ABSTRACT
In the present work, a series of Bi3+ -activated Ca2 BO3 Cl phosphors was synthesized using the conventional high-temperature solid-state reaction method. The crystal structure of the prepared sample was determined to be monoclinic with space group P21/c. Scanning electron microscopy (SEM) analysis demonstrated the surface morphology with aggregated particles and sizes in the nano range. The presence of vibrational features and their luminescence characteristics were studied using Fourier transform infrared spectroscopy and photoluminescence (PL) techniques, respectively. At the 486 nm excitation wavelength, the PL spectrum revealed a sharp emission centred at 732 nm that was attributed to the 3 P1 â1 S0 transition of Bi3+ . The emission spectra exhibited the highest emission intensity at 0.5 mol% Bi3+ ion concentration, beyond this the emission intensity decreased due to the concentration quenching phenomenon attributed to multipolar interaction. The Commission Internationale de l'éclairage coordinates located at (0.7347, 0.2653) confirmed emission in the deep-red region with a colour purity of 99.98%. The obtained outcomes suggested that the reported material may be a promising candidate as a red-emitting phosphor for w-LEDs and plant growth applications.
Subject(s)
Luminescence , Microscopy, Electron, Scanning , Spectroscopy, Fourier Transform InfraredABSTRACT
The present communication is strongly focused on the investigation of synthesis, structural and luminescence properties of cerium (Ce3+ )- and europium (Eu3+ )-activated Zn4 Al22 O37 phosphors. Ce3+ - and Eu3+ -doped Zn4 Al22 O37 novel phosphors were prepared using a solution combustion synthesis route. Structural properties were studied using powder X-ray diffraction and high-resolution transverse electron microscopy. The optical properties were studied using ultraviolet-visible light spectroscopy and Fourier transform infrared spectroscopy; luminescence properties were studied using a photoluminescence (PL) technique. The crystal structure of the prepared Zn4 Al22 O37 host and Ce3+ - and Eu3+ -activated Zn4 Al22 O37 phosphors was investigated and was found to have a hexagonal structure. The measured PL emission spectrum of the Ce3+ -doped Zn4 Al22 O37 phosphor showed an intense and broad emission band centred at 421 nm under a 298 nm excitation wavelength. By contrast, the Eu3+ -doped Zn4 Al22 O37 phosphor exhibited two strong and intense emission bands at approximately 594 nm (orange) and 614 nm (red), which were monitored under 395 nm excitation. The Commission Internationale de l'Eclairage (CIE) colour coordinates of the Ce3+ -doped Zn4 Al22 O37 were investigated and found to be x = 0.1567, y = 0.0637 (blue) at 421 nm and for Eu3+ -doped Zn4 Al22 O37 were x = 0.6018, y = 0.3976 (orange) at 594 nm and x = 0.6779, y = 0.3219 (red) at 614 nm emission. The luminescence behaviour of the synthesized phosphors suggested that these phosphors may be used in lighting applications.
Subject(s)
Europium , Luminescence , Europium/chemistry , Ions , X-Ray Diffraction , ZincABSTRACT
In the present study, the thermoluminescence (TL) properties of an Eu3+ -doped CaNa2 (SO4 )2 phosphor were studied. The Eu3+ -doped CaNa2 (SO4 )2 phosphor was synthesized using the combustion method. The samples were well crystallized in the monoclinic phase. The TL glow curve of the Eu3+ -doped CaNa2 (SO4 )2 phosphor showed a single prominent peak at around 210°C with showed linearity on increasing exposure. The response curve of the synthesized phosphor showed linearity in the range 500-7000 Gy. Trapping parameters of synthesized phosphors such as activation energy, frequency factor, and order of kinetics were calculated in the study. These trapping parameters were determined by different methods such as Chen's peak method, the initial rise method, and Ilich's method. Each characteristic of these outcomes demonstrated that the synthesized Eu3+ -doped CaNa2 (SO4 )2 phosphor had outstanding TL properties and might be valuable for TL dosimetry application.
Subject(s)
Europium , Luminescent Measurements , Thermoluminescent Dosimetry , X-Ray DiffractionABSTRACT
A Eu3+ -activated Ca7 Mg2 (PO4 )6 phosphor was prepared at high temperature (800°C) using a solid-state reaction method. The crystal structure, phase formation of the prepared phosphor was characterized using X-ray diffraction patterns and Fourier transformed infrared analysis. The luminescence properties of the synthesized phosphor were characterized using photoluminescence and thermoluminescence techniques. The prepared phosphor showed two emission peaks at 594 nm with an orange colour due to the 5 D0 â7 F1 transition and at 612 nm a red colour due to the 5 D0 â7 F2 transition under 396 nm near-UV excitation. The prepared phosphors were irradiated with different doses of γ-rays from a 60 Co gamma irradiation source. Thermoluminescence glow curves for this sample phosphor were obtained using a Nucleonix 1009I TL reader. Synthesized phosphor samples were exposed to a 3.6 kGy dose of γ-rays. The thermoluminescence glow curve of the Ca7 Mg2 (PO4 )6 :0.05 mol%Eu3+ phosphor showed maximum intensity at all concentrations of Eu3+ ions. The Ca7 Mg2 (PO4 )6 :0.05 mol%Eu3+ phosphor was irradiated with different doses of 60 Co γ-irradiation and a linear response was observed between 0.6 kGy and 3.6 kGy. Trapping parameters such as activation energy, frequency factor and order of kinetics were calculated. The CIE chromaticity diagram showed the colour coordinates of the synthesized phosphor in the orange and red regions of the visible spectrum; this spectral feature revealed high colour purity and excellent chromaticity coordinate characteristics. Photoluminescence and thermoluminescence properties revealed that the prepared phosphor could be a potential red-emitting phosphor for eco-friendly white light generation and an excellent thermoluminescent dosimeter material for thermoluminescence dosimetric applications.
