Thermal effects on rapid microwave synthesized Co: ZnAl2O4 spinel nanoparticles

Samvit G. Menon, K. S. Choudhari, S. A. Shivashankar, C. Santhosh, Suresh D. Kulkarni

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


A rapid (10 min) microwave-assisted synthesis of CoxZn(1-x)Al2O4 nanoparticles using metal organic precursors is reported for the first time. The nanoparticles formed at 185 °C were phase-pure in the as-prepared form with an average crystallite size of ∼5 nm. Sample with x = 0.0025 showed intense photoluminescence (PL) emission and was used to study the effect of annealing temperature on the structural and optical properties. Annealing in air until 1200 °C gradually (i) increased the crystallite size to as much as 31 nm (ii) change of colour tone from colourless to blue which has been attributed to the diffusion of Co2+ in host lattice (iii) increase in intensity of Co2+ bands in the diffuse reflectance spectra (DRS). The emission spectra comprised of the broad 4T1(4P) → 4A2(4F) spin allowed transition pertaining to tetrahedral Co2+ at ∼649 nm whose intensity increased with annealing temperature. The crystal field splitting parameter (Dq) and the Racah parameter B, were calculated from the excitation spectra and the Tanabe-Sugano diagrams. The novelty of this work lies in the simplicity and swiftness of the microwave-assisted synthesis that can be extended to other ceramic phosphors suitable for lasing and sensing applications.

Original languageEnglish
Pages (from-to)1083-1090
Number of pages8
JournalJournal of Alloys and Compounds
Publication statusPublished - 25-12-2017

All Science Journal Classification (ASJC) codes

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry


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