Luminescence investigation of Eu 3+ ion in the RE 2 (WO 4 ) 3 matrix ( RE =La and Gd) produced using the Pechini method

Kodaira, Cláudia Akemi; Brito, Hermi F.; Felinto, M.C.F.C.

doi:10.1016/s0022-4596(02)00221-9

Cited by 231 publications

(116 citation statements)

References 20 publications

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“…A much studied group of novel red phosphor materials for WLED are Eu 3+ -doped oxides of Mo and W, including compounds such as NaLa(WO4)(MoO4) (Li et al 2013), La2(WO4)3 (Kodaira et al 2003) and double perovskites within the (Sr,Ba)2Ca(W,Mo)O6 series (Ye et al 2011). The most common synthesis method of these materials is solid state reaction, but there are several reports of modified Pechini synthesis being used (Zalga et al 2011).…”

Section: Phosphorsmentioning

confidence: 99%

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Modified Pechini Synthesis of Oxide Powders and Thin Films

Sunde

Grande

Einarsrud

2016

Handbook of Sol-Gel Science and Technology

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The modified Pechini method has become one of the most popular synthesis methods for complex oxide materials due to its simplicity and versatility. The method can be applied to synthesize nano-crystalline powders, bulk materials as well as oxide thin films. Here, we present a comprehensive review of the method with focus on the chemistry through the three stages of the process; preparation of stable aqueous solution, poly-esterification to form a solid polymeric resin and finally decomposition/combustion of the resin to form an amorphous oxide followed by crystallization of the desired oxide phase. The review include

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Section: Phosphorsmentioning

confidence: 99%

“…In most of the reports, CA and EG are used as complexing and polymerization agents (Kodaira et al 2003;Wang et al 2008b), but other complexing agents have also been used. In a work by Sletnes et al, NaLa(WO4)(MoO4) was synthesized by using malic and tartaric acid, with and without EG (Sletnes et al 2016).…”

Section: Phosphorsmentioning

confidence: 99%

Modified Pechini Synthesis of Oxide Powders and Thin Films

Sunde

Grande

Einarsrud

2016

Handbook of Sol-Gel Science and Technology

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“…12 Recently we have reported the preparation, characterization and photoluminescent studies of the RE 2 (WO 4 ) 3 system (where RE = La, Eu and Gd), which was produced by the Pechini method. [13][14][15] The electronic spectra of the RE 3+ ions present narrow and low intensity bands due to the shielding of the 4f electrons from ligand field effects by the electrons of the filled 5s and 5p sub-shells. 16 The Sm 3+ ion has an odd electron configuration ([Xe] 4f 5 ) labeled as a Kramer's ion, which requires that the electronic states of this ion be at least doubly degenerate by the ligand-field for any chemical environment.…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence behavior of the Sm3+ and Tb3+ ions doped into the Gd2(WO4)3 matrix prepared by the Pechini and ceramic methods

Kodaira¹,

Brito²,

Teotonio³

et al. 2004

J. Braz. Chem. Soc.

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The Gd 2 (WO 4 ) 3 :RE 3+ compounds (where RE 3+ = Sm and Tb) were prepared by the Pechini and ceramic methods and characterized by X-ray diffraction and infrared spectroscopy. These rare earth materials present high orange (Sm 3+ -compound) and green (Tb 3+ -compound) luminescence intensity under UV radiation. The excitation spectra of these compounds presented broad bands arising from ligand-to-metal charge transfer (O→W and O→RE 3+) and narrow bands from 4f-intraconfigurational transitions. The excitation spectra of Tb 3+ system also exhibit broad bands attributed to the interconfigurational transition (4f-5d). The emission spectra exhibited the , respectively, while a broad band assigned to the LMCT (O→W) is observed when the excitation is monitored on the O→W LMCT state around 270 nm. The experimental intensity parameters η Sm and η Eu present similar behaviors, suggesting that the Sm 3+ ion is in a highly polarizable chemical environment with similar covalent character of the metal-donor atom interaction to the tungstate doped europium system. The cross-relaxation process from the 5 D 3 to the 5 D 4 levels of the Gd 2 (WO 4 ) 3 :Tb 3+ system has been also reported.

