Amorphization Mitigation in Boron-Rich Boron Carbides Quantified by Raman Spectroscopy

Depressurization amorphization of single-crystal boron carbide.

We report depressurization amorphization of single-crystal boron carbide (B4C) investigated by in situ high-pressure Raman spectroscopy. It was found that localized amorphization of B4C takes place during unloading from high pressures, and nonhydrostatic stresses play a critical role in the high-pressure phase transition. First-principles molecular dynamics simulations reveal that the depressur...

Thermal conductivity behavior of boron carbides.

Knowledge of the thermal conductivity of boron carbide is necessary o evaluate its potential for high temperature thermoelectric energy conversion applications. We have measured the thermal diffusivity of hot -pressed boron carbide B1_xCx samples as a function of composition (0.1 < x < 0.2), temperature (300 K to 1700 K) and temperature cycling. These data in concert with density and specific h...

Raman spectroscopy of single-wall boron nitride nanotubes.

Single-wall boron nitride nanotubes samples synthesized by laser vaporization of a hexagonal BN target under a nitrogen atmosphere are studied by UV and visible Raman spectroscopy. We show that resonant conditions are necessary for investigating phonon modes of BNNTs. Raman excitation in the UV (229 nm) provides preresonant conditions, allowing the identification of the A1 tangential mode at 13...

Conductivities and Seebecis Coefficients of Boron Carbides: “softening-bipolaron” Hopping

3d transition metal doping of semiconducting boron carbides

The introduction metallocenes, in particular ferrocene (Fe(η-C5H5)2), cobaltocene (Co(η-C5H5)2), and nickelocene (Ni(η-C5H5)2), together with the carborane source molecule closo-1,2-dicarbadodecaborane, during plasma enhanced chemical vapor deposition, will result in the transition metal doping of semiconducting boron carbides. Here we report using ferrocene to introduce Fe dopants, and a semic...