ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Structural, optical, and luminescence properties of Ni²⁺-doped ZnO–CdS nanocomposite: synthesis and investigations for green light emission

Thirumala Rao Gurugubelli, R. V. S. S. N. Ravikumar, and Ravindranadh Koutavarapu

Physics Division, Department of Basic Sciences and Humanities, GMR Institute of Technology, Rajam, India

E-mail: thirumala.phy@gmail.com

Received: 28 July 2021  Accepted: 18 September 2021

Abstract:

In this study, we investigate the effects of Ni²⁺-ion incorporation on the crystal structure, morphology, optical and emission properties of ZnO–CdS nanocomposites. X-ray diffraction analysis confirmed the preservation of the hexagonal crystal structure of ZnO and CdS, with a mean grain size of 17 nm. The lattice cell parameters and internal lattice strain of the nanocomposites were also estimated. Scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy were used to determine the morphological properties and chemical composition of the nanocomposites. Furthermore, electron paramagnetic resonance (EPR) analysis, optical absorption measurements, and photoluminescence (PL) spectroscopy were utilized to investigate the coordination geometry, bonding nature, and luminescent properties of the Ni-doped nanocomposites. The EPR spectrum exhibited a well-resolved signal resonance at g ≈ 2.194, signifying the octahedral geometry of the Ni²⁺ atoms. The crystal field parameter (Dq = 845) and Racah parameters (B = 820 cm⁻¹ and C = 3250 cm⁻¹) were calculated based on the results of the optical absorption study. EPR and optical investigations revealed that the Ni atoms were positioned in an octahedral geometry and bonded covalently with neighboring ligands. Moreover, the effect of Ni²⁺ ions on the ZnO–CdS nanocomposites was confirmed through PL spectroscopy: the intense green emission band at 547 nm was attributed to the d-d transitions of the Ni²⁺ ions. The evaluated correlated color temperature of 6625 K suggests a green light emission near cold white light.

Keywords: Nanocomposite; Ni ions; ZnO–CdS; Doping; Octahedral site symmetry; Photoluminescence

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-01888-1

Chemical Papers 76 (1) 557–566 (2022)