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Optical metamaterials present opportunities and challenges for manipulation of light. However, metamaterials with visible and near infrared responses are still particularly challenging to fabricate due to the complex preparation process and high loss. Here, a visible light poly(amidoamine) (PAMAM)-Ag metamaterial is prepared with the assistance of fifth-generation PAMAM (5G PAMAM), based on the dendritic structure. The large area of metamaterials, where Ag nanoparticles are spherical with diameters of ∼ 9 nm and distributed in a multilevel netlike sphere, results in broadband resonance. The negative Goos–Hänchen shift and anomalous spin Hall effect of light generated by 5G PAMAM-Ag in visible broadband are observed, and a strong slab focusing effect at 750–1050 nm is demonstrated. In addition, the simulation shows possible application of the dendritic structure in topological photonics. The results offer advances in the preparation of large-scale visible light metamaterials, showing the potential for subwavelength super-resolution imaging and quantum optical information fields.

The size and shape of functional micro/nanomaterials have crucial influence on their physical and chemical properties. The monoclinic Y4O(OH)9NO3 with nanosheets, submicrospheres, and microrods have been successfully prepared by a non-aqueous solvothermal method. The precursors Y4O(OH)9NO3 decompose into cubic Y2O3:Eu3+ phosphors after sintering at 800 °C for 2 h. The morphologies and sizes of Y2O3:Eu3+ particles can be easily controlled by changing the growth rates of various crystallographic facets during solvothermal process. With the increment of the rare-earth nitrates concentration, the morphologies transform from 2D nanosheets to sub-microspheres, and eventually to microrods. The bright red emission, owing to Eu3+ f-orbital transitions, can be easily observed under ultraviolet excitation. Furthermore, the dependence of Y2O3:Eu3+ luminescence performances on different morphologies are discussed in the present work.

Using a one-step microwave method without any further calcination, various rare-earth (Re) ions doped anatase titania microspheres were synthesized successfully in less than 10 min. TiCl4 aqueous solution and rare-earth salt solution are used as reactant, and ethanol was used as solvent. Anatase titania microspheres doped with rare-earth ions including Ce(IV), Sm(III), Tm(III) and Tb(III) were obtained without using any template or surfactant. The scanning electron microscopy images show that the particles have well-defined spherical shapes with a relatively narrow size distribution. X-ray diffraction and Raman spectra demonstrate the crystalline phase of the particles to be anatase. The energy-dispersive spectroscopy spectra and elemental mapping identify rare earth elementals distribute in the microspheres uniformly. The valence state of rare-earth in the samples was determined by X-ray photoelectron spectroscopy spectra. The studies provide a super-rapid method to prepare rare earth doped crystalline TiO2 microspheres, which are useful materials for optical, biological and environmental applications.

Homogeneous and size-controlled YVO4:Eu3+ micro/nanosheets were successfully synthesized on a large scale by using an ammonium oxalate (AO)-assisted hydrothermal route and post-calcination process. In this study, the shape and size of the as-prepared architectures can be changed effectively by controlling a series of experimental parameters, such as the precursor’s reaction temperature, hydrothermal reaction time and molar ratio of organic additive AO:Y3+. YVO4:Eu3+ micro/nanosheets were synthesized with lengths ranging from 2000 to 400 nm and thicknesses ranging from 200 to 50 nm. When changing the precursor’s reaction temperature and reducing the hydrothermal reaction time to 2 h, the phase composition was transformed into Y2O3 instead of YVO4. Functioning as a precipitant and shape modifier, AO exerted a dynamic effect by adjusting the growth rate of different facets under the various experimental conditions, resulting in the formation of different shapes and sizes of the final products. The correlative growth mechanism was analyzed in detail. Photoluminescence and Electroluminescence properties of the products exhibited a strong red emission focused on 618 nm under 275 nm ultraviolet excitation or direct current high-voltage field. Small sample sizes exhibited high EL intensity. The size-controlled products synthesized successfully via the hydrothermal method could provide a great opportunity for systematically evaluating their luminescence properties and accelerating the use of different types of applications in color display devices.

