CaB2C2: Reinvestigation of a Semiconducting Boride Carbide with a Layered Structure and an Interesting Boron/Carbon Ordering Scheme
- 1 December 1999
- journal article
- research article
- Published by American Chemical Society (ACS) in Inorganic Chemistry
- Vol. 38 (26) , 6159-6163
- https://doi.org/10.1021/ic9907821
Abstract
Calcium diboride dicarbide, CaB2C2, was synthesized as a crystalline powder and investigated by electron energy loss spectroscopy, X-ray powder diffractometry, conductivity measurements, and LMTO band structure calculations. A new structure model was derived, and the crystal structure was refined by Rietveld methods in the tetragonal space group I4/mcm (No. 140, a = 537.33(1) pm and c = 741.55(2) pm, Z = 4). The boron and carbon atoms are well ordered within layers consisting of four- and eight-membered rings. A convincing coloring scheme is proven by the detection of a superstructure reflection. An earlier assignment of the compound into the LaB2C2 structure family (space group P4̄2c or P42/mmc, respectively) has been shown to be incorrect. LMTO band structure calculations suggest semiconducting behavior for CaB2C2, which has been confirmed by conductivity measurements.Keywords
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