High brightness LaPO4:Ce,Tb phosphor particles with spherical shape

Kang, Yun Chan; Kim, Eun Joung; Lee, Dong Youl; Park, Hee Dong

doi:10.1016/s0925-8388(02)00747-8

Cited by 93 publications

(52 citation statements)

References 9 publications

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“…In fact, doped with Ce and Tb constitutes one of the classical phosphors used in high-quality fluorescent lighting due to its high quantum yield and stability at high temperature [1][2][3][4]. By varying the dopants (Pr, Nd, Eu, …) the optical properties can be tuned over a wide spectral range, with emerging applications in different fields such as biomedicine [5][6], photonic band gap materials or optical amplification [7][8].…”

Section: -Introductionmentioning

confidence: 99%

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LaPO4:Er microspheres with high NIR luminescent quantum yield

García‐Sevillano

Cantelar

Justo

et al. 2013

Materials Chemistry and Physics

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Er-doped LaPO 4 micro-spheres have been synthesized by spray pyrolysis and the near infrared (NIR) properties have been characterized. It has been found that, following an adequate post-annealing treatment, the emission properties are remarkably improved. The NIR luminescence intensity is highly enhanced and its decay time increases to a value almost coincident with the reported radiative lifetime, which implies that the quantum yield approaches   100%. This improvement in luminescence characteristics is probably related to the suppression of residual OH -radicals, that otherwise act as NIR luminescence quenchers, and to the increase in material's crystallinity. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 2 *Manuscript Click here to view linked References 1.-INTRODUCTIONLanthanide phosphate (LaPO 4 ) and, in particular, its monoclinic polymorph (monazite), has been widely used as a host for the preparation of lanthanide-based phosphors. In fact, doped with Ce and Tb constitutes one of the classical phosphors used in high-quality fluorescent lighting due to its high quantum yield and stability at high temperature [1][2][3][4]. By varying the dopants (Pr, Nd, Eu, …) the optical properties can be tuned over a wide spectral range, with emerging applications in different fields such as biomedicine [5][6], photonic band gap materials or optical amplification [7][8]. In particular, for optical amplifiers and lasers, Er becomes the most interesting dopant because of its characteristic emission, at around 1.5 m, coincident with the transparency window of optical fibers [8][9]. Along this line, there has been a considerable effort along the last years in order to prepare Er doped phosphate particles incorporated into polymer-based components, in order to improve luminescence characteristics and trying to achieve long lifetimes and high quantum efficiencies [10][11][12][13][14][15][16][17]. The data reported in the literature for the 1.5 m emission lifetime vary within a very large range (60 s [14] to 3.7 ms [17]), reflecting possibly the large variety of dopants concentration, particle size and fabrication processes; affecting material's properties such as crystallinity or impurities content [10][11][12][13][14][15][16][17].Spray pyrolysis is a well known technique for the synthesis of powdered materials, whose main advantages are simplicity and continuous character, which, along with its suitability to control particle size (micrometric) and shape (spherical), make it very attractive for industrial purposes [18][19]. Recently, this method has been used to prepare LaPO 4 spheres doped with Ce and Tb ions, which showed a high luminescence efficiency after a post heating treatment at >1300ºC [20][21]. However, up to our knowledge, this synthesis method has never been applied to the synthesis of Er-doped LaPO ...

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Section: -Introductionmentioning

confidence: 99%

“…Recently, this method has been used to prepare LaPO 4 spheres doped with Ce and Tb ions, which showed a high luminescence efficiency after a post heating treatment at >1300ºC [20][21]. However, up to our knowledge, this synthesis method has never been applied to the synthesis of Er-doped LaPO 4 with NIR luminescence.…”

Section: -Introductionmentioning

confidence: 99%

LaPO4:Er microspheres with high NIR luminescent quantum yield

García‐Sevillano

Cantelar

Justo

et al. 2013

Materials Chemistry and Physics

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“…doped with Sm 3 þ ions is higher [20,21]. Further, the morphology of phosphors (shape and size of the powder particles) is one of the key parameters of their industrial application [22,23]. In order to obtain optimum emission characteristics for device applications, the characteristic features of host as well as concentration dependent studies of Sm 3 þ are essential.…”

Section: Introductionmentioning

confidence: 99%

Effect of NaF flux on microstructure and thermoluminescence properties of Sm3+ doped CdSiO3 nanophosphor

