A key focus in industrial processing is finding greener routes to well-established, high performance materials. Boron carbide is such a material, with excellent mechanical and thermal properties and high commercial value. The conventional synthesis of boron carbide is time- and energy- intensive, requiring prolonged heating at high temperatures and often producing low-quality products. Microwave synthesis of carbides is emerging as a viable alternative to conventional solid state techniques since carbon interacts strongly with a MW field. While the general structural features of the boron carbides are known, the composition and bonding of the inter-icosahedral units (and indeed the icosahedra themselves) remain unclear. PND data should allow precise location of B and C; indicate vacancy concentration and clarify the temperature dependence of the displacement parameters