Photoluminescence and thermoluminescence studies of Mg2SiO4:Eu3+ nano phosphor (original) (raw)
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The MgAl2O4 spinel doped with Eu2+ ions powder phosphor was prepared at temperature as low as 500 oC using the combustion route. A structural property of the powder was characterized by X-ray diffraction (XRD). This XRD pattern shows the well crystallized cubic phase, Fd-3m space group of MgAl2O4. The estimated average crystalline size is about 36 and 30 nm for MgAl2O4 and Eu doped MgAl2O4 particles respectively. The photoluminescent property of prepared powder was investigated using excitation and emission spectroscopy at room temperatures. Energy levels scheme is proposed for emission from MgAl2O4: Eu2+.
Photo and Thermo-luminescence Properties of Mn 4+ , Ce 4+ and Sm 3+ in MgAl 2 Si 2 O 8 Phosphor
Journal of the Chinese Chemical Society, 2015
Mn 4+ , Ce 4+ and Sm 3+ doped MgAl 2 Si 2 O 8-based phosphors were synthesized at 1300°C by solid state reaction and characterized by thermogravimetry (TG), differential thermal analysis (DTA), X-ray powder diffraction (XRD), photoluminescence (PL), thermoluminescence (TL) and scanning electron microscopy (SEM). The phosphors showed broad red emission bands in the range of 610-715 nm and different maximum intensity when activated by UV illumination. Such a red emission can be attributed to the intrinsic 2 E® 4 A 2 transitions of Mn 4+ .
Optik, 2019
A series of novel red MGdAlO 4 :Eu 3+ (M = Mg 2+ , Ca 2+ , Sr 2+ and Ba 2+) was synthesizedand investigated. The samples were synthesized via rapid-gel combustion route at a temperature of 600°C and examined over large doping concentration of 0.01 to 0.05 mol. The optimal concentration of activator ion has been found to be 0.03 mols for MGdAlO 4 lattice. Using the excitation wavelength of 393 nm, these phosphors exhibited strong emission in the red region owing to 5 D 0 → 7 F 2 (electric dipole allowed) transition located at 610-615 nm. The effect of reaction temperature on luminescence was also analyzed for these materials. The structural characteristics of phosphors were studied via joint approach of X-ray diffraction (XRD) and Transmission electron microscopy (TEM). Diffraction patterns of prepared phosphor contain sharp peaks in 10°-80°region. The proposed materials have single phase tetragonal structure having I4/mmm space group. The degree of crystallization has been found to increase with temperature. The TEM micrographs exhibited the spherical shape of particles in 15-35 nm size. The FTIR spectra of CaGdAlO 4 showed peaks at 699 and 461 cm −1 analogous to Al-O and Gd-O stretching vibrational modes. Due to excellent luminescent response the Eu 3+ doped MGdAlO 4 can be excellent materials for the growth of effective red phosphor in WLEDs and fluorescent panels.
Journal of Alloys and Compounds, 2012
Eu 2+ and Eu 2+ -Mn 2+ codoped (Ba,Sr)Mg 2 Al 6 Si 9 O 30 phosphors have been synthesized by solid state reaction, and their luminescent properties are investigated. Under the excitation of 330 nm, it is observed that the emission of Eu 2+ consists of two emission bands, located at around 370 and 450 nm, which are attributed to two Eu 2+ centers (Eu 2+ (I) and Eu 2+ (II)) ions substituting for two different Ba 2+ and Mg 2+ sites, respectively. As Sr 2+ gradually substitutes Ba 2+ , the emission bands of Eu 2+ (I) shift to longer wavelength whereas the emission bands of Eu 2+ (II) exhibit no change. This phenomenon is discussed in terms of the crystal-field strength. A detail analysis on the energy transfer from Eu 2+ to Mn 2+ in SrMg 2 Al 6 Si 9 O 30 host is presented, which indicates the energy of the red emission of Mn 2+ is derived mainly from Eu 2+ (I). We have also demonstrated that BaMg 2 Al 6 Si 9 O 30 :Eu 2+ , Mn 2+ exhibits better thermal quenching properties than that of SrMg 2 Al 6 Si 9 O 30 :Eu 2+ , Mn 2+ because of bigger activation energy.
