Phase equilibria and crystal structure relationships in the ternary Li–B–C system

Abstract

Phase equilibria in the Li–B–C ternary system have been investigated by X-ray powder diffraction, scanning electron microscopy, electron probe microanalysis and differential scanning calorimetry. The isothermal section of the phase diagram has been constructed over the whole concentration range at 400 °C. The Li–B–C system is characterized by the formation of six ternary compounds: τ₁ – LiBC₃, τ₂ – LiB₂C₂, τ₃ – LiBC, τ₄ – Li₂B₂C, τ₅ – LiB₆C and τ₆ – LiB₁₃C₂. The formation of the new ternary compound LiB₂C₂ (own structure type, space group P6₃/mmc, a = 2.5930(3) Å, c = 22.680(1) Å) and binary BC₃ (space group Pm2, a = 2.4588(4) Å, c = 6.770(2) Å) has been revealed. The crystal structures are discussed in the light of the underlying graphene and heterographene networks.