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Combined EXAFS and First-Principles Theory Study of Pb1-xGexTe



Bruce D. Ravel, Eric J. Cockayne, E Newville, K M. Rabe


The narrow band-gap semiconductor Pb1-xGexTe has a low-temperature ferroelectric rhombohedral phase whose average structure is a distorted rocksalt structure. We have measured the Extended X-Ray-Absorption Fine-Structure (EXAFS) spectra of Pb1-xGexTe with x {nearly equal to} 0.3 at the Ge and Te K edges and at the Pb LIII edge. Guided by first-principles calculations, we create a model for the local structure as a distortion from the ideal rock salt structure. By co-refining the spectra from these edges, we demonstrate that the data are consistent with our fitting model and we directly measure several secondary structural distortions predicted by the theory. This work demonstrates a powerful approach to the determination of local structures in complex materials by using first-principles calculations in conjunction with EXAFS measurements.
Physical Review B (Condensed Matter and Materials Physics)
No. 21


EXAFS, ferroelectric, functional theory, local density
Created December 1, 1999, Updated February 19, 2017