New Ternary Compounds Sc 3B 0.75C 3, Sc 2B 1.1C 3.2, ScB 15C 1.60 and Subsolidus Phase Relations in the Sc-B-C System at 1700°C
Abstract
The phase relations in the ternary system scandium-boron-carbon with special emphasis on the boron-rich section have been investigated in an isothermal section at 1700°C. Ternary compounds with the following stoichiometries were identified: Sc2BC2, Sc3B0.75C3, Sc2B1.1C3.2, ScB2C2, ScB17C0.25, ScB15C0.80, and ScB15C1.60. Four of them, Sc3B0.75C3, Sc2B1.1C3.2, ScB15C1.60, and ScB15C0.80, were synthesized for the first time. The first three could be indexed, i.e., Sc3BC3 shows tetragonal symmetry with a=3.3308(3) Å and c=7.680(2) Å; the basic hexagonal unit cell of Sc2B1.1C3.2 is a=3.3991(2) Å, c=6.7140(6) Å, with a two-dimensional incommensurate structure with magnitude ∣qi∣=(2/7+0.005) ∣q100∣ Å-1 along <100> directions; and ScB15C1.60 shows a body centered orthorhombic lattice a=10.027(1) Å, b=8.0138(9) Å and c=5.6668(6) Å. A crystal of Sc2BC2 was grown by the floating zone method and the crystal structure was refined from single crystal data, which crystallizes with tetragonal symmetry: I4/mmm, a=3.3259(2) Å, c=10.6741(8) Å, Z=2, R=0.011 for 263 unique reflections and 10 variables.
- Publication:
-
Journal of Solid State Chemistry France
- Pub Date:
- December 1999
- DOI:
- 10.1006/jssc.1999.8446
- Bibcode:
- 1999JSSCh.148..250S
- Keywords:
-
- scandium borides;
- scandium carbides;
- scandium boron-carbides;
- phase relations;
- crystal structure refinement;
- Sc<SUB>3</SUB>B<SUB>0.75</SUB>C<SUB>3</SUB>;
- Sc<SUB>2</SUB>B<SUB>1.1</SUB>C<SUB>3.2</SUB>;
- ScB<SUB>15</SUB>C<SUB>1.60</SUB>;
- ScB<SUB>15</SUB>C<SUB>0.80</SUB>;
- Sc<SUB>2</SUB>BC<SUB>2</SUB>.