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Doctoral Thesis
DOI
10.11606/T.46.2019.tde-07022019-111919
Document
Author
Full name
Cesar dos Santos Cunha
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2018
Supervisor
Committee
Brito, Hermi Felinto de (President)
Constantino, Vera Regina Leopoldo
Gonçalves, Rogéria Rocha
Sigoli, Fernando Aparecido
Title in Portuguese
Sintonização de cores de emissão fotoluminescente da rede de coordenação [Bi(HPyr)] dopada com íons TR3+
Keywords in Portuguese
Bismuto
Fotoluminescência
Materiais metal-orgânicos
Método hidrotérmico de alto rendimento
Sintonização de cores de emissão
Terras raras
Abstract in Portuguese
A rede de coordenação constituída por íons bismuto trivalente e ácido piromelítico (H4Pyr), [Bi(HPyr)], foi utilizada com sucesso como matriz hospedeira para a incorporação in situ dos íons terras raras trivalentes TR3+: Sm3+, Eu3+, Tb3+ e Dy3+. O método de alto rendimento para a síntese permitiu preparar e estudar a pureza de fase e cristalinidade das séries de amostras, acelerando e facilitando a comparação entre os parâmetros de síntese. As técnicas de espectroscopia de absorção no infravermelho, análise elementar e termogravimétrica, microscopia eletrônica de varredura e espectroscopia de energia dispersiva de raios X, bem como a difração de raios X de pó e o refinamento de Le Bail dos compostos indicaram que a dopagem não afetou a estrutura, cristalinidade, morfologia e estabilidade térmica da matriz. O estudo das propriedades espectroscópicas da matriz [Bi(HPyr)] não dopada e dopada com íons TR3+ permitiu a investigação dos processos de sensibilização do íons ativadores TR3+. As propriedades espectroscópicas características do íon Eu3+ foi utilizada para estudar o sítio e ambiente de coordenação dos dopantes por meio dos parâmetros de intensidades experimentais Ωλ (λ: 2 and 4), além do rendimento quântico intrínseco (QEUEU ) do material [Bi(HPyr)] mono dopado com Eu3+. A sintonização da cor de emissão pela mudança da concentração relativa dos íons dopantes é investigada para os sistemas duplamente dopados com os íons Tb3+:Eu3+, Tb3+:Sm3+, Dy3+:Eu3+ e Dy3+:Sm3+. Os sistemas contendo íons Dy3+ apresentam diferentes tonalidades de emissão branca e ampla faixa de temperatura de cor correlata (CCT - 2500 a 7500 K), sendo promissores para o desenvolvimento de dispositivos emissores de luz branca de fase única.
Title in English
Photoluminescent emission color tuning of the coordination network [Bi(HPyr)] doped with RE3+ ions
Keywords in English
Bismuth
Emission color tuning
High-throughput hydrothermal method
Metal-organic materials
Photoluminescence
Rare earths
Abstract in English
The coordination network consisting of trivalent bismuth ions and pyromellitic acid (H4Pyr), [Bi(HPyr)], was successfully applied as host matrix for in situ incorporation of the trivalent rare earth ions RE3+: Sm3+, Eu3+, Tb3+ and Dy3+. The high-throughput methods for hydrothermal synthesis allowed to prepare and study phase purity and crystallinity of sample series, accelerating and facilitating the comparison between the synthesis parameters. Infrared absorption spectroscopy, elemental and thermogravimetric analysis, scanning electron microscopy and energy-dispersive X-ray spectroscopy, as well as powder X-ray diffraction and the Le Bail refinement of the compounds indicated that doping did not affect the structure, crystallinity, morphology and thermal stability of the matrix. The study of the spectroscopic luminescence properties of the nondoped and doped [Bi(HPyr)] allowed the investigation of the sensitization processes of dopant RE3+ ions. The characteristic spectroscopic properties of the Eu3+ ion were used to study the incorporation site and coordination environment of the dopant by the calculation of the experimental intensity parameters Ωλ (λ: 2 and 4), besides the intrinsic quantum yield (QEUEU) of the Eu3+ single-doped [Bi(HPyr)]. Straightforward emission color tuning by changing the relative concentrations of the dopant ions is possible and has been studied for the systems double-doped with Tb3+:Eu3+, Tb3+:Sm3+, Dy3+:Eu3+ and Dy3+:Sm3+ ions. The Dy-containing systems show different shades of white emission and a wide range of correlated color temperatures (CCT - 2500 to 7500 K), hence being a promising candidate for the development of single-phase white light emitting devices.
 
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Publishing Date
2019-02-20
 
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