Papers by Keyword: Luminescent Materials

Abstract: Light is essential for plant growth and plays a crucial role in photosynthesis. However, sunlight often falls short of ensuring photosynthesis efficiency due to its wavelength composition, changing weather conditions, and the unique characteristics of plants, which create challenges for agricultural productivity. To address this, many innovative farming practices have been developed, including controlled environment agriculture, which creates microclimates that optimize conditions for plants. To improve light efficiency in these microclimates, researchers have turned to luminescent and light-conversion materials. These materials are incorporated into polymers to convert underutilized wavelengths, such as UV and blue light, into photosynthetically active radiation (PAR). Luminescent materials like fluorescent pigments, quantum dots, and rare-earth-doped compounds, when incorporated into polymers, produce films that enhance light absorption and improve spectral energy distribution. They have shown great potential to increase crop yield, biomass, and the quality of fruits and vegetables. Despite their potential, challenges remain on the path to widespread adoption. Environmental impact, scalability, and economic feasibility are significant concerns. This review explores the integration and functionality of photoluminescent polymer nanocomposites as light-converting materials. It also examines current limitations while offering future perspectives on how these materials can be used for sustainable light solutions to improve agricultural productivity.

Abstract: One-dimensional BaAl₁₂O₁₉:Mn²⁺ nanofibers were fabricated by electrostatic spinning method. The effects of some factors on the product preparation were investigated, such as the pH value of precursors; the proportion of citric acid; calcination temperatures, and then the optimal synthetic conditions was obtained. The calcination temperatures of optimal sample is only 1100 °C, less about 400 °C than that of the traditional solid state reaction method. X-ray diffraction, scanning electron microscopy, transmission electron microscopy and photoluminescence spectroscopy were adopted to detect the structure, grain size, morphology and optical properties of the nanofibers, respectively. The fiber samples with good crystallinity consist of a great quantity of nanoparticles. The size of each nanoparticle is below 50 nm and the fiber diameter is about 400 nm. Possible formation process of the nanofibers by electrostatic spinning was also discussed.

Abstract: Finely-dispersed phosphors of Y₂O₃:Eu and Y₃Al₅O₁₂:Eu have been synthesized with the help of Pechini method and the method of self-propagating high-temperature synthesis (SHS). During the synthesis of phosphors on the basis of Y₂O₃ carried out with Pechini method the size of crystallites increases with the enlargement of concentration of yttrium, but it decreases when the method of SHS is applied. The structure of phosphors on the basis of Y₃Al₅O₁₂ (YAG) is strongly amorphized. This fact agrees with the data of XRD and with the prevalence of the band with λ_max = 613 nm in the spectra of this phosphor. The enlargement of yttrium concentration in it promotes the amorphisation of yttrium aluminum garnet and the decrease of a crystal phase content. The sample of Y₃Al₅O₁₂:Eu synthesized with Pechini method has the maximum intensity, while in conditions of excitement with “high-level” X-ray radiation which corresponds to the radiation of industrial medical X-ray apparatus, the phosphor of Y₂O₃:Eu synthesized with the help of SHS showed the largest intensity. Colloid solutions prepared with the use of the samples synthesized by SHS method revealed a higher steadiness and a lower disposition to the sedimentation process. The samples of Y₂O₃:Eu phosphor possessing the smallest size of particles and the highest intensity of X-ray luminescence are the most suitable for the creation of pharmacological drugs used for photodynamic therapy.

Abstract: Sulfide based luminescent materials have attracted a lot of attention for a wide range of photo-and electroluminescence applications. Among the sulfides, ZnS is promising host material for development of phosphors in different visible emission bands. Doping of Ag can affect the electroluminescence of the host material. Incorporation of host ZnS into the polymer matrix is one of the best method to display their special functions, which stabilize the nanoparticles. Here we report a synthesis and electroluminescence of silver doped ZnS/PVK nanocomposites thin films. Reported films were prepared by using chemical route with varying Ag doping and ZnS loading in the composite. Structural and morphological characterization were carried out through XRD and SEM techniques, which confirmed the particles in nanoregime. Though optical absorption spectra and band gap of ZnS semiconductor nanoparticles in ZnS:Ag/PVK matrix were estimated, and using EMA model, particle size was calculated which supports the results of XRD. Electroluminescence of nanocomposite samples was studied and it was found that threshold voltage depends on doping of Ag and also on loading of ZnS. Voltage brightness characteristics support the production of EL by acceleration-collision mechanism.Contents of Paper