Role of atomistic structure in the stochastic nature of conductivity in substoichiometric tantalum pentoxide
Abstract
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 advancementmore »
- Authors:
-
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Publication Date:
- Research Org.:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Org.:
- USDOE National Nuclear Security Administration (NNSA)
- OSTI Identifier:
- 1248534
- Alternate Identifier(s):
- OSTI ID: 1421088
- Report Number(s):
- SAND-2016-0408J
Journal ID: ISSN 0021-8979; JAPIAU; 618608
- Grant/Contract Number:
- AC04-94AL85000
- Resource Type:
- Journal Article: 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)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; tantalum; crystal structure; amorphous metals; electrical resistivity; carrier density
Citation Formats
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., 2016.
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. https://doi.org/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. https://doi.org/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},
url = {https://www.osti.gov/biblio/1248534},
journal = {Journal of Applied Physics},
issn = {0021-8979},
number = 12,
volume = 119,
place = {United States},
year = {Tue Mar 22 00:00:00 EDT 2016},
month = {Tue Mar 22 00:00:00 EDT 2016}
}
Web of Science