Materials Letters: X最新文献

A series of Ba₂Ca(PO₄)₄:Dy³⁺ phosphors were synthesized by the wet chemical method and the photoluminescence properties were systematically investigated. Under the 350 nm near ultraviolet excitation, Ba₂Ca(PO₄)₄:Dy³⁺ phosphor shows emission peak at 475 nm (blue) and 572 nm (yellow). At 0.5 mol% of Dy³⁺ ions, concentration quenching was shown. The present study implies that the Ba₂Ca(PO₄)₄:Dy³⁺ phosphors would be a suitable choice for solid-state lighting applications as a near ultraviolet convertible phosphor.

Aluminum oxide phosphors were synthesized by solution combustion method using urea and glycine as fuel. XRD results show that the sample synthesized with urea as a fuel is $\alpha -A{l}_2{O}_3$ and glycine as a fuel is $\gamma -A{l}_2{O}_3$ with rhombohedral (R-3c) and cubic (Fd-3m) structures, respectively. The PL spectra of unirradiated and Ni⁷⁺ ions irradiated $\alpha -A{l}_2{O}_3$ show a broad peak between 1.92 and 3.2 eV with maxima at 2.25 eV. This broad emission is assigned to the combination of F₂ and $F_2^{2+}$ centers. In addition, two sharp emissions observed at 1.83 eV (678 nm) and 1.78 eV (695) are due to R-lines of Mn⁴⁺ and Cr³⁺ respectively. The PL intensity is enhanced after Ni⁷⁺ ion irradiation in $\alpha -A{l}_2{O}_3$ and the highest intensity is observed for 1 × 10¹² Ni⁷⁺ cm⁻². PL intensity decreases beyond this fluence. Unirradiated $\gamma -A{l}_2{O}_3$ samples have greater PL intensity, which decreases with Ni⁷⁺ ion irradiation. PL emissions of R-lines of Mn⁴⁺ and Cr³⁺ are missing in $\gamma -A{l}_2{O}_3$ due to a lower crystal field in the gamma phase.

The chemical instability of CaS:Eu phosphors is a curial problem that hinders its practical application, especially under high temperature and humid environment. In this work, CaS:Eu capped by methacrylate-functionalized Si compound are successfully prepared under a mild condition, without seriously sacrificing the photoluminescence capability. The stability of the as-prepared samples is subsequently tested in stirred hot water (90 °C) for over a month, the outstanding hydrophobicity and chemical stability of the as-prepared samples sufficiently reserve the optical and chemical properties. Systematic characterizations are conducted to reveal the chemical features of the modified CaS:Eu phosphor.

A series of KCaPO₄:Eu³⁺ phosphors was effectively synthesized utilizing a wet chemical method. The photoluminescence excitation and emission properties of the phosphor were investigated. The KCaPO₄:Eu³⁺ phosphor was efficiently excited at 394 nm, and the PL (Photoluminescence) emission spectra were obtained at 591 and 614 nm. Concentration quenching occurred at a Eu³⁺ ion concentration of 0.5 mol%. The present work suggests that the KCaPO₄:Eu³⁺ phosphors may be a potential candidate as a near-UV (Ultraviolet) convertible material for solid state lighting applications.

Mn⁴⁺ is an impressive activator and sensitizer for luminescent material, which has been comprehensively investigated during the recent decades. In the present work, we give an account of the luminescence properties of Mn⁴⁺ activated KBa(PO₃)₅ glasses are successfully synthesized by using Melt quenching technique. SEM investigation confirms the proposed phosphite glass's morphological behaviour. A photoluminescence research showed that the proposed phosphor's emission peak was positioned in the far red emission area after being excited in the blue region. There are numerous indications that the peaks seen in the 650–750 nm region are helpful for growing plants. Therefore, the suggested glass sample is a promising contender for the use of cultivating far-red emitting plants.

The synthesized photoluminescent and highly dielectric ZnO nanostructures are theoretically investigated as the metamaterial. Herein, the electric and magnetic responses of the ZnO nanomaterial are enhanced by introducing gold into ZnO to form Au-ZnO core–shell nanomaterial. The ZnO nanostructures are studied by optimizing their particle size in the near-infrared and far-field frequency region using Mie theory. The intense light scattering peaks with a peak shift for the Au-ZnO core–shell nanomaterial at the optimized particle size and particular wavelength in the near-infrared region are observed. A strong electric and magnetic pattern for the Au-ZnO core–shell nanomaterial is observed in the near-infrared and far-field frequency region as compared to the ZnO nanoparticles due to the surface plasmon property of the gold. The results pave the way for the design of complex dielectric materials for different optical applications through metamaterial technologies.

In this study, a method was developed for the management of marine plastic waste via the production of activated carbon. The specific surface area, micropore volume, and mesopore volume of marine-plastic-based activated carbon prepared at selected temperatures and using selected activator weight ratios were measured, and the specific capacitance and supercapacitor electrode performance were evaluated. At an activation temperature of 800 °C and a raw material to 8 M KOH weight ratio of 1:7, a specific capacitance of 201F/g and a high surface area of 2389 m²/g were obtained. Therefore, marine plastic waste-based activated carbon can be used as the electrode material in supercapacitors.

Mn₃O₄@CC electrodes were synthesized via a fast one-step molten salt method for flexible quasi-solid symmetric supercapacitors. Mn₃O₄ grows rapidly in a high polarity molten salt system and strongly anchors to carbon cloth. The molten salt method can realize sodion embedded in Mn₃O₄ and then improve the conductivity and capacitance. The results show that the Na-0.9-based supercapacitor exhibits a high capacitance of 1225.7 mF cm⁻² at 5 mA cm⁻². The preparation method, design strategy on structure of composition in this work will provide a novel route to realize high-performance flexible supercapacitors.

Carbon nanodots (CDs) synthesized via the microwave pyrolysis approach are monodisperse with the nano-size distribution. The CDs show color tunability simply by changing the excitation wavelength. Also, the emission intensity varies with varying different microwave response times. Detail characterizations indicate that the carbon defects that lead to heterogeneous emission levels are responsible for the emission properties of the CDs.

Pure and Eu³⁺ doped La₂O₃ nanophosphor was synthesized by sol gel process. PL spectra of undoped La₂O₃ samples shows broad emission peaks between 400 and 600 nm and Eu³⁺ doped samples show PL emission peaks at 510, 515, 531, 537, 553, 578, 585, 594, 612 and 624 nm. These peaks are attributed to ⁵D₁ → ⁷F₂, ⁵D₁ → ⁷F₂, ⁵D₀ → ⁷F₀, ⁵D₀ → ⁷F₁,⁵D₀ → ⁷F₂ transitions of Eu^{3 +} ions. The electronic dipole transition corresponding to⁵D₀ → ⁷F₂ (624, 612 nm) is stronger than the magnetic dipole transition of ⁵D₀ → ⁷F₁ (585, 594 nm) of Eu³⁺ ions. Luminescence behavior of Eu³⁺ in La₂O₃ is analyzed by Judd–Ofelt intensity parameters.