Optical and Electrical Properties of Mechanochemically Synthesized Nanocrystalline Delafossite CuAlO₂

Abstract

Nanocrystalline p-type semiconductor copper aluminum oxide (CuAlO2) has been synthesized by mechanical alloying using freshly prepared Cu2O and alpha-AlO2O3 nanocrystals in toluene medium. A study on structural property performed with different alloying and post annealing durations, by X-ray diffraction (XRD) reveals the formation of single phase with average crystallite size approximately 45 nm. Optical absorbance onset at 364.5 nm confirms its wide band gap nature (E(g) = 3.4 eV) and the fluorescence emission behaviour (390 nm) confirms its direct band type transition. The activation energy for electrical conduction has been calculated by Arrhenius plots using impedance measurement. Both grain and grain boundary conductivity takes place with almost equal activation energies of approximately 0.45 eV. The paper discusses synthesis, structural, optical and electrical properties of delafossite CuAlO2 in detail.

Optical and electronic properties of delafossite CuBO2 p-type transparent conducting oxide

“…These are the two co-operating factors of the photon and phonon energy, for transition across the interband gap. Fluorescence spectroscopy is used to confirm the direct band type transition 21 of CuBO 2 , and its emission spectrum is shown in Fig. 9.…”

Influence of temperature on AC conductivity of nanocrystalline CuAlO2

“…Techniques like pulsed laser deposition [2], ion exchange reaction [3] and sputtering [4] were widely used to synthesis single phase CuAlO 2 . Recently the author reported the synthesis of nanocrystalline CuAlO 2 by mechanical alloying process using Cu 2 O and α-Al 2 O 3 powders, the grain and grain boundary contribution electrical conductivities [5] and the existence of Debye type dielectric relaxation behaviour [6]. This paper reports the AC conductivity, scaling behaviour, correlations between DC and AC conductivities and cross-over frequencies of nanocrystalline CuAlO 2 .…”

p‐Type Optoelectronic and Transparent Conducting Oxide Properties of Delafossite CuAl1/2Fe1/2O2

“…Figure shows the emission spectrum for Cu(Al 1/2 Fe 1/2 )O 2 under a 350 nm excitation wavelength at room temperature. The emission was centered around 390 nm (3.17 eV), confirming the existence of a direct transition band gap . The value of 3.17 eV corresponds to the green emission band, which is close to the optical gap of the ultraviolet near‐band‐edge emission.…”

“…The emission was centered around 390 nm (3.17 eV), confirming the existence of a direct transition band gap. 24 The value of 3.17 eV corresponds to the green emission band, which is close to the optical gap of the ultraviolet near-band-edge emission. The luminescence at room temperature appeared under the emission of the electron interconfiguration transition from 3d 9 4s 1 to 3d 10 in Cu + ions.…”