Homogeneous Y2O3:Eu3+ nanorods with the lengths of several micrometres were successfully synthesised on a large scale by using a urea-assisted hydrothermal method and a post-calcining process. In this study, the influences of urea content and NaOH concentration on the oriented growth, photoluminescence (PL) and electroluminescence (EL) intensity enhancement of Y2O3:Eu3+ were investigated. As a precipitant for isotropic growth, urea can counteract the effect of NaOH on oriented growth along the c-axis during hydrothermal treatment. The Y2O3:Eu3+ powders exhibited a strong red emission centred at 613 nm under either 245 nm UV excitation or the direct current high electric field. The PL intensity of the Y2O3:Eu3+ phosphor prepared with 0.3 g of urea reached 141 % that of the sample prepared under the same conditions but without urea. The strategy for controlling the oriented growth, PL and EL enhancement of Y2O3:Eu3+ can be extended to the synthesis of other inorganic nano/micromaterials.

Mesoporous europium-doped yttrium oxide phosphors were successfully synthesized by a simple Pechini sol–gel method. The prepared powders were characterized by X-ray diffraction, scanning electron microscopy, Surface area and pore size analyzer and fluorescence spectrophotometer. The XRD spectrum of the calcined samples confirm the presence of Y2O3. The surface area and pore size analyzer was employed to demonstrate the existence of mesoporous structure in these samples. The room temperature photoluminescence (PL) emissions of Y2O3:Eu samples can be observed under 245 nm excitation. PL results show that the emission intensity of as-prepared mesoporous Y2O3:Eu phosphors are higher than that of particles without special structures. Large surface area and pores play an important role in the increasing of PL intensity. The intensity ratio between 5D0 → 7F2 and 5D0 → 7F1 transitions which related to the local environment of Eu3+ were also studied.

Porous ZnS precursors were prepared by soft template method and Soxhlet extraction method. We used three surfactants with different molecular weight, which included ODA, Pluronic P123, and Pluronic F127, as soft template agents. Nitrogen adsorption–desorption results indicated that larger molecular weight and larger amounts of the template agent made porous ZnS precursors with larger pore sizes and smaller specific surface areas. The final ZnS fluorescent samples were obtained through calcinations method in tube furnace. The emission peaks of ZnS porous fluorescent samples were approximately 490 nm because of zinc vacancy, which was similar to ZnS nanoparticles. However, the emission intensity of porous ZnS fluorescent samples was 2.3-fold greater than that of ZnS nanoparticles, because that the porous cavity can increase the utilization ratio of excitation light and cause more absorption of excitation light, improve the luminescent properties of ZnS phosphor.

In this study, uniform gold (Au) nanoparticles (NPs) were prepared using seed-mediated growth method. The particle size was controlled by tuning the dosage of seed solution. Au@PS core–shell NPs were then synthesized by introducing a polystyrene (PS) shell (2–3 nm thick) around the core of Au NPs (115 nm). Evaluation of the surface plasmon (SP) optical properties indicated that wavelength of SP resonance of Au NPs increased gradually with increase in the particle size. This red shift was about 0.92 nm per 1 nm increase in particle size. The results also indicated that the zeta potential and optical properties of Au NPs could be adjusted by coating PS on the outside. Therefore, surface modifications and surface coating were effective ways to control the optical properties of Au NPs.

In this study, we prepared a novel Au–ZnS nanocomposite by simple homogeneous precipitation at room temperature. It is found that the defect emission (around 490 nm) from ZnS is dramatically tailored by the presence of Au nanoparticles. Specifically, the photoluminescent performance of this structure is strongly influenced by the size and concentration of Au cores and the surfactant. When the Au core is 12 nm and the mass fraction of Au is 0.050%, an enhancement of up to 38.5% in the photoluminescent intensity was observed. This enhancement is attributed to energy transfer from ZnS to Au followed by a large local electromagnetic field on or near the surface of the Au nanoparticles.

