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Rare-earth elements ${\text{Sm}}^{3+}$-, ${\text{Pr}}^{3+}$-, ${\text{Ho}}^{3+}$- and ${\text{Er}}^{3+}$-doped (${\text{K}}_{0.5}$${\text{Na}}_{0.5}$)${}_{0.974}$${\text{La}}_{0.025}$${\text{Nb}}_{0.975}$${\text{Bi}}_{0.025}$O₃ ceramics (abbreviated as KNLNB-0.1%RE) were prepared by conventional solid-phase sintering method. The structure, transparency, energy storage and photoluminescence properties of the samples are investigated. All ceramics have the pseudo-cubic phase structure without the impurity phase at room temperature. KNLNB-0.1%RE ceramics exhibit excellent optical transmittance, with KNLNB-0.1%Ho achieving 71.8% transmittance in the visible wavelength range (780nm) and largest effective energy storage density of 1.45J/cm³. In our experiments, rare-earth-doped KNLNB ceramics exhibit photoluminescence effects. This work facilitates the development of transparent energy storage ceramics with fluorescent effects.

In this paper, we investigated the luminescence and kinetic properties of 1.1-nm-thick colloidal CdSe nanoplatelets rolled up into scrolls in an external electric field in the range of 0–150kV/cm. Luminescence spectroscopy revealed that placing CdSe nanoscrolls in an external electric field leads to quenching of the intensity of luminescence bands with an increasing electric field, whereas time-correlated single photon counting measurements demonstrate the acceleration of the relaxation processes of electronic excitation. These effects are due to a reduction in the overlap integral between the electron and hole wavefunctions which is the reason for the emergent field-induced luminescence quenching.

In this study, the sol–gel method was used to prepare ZnO seed layer for synthesizing ZnO nanorods, and we would investigate the effects of different Zn(CH₃COO)₂ and C₆H${}_{12}$N₄ concentrations on the synthesized characteristics of ZnO nanorods. First, the ZnO gel was dipped on the surface of the $P$-type $\mathrm{\text{Si}}〈100〉$ wafer as a seed layer. Then, the hydrothermal method with different Zn(CH₃COO)₂ and C₆H${}_{12}$N₄ concentrations as precursors was used to synthesize ZnO nanorods on $P$-type $\mathrm{\text{Si}}〈100〉$ wafer. X-ray diffraction (XRD) pattern, focused ion beam-field emission scanning electron microscopy (FIB-FESEM) and photoluminescence (PL) spectrometry were employed to observe and analyze the crystal properties, surface morphologies, and optical properties of the prepared ZnO seed layer and synthesized ZnO nanorods. $90^{\circ }$C and 60 min were used as the synthesis temperature and time, and we found that Zn(CH₃COO)₂ and C₆H${}_{12}$N₄ concentrations had an apparent effect on the height, diameter, total surface area, total volume, density, and PL property of ZnO nanorods. The maximum PL emission intensity of ZnO nanorods presented in the samples with Zn(CH₃COO)₂ and C₆H${}_{12}$N₄ concentrations of 0.2 M. The results of XRD patterns suggest that ZnO nanorods have the property of $c$-axis preferred orientation. We showed that the different Zn(CH₃COO)₂ concentrations had large effects on the average height, average diameter, aspect ratio, total surface area (S, nm${}^2)$, total volume (V, nm${}^3)$, S/V ratio, and PL property of ZnO nanorods.

