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Title: Role of atomistic structure in the stochastic nature of conductivity in substoichiometric tantalum pentoxide

In this study, first-principles calculations of electrical conductivity (σ o) are revisited to determine the atomistic origin of its stochasticity in a distribution generated from sampling 14 ab-initio molecular dynamics configurations from 10 independently quenched models (n = 140) of substoichiometric amorphous Ta 2O 5, where each structure contains a neutral O monovacancy (V O 0). Structural analysis revealed a distinct minimum Ta-Ta separation (dimer/trimer) corresponding to each V O 0 location. Bader charge decomposition using a commonality analysis approach based on the σ o distribution extremes revealed nanostructural signatures indicating that both the magnitude and distribution of cationic charge on the Ta subnetwork have a profound influence on σ o. Furthermore, visualization of local defect structures and their electron densities reinforces these conclusions and suggests σ o in the amorphous oxide is best suppressed by a highly charged, compact Ta cation shell that effectively screens and minimizes localized V O 0 interaction with the a-Ta 2O 5 network; conversely, delocalization of V O 0 corresponds to metallic character and high σ o. The random network of a-Ta 2O 5 provides countless variations of an ionic configuration scaffold in which small perturbations affect the electronic charge distribution and result inmore » a fixed-stoichiometry distribution of σ o; consequently, precisely controlled and highly repeatable oxide fabrication processes are likely paramount for advancement of resistive memory technologies.« less
Authors:
 [1] ;  [1] ;  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Report Number(s):
SAND-2016-0408J
Journal ID: ISSN 0021-8979; JAPIAU; 618608
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 119; Journal Issue: 12; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; tantalum; crystal structure; amorphous metals; electrical resistivity; carrier density
OSTI Identifier:
1248534
Alternate Identifier(s):
OSTI ID: 1421088

Bondi, Robert James, Fox, Brian Philip, and Marinella, Matthew J. Role of atomistic structure in the stochastic nature of conductivity in substoichiometric tantalum pentoxide. United States: N. p., Web. doi:10.1063/1.4943163.
Bondi, Robert James, Fox, Brian Philip, & Marinella, Matthew J. Role of atomistic structure in the stochastic nature of conductivity in substoichiometric tantalum pentoxide. United States. doi:10.1063/1.4943163.
Bondi, Robert James, Fox, Brian Philip, and Marinella, Matthew J. 2016. "Role of atomistic structure in the stochastic nature of conductivity in substoichiometric tantalum pentoxide". United States. doi:10.1063/1.4943163. https://www.osti.gov/servlets/purl/1248534.
@article{osti_1248534,
title = {Role of atomistic structure in the stochastic nature of conductivity in substoichiometric tantalum pentoxide},
author = {Bondi, Robert James and Fox, Brian Philip and Marinella, Matthew J.},
abstractNote = {In this study, first-principles calculations of electrical conductivity (σo) are revisited to determine the atomistic origin of its stochasticity in a distribution generated from sampling 14 ab-initio molecular dynamics configurations from 10 independently quenched models (n = 140) of substoichiometric amorphous Ta2O5, where each structure contains a neutral O monovacancy (VO0). Structural analysis revealed a distinct minimum Ta-Ta separation (dimer/trimer) corresponding to each VO0 location. Bader charge decomposition using a commonality analysis approach based on the σo distribution extremes revealed nanostructural signatures indicating that both the magnitude and distribution of cationic charge on the Ta subnetwork have a profound influence on σo. Furthermore, visualization of local defect structures and their electron densities reinforces these conclusions and suggests σo in the amorphous oxide is best suppressed by a highly charged, compact Ta cation shell that effectively screens and minimizes localized VO0 interaction with the a-Ta2O5 network; conversely, delocalization of VO0 corresponds to metallic character and high σo. The random network of a-Ta2O5 provides countless variations of an ionic configuration scaffold in which small perturbations affect the electronic charge distribution and result in a fixed-stoichiometry distribution of σo; consequently, precisely controlled and highly repeatable oxide fabrication processes are likely paramount for advancement of resistive memory technologies.},
doi = {10.1063/1.4943163},
journal = {Journal of Applied Physics},
number = 12,
volume = 119,
place = {United States},
year = {2016},
month = {3}
}