title: Synthesis, characterization and spectroscopic investigation of Cr3+ doped wollastonite nanophosphor.
abstract: This work explores the preparation of nanocrystalline Cr(3+) (1-5 mol%) doped CaSiO3 phosphors by solution combustion process and study of its photoluminescence (PL) behavior. The nanopowders are well characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infra-red (FTIR) spectroscopy. PXRD results confirm monoclinic phase upon calcination at 950°C for 3h. SEM micrographs indicates that the powder is highly porous and agglomerated. The TEM images show the powder to consist of spherical shaped particles of size ∼30-60 nm. Upon 323 nm excitation, the emission profile of CaSiO3:Cr(3+) exhibits a narrow red emission peak at 641nm due to (2)E→(4)A2 transition and broad band at 722 nm due to (4)T2g→(4)A2g. It is observed that PL intensity increases with increase in Cr(3+) concentration and highest PL intensity is observed for 3 mol% doped sample. The PL intensity decreases with further increase in Cr(3+) doping. This decrease in PL intensity beyond 3 mol% is ascribed to concentration quenching. Racah parameters are calculated to describe the effects of electron-electron repulsion within the crystal lattice. The parameters show 21% reduction in the Racah parameter of free ion and the complex, indicating the moderate nephelauxetic effect in the lattice.
authors.affiliation: Jawaharlal Nehru Technological University, Anantapur 515 002, India; Department of Physics, REVA Institute of Technology & Management, Bangalore 560 064, India. Electronic address: madesh3876@yahoo.co.in.
authors.forename: M
authors.initials: M
authors.lastname: Madesh Kumar
authors.affiliation: Prof. C.N.R. Rao Centre for Advanced Materials Research, Tumkur University, Tumkur 572 103, India.
authors.forename: H
authors.initials: H
authors.lastname: Nagabhushana
authors.affiliation: Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore 560 054, India.
authors.forename: B M
authors.initials: BM
authors.lastname: Nagabhushana
authors.affiliation: Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, India.
authors.forename: N
authors.initials: N
authors.lastname: Suriyamurthy
authors.affiliation: Chhattisgarh Swamy Vivekananda Technical University, North Park Avenue, Bhilai, Chhattisgarh 490 009, India.
authors.forename: S C
authors.initials: SC
authors.lastname: Sharma
authors.affiliation: Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: C
authors.initials: C
authors.lastname: Shivakumara
authors.affiliation: Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore 560 054, India. Electronic address: rhk.chem@gmail.com.
authors.forename: R
authors.initials: R
authors.lastname: Hari Krishna
mesh_terms: D017610:Calcium Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D017640:Silicates / Q000138:chemical synthesis* / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods
chemical_list: D017610:Calcium Compounds; D017640:Silicates; D002857:Chromium; C031293:calcium silicate
keywords: Nanophosphor; Photoluminescence; Silicates; Solution combustion