Synthesis, characterization, photoluminescence and EPR investigations of Mn doped MgAl2O4 phosphors

✍ Scribed by Vijay Singh; R.P.S. Chakradhar; J.L. Rao; Dong-Kuk Kim

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 988 KB
• Volume: 180
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1016/j.jssc.2007.04.030

✦ Synopsis

MgAl 2 O 4 :Mn phosphors have been prepared at 500 1C by combustion route. Powder X-ray diffraction (XRD) indicated the presence of mono-MgAl 2 O 4 phase. Scanning electron microscopy showed that the powder particle crystallites are mostly angular. Fourier transform infrared spectroscopy confirmed the presence of AlO 6 group which makes up the MgAl 2 O 4 spinel. Photoluminescence studies showed green/red emission indicating that two independent luminescence channels in this phosphor. The green emission at 518 nm is due to 4 T 1 -6 A 1 transition of Mn 2+ ions. The emission at 650 nm is due to the charge-transfer deexcitation associated with the Mn ion. EPR spectrum exhibits allowed and forbidden hyperfine structure at g ¼ 2.003. The gE2.00 is due to Mn 2+ ion in an environment close to tetrahedral symmetry. It is observed that N and w increase with decrease of temperature obeying the Boltzmann law. The variation of zero-field splitting parameter (D) with temperature is evaluated and discussed.