The effect of crystallite size and applied DC bias voltage on dielectric permittivity of CuO was studied using impedance spectroscopy. The measurements were performed at room temperature in a wide frequency range of 1 Hz to 1 MHz under applied DC bias voltages from 0 to 3 V in the periodic increment of 0. 2 V. The observed applied DC bias voltage effect on giant dielectric constant (e{open}′ = 104) were analyzed with 'grain boundary double Schottky potential barrier height model'. The percentage of tunability (T %) at the frequency 100 Hz is found to be 45. 5% for the case of nanocrystalline CuO in contrast to 0% tunability in bulk CuO. © 2013 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.

Budaraju Srinivasa Murty

Department of Metallurgical and Materials Engineering

Bode plots

CRYSTALLITE SIZE EFFECTS

DC BIAS VOLTAGE

Dielectric permittivities

GIANT DIELECTRIC CONSTANTS

GIANT DIELECTRIC PERMITTIVITY

Impedance spectroscopy

NANOCRYSTALLINE CUO

POTENTIAL BARRIER HEIGHT

Room temperature

Schottky

Tunabilities

VOLTAGE-TUNABLE

WIDE FREQUENCY RANGE

Grain boundaries

Permittivity

Dielectric materials

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IIT Madras

Electronic Materials Letters

Dielectric relaxation in sol-gel-derived anatase titanium oxide nanocrystals (6, 9, and 20 nm) has been investigated using impedance spectroscopy in a wide frequency range from 1 Hz to 1 MHz as a function of applied DC bias voltage, ranging from 0 to 4.2 V in a periodic interval of 0.3 V. Under the equilibrium condition, around three order of magnitude variations in the dielectric relaxation time (τ) was observed for the grain size if reduced to 6 nm from 20 nm. An unambiguous evidence for the absence of such a crystallite size effect was experimentally observed in higher biased conditions because of grain boundary Schottky potential barrier height suppression. These experimental results obey the grain boundary double Schottky barrier model. © 2011 American Institute of Physics.

Fulltext

Journal of Applied Physics

Influence of bias voltage on dielectric relaxation of nanocrystalline anatase TiO2 using modulus formalism

Transparent semiconductor CuAlO2 in nanodimension was prepared by mechanical alloying of Cu2 O and α -Al2 O3 powders in toluene medium. The formation of single phase CuAlO2 with an average crystallite size of 45 nm was confirmed by x-ray diffraction analysis. The nanocrystalline nature of CuAlO2 was confirmed by atomic force microscopy. Frequency-dependent dielectric property measurements and the relaxation behavior were studied using impedance spectroscopy. Dielectric relaxation time estimated from the modulus curves was found to be decreasing with increase in temperature. The existence of stretched exponent parameter Β<1 in the present nanocrystalline CuAlO2 implies non-Debye type relaxation behavior in this material. © 2007 American Institute of Physics.

Dielectric relaxation studies of nanocrystalline CuAlO2 using modulus formalism

Applied Physics Letters

Giant dielectric permittivity observed in CaCu3Ti4O12∕(Li,Ti)-doped NiO composites

Copper (II) oxide as a giant dielectric material

Direct current bias effects on grain boundary Schottky barriers in CaCu3Ti4O12

Crystallite size effect on voltage tunable giant dielectric permittivity of nanocrystalline CuO

Journal	Electronic Materials Letters
ISSN	17388090
Open Access	No