Crystal chemistry of carbon-substituted MgB2
By M. Avdeev, J. Jorgensen, R. Ribeiro, S. Bud’ko, Paul C. Canfield. 2003
208 citations recorded by the source corpus.
Abstract Neutron powder diffraction has been used to characterize a sample of C-substituted MgB 2 synthesized from Mg and B 4 C (with isotopically enriched 11 B). The sample is multiphase, with the major phase [73.4(1) wt%] being Mg(B 1− x C x ) 2 with x =0.10(2). Minor phases include MgB 2 C 2 , Mg, and MgO. The major Mg(B 1− x C x ) 2 phase displays diffraction peak widths as sharp as for pure MgB 2 , indicating good C homogeneity. There is no evidence for ordering of the substituted C atoms or distortion of the host structure other than contraction of the a axis and slight expansion of the c axis. The observed changes in lattice parameters vs. C concentration provide a means for estimating the C concentration in other Mg(B 1− x C x ) 2 samples. The reduction in T c resulting from 10% C substitution is much larger than previously reported, suggesting that previous reports of the C concentration in Mg(B 1− x C x ) 2 are overestimated. The Mg site occupancy is determined to be 0.990(4) which is consistent with full Mg occupancy. Given these results, the stoichiometry Mg(B 0.9 C 0.1 ) 2 should be used by future attempts (band structural or otherwise) to explain (i) the dramatic suppression of T c ( T c ≈22 K) and (ii) the persistence of the two-superconducting-gap feature in the specific heat data.
Subfields: Condensed Matter Physics, Materials Chemistry
View Paper: https://www.semanticscholar.org/paper/6a5bd5c985d317ac4fd26910732aeda2c7dc1899
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In Condensed Matter Physics
In Materials Chemistry
Citations in the corpus
- Two-band superconductor magnesium diboride (2008, background): “Unlike carbon-doped single crystals, where the lattice constant a decreases but c remains almost constant [215, 216], both the c and a axes in the carbon-alloyed HPCVD films expand with increasing carbon content [91].”