This study aimed to use a simple, low-cost and eco-friendly microwave-assisted method for the synthesis of carbon dots-based fluorescent sensor that can detect more one target analyte in aqueous media. Herein, we report the synthesis of carbon dots (CDs) from peels of an indigenous and abundant wild fruit called wild medlar (Vangueria infausta). Functional groups such as hydroxyl (–OH) and carbonyl (C=O) were revealed on the surface of the as-prepared carbon dots using Fourier transform infrared spectroscopy (FTIR). The as-prepared CDs exhibited an amorphous structure and a broad distribution of particle size with an average size of 10 nm. In addition, the as-prepared CDs demonstrated excellent hydrophilicity and intense blue photoluminescence under UV light at 365 nm. The water-soluble CDs were employed for the detection of Al${}^{3+}$ using a ‘turn on’ mechanism and Hg${}^{2+}$ using a ‘turn off’ mechanism. Addition of increasing concentration of Al${}^{3+}$ resulted in an increase in the fluorescence intensity of the as-prepared CDs while addition of increasing concentration of Hg${}^{2+}$ resulted in quenching of the fluorescence intensity of CDs. The lowest limit of detection (LOD) for Al${}^{3+}$ and Hg${}^{2+}$ ions in aqueous media was determined at 817 nM and 612 nM, respectively. Furthermore, the as-prepared CDs have excellent selectivity towards Al${}^{3+}$ and Hg${}^{2+}$ among other potential metal ion interferences. Practical application of the as-prepared CDs towards detection of Al${}^{3+}$ and Hg${}^{2+}$ in tap water revealed good recovery rates of 86.0% to 87.4% and 96.4% to 106.5%, respectively. Therefore, this work has demonstrated a potent strategy for potential application of this nanoprobe towards dual detection of Al${}^{3+}$ and Hg${}^{2+}$ in aqueous samples.

The quest for the design and synthesis of carbon dots with anti-counterfeit properties that are derived via green, environmentally friendly and economical procedures is a continuous process. Carbon dots (C-dots) derived from biowaste are cheap to synthesize, possess good photo-stability and high synthetic yield, making them applicable in the anti-counterfeiting of currency. Herein, we report a novel eco-friendly, cheaper, and faster method for the synthesis of carbon dots with strong photoluminescence properties from monkey orange fruit (Strychnos spinosa) biowaste. The presence of the hydroxyl and carbonyl functional groups of the carbon dots were determined by the Fourier transform infrared spectroscopy (FTIR). The carbon dots showed strong blue emission fluorescence (emission wavelength of 452nm) when excited at 330nm. The morphology and size were determined by the atomic force microscopy (AFM) which indicated amorphous and spherical nanoparticles with an average size of less than 2nm. The no-crystallinity of the as-prepared carbon dots was confirmed using X-ray diffraction which showed the graphite-like structure. The carbon dots were produced and demonstrated good photo and chemical stability as well as high covert properties. The anti-counterfeiting of currency application by the synthesized carbon dots was demonstrated when the subsequent gel ink printed on the currency showed excellent chemical stability when exposed to washing with water, ethanol, and acetone. It also showed superior photostability when exposed to UV light at 365nm and daylight for an extended period of up to 6h. This work provides a facile, economical, and green approach for large scale production of carbon dots from the abundant biowaste.

We report here the weak quantum confinement effect in zinc oxide nanorods fabricated by a simple wet chemical method at room temperature. The formation of nanorods was confirmed through X-ray diffraction measurements. The particle size was also determined from the X-ray diffraction pattern and was found to be 20 nm. The band gap was calculated from the UV-Visible spectrum and found to be 3.72 eV, which is higher as compared to the bulk ZnO. It owes its value to the quantum confinement effect. However, the large particle size indicates that the confinement is weak in nature. The photoluminescence spectrum shows a strong emission peak at 421 nm accompanied by several much weaker defect related emissions in the visible region. Using the weak confinement model, we identified the transition levels for those emissions.

In this paper, Eu³⁺-doped CaTiO₃ (CTO) nanoparticles were prepared by a sol-gel method. Three different charge compensation mechanisms were realized by substituting Eu ion at different sites. (i) Ca site substitution with Ca vacancy compensation (CTO-A); (ii) Ti site substitution with O vacancy compensation (CTO-B); (iii) simultaneous substitution at both Ca and Ti sites with self-compensation (CTO-AB). Strongly related to the site substitution, the photoluminescent (PL) intensities were increasing in the sequence of CTO-B > CTO-AB > CTO-A. The absorbance spectra analysis of pure CTO nanoparticles