Title
Bifunctional ferromagnetic Eu-Gd-Bi-codoped hybrid organo-silica red emitting phosphors synthesized by a modified Pechini sol-gel method
Author
S.M. Abo-Naf, S.A.M. Abdel-Hameed, M.A. Marzouk, Y.M. Hamdy
Year
2017
Journal
Materials Chemistry and Physics
Abstract
Red phosphor, composed of Eu-Gd-Bi-codoped hybrid organo-silica glass, has been synthesized via a modified Pechini sol-gel process. The synthesized hybrid glass was analyzed with powder X-ray diffraction (XRD), differential thermal analysis coupled with thermogravimetry (DTA-TG) and Fourier transform infrared (FTIR) spectroscopy. XRD and DTA-TG confirmed its amorphous structure up to 1000 °C. Magnetic behavior of the produced phosphor was investigated using vibrating specimen magnetometer (VSM) and the obtained results revealed its unsaturated ferromagnetic behavior. Photoluminescence (PL) properties of the obtained phosphor have been investigated under near-UV excitation at 395 nm. The influence of calcination temperature on the PL intensity and its decay behavior as well as on the ferromagnetic characteristics has been studied to determine the optimal reaction temperature of the phosphor. The PL emission spectra show the characteristic emission bands of Eu3+ ions in the wavelength range from 580 to 700 nm. These emission spectra have been dominated by the electric dipole 5D0→7F2 transition of the Eu3+ peaked at 610–620 nm producing the red light emission of the phosphors. It was found that the phosphor performance, expressed by its PL intensity and life time, could be significantly improved by increasing of the heat treatment temperature up to 900 °C. Also, calcination at 900 °C for 6 h greatly increased both of the magnetization and retentivity, while decreased the coercivity value. The organic phenomenon of metal citrate-ethylene glycol chelation and its degradation by calcination were well followed by FTIR spectroscopy. The obtained results are promising and could afford a basis for designing of efficient red phosphors for displays, lighting and bifunctional biosensors for biomedical applications.
Instrument
FP-6500
Keywords
Fluorescence, Photoluminescence, Thermal stability, Inorganic chemistry, Materials, Sensors