Effective charge on silicon atom in the metal silicides Mg{sub 2}Si and CaSi

Journal Article · Sun May 15 04:00:00 EDT 2005 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PhysRevB.71.205202· OSTI ID:20719021

Ishii, Hideshi; Karimov, Pavel; Kawai, Jun ^[1]; Matsuo, Shuji ^[1]; Tanaka, Koki ^[2]

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1. Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan)
2. Materials Characterization Laboratory, Advanced Technology Research Laboratories, Nippon Steel Corporation, 20-1 Shintomi, Futsu, Chiba 293-8511 (Japan)

The effective charges of Si in both magnesium (Mg{sub 2}Si) and calcium silicides (CaSi and Ca{sub 2}Si) have been investigated by measuring high-resolution Si K{alpha} x-ray fluorescence spectra. CaSi showed small but positive chemical shifts (+0.03 eV), while the chemical shift of Mg{sub 2}Si was negative (-0.14 eV), as expected from their electronegativity (Ca: 1.00; Mg: 1.31; Si: 1.90). The similarity of the chemical shift for the Fe silicides and the calculations for the free single Si atom suggested that the effective charge of Si for CaSi was positive. From the observations the effective charges on Si in CaSi and Mg{sub 2}Si were estimated to be +0.1 and -0.3 electrons. The discrete variation Hatree-Fock-Slater calculations for Mg{sub 2}Si and CaSi also showed opposite chemical shifts and effective charges: -0.09 eV and -0.35 electrons for Mg{sub 2}Si and +0.09 eV and +0.26 electrons for CaSi, respectively. The composition of the nearest-neighbor atoms of Si, which are Si in CaSi and Mg in Mg{sub 2}Si, cause the opposite effective charges between the two silicides.

• OSTI ID: 20719021
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 20 Vol. 71; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ATOMS
CALCIUM SILICIDES
CHEMICAL SHIFT
EFFECTIVE CHARGE
ELECTRONEGATIVITY
ELECTRONS
EMISSION SPECTRA
EV RANGE
FLUORESCENCE SPECTROSCOPY
MAGNESIUM
MAGNESIUM SILICIDES
RESOLUTION
SILICON
VARIATIONS
X RADIATION
X-RAY FLUORESCENCE ANALYSIS
X-RAY SPECTRA