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Synthesis, structural and optical properties of nanocrystalline ZnO powders prepared by a PVApolymer complex solution route

K. PATO1, E. SWATSITANG1, W. JAREONBOON1, S. MAENSIRI1,* , V. PROMARAK2

Affiliation

  1. Integrated Nanotechnology Research Center (INRC) and Small & Strong Solid Group (SSMG), Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen, 40002, Thailand
  2. Advanced Organic Materials and Devices Laboratory, Department of Chemistry, Faculty of Science, Ubon Ratchathani University, Varinchamrap, Ubon Ratchathani 34190, Thailand

Abstract

This paper reports the synthesis, structural and optical properties of nanocrystalline ZnO powders with crystalline sizes of 26-69 nm (estimated by XRD) prepared by a PVA-polymer complex solution route (PCS). To obtain nanocrystalline ZnO powders, the precursor was calcined in air at temperatures between 500°C and 800°C for 2 h. The results of XRD and Raman spectroscopy confirmed the formation of polycrystalline wurtzite structure. The SEM observation revealed that the samples consisted of agglomerated nanoparticles with particle sizes of ~50-200 nm. The optical properties of the samples were also investigated by measuring the UV-vis absorption and photoluminescence spectra at room temperature. The synthesized powders exhibited the UV absorption below 400 nm (3.10 eV) with a well defined absorption peak at around 290 nm (4.28 eV). The estimated direct band gaps were obtained to 3.03, 3.07, 3.04, and 3.03 eV for the ZnO samples calcined at 500, 600, 700, and 800°C, respectively. All the samples exhibited room-temperature photoluminescence (PL) showing a strong UV emission broad band at ~ 390 nm (3.18 eV), a weak UV band at ~420 nm (2.96 eV), a week bluegreen band at 484 nm (2.57 eV), and a green band at 530 nm (2.34 eV). The mechanisms responsible for photoluminescence of the samples were discussed.

Keywords

Crystal structure, Growth from solutions, Nanomaterials, Zinc compounds, Semiconducting II-VI materials, Optical properties.

Citation

K. PATO, E. SWATSITANG, W. JAREONBOON, S. MAENSIRI, V. PROMARAK, Synthesis, structural and optical properties of nanocrystalline ZnO powders prepared by a PVApolymer complex solution route, Optoelectronics and Advanced Materials - Rapid Communications, 1, 6, June 2007, pp.287-293 (2007).

Submitted at: March 14, 2007

Accepted at: April 25, 2007