TITLE:
Evaluation of Gallium Arsenide Thermal Expansion Coefficient by Extended X-Ray Absorption Fine Structure
AUTHORS:
Gora Dieye, Sameh I. Ahmed, Abdou C. Wade, Djibril Diop
KEYWORDS:
Negative Thermal Expansion, Tension Effects, EXAFS, Asymmetry, Gallium Arsenide
JOURNAL NAME:
World Journal of Condensed Matter Physics,
Vol.9 No.2,
March
13,
2019
ABSTRACT: Negative thermal expansion of gallium arsenide has been investigated through temperature dependent Extended X-ray Absorption Fine Structure (EXAFS) measurements. The bond thermal expansion coefficient αbond has been evaluated and compared to negative expansion coefficient αtens due to tension effects. The overall thermal expansion coefficient is the sumofαbondand αtens. Below 60 K, αtens is greater than αbond yielding to a negative expansion in this temperature region. Tension effects are progressively overcome by the stretching effects in the region 60 - 300 K. The asymmetry of nearest neighbors distribution is not negligible since the gaussian approximation underestimates the bond expansion by about 0.00426 Å. This error decreases when the temperature is lowered. The accuracy in the thermal expansion evaluation and the connection between third cumulant and thermal expansion are discussed.