Phase Diagram of the B−BN System at 5 GPa

Abstract

The chemical interaction and phase relations in the B-BN system have been in situ studied at 5 GPa and temperatures up to 2800 K using X-ray diffraction with synchrotron radiation. The thermodynamic analysis of the B-BN system based on experimental data allowed us to construct equilibrium and metastable phase diagrams of the system at 5 GPa. The only thermodynamically stable boron subnitride, B(13)N(2), melts incongruently at 2600 K and forms eutectic equilibrium with boron at 2300 K and 4 at. % of nitrogen.

Composition and bonding structure of boron nitride B1−xNx thin films grown by ion-beam assisted evaporation

“…Considerably less research has been carried out on the synthesis and properties of nonstoichiometric B 1-x N x boron nitrides. Mainly, boron subnitrides (x<0.5) resembling the α-rhombohedral (rh) boron structure have attracted some interest in the last decades [12][13][14][15][16][17][18][19][20][21], inspired by the technological interest of boron-rich hard refractory compounds (B 4 C, B 6 O,…) [22].…”

“…Using this technique in combination with synchrotron x-ray diffraction, Solozhenko et al determined the structure of a new α-rh B 13 N 2 phase with N-B-N linear chains between B 12 icosahedra [12,15,17,18,23,24]. They also studied the phase diagram of the B-BN system and observed the formation of an I-tetragonal B 50 N 2-x B x solid solution [15,17]. Hubert and co-workers reported the HP-HT synthesis of an α-rh B 12 N 2 phase similar to B 6 O [16,25], but the results were questioned later on by the group of Solozhenko [13].…”

“…All experiments were carried out with a B flux between (1.50.2)10 15 and (9.50.5)10 15 at. cm 2 s 1 , while the impinging N flux was kept constant at (2.00.5)10 15 at.…”

Disordered Icosahedral Boron-Rich Solids: A Theoretical Study of Thermodynamic Stability and Properties

“…Compared to the other icosahedral boron-rich solids, in particular boron carbide, having been frequently addressed in the literature [1,6,17,20,25,27,28,30,35,36,84,91,[94][95][96][108][109][110][111][112][113][114], relatively few studies have so far been made on boron subnitride [19,[115][116][117][118][119][120]. For this reason, several issues about boron subnitride, for example its stable compositions, properties, as well as the correct representation of its basic structural unit, are still inconclusive.…”

“…Due to the small variation of lattice parameters of the as-synthesized boron subnitrides found in experiments, it has been suggested that boron subnitride, instead of a solid solution, is an individual line compound [119]. Furthermore, due to the incompleteness of the reactions, the as-synthesized boron subnitrides had often poor crystalline quality, and were always found in a mixture with β-rhombohedral boron, hexagonal boron nitride and α-tetragonal boron subnitride, limiting accessibility to the properties of boron subnitride in experiments [119,120].…”