Luminescence : the journal of biological and chemical luminescence, 2015
A europium (Eu)-doped di-calcium magnesium di-silicate phosphor, Ca2 MgSi2 O7 :Eu(2+) , was prepared using a solid-state reaction method. The phase structure, particle size, surface morphology, elemental analysis, different stretching mode and luminescence properties were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR) spectroscopy, photoluminescence (PL) and mechanoluminescence (ML). The phase structure of Ca2 MgSi2 O7 :Eu(2+) was an akermanite-type structure, which belongs to the tetragonal crystallography with space group P4̅21 m; this structure is a member of the melilite group and forms a layered compound. The surface of the prepared phosphor was not found to be uniform and particle distribution was in the nanometer range. EDX and FTIR confirm the components of Eu(2+) -doped Ca2 MgSi2 O7 phosphor. Under UV excitation...
MgO:Eu3+ red nanophosphor: Low temperature synthesis and photoluminescence properties
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2014
h i g h l i g h t s Nanomaterials offer promising opportunities for applications in various fields. Magnesium oxide (MgO) is an excellent wide band gap insulator. Structural and PL of MgO:Eu 3+ nanophosphor was studied. Highest emission was recorded at 3 mol% of Eu 3+ doped MgO.
Nanomaterials and Nanotechnology
Mg1.5Al2O4.5: x% Eu3+ (0 ≤ x ≤ 2) nanopowders were successfully synthesized via sol–gel method. The X-ray diffraction (XRD) spectrum revealed that the Mg1.5Al2O4.5: x% Eu3+ matches the single phase of face-centred cubic MgAl2O4. The estimated average crystallite sizes calculated using the XRD spectra were found to be in the order of 4 nm. The estimated crystal size was confirmed by the high-resolution transmission electron microscopy. The energy dispersive X-ray spectroscopy confirmed the presence of all expected elementary composition (Mg, Al, O and Eu). The field emission gun scanning electron microscope showed that varying the Eu3+ concentration influence the morphology of the prepared nanophosphor. The photoluminescence results showed that the host emits the violet colour at around 382 nm, which was attributed to the defects within the band gap ( Eg) of host material. The Eu3+-doped samples showed the emission at around 560, 580, 593, 618, 655 and 704 nm which are, respectively,...
Bulletin of Materials Science, 2014
Europium and dysprosium-doped calcium magnesium silicate powder with different concentrations of dysprosium were synthesized using solid-state reaction. The Fourier transform infrared (FT-IR) spectra confirmed the proper preparation of the sample. The prepared phosphors were characterized using photoluminescence excitation and emission spectra. Prominent green colour emission was obtained under ultraviolet excitation. The thermoluminescence glow curves of the samples were measured at various delay times. With increased delay time, the intensity of the thermoluminescence peak decays and the position of the thermoluminescence peak shifts towards higher temperature, indicating the considerable retrapping associated with general order kinetics.
Luminescent nanoparticles of MgAl 2O 4:Eu, Dy prepared by citrate sol–gel method
Optical Materials, 2008
MgAl 2 O 4 :Eu, Dy nanoparticles were prepared by citrate sol-gel method and thermally treated at 600, 700, 800 and 900°C. The trivalent europium ion is partially reduced to the divalent state at 700 and 800°C. Infrared spectra of the phosphors showed bands around 700 and 520 cm À1 corresponding to the AlO 6 groups. X-ray diffraction patterns present sharp reflections of samples heated from 700 to 900°C indicating the MgAl 2 O 4 spinel phase. Grain size in the range 20-30 nm were observed by measurement of transmission electron microscopy (TEM). The emission spectra of the phosphors show a broadened band at 480 nm assigned to the 4f 6 5d ? 4f 7 ( 8 S 7/2 ) transition of Eu 2+ ion overlapped to the 4 F 9/2 ? 6 H 15/2 transition of the Dy 3+ ion. Besides, the 4 F 9/2 ? 6 H 13/2 transition (579 nm) of Dy 3+ ion is overlapped with the 5 D 0 ? 7 F 0 (578 nm) and 5 D 0 ? 7 F 1 (595 nm) transitions from the Eu 3+ ion. Excitation spectra of the sample heated at 900°C monitoring the excitation at 615 nm of 5 D 0 ? 7 F 2 transition of Eu 3+ ion exhibit a broad band assigned to the O ? Eu 3+ ligand-to-metal charge-transfer states (LMCT) around 280 nm. The samples present green persistent luminescence after exposure to UV radiation. The chromaticity coordinates were obtained from the luminescence emission spectrum.