Synthesis, surface modification and optical properties of Tb<sup>3+</sup>-doped ZnO nanocrystals

Pereira, Angela S.; Peres, M.; Soares, M.J.; Alves, E.; Neves, A.J.; Monteiro, T.; Trindade, Tito

doi:10.1088/0957-4484/17/3/037

Cited by 78 publications

(55 citation statements)

References 44 publications

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“…To draw the ground state energies for the trivalent lanthanides we will base on information on the Tb 3+ emission. Pereira et al [34] which is nearly the same as for YPO 4 in Fig. 1.…”

Section: Znosupporting

confidence: 71%

Lanthanide impurity level location in GaN, AlN, and ZnO

Dorenbos

Kolk

2007

SPIE Proceedings

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A method that has proven succesful in locating the energy levels of divalent and trivalent lanthanide ions (Ce, Pr,..., Eu,...Yb, Lu) in wide band gap inorganic compounds like YPO 4 and CaF 2 is applied to locate lanthanide levels in the wideband semiconductors GaN, AlN, their solid solutions Al x Ga 1-x N, and ZnO. The proposed schemes provide a description of relevant optical and luminescence properties of these lanthanide doped semiconductors. Especially, the relation between thermal quenching of Tb 3+ emission and the location of the energy levels is explained.

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“…To draw the ground state energies for the trivalent lanthanides we will base on information on the Tb 3+ emission. Pereira et al [34] which is nearly the same as for YPO 4 in Fig. 1.…”

Section: Znosupporting

confidence: 71%

Lanthanide impurity level location in GaN, AlN, and ZnO

Dorenbos

Kolk

2007

SPIE Proceedings

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“…This material is suitable for short-wavelength optoelectronic applications 4 , 5 , energy storage devices, field emission displays 6 , solar cells 7 , chemical 8 and biological sensors 9 , among other applications. In addition, ZnO is a versatile material that can be grown in several morphologies and by a large number of techniques, which include colloidal synthesis 10 , chemical vapor deposition 11 , pulsed laser deposition 12 , molecular beam epitaxy 13 , thermal evaporation 14 , among others.…”

Section: Introductionmentioning

confidence: 99%

ZnO micro/nanocrystals grown by laser assisted flow deposition

et al. 2014

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Laser assisted flow deposition (LAFD) is a very high yield method based on a vapor-solid mechanism, allowing the production of ZnO crystals in a very short time. The LAFD was used in the growth of different morphologies (nanoparticles, tetrapods and microrods) of ZnO micro/nanocrystals and their microstructural characterization confirms the excellent crystallinity of the wurtzite structure. The optical properties of the as-grown ZnO crystals investigated by low temperature photoluminescence (PL) evidence a well-structured near band edge emission (NBE) due to the recombination of free (FX), surface (SX) and donor bound (D 0 X) excitons. Among the most representative emission lines, the 3.31 eV transition was found to occur in the stacking faults-free microrods. The luminescence behavior observed in H passivated samples suggests a closer relationship between this optical center and the presence of surface states.Besides the unintentionally doped micro/nanocrystals, ZnO/Ag and ZnO/carbon nanotubes (CNT) hybrid structures were processed by LAFD. The former aims at the incorporation of silver as a p-type dopant and the latter envisaging photovoltaic applications. Silver-related spherical particles were found to be inhomogeneously distributed at the microrods surface, accumulating at the rods tips and promoting the ZnO nanorods re-nucleation. Despite the fact that energy dispersive X-ray measurements suggest that a fraction of the silver could be incorporated in the ZnO rods, no new related luminescence lines or bands were observed when compared with the as-grown samples. For the case of the ZnO/CNT composites two main approaches were adopted: i) a direct deposition of ZnO particles on the surface of vertically aligned multi-walled carbon nanotubes (VACNTs) forests without employing any additional catalyst and ii) new ZnO/CNT hybrids were developed as buckypaper nanocomposites. The use of the LAFD technique in the first approach preserves the CNTs structure and alignment and avoids the collapse of the VACNTs array, which is a major advantage of this method. On the other hand, LAFD grown ZnO nanoparticles and tetrapods were used to produce ZnO/CNT buckypaper nanocomposites. When compared with the as-grown samples the PL spectra of the composites structures behave differently. For the case of the ZnO/VACNTs no changes on the peak position and spectral shape were observed. Only an enhancement of the overall luminescence was found to occur. On contrary, for the buckypaper nanocomposites notable changes on the spectral shape and peak position were observed, likely due to distinct surface band bending effects for the ZnO nanoparticles and tetrapods embedded in the CNTs.

