The ionic transport properties of nanocrystalline 20 mol% Eu, Gd, Dy, and Ho doped cerias, with average grain size of around 14 nm were studied by correlating electrical, dielectric properties, and various dynamic parameters. Gd-doped nanocrystalline ceria shows higher value of conductivity (i. e., 1. 8 × 10 -4 S cm -1 at 550°C) and a lower value of association energy of oxygen vacancies with trivalent dopants Gd 3+ (i. e., 0. 1 eV), compared to others. Mainly the lattice parameters and dielectric constants (ε ∞) are found to control the association energy of oxygen vacancies in these nanomaterials, which in turn resulted in the presence of grain and grain boundary conductivity in Gd- and Eu-doped cerias and only significant grain interior conductivity in Dy- and Ho-doped cerias. © The Author(s) 2010.

Sankaranarayanan V

Department Of Physics

ASSOCIATION ENERGIES

ASSOCIATION ENERGY

Average grain size

Dielectric constants

DOPED CERIA

DYNAMIC PARAMETERS

Electrical transport

GRAIN BOUNDARY CONDUCTIVITY

Grain interiors

Ionic transports

Lattice parameters

Nano-materials

Nanocrystallines

Cerium

CERIUM COMPOUNDS

Dielectric properties

Dielectric relaxation

Doping (additives)

Europium

Gadolinium

Grain boundaries

Grain size and shape

Holmium

Ionic conduction

Lattice constants

Nanostructures

Oxygen

Transport properties

Oxygen vacancies

Fulltext

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IIT Madras

Nanoscale Research Letters

The nanocrystalline material of 15 mol% Gd-doped ceria (Ce 0.85Gd0.15O2-δ ) was prepared by citrate auto ignition method. The electrical study and dielectric relaxation technique were applied to investigate the ionic transport process in this nanocrystalline material with an average grain size of 13 nm and the dynamic relaxation parameters are deduced in the temperature range of 300-600°C. The ionic transference number in the material is found to be 0.85 at 500°C at ambient conditions. The oxygen ionic conduction in the nanocrystalline Ce 0.85Gd0.15O2-δ material follows the hopping mechanism. The grain boundary relaxation is found to be associated with migration of charge carriers. The frequency spectra of modulus M exhibited a dielectric relaxation peak corresponding to defect associates (Gd-Vo ■ ■) ■. The material exhibits very low values of migration energy and association energy of the oxygen vacancies in the long-range motion, i.e., 0.84 and 0.07 eV, respectively. © 2009 Springer-Verlag.

Applied Physics A: Materials Science and Processing

Electrical study and dielectric relaxation behavior in nanocrystalline Ce0.85Gd0.15O2-δ material at intermediate temperatures

The ac electrical conductivity and dielectric relaxation properties of nanocrystalline 20 mol% Ho doped ceria (Ce0.8Ho0.2O2-δ) prepared by citrate auto ignition method, were studied in the temperature range 300-550 °C. The conductivity behaviour showed the absence of any precipitation of Ho inside the grains, even though it has the tendency of forming a C-type structure similar to Ho2O3 in association with oxygen vacancies. The frequency spectra of electric modulus M″ exhibits a single relaxation peak corresponding to relaxation reorientation of oxygen vacancy around the Ho+3 ions in the cubic nanostructured material. The migration of oxygen ions in the nanocrystalline Ce0.8Ho0.2O2-δ material takes place through hopping and the migration energy and association energy of oxygen vacancies in the long range order motion are found to be 1.02 and 0.24 eV, respectively. © 2009 Elsevier B.V. All rights reserved.

Physica B: Condensed Matter

Ion transport and dielectric relaxation studies in nanocrystalline Ce0.8Ho0.2O2-δ material

Morphology-Controllable Synthesis of CeO2 on a Pt Electrode

Inorganic Chemistry

Synthesis of CeO2Nanorods via Ultrasonication Assisted by Polyethylene Glycol

Chemistry of Materials

Highly Reducible CeO2Nanotubes

Ionic Transport Properties in Nanocrystalline Ce 0.8A 0.2O 2-δ (with A = Eu, Gd, Dy, and Ho) Materials

Journal	Nanoscale Research Letters
ISSN	19317573
Open Access	Yes