Preparation and Properties of Si Doped $\hbox{Mg}{( \hbox{B}_{1 - x}\hbox{C}_{x})}_{2}$ Using Silica Sol-Gel and Carbon Chemical Vapor Coated Boron

Coating a precursor nano powder by depositing a thin layer of dopant can achieve a controllable homogeneous distribution of the dopant per nano grain. Previously, we have shown that a simple, scalable chemical vapor deposition method is capable of achieving a uniform deposition of carbon onto boron powder, since the dopant is evenly distributed on each precursor grain. In this paper, we implement a new technique using a sol-gel method (using tetraethyl orthosilicate as a precursor) to coat silica on nano-sized boron powder. The silica-coated boron is also subsequently coated with carbon using the technique detailed previously. Both silica-coated and silica+carbon coated powders are reacted with magnesium using the in situ process. Analysis using transmission electron microscopy, powder X-ray diffraction and the field and temperature-dependence of critical current density is used to evaluate the effectiveness and homogeneity of this method.