skip to main content

DOE PAGESDOE PAGES

Title: Polaronic conduction and Anderson localization in reduced strontium barium niobate

Electron transport mechanisms in reduced Sr 0.5Ba 0.5Nb 2O 6 (SBN50) are investigated from ~100 to 955 K through an analysis of the electrical conductivity (σ) and the Seebeck coefficient (S) with respect to temperature (T). Notably, experimental evidence is presented that supports a scenario of Anderson localization below 600 K and carrier excitation across a mobility edge at higher temperature. As a relaxor ferroelectric, stoichiometric SBN has intrinsic disorder associated with both the distribution of Sr/Ba vacancies and the formation of polarized nanoregions. The removal of oxygen through reduction generates conduction electrons in SBN. At the lowest temperatures measured (100–155 K), the electrical conductivity exhibits a temperature dependence characteristic of variable range hopping, followed by a transition to small polaron hopping at intermediate temperatures (250–545 K). In both the variable range and small polaron hopping regimes, a semiconductor-like temperature dependence of the electrical conductivity ( dσ/dT > 0) was observed. However, above 615 K, dσ/dT decreases dramatically and eventually becomes metal-like ( dσ/dT < 0). Concomitantly, the Seebeck coefficient exhibits a linear dependence on lnT from 615 to 955 K with the same slope (~104 μ V/K) for both polycrystalline SBN50 and single crystalline SBN61 (both reduced), indicating amore » similar, constant density of states near the Fermi level for both compositions. Here, the application of Seebeck coefficient theory to this inherently disordered material reveals that the excitation of carriers across a mobility edge is likely responsible for the change in dσ/dT at high temperature. Such findings may have a significant impact in the field of conductive ferroelectrics.« less
Authors:
ORCiD logo [1] ;  [1] ;  [1] ;  [2] ;  [1]
  1. Univ. of Washington, Seattle, WA (United States)
  2. Clemson Univ., Clemson, SC (United States)
Publication Date:
Grant/Contract Number:
FE0007272
Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 107; Journal Issue: 23; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Research Org:
Univ. of Washington, Seattle, WA (United States)
Sponsoring Org:
USDOE Office of Fossil Energy (FE)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1468470
Alternate Identifier(s):
OSTI ID: 1228437

Dandeneau, Christopher S., Yang, YiHsun, Olmstead, Marjorie A., Bordia, Rajendra K., and Ohuchi, Fumio S.. Polaronic conduction and Anderson localization in reduced strontium barium niobate. United States: N. p., Web. doi:10.1063/1.4937435.
Dandeneau, Christopher S., Yang, YiHsun, Olmstead, Marjorie A., Bordia, Rajendra K., & Ohuchi, Fumio S.. Polaronic conduction and Anderson localization in reduced strontium barium niobate. United States. doi:10.1063/1.4937435.
Dandeneau, Christopher S., Yang, YiHsun, Olmstead, Marjorie A., Bordia, Rajendra K., and Ohuchi, Fumio S.. 2015. "Polaronic conduction and Anderson localization in reduced strontium barium niobate". United States. doi:10.1063/1.4937435. https://www.osti.gov/servlets/purl/1468470.
@article{osti_1468470,
title = {Polaronic conduction and Anderson localization in reduced strontium barium niobate},
author = {Dandeneau, Christopher S. and Yang, YiHsun and Olmstead, Marjorie A. and Bordia, Rajendra K. and Ohuchi, Fumio S.},
abstractNote = {Electron transport mechanisms in reduced Sr0.5Ba0.5Nb2O6 (SBN50) are investigated from ~100 to 955 K through an analysis of the electrical conductivity (σ) and the Seebeck coefficient (S) with respect to temperature (T). Notably, experimental evidence is presented that supports a scenario of Anderson localization below 600 K and carrier excitation across a mobility edge at higher temperature. As a relaxor ferroelectric, stoichiometric SBN has intrinsic disorder associated with both the distribution of Sr/Ba vacancies and the formation of polarized nanoregions. The removal of oxygen through reduction generates conduction electrons in SBN. At the lowest temperatures measured (100–155 K), the electrical conductivity exhibits a temperature dependence characteristic of variable range hopping, followed by a transition to small polaron hopping at intermediate temperatures (250–545 K). In both the variable range and small polaron hopping regimes, a semiconductor-like temperature dependence of the electrical conductivity (dσ/dT > 0) was observed. However, above 615 K, dσ/dT decreases dramatically and eventually becomes metal-like (dσ/dT < 0). Concomitantly, the Seebeck coefficient exhibits a linear dependence on lnT from 615 to 955 K with the same slope (~104 μ V/K) for both polycrystalline SBN50 and single crystalline SBN61 (both reduced), indicating a similar, constant density of states near the Fermi level for both compositions. Here, the application of Seebeck coefficient theory to this inherently disordered material reveals that the excitation of carriers across a mobility edge is likely responsible for the change in dσ/dT at high temperature. Such findings may have a significant impact in the field of conductive ferroelectrics.},
doi = {10.1063/1.4937435},
journal = {Applied Physics Letters},
number = 23,
volume = 107,
place = {United States},
year = {2015},
month = {12}
}