GdCo_2B_2C_x(x=0〜1)の合成及びC量xの変化に伴う結晶構造の変化に関する研究

概要

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GdCo_2B_2C_x(x=0-1)has been synthesized to study the role of C in the formation of a new quaternary compounds RT_2B_2C(R=rare earth, T=transition metal); RT_2B_2C belongs to a tetragonal system with ThCr_2Si_2 derivative type. Samples of GdCo_2B_2C_x(x=0, 0.25, 0.50, 0.75 and 1.00)were prepared by the arc-melting synthetic method. According to backscattered SEM study, the obtained compound of tetragonal phase was observed as rectangular, narrow-ribbon and wide-ribbon for x=0, 0.25-0.75 and 1.00 in GdCo_2B_2C_x, respectively. The lattice parameter α sligtly decreased, while the lattice parameter c and the unit cell volume increased appreciably with increasing x in GdCo_2B_2C_x. This result shows that C element serves to expand the entire unit cell in the shape of a square column composed of R atoms(eight at the corners)especially along the c-direction, and permit T atoms, which are too large for the normal lattice, to join in combination. The role of C to form the quaternary borocarbides RT_2B_2C has been demonstrated.
社団法人日本セラミックス協会の論文
1998-03-01