Phase diagram of boron carbide with variable carbon composition

Interaction of Lanthanum with Boron and Carbon: Phase Diagram and Structural Chemistry

8 The isothermal section of the La–B–C phase diagram at 1270 K has been investigated by 9 means of X-ray, neutron powder diffraction, microstructure and EPMA analyses. Eight ternary 10 compounds were found, and for six of them the crystal structures have been established. The 11 phase with the structure type of La5B2C6 has a broad homogeneity range described by the 12 formula La5(BC)x (5.6x8....

Phase Transitions of Boron Carbide: Pair Interaction Model of High Carbon Limit

Boron Carbide exhibits a broad composition range, implying a degree of intrinsic substitutional disorder. While the observed phase has rhombohedral symmetry (space group R3̄m), the enthalpy minimizing structure has lower, monoclinic, symmetry (space group Cm). The crystallographic primitive cell consists of a 12-atom icosahedron placed at the vertex of a rhombohedral lattice, together with a 3-a...

Boron under Pressure: Phase Diagram and Novel High-pressure Phase

Boron has a unique chemistry, responsible for remarkable complexities even in the pure element. I review some of the history of the discovery of this element, and recent surprises found in boron under pressure. I discuss the recent discovery of a new high-pressure phase, γ-B28, consisting of icosahedral B12 clusters and B2 pairs in a NaCl-type arrangement: (B2)(B12), and displaying a significan...

Prediction of orientational phase transition in boron carbide

The assessed binary phase diagram of boron-carbon exhibits a single intrinsically disordered alloy phase designated “B4C” with rhombohedral symmetry occupying a broad composition range that falls just short of the nominal carbon content of 20%. As this composition range is nearly temperature independent, the phase diagram suggests a violation of the third law of thermodynamics, which typically ...

Boron carbide/n-silicon carbide heterojunction diodes