APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014;
Denver, Colorado
Session L41: Focus Session: Local Ionic Dynamics and Domain Walls in Oxides
8:00 AM–10:48 AM,
Wednesday, March 5, 2014
Room: Mile High Ballroom 3C
Sponsoring
Unit:
DMP
Chair: Lane Martin, University of Illinois
Abstract ID: BAPS.2014.MAR.L41.1
Abstract: L41.00001 : Probing Local Ionic Dynamics in Functional Oxides: From Nanometer to Atomic Scale
8:00 AM–8:36 AM
Preview Abstract
Abstract
Author:
Sergei Kalinin
(Oak Ridge National Lab)
Vacancy-mediated electrochemical reactions in oxides underpin multiple
applications ranging from electroresistive memories, to chemical sensors to
energy conversion systems such as fuel cells. Understanding the
functionality in these systems requires probing reversible (oxygen
reduction/evolution reaction) and irreversible (cathode degradation and
activation, formation of conductive filaments) electrochemical processes. In
this talk, I summarize recent advances in probing and controlling these
transformations locally on nanometer level using scanning probe microscopy.
The localized tip concentrates the electric field in the nanometer scale
volume of material, inducing local transition. Measured simultaneously
electromechanical response (piezoresponse) or current (conductive AFM)
provides the information on the bias-induced changes in material. Here, I
illustrate how these methods can be extended to study local electrochemical
transformations, including vacancy dynamics in oxides such as titanates,
La$_{x}$Sr$_{\mathrm{1-x}}$CoO$_{3}$, BiFeO$_{3}$,
and Y$_{x}$Zr$_{\mathrm{1-x}}$O$_{2}$. The formation of
electromechanical hysteresis loops and their bias-, temperature- and
environment dependences provide insight into local electrochemical
mechanisms. In materials such as lanthanum-strontium cobaltite, mapping both
reversible vacancy motion and vacancy ordering and static deformation is
possible, and can be corroborated by \textit{post mortem} STEM/EELS studies. In ceria, a broad
gamut of electrochemical behaviors is observed as a function of temperature
and humidity. The possible strategies for elucidation ionic motion at the
electroactive interfaces in oxides using high-resolution electron microscopy
and combined ex-situ and in-situ STEM-SPM studies are discussed. In the
second part of the talk, probing electrochemical phenomena on in-situ grown
surfaces with atomic resolution is illustrated. I present an approach based
on the multivariate statistical analysis of the coordination spheres of
individual atoms to reveal preferential structures and symmetries. The
relevant statistical techniques including k-means clustering, principal
component analysis, and Baesian unmixing are briefly intriduced. This
approach is illustrated for several systems, including chemical phase
identification, mapping ferroic variants, and probing topological and
structural defects, and provides real space view on surface atomic
processes.
Research supported (SVK) by the U.S. Department of Energy, Basic Energy
Sciences, Materials Sciences and Engineering Division and partially
performed at the Center for Nanophase Materials Sciences (AK, SJ), a DOE-BES
user facility.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2014.MAR.L41.1