Influence of Catalyses on the Preparation of YVO4:Eu3+ Phosphors by the Sol–gel Methodology

Abstract

YVO(4):Eu(3+) phosphors have been prepared by the hydrolytic sol-gel methodology, with and without alkaline catalyst. The solid powder was obtained by reaction between yttrium III chloride and vanadium alkoxides; the europium III chloride was used as structural probe. The powder was treated at 100, 400, 600, or 800 °C for 4 h. The samples were characterized by X-ray diffraction, thermal analysis, and photoluminescence. The XRD patterns revealed YVO(4) crystalline phase formation for the sample prepared without the catalyst and heat-treated at 600 °C and for the sample prepared in the presence of ammonium as catalyst and heat-treated at 100 °C. The average nanosized crystallites were estimated by the Scherrer equation. The sample which was produced via alkaline catalysis underwent weight loss in two stages, at 100 and 400 °C, whereas the sample obtained without catalyst presented four stages of weight loss, at 150, 250, 400, and 650 °C. The excitation spectra of the samples treated at different temperatures displayed the charge transfer band (CTB) at 320 nm. PL data of all the samples revealed the characteristic transition bands arising from the (5)D(0) → (5)F(J) (J = 0, 1, 2, 3, and 4) manifolds under maximum excitation at 320, 394, and 466 nm in all cases. The (5)D(0) → (7)F(2) transition often dominates the emission spectra, indicating that the Eu(3+) ion occupies a site without inversion center. The long lifetime suggests that the matrix can be applied as phosphors. In conclusion, the sol-gel methodology is a very efficient approach for the production of phosphors at low temperature.

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

“…[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.…”

Structural and photoluminescence properties of red-light emitting YVO4:Eu3+ phosphor synthesized by combustion and solid-state reaction techniques: a comparative study

“…High melting point makes it thermally stable and small phonon energy reduces the non-radiative transitions in photoluminescence phenomenon. Overall, vanadate hosts provide a good environment for doping and efficient energy transfer from host to dopant [12,13]. The rare earth ions that act as activators have 4f manifolds or 4f n-1 and 5d configurations which give emission of light due to electric dipole or magnetic dipole transitions.…”

EFEITO DA CONCENTRAÇÃO DOS ÍONS Eu3+ E Bi3+ NAS PROPRIEDADES FOTOLUMINESCENTE DA MATRIZ DE YVO4

“…49 O tamanho dos cristalitos podem ser estimados através da equação de Scherrer (Eq. 1), 30,50 usando a largura a meia altura dos picos de reflecção obtidos no DRX.…”

“…em que L é o tamanho médio dos cristalitos, λ comprimento de onda A literatura tem descrito a preparação da matriz YVO 4 dopada com íons Eu 3+ obtida pelo metodologia sol-gel hidrolítica e não--hidrolítica, 28,27,30 os quais apresentam bandas de transferência de carga no intervalo de 308 à 324 nm, uma banda simétrica. Nas amostras após a adição do íon Bi 3+ a larga banda na região de menor comprimento de onda aparece assimétrica composto de pelo menos duas outras bandas (Tabela 4), as quais podem ser atribuídas ao ânion VO 4 3-(λ = 303 à 311 nm) 20 e ao íon Bi 3+ (λ = 325 à 340 nm).…”

“…24 Uma variedade de redes hospedeiras podem ser obtidas por essa metodologia. 20,[25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] Diante disso, o objetivo deste trabalho foi obter por meio do processo sol gel rota não-hidrolítica a matriz de YVO 4 dopadas com o íon ativador Eu 3+ e Bi 3+ como sensibilizador, ambos em diferentes concentrações com o intuito de promover a intensificação da emissão do íon Eu 3+ . As caracterizações foram realizadas através da difração de raios X para identificação da fase cristalina formada e fotoluminescência do íon Eu 3+ avaliando as propriedades espectroscópicas.…”