Rao GT, Babu B, Stella RJ, Manjari VP, Ravikumar RVSSN. Spectral investigations on undoped and Cu²⁺ doped ZnO-CdS composite nanopowders.
SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015;
139:86-93. [PMID:
25554956 DOI:
10.1016/j.saa.2014.12.021]
[Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2014] [Revised: 11/13/2014] [Accepted: 12/09/2014] [Indexed: 06/04/2023]
Abstract
Undoped and Cu(2+) doped ZnO-CdS composite nanopowders were synthesized by simple chemical precipitation method. Structural and spectroscopic properties of the prepared samples have been characterized by XRD, SEM with EDS, TEM, FT-IR, UV-Vis, EPR and Photoluminescence studies. X-ray diffraction pattern contains a series of peaks corresponds to hexagonal phase of ZnO and CdS. The average crystallite sizes of undoped and Cu(2+) doped samples are determined and are in the range of 25-30 nm. SEM and TEM micrographs reveal that the samples show spherical like structures with little agglomeration. FT-IR spectra show the fundamental mode of vibrations of ZnO at 515 cm(-1), CdS at 621 cm(-1) and other functional groups. Optical absorption spectrum of Cu(2+) doped sample consists of three bands at 665, 823 and 1192 nm attributed to the transitions (2)B1g→(2)Eg, (2)B2g and (2)A1g respectively. Crystal field and tetragonal field parameters are evaluated as Dq=1214, Ds=1610 and Dt=389 cm(-1). From EPR, spin-Hamiltonian and hyperfine splitting parameters are evaluated for Cu(2+) doped sample as g‖=2.3391, g⊥=2.0550 and A‖=130×10(-4) cm(-1), A⊥=36×10(-4) cm(-1). The optical and EPR data suggests that Cu(2+) entered into host lattice as tetragonally distorted octahedral site symmetry. PL spectra consists two emission bands at 367, 380 nm in UV region. A sharp blue emission peak at 425 nm and a broad green emission peak in the range of 450-570 nm are observed. The enhanced visible emission is observed after doping.
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