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“…16,17 This surface modification step was employed to confer a hydrophobic character to the inorganic NCs, thus promoting their dispersion in the monomers and enhancing their stability in the reaction medium. 18 For the ex situ preparation, both components, ZnO/topo NCs and poly-{trans-[RuCl 2 (vpy) 4 ]/sty}, were mixed in CH 2 Cl 2 to produce cast films of the nanocomposite. Firstly, the co-polymer was completely solubilized in 10 mL of CH 2 Cl 2 under stirring.…”

Section: Methodsmentioning

confidence: 99%

“…When compared with the spectrum of the polymeric matrix, the FTIR spectra recorded for both ex situ and in situ nanocomposites show a broad band in the 445-475 cm -1 region as a distinctive spectral feature that is due to ZnO NCs dispersed in the polymer. 18,25 All other vibrational bands are typical of the poly-{trans-[RuCl 2 (vpy) 4 ]/sty} used as the matrix. 14,19 Although the FTIR spectra shown in Figure 3 can only provide a qualitative analysis of the nanocomposites, it clearly reveals that there were no detrimental effects of the ZnO NCs on the polymer, either using the in situ or ex situ methods for nanocomposite preparation.…”

Section: 22mentioning

confidence: 99%

“…This absorption band is assigned to the first electronic transition of the ZnO exciton and is shifted to higher energies when compared to the typical bulk band gap value for ZnO (E g = 3.37 eV or 368 nm at room temperature, r.t.), showing that the average diameter of the ZnO nanoparticles is in the quantum regime. 18,20 In fact, this has been explained as consequence of quantum size effects occurring in nanosized particles with dimensions comparable to the Bohr radius (a B ) of the exciton of the bulk semiconductor. For the case of ZnO, the enlargement of the band gap due to particle size decrease is expected to occur for diameters comparable (or less) than 4 nm.…”

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confidence: 99%

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In situ and ex situ preparations of ZnO/poly-{trans-[RuCl2(vpy)4]/styrene} nanocomposites

Segala

Dutra

Franco

et al. 2010

J. Braz. Chem. Soc.

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As nanopartículas de semicondutores são de grande interesse científico e tecnológico devido ao fato das suas propriedades eletrônicas e ópticas dependerem do tamanho das partículas. Os nanocristais de semicondutores têm sido intensamente investigados, por exemplo, como nanocargas em diversas matrizes poliméricas. Neste trabalho é apresentada a síntese de nanocompósitos obtidos pela incorporação de nanocristais (NCs) de ZnO no copolímero poli-{trans-[RuCl 2 (vpy) 4 ]/sty} (sty = estireno e vpy = 4-vinilpiridina). Numa primeira etapa, o copolímero foi preparado por meio da reação entre os monômeros trans- [RuCl 2 (vpy) 4 ] e estireno. Em seguida, NCs de ZnO passivados organicamente foram misturados com o copolímero poli-{trans-[RuCl 2 (vpy) 4 ]/sty}, em CH 2 Cl 2 , para produzir filmes poliméricos do nanocompósito após evaporação do solvente (método ex situ). As propriedades destes materiais foram comparadas com as de nanocompósitos análogos obtidos a partir da polimerização in situ na presença de NCs de ZnO.Nanosized semiconductor particles are of great scientific and technological interest because of their size-dependent electronic and optical properties. Semiconductor nanocrystals have been investigated, for example, as nano-fillers for diverse polymer matrices in order to produce new optically active materials. Here we report, for the first time, results concerning the preparation of nanocomposites made of ZnO nanocrystals (NCs) incorporated in the co-polymer poly-{trans-[RuCl 2 (vpy) 4 ]/sty (sty = styrene and vpy = 4-vinylpyridine). In a first step, the co-polymer was prepared by reaction of trans-[RuCl 2 (vpy) 4 ] with styrene. Then, organically capped ZnO NCs and poly-{trans-[RuCl 2 (vpy) 4 ]/sty} were mixed in CH 2 Cl 2 to produce cast films of the nanocomposites after evaporation of the solvent (ex situ method). The properties of these materials were compared to those of nanocomposites obtained by in situ polymerization in the presence of ZnO NCs. Keywords: ruthenium(II) complexes, nanocomposites, ZnO nanocrystals IntroductionSemiconductor nanocrystals (NCs) show size-dependent optical properties and have been investigated as new optical materials in the field of nanotechnology.1 For example, these nanosized particles have been used together with polymers to produce new optically active inorganic/ polymer nanocomposites. This approach takes advantage not only of the intrinsic properties of the starting materials but might also result in new properties due to synergistic effects arising from the combination of the inorganic and organic components.2 Depending on the nanoparticles' characteristics and the synthesis/processing of the polymer matrices, there are several synthetic strategies to prepare polymer nanocomposites. Available approaches include solgel methods, 3 melt-processing 4,5 and in situ polymerization.6,7The homogeneous distribution of inorganic nanoparticles within the polymer matrix and the strong interface adhesion between the matrix and nano-fillers are important aspects to be conside...

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Synthesis, surface modification and optical properties of Tb³⁺-doped ZnO nanocrystals

Cited by 78 publications

References 44 publications

Lanthanide impurity level location in GaN, AlN, and ZnO

Lanthanide impurity level location in GaN, AlN, and ZnO

ZnO micro/nanocrystals grown by laser assisted flow deposition

In situ and ex situ preparations of ZnO/poly-{trans-[RuCl2(vpy)4]/styrene} nanocomposites

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Synthesis, surface modification and optical properties of Tb3+-doped ZnO nanocrystals

Cited by 78 publications

References 44 publications

Lanthanide impurity level location in GaN, AlN, and ZnO

Lanthanide impurity level location in GaN, AlN, and ZnO

ZnO micro/nanocrystals grown by laser assisted flow deposition

In situ and ex situ preparations of ZnO/poly-{trans-[RuCl2(vpy)4]/styrene} nanocomposites

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Synthesis, surface modification and optical properties of Tb³⁺-doped ZnO nanocrystals