skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: First-principles study of phonon anomalies and the bcc-hcp martensitic phase transition

Abstract

First-principles total energy calculations have been performed for transition metal Zr in the ..omega.., bcc, hcp, fcc structures and for Ba in the bcc, fcc structures. From our calculations we obtained equilibrium lattice constants, cohesive energies, bulk moduli and energy difference between the bcc and the hcp phases which are in good agreement with experiment. The total energy of ..omega.. phase was found to be very close to that of hcp phase in Zr. Recent neutron scattering experiments on a single crystal of bcc Ba have revealed that the longitudinal branch along the (100) direction is lower than the transverse branch. This anomalous behavior has been studied with use of the frozen-phonon method and is shown to arise from d-electron interactions. For the pressure induced bcc-hcp transition in Ba, the volume dependence of the complete energy surface from the bcc to the hcp structure has been determined as a function of the atomic displacements corresponding to the T/sub 1/ N-point phonon mode and a long wavelength shear. Results from frozen phonon calculations for Zr indicate an instability toward the hcp phase at t = 0 K in the bcc-hcp transition and determine the third and fourth order anharmonic coupling strengthsmore » which were used to evaluate the temperature dependence of selected frequencies. 135 refs., 29 figs., 13 tabs.« less

Authors:
Publication Date:
Research Org.:
Ames Lab., IA (USA)
OSTI Identifier:
6986884
Report Number(s):
IS-T-1275
ON: DE87003050
DOE Contract Number:  
W-7405-ENG-82
Resource Type:
Technical Report
Resource Relation:
Other Information: Thesis
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE; BARIUM; CRYSTAL-PHASE TRANSFORMATIONS; LATTICE PARAMETERS; ZIRCONIUM; COUPLING CONSTANTS; EIGENVALUES; EXCITATION; MATHEMATICAL MODELS; PHONONS; TEMPERATURE DEPENDENCE; THEORETICAL DATA; VALENCE; ALKALINE EARTH METALS; DATA; ELEMENTS; ENERGY-LEVEL TRANSITIONS; INFORMATION; METALS; NUMERICAL DATA; PHASE TRANSFORMATIONS; QUASI PARTICLES; TRANSITION ELEMENTS; 656002* - Condensed Matter Physics- General Techniques in Condensed Matter- (1987-); 360102 - Metals & Alloys- Structure & Phase Studies

Citation Formats

Chen, Y. First-principles study of phonon anomalies and the bcc-hcp martensitic phase transition. United States: N. p., 1986. Web.
Chen, Y. First-principles study of phonon anomalies and the bcc-hcp martensitic phase transition. United States.
Chen, Y. 1986. "First-principles study of phonon anomalies and the bcc-hcp martensitic phase transition". United States.
@article{osti_6986884,
title = {First-principles study of phonon anomalies and the bcc-hcp martensitic phase transition},
author = {Chen, Y},
abstractNote = {First-principles total energy calculations have been performed for transition metal Zr in the ..omega.., bcc, hcp, fcc structures and for Ba in the bcc, fcc structures. From our calculations we obtained equilibrium lattice constants, cohesive energies, bulk moduli and energy difference between the bcc and the hcp phases which are in good agreement with experiment. The total energy of ..omega.. phase was found to be very close to that of hcp phase in Zr. Recent neutron scattering experiments on a single crystal of bcc Ba have revealed that the longitudinal branch along the (100) direction is lower than the transverse branch. This anomalous behavior has been studied with use of the frozen-phonon method and is shown to arise from d-electron interactions. For the pressure induced bcc-hcp transition in Ba, the volume dependence of the complete energy surface from the bcc to the hcp structure has been determined as a function of the atomic displacements corresponding to the T/sub 1/ N-point phonon mode and a long wavelength shear. Results from frozen phonon calculations for Zr indicate an instability toward the hcp phase at t = 0 K in the bcc-hcp transition and determine the third and fourth order anharmonic coupling strengths which were used to evaluate the temperature dependence of selected frequencies. 135 refs., 29 figs., 13 tabs.},
doi = {},
url = {https://www.osti.gov/biblio/6986884}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1986},
month = {11}
}

Technical Report:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that may hold this item. Keep in mind that many technical reports are not cataloged in WorldCat.

Save / Share: