Erbium-doped nanocrystal (NC)-dispersed polymer thin films are attractive core materials for use in optical waveguides as they can provide high optical gain and enable the formation of compact waveguide amplifiers. Nonetheless, there are significant challenges associated with obtaining good dispersibility of NCs into a polymer matrix and favorable optical properties. Therefore, in this paper, we report the fabrication of Er3+-doped ceria (EGC) NCs employing the Leeds alginate process (LAP) and their incorporation into a siloxane polymer matrix. The surface morphology and compositional, structural, and optical properties of the fabricated films are evaluated to assess the NC dispersion and their suitability for the waveguide amplifier. The photoluminescence (PL) and lifetime measurements of the NCs–polymer nanocomposite thin film samples show intense, broadband PL emission of the Er3+ ions at 1534 nm (4I13/2 → 4I15/3 transition) with a full width at half-maximum (fwhm) of ∼64 nm and lifetime in the range of 2.6–3.0 ms. The inhomogeneously broadened PL spectra and improvement in lifetime of NCs in the polymer are important results that we report. The EGC NCs–polymer nanocomposite thin films also exhibit excellent transparency in the NIR wavelength range and a refractive index in the range of 1.53–1.58 in the visible wavelength. The work presented here clearly demonstrates the potential of using high-quality Er-doped nanocomposite polymer thin films for interesting applications such as compact low-cost waveguide amplifiers and lasers.
This research investigated the effect of synthesis pH on the microstructure and morphology of the zinc oxide (ZnO) particles prepared using pineapple (Ananas comosus) peel extract. In this study, ZnO powder were synthesized at different pH, i.e. 8, 9, 10, 11, and 12. ZnO samples were characterized using UV-Vis spectroscopy, Fourier Transform InfraRed spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The UV-Vis absorbances spectroscopy shows the optical absorption peak of the ZnO sample occurred in a wavelength range of 300-360 nm, with bandgap energy of ∼3.22 eV. The FT-IR spectrum shows the peak of Zn-O absorption at the wavenumber of 437.55 cm-1 and the reduction of aromatic compounds with increasing of pH. The micrograph of ZnO particles synthesized at different pH shows that the pH affected the size and shape of ZnO. Micro-sized particles with a granular shape have been found at pH 8, and 9, a spherical shape have been found at pH 10, while micro-sized flower-shaped particles have been found at pH 11 and 12. The XRD pattern reveals a wurzite hexagonal ZnO crystal phase with the hkl plane of (101) as the strongest peak, as well as the purity of the sample increasing as the pH value rises. As the conclusion, synthesis pH has a significant impact on the optical, structural, and morphological properties of ZnO biosynthetic powder.
The crystal structure of CeGdHoO (cerium gadolinium holmium oxide) has been determined from powder X-ray diffraction data. This is a promising material for application as a solid electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Nanoparticles were prepared using a novel sodium alginate sol-gel method, where the sodium ion was exchanged with ions of interest and, after washing, the gel was calcined at 723 K in air. The crystallographic features of Gd and Ho co-doped cerium oxide were investigated around the desired operating temperatures of IT-SOFCs, i.e. 573 ≤ T ≤ 1023 K. We find that the crystal structure is a stable fluorite structure with the space group Fm-3m in the entire temperature range. In addition, the trend in lattice parameters shows that there is a monotonic increase with increasing temperature.
The perovskite nanopowders of lanthanum strontium cobalt ferrite (LSCF) have been synthesized using the alginate mediated ion-exchange process. This perovskite-based material is a promising cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs) due to its high electrical conductivity, low polarizability, high catalytic activity for oxygen reduction, enhanced chemical stability at an elevated temperature in high oxygen potential environment and high compatibility with the ceria based solid electrolytes. Phase pure LSCF 6428, LSCF 6455, and LSCF 6482 corresponding to La0.6Sr0.4Co0.2Fe0.8O3-δ, La0.6Sr0.4Co0.5Fe0.5O3-δ, and La0.6Sr0.4Co0.8Fe0.2O3-δ, respectively were successfully synthesized. The simultaneous thermal analysis (DSC-TGA) and XRD were used to determine the optimum calcination temperature for the dried ion-exchanged beads. Single phase nanopowders of LSCF (6428, 6455, and 6482) have been successfully prepared at a calcination temperature of 700 °C. The TGA analysis showed that every ton of LSCF-ALG dried beads can potentially yield 360 kg of LSCF nanopowders suggesting a potential for scaling-up of the process of manufacturing nanopowders of LSCF.
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