title: Novel EGCG assisted ultrasound synthesis of self-assembled Ca2SiO4:Eu(3+) hierarchical superstructures: Photometric characteristics and LED applications.
abstract: This paper reports for the first time ultrasound, EGCG assisted synthesis of pure and Eu(3+) (1-5mol%) activated Ca2SiO4 nanophosphors having self-assembled superstructures with high purity. The shape, size and morphology of the product were tuned by controlling influential parameters. It was found that morphology was highly dependent on EGCG concentration, sonication time, pH and sonication power. The probable formation mechanism for various hierarchical superstructures was proposed. The PL studies of Ca2SiO4:Eu(3+) phosphors can be effectively excited by the near ultraviolet (UV) (396nm) light and exhibited strong red emission around 613nm, which was attributed to the Eu(3+) ((5)D0→(7)F2) transition. The concentration quenching phenomenon was explained based on energy transfer between defect and Eu(3+) ions, electron-phonon coupling and Eu(3+)-Eu(3+) interaction. The Judd-Ofelt intensity parameters and radiative properties were estimated by using PL emission spectra. The photometric studies indicate that the obtained phosphors could be a promising red component for possible applications in the field of white light emitting diodes.
authors.affiliation: Department of Physics, Govt. First Grade College, Sira, Tumkur 572 103, India; Research and Development Center, Bharathiar University, Coimbatore 641046, India.
authors.forename: M
authors.initials: M
authors.lastname: Venkataravanappa
authors.affiliation: Prof. C.N.R. Rao Centre for Advanced Materials, Tumkur University, Tumkur 572 103, India. Electronic address: bhushanvlc@gmail.com.
authors.forename: H
authors.initials: H
authors.lastname: Nagabhushana
authors.affiliation: Department of Physics, Acharya Institute of Graduate Studies, Bangalore 560 107, India; Research and Development Center, Bharathiar University, Coimbatore 641046, India.
authors.forename: G P
authors.initials: GP
authors.lastname: Darshan
authors.affiliation: Department of Physics, BMS Institute of Technology and Management, VTU-affiliated, Bangalore 560 064, India.
authors.forename: B
authors.initials: B
authors.lastname: Daruka Prasad
authors.affiliation: Department of Chemistry, University College of Science, Tumkur University, Tumkur 572 103, India.
authors.forename: G R
authors.initials: GR
authors.lastname: Vijayakumar
authors.affiliation: Department of Physics, Dayananda Sagar Academy of Technology and Management, Bangalore 560082, India.
authors.forename: H B
authors.initials: HB
authors.lastname: Premkumar
authors.affiliation: Department of Chemistry, Siddaganga Institute of Technology, Tumkur 572 103, India.
authors.lastname: Udayabhanu
keywords: Light emitting diodes; Nanophosphor; Photoluminescence; Sonochemical synthesis; Superstructures