Manjunatha

Nagabhushana

Sunitha

et al. 2013

Journal of Luminescence

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a b s t r a c tThis work reports the preparation of CdSiO 3 :Sm 3 þ (1-7 mol%) nanophosphors by a low temperature solution combustion method. For the first time the effect of NaF flux on the crystallization behavior, morphology, and thermoluminescence property of 5 mol% Sm 3 þ doped CdSiO 3 has been investigated. The nanopowders are well characterized by powder X-ray diffraction (PXRD), Fourier Transform InfraRed (FT-IR), and scanning electron microscopy (SEM). PXRD results indicate that the powder calcined at 800 1C for 2 h has monoclinic phase. SEM results show that the powder is highly porous and the pore size and shape can be modified by the addition of NaF flux. Addition of NaF could lead to formation of particle type morphology and the increase in wt% of NaF changes crystallinity and phase. The thermoluminescence glow curves for 2-6 wt% NaF in CdSiO 3 :Sm 3 þ show a single, well resolved glow peak at 126, 130 and 150 1C, respectively. But for the sample prepared with 8 wt% of NaF flux shows two glow peaks at 148 and 220 1C. With the addition of NaF flux, TL intensity can be effectively enhanced.&

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“…. Improvement of the morphology control is of great interest and different ways are tried in order to achieve this aim [1][2][3]. In fact, size and shape of the phosphor particles have an important influence on the emission intensity and the efficiency of the device [4].…”

mentioning

confidence: 99%

“…In the industry, phosphors are generally elaborated from oxides or carbonates by a solid state reaction : a high temperature heat treatment with or without fluxes. But this synthesis method does not allow an efficient control of the chemical homogeneity, neither the morphology of the phosphor particles without a grinding step, harmful to its optical properties [2,6]. The use of precursors elaborated by the wet method (rare earth phosphates, rare earth borates,…), has been a breakthrough for the control of the phosphor particles size distribution.…”

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confidence: 99%

Effect of different fluxes on the morphology of the LaPO4:Ce, Tb phosphor

et al. 2005

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Abstract. LaPO 4 :Ce, Tb (LaCeT) is a green phosphor used in fluorescent lamps and plasma display panels. In order to improve the fabrication process of this phosphor, different fluxes have been used. Their influence on the particles size and shape is described thanks to SEM analyses. Fluxes were found to control the morphology of particles : LaCeT particles, from spherical to parallelepiped-like shape, with suitable sizes, from 0.1 to 10 µm, have been synthesized. Furthermore the photoluminescence emission of the obtained powders has been checked, and it has been proved that the effect of the fluxes studied is not harmful to the LaCeT final optical properties. . Improvement of the morphology control is of great interest and different ways are tried in order to achieve this aim [1][2][3]. In fact, size and shape of the phosphor particles have an important influence on the emission intensity and the efficiency of the device [4]. Phosphor particles should be non-aggregated and their particles size distribution should range between 1 to 8 µm depending on the application. This morphology is required for the coating technique, which enhances the compactness of the powder and thus, the brightness of the device [1,4]. LaPO 4 :Ce, Tb (LaCeT), is a green phosphor which fluorescent lamps (FL) is the main application. In order to coat the lamps surface, the inside of the tube is put into contact with a suspension containing the LaCeT powder [5]. So, the phosphor grains should have a size as homogeneous as possible and above all without any aggregates nor agglomerates. Otherwise dispersion and sedimentation problems could occur. Moreover an optimal compactness of the powder is suitable in order to enhance the brightness of the display and to enable to lower the production cost. In order to improve the efficiency of the phosphors, the surface particles should also be as smooth as possible and a high crystallization degree is required. In the industry, phosphors are generally elaborated from oxides or carbonates by a solid state reaction : a high temperature heat treatment with or without fluxes. But this synthesis method does not allow an efficient control of the chemical homogeneity, neither the morphology of the phosphor particles without a grinding step, harmful to its optical properties [2,6]. The use of precursors elaborated by the wet method (rare earth phosphates, rare earth borates,…), has been a breakthrough for the control of the phosphor particles size distribution. In order to control the particles morphology, fluxes as Li 3 PO 4 , Li 2 CO 3 , K 2 CO 3 , MgF 2 , are added to the phosphor precursor and then the powder is fired at high temperature [1,7]. This KEY-WORDS

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High brightness LaPO4:Ce,Tb phosphor particles with spherical shape

Cited by 93 publications

References 9 publications

LaPO4:Er microspheres with high NIR luminescent quantum yield

LaPO4:Er microspheres with high NIR luminescent quantum yield

Effect of NaF flux on microstructure and thermoluminescence properties of Sm3+ doped CdSiO3 nanophosphor

Effect of different fluxes on the morphology of the LaPO4:Ce, Tb phosphor

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