The Unexpected Formation of MB₂ Layers (M = Refractory Metal) on Metal Surfaces

Abstract

The reactions between refractory metals (Ti, Zr, V, Nb, Ta, Mo, W) and BCl 3 vapour at high temperatures have been studied. For this purpose, the metal wires were heated up by an electrical current in a BCl 3 atmosphere for a couple of hours. Optical and X-ray diffraction methods were used to analyze the solid products, whereas mass spectrometry was used to study the gas phase composition. In the reactions

Nanoscaled Metal Borides and Phosphides: Recent Developments and Perspectives

“…Upon an increase of the temperatures of boriding and annealing, the B(1s) XPS peak sharpens (Figure ), indicating complete incorporation of boron into the HfB 2 structure with a stoichiometric ratio of 1:2. Friedhoff et al reported more recently the reaction between BCl 3 at a static pressure of 1 bar and wires of various metals including V, Nb, Ta, Ti, Mo, and Zr . In the absence of any additional reactant to reduce efficiently BCl 3 , high temperatures between 1200 and 1500 °C were required to carry out the reaction.…”

“…In the absence of any additional reactant to reduce efficiently BCl 3 , high temperatures between 1200 and 1500 °C were required to carry out the reaction. As a consequence, only micrometer-sized structures were obtained . Metallization of boron nanostructures was also investigated for MgB 2 synthesis (see subsection 3.2.5) and TiB 2 …”