monitoring of the Mechanochemical Synthesis of Metal Chalcogenides Suitable for Thermoelectrics
Published on: August 30, 2024
11:50Metal-silicate Partitioning at High Pressure and Temperature: Experimental Methods and a Protocol to Suppress Highly Siderophile Element Inclusions
Published on: June 13, 2015
関連する概念動画
Phase Diagrams
A phase diagram combines plots of pressure versus temperature for the liquid-gas, solid-liquid, and solid-gas phase-transition equilibria of a substance. These diagrams indicate the physical states that exist under specific conditions of pressure and temperature and also provide the pressure dependence of the phase-transition temperatures (melting points, sublimation points, boiling points). Regions or areas labeled solid, liquid, and gas represent single phases, while lines or curves represent...
Phase Diagram
The phase of a given substance depends on the pressure and temperature. Thus, plots of pressure versus temperature showing the phase in each region provide considerable insights into the thermal properties of substances. Such plots are known as phase diagrams. For instance, in the phase diagram for water (Figure 1), the solid curve boundaries between the phases indicate phase transitions (i.e., temperatures and pressures at which the phases coexist).
Phase Diagram
A phase diagram is a graphical representation of the physical states of a substance under different conditions of temperature and pressure. It shows the boundaries between solid, liquid, and gas phases and the conditions at which these phases coexist in equilibrium. An area in a phase diagram represents a single phase, whereas lines or phase boundaries represent the equilibrium between two phases.In the phase diagram of water, the boundary line between the solid and liquid states illustrates...
Phase Diagrams of Ternary Systems
Consider a ternary system, which is composed of three components: water (W), ethanoic acid (E), and trichloromethane (T). Here, Ethanoic acid (E) is fully miscible with both water (W) and trichloromethane (T), meaning it can mix entirely with either of them. However, water and trichloromethane have partial miscibility, meaning they can only mix to a certain extent, beyond which two separate phases will form.The phase diagram of a ternary system is represented as an equilateral triangle, where...
The Phase Rule
The phase rule describes the relationship between the variance (degrees of freedom), the number of components, and the number of phases in a system at equilibrium.Variance is a concept that denotes the number of independent intensive properties (properties are those that do not depend on the amount of material in the system), such as temperature, pressure, and composition, that can be altered without impacting the number of phases in equilibrium.In a single-component system, such as pure water,...
Solid–Solid Solutions
The temperature-composition phase diagram of two solids, A and B, which are immiscible in the solid phase but form miscible liquids, shows that when the temperature is low, these two exist as separate, pure solids (A and B). As the temperature increases, they transition into a single-phase liquid solution where A and B coexist. Moving from point a1 to a2 in the phase diagram, the composition changes such that solid B begins to separate from the solution, enriching the remaining liquid with A.
