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Proceedings ArticleDOI

A comparative study on the luminescence properties of Ce3+/Tb3+ doped Gd-based host nanomaterials

24 Apr 2018-Vol. 1952, Iss: 1, pp 020062
TL;DR: A comparative study on the crystal phases and their respective luminescence behavior of Gd3+ based host materials such as GdPO4, GdF3, GdingVO4 and Gding2O3 sensitized with 7at.% Ce3+ and activated with 5 at.% Tb3+ have been reported as discussed by the authors.
Abstract: A comparative study on the crystal phases and their respective luminescence behaviour of Gd3+ based host materials such as GdPO4, GdF3, GdVO4 and Gd2O3 sensitized with 7at.% Ce3+ and activated with 5 at.% Tb3+ have been reported. The nanomaterials were prepared by polyol method using ethylene glycol as solvent and found to have different crystal structures such as monoclinic, orthorhombic, tetragonal and cubic phase. Clear characteristics emission from Tb3+ has been observed in all the samples when excited in the absorption wavelength of Ce3+ and Gd3+ (∼280 nm). Among all the above materials, intense emission of Tb3+ is found in GdPO4 followed by GdF3, Gd2O3 and GdVO4 respectively. The Tb3+ emission is strongly influenced by the energy transfer process and crystal structure of the host materials and hence this study will be important for choosing suitable materials for display devices and biomedical applications.A comparative study on the crystal phases and their respective luminescence behaviour of Gd3+ based host materials such as GdPO4, GdF3, GdVO4 and Gd2O3 sensitized with 7at.% Ce3+ and activated with 5 at.% Tb3+ have been reported. The nanomaterials were prepared by polyol method using ethylene glycol as solvent and found to have different crystal structures such as monoclinic, orthorhombic, tetragonal and cubic phase. Clear characteristics emission from Tb3+ has been observed in all the samples when excited in the absorption wavelength of Ce3+ and Gd3+ (∼280 nm). Among all the above materials, intense emission of Tb3+ is found in GdPO4 followed by GdF3, Gd2O3 and GdVO4 respectively. The Tb3+ emission is strongly influenced by the energy transfer process and crystal structure of the host materials and hence this study will be important for choosing suitable materials for display devices and biomedical applications.
References
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Journal ArticleDOI
TL;DR: In this article, the substitution of vanadium (V5+) by phosphorous (P5+) ions in YVO4 was confirmed by X-ray diffraction studies and also supported by Fourier transform infrared spectroscopy, transmission electron microscopy, and photoluminescence (PL) studies.
Abstract: Nanorods of YPxV1−xO4:Ln3+ (Ln3+ = Dy3+, Eu3+, Sm3+) have been synthesized hydrothermally. The substitution of vanadium (V5+) by phosphorous (P5+) ions in YVO4 was confirmed by X-ray diffraction studies and also supported by Fourier transform infrared spectroscopy, transmission electron microscopy and photoluminescence (PL) studies. The energy transfer (ET) rate to the activator can be controlled either by activator concentration or by doping with P in the crystal. The ET is reduced by P doping due to the increase in separation between vanadium ions. This has been established from both steady state luminescence and decay studies. The controlled ET leads to the blue color emission from the vanadate (VO43−) transition in YPxV1−xO4 and generates a multicolored light emission even with single doping of the activator. Further, the color of emission can also be tuned by multiple doping of the activators. Interestingly, white light is obtained by doping with Dy3+ (1 at.%) and Sm3+ (0.75 at.%) in YP0.8V0.2O4. The quantum yield of white light emission is found to be 25%. CIE chromaticity supports the tunability of the light and the white light emission.

67 citations

Journal ArticleDOI
TL;DR: This approach is compared with an alternative model that is based on electron transfer from the valence band to a lanthanide, the so-called intervalence charge transfer (IVCT).
Abstract: The spectral properties of LaVO4, GdVO4 and LuVO4 crystals doped with Ce3+, Pr3+, Eu3+ or Tb3+ have been investigated in order to determine the position of the energy levels relative to the valence and conduction bands of the hosts along the trivalent and divalent lanthanide series. Pr3+ and Tb3+ ground state levels are positioned based on the electron transfer energy from those states to the conduction band, the so-called intervalence charge transfer (IVCT). This approach is compared with an alternative model that is based on electron transfer from the valence band to a lanthanide.

66 citations

Journal ArticleDOI
TL;DR: In this paper, the enhanced green emission from Tb3+-doped GdPO4 nanorods sensitized with Ce3+ was reported, and the increase in the rate of nonradiative transition processes in sensitizer due to efficient energy transfer to activator was realized from steady-state and dynamic luminescence studies.
Abstract: Herein we report the enhanced green emission from Tb3+-doped GdPO4 nanorods sensitized with Ce3+. The increase in the rate of nonradiative transition processes in sensitizer due to efficient energy transfer to activator is realized from steady-state and dynamic luminescence studies. Luminescence quenching due to cross relaxation is least significant up to 20 at. % Ce3+ and 7 at. % Tb3+ concentration. The quantum yield of the sample with maximum luminescence, i.e., GdPO4:Tb3+ (5 at. %)/Ce3+ (7 at. %), is found to be 28%. Also, samples are readily redispersible in water and could be easily incorporated in polymer-based films that show strong green light emission under UV excitation. The luminescence switching (ON and OFF) behavior is examined using alternately an oxidizing agent (KMnO4) and then a reducing agent (ascorbic acid) through a redox reaction (Ce3+/Ce4+). Both GdPO4:Tb3+ and GdPO4:Tb3+/Ce3+ are observed to be paramagnetic.

61 citations

Journal ArticleDOI
TL;DR: In this article, the authors observed the high quenching of the luminescence intensity of Eu3+ doped GdPO4 prepared in water (H2O) medium.
Abstract: Luminescence intensity of rare-earth doped materials can be varied depending on shape of particles, capping agent, and heat-treatment. This is related to the non-radiative rate possessed by the material. Here, we observed the high quenching of the luminescence intensity of Eu3+ doped GdPO4 prepared in water (H2O) medium. On the contrary, in ethylene glycol (EG) medium, it shows high luminescence. Luminescence intensity is recovered when Eu3+ doped GdPO4 nanorods prepared in H2O medium is heated above 700 °C. This transforms hexagonal to monoclinic structure following the removal of water. Luminescence intensity is enhanced by changing the medium from H2O to D2O and also if core-shell formation occurs. Also, we found significant variation in bending and stretching vibrations of O-H and microstructure in this material prepared in H2O and EG. Two types of O-H stretching frequencies are observed at 3450 and 3520 cm−1 in H2O medium prepared sample which are assigned to the O-H having the hydrogen bonding (surface water) and the confined water, respectively. The formation of nanorods is due to the presence of water on the surface of particles or/and inside the pores of compound. The available water in the nanoparticles pores can be utilized for the efficient killing of mass cells tumor by generating reactive free radicals (H· and OH·) through the application of laser near infrared (NIR) source and the subsequent irradiation of gamma ray. This proposed mechanism is quite different from the conventional treatment of mass cell/malignant tumor using gamma ray radiation. Sample is highly paramagnetic and it will be useful for magnetic resonance imaging contrast agent.

51 citations