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“…The increase of Dy 3+ concentration reduced the blue emission broad band attributed to the matrix and intensified the transition 4 F 9/2 → 6 H 13/2 (575 nm). 22,47,48 The emission profiles of the samples excited at 352, 387, and 450 nm also displayed bands due to transitions related to Dy 3+ ( 4 F 9/2 → 6 H J , J = 15/2, 13/2, and 11/2). Nevertheless, the band corresponding to the emission from the matrix decreased considerably which suggested that these excitation wavelengths favored the Dy 3+ emission.…”

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confidence: 96%

Effect of Dy3+ Amount on the Structural and Luminescence Properties of LaNbO4:Dy3+ Phosphor Obtained by One-Step Spray Pyrolysis Process

Freiria¹,

Ribeiro²,

Verelst³

et al. 2017

J. Braz. Chem. Soc.

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In this study, Dy 3+ -doped LaNbO 4 phosphors with a blue to white emission that can be tuned by varying the activator concentration were prepared by one-step spray pyrolysis process. According to the powder X-ray diffraction results, increasing Dy 3+ concentration favored the tetragonal phase. Slight changes were observed in the recorded Raman spectra as a function of Dy 3+ concentrations while SEM (scanning electron microscopy) micrographs presented similar profiles regardless the Dy 3+ amount. Investigation of Dy 3+ emission data in the visible range showed that rising the Dy 3+ concentration progressively shifted the emission towards the white color. All samples presented a wide excitation range from 254 to 475 nm. Keywords: spray pyrolysis, luminescence, lanthanum niobate IntroductionOver the last years, rare earth ions (RE 3+ ) have received increasing attention: solid-state materials doped with these ions can be applied in color screens, lighting, and optical devices. [1][2][3][4][5] The luminescence properties of these materials heavily depend on the structure of the electron energy levels. In RE 3+ , chemical binding affects these levels very little because orbitals 5s and 5p shield orbital 4f efficiently. 6 The f-f transitions in RE 3+ cause an array of emissions at different wavelengths, giving rise to a plethora of colors. However, f-f transitions are forbidden by the parity selection rule (Laporte rule), so they have low excitation efficiency. Excitation requires the use of a matrix and/or sensitizer that is able to absorb energy and transfer it to an emitting ion. 6,7 Lanthanum niobate (LaNbO 4 ) is a promising material for multifunctional applications. It has a band-gap of approximately 4.8 eV and emits blue and ultraviolet light when excited with ultraviolet (UV) radiation and X-rays, respectively. 8,9 Moreover, LaNbO 4 can transfer the absorbed energy to other emitting species, leading to different fluorescence emissions. 10,11 This oxide has been prepared by a number of techniques; for example, spray pyrolysis (SP), 12-14 solid-state reaction, 15-17 reactions in solution [18][19][20] and sol-gel route. 10,21 However, with an exception of our previously published work, 22 the authors were not able to finely control the size, shape, and distribution properties. Moreover, the SP process is completed in only several seconds, while other currently available methods require several hours or days to complete the process, even requiring a post annealing treatment. Briefly, SP process involves the vaporization of precursor solution followed by the drying, precipitation and decomposition in heated tubular furnace reactors. The stoichiometric ratio in the final prepared material is the same as the precursor solution, since the reaction and aggregation volume are confined in each generated micrometric droplet, which can be seen as a micro reactor. Therefore, particles synthesized by the SP process can be obtained on a laboratory or on an industrial scale. [22][23][24][25] Among the various material...

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Luminescence investigation of Eu 3+ ion in the RE 2 (WO 4 ) 3 matrix ( RE =La and Gd) produced using the Pechini method

Cited by 231 publications

References 20 publications

Modified Pechini Synthesis of Oxide Powders and Thin Films

Modified Pechini Synthesis of Oxide Powders and Thin Films

Photoluminescence behavior of the Sm3+ and Tb3+ ions doped into the Gd2(WO4)3 matrix prepared by the Pechini and ceramic methods

Effect of Dy3+ Amount on the Structural and Luminescence Properties of LaNbO4:Dy3+ Phosphor Obtained by One-Step Spray Pyrolysis Process

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