We have successfully prepared monodispersed fluorescent ultra-small Au nanoclusters (about 2 nm) via a two-phase liquid–liquid method. The products are extremely stable and can be dissolved in toluene in any concentration without agglomeration, even be stored in air for months. This stability is mainly attributed to the surfactant dodecanethiol whose operative part is the Au–S bond. On the Au nanocluster surface, the Au–S group makes the particles exclude each other to form the monodispersed stable Au nanocluster. The products did not exhibit surface plasmon absorption owing to their insulating molecular state. At the same time, they emitted near-infrared extreme narrow fluorescent emission spectrum under 370 nm excitation. Here, dodecanethiol also plays an important role to enhance the fluorescent intensity due to charge transfer from surface ligands to gold. Because of their superiority in stability and sharp emission peak, Au nanoclusters appear to be an attractive fluorescent material for bioimaging and biological marker.

Uniform hollow Sm3+-doped titania phosphors were prepared via a facile method using polystyrene spheres as template. After calcination at 500 °C for 3 h, hollow TiO2:Sm3+ spheres with outer diameters of approximately 250 nm and a shell thicknesses ranging from 50 to 70 nm were obtained. A possible formation mechanism of the evolution process of the spheres was discussed in this paper. Photoluminescence (PL) results showed that the emission intensity of the as-prepared hollow TiO2:Sm3+ spheres was 2.1 times higher than that of amorphous nanoparticles (NPs). We propose that this PL enhancement is due to the unique hollow structures obtained.

We report a facile method for the fabrication of polystyrene/silver composite nanoparticles with core-shell nanostructures. First, polystyrene (PS) nanoparticles with carboxyl acid groups on their surfaces were prepared via the dispersion polymerisation of styrene in water with the assistance of acrylic acid. Second, with the addition of [Ag(NH3)2]+ to the PS dispersion, [Ag(NH3)2]+ was absorbed onto the surfaces of the modified PS nanoparticles. Finally, the [Ag(NH3)2]+ complex ions were reduced to Ag to form the PS/Ag nanocomposites upon heating. The resulting PS/Ag composite nanoparticles were characterized via scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and dynamic light scattering.

In this study, a novel hybrid nanostructure for enhancing photoluminescence (PL) was prepared by doping samarium (Sm) and gold (Au) into titania (TiO 2 :Sm 3+ :Au) via a simple sol–gel method. The X-ray diffraction and PL results indicate that the sample with better crystallinity has better emitting performance. The dependence of the PL intensity was examined as a function of the concentration of Au nanoparticles (NPs) while keeping the Sm content constant at 2%. It is found that PL enhancement and quenching can be obtained by tuning the content of Au NPs. The PL results suggest that the PL emission of this hybrid system relies on the energy (emitting light) transferred from TiO 2 :Sm 3+ to Au NPs. The plasmon state around Au NPs can be excited to bring out PL enhancement only when the intensity of the transferred energy meets the requirement of Au NPs.

In this paper, a novel plasmon-enhanced photoluminescence (PL) hybrid system is presented based on metal–semiconductor nanostructure, in which TiO2:Sm3+ works as luminophor while the gold nanoparticle (NP) as the promoter of plasmon resonance. The plasmon-enhanced PL is obtained by optimizing the plasmon resonance peak of gold NP employed in the system, and it is deduced that there is energy transfer from TiO2:Sm3+ to Au NPs during the process of light emitting. When the localized surface plasmon resonance (LSPR) spectra of Au NPs overlap with the PL spectra of TiO2:Sm3+, the Au NPs absorb the energy transferred from TiO2:Sm3+, and then the plasmonic mode confined around Au NPs can be excited to bring out the PL enhancement. Schematic illustration of the process of plasmon-enhanced emission. The different steps are (a) light emitting of TiO2:Sm3+, (b) energy transferred from TiO2:Sm3+ to the Au NPs, and (c) enhanced emitting of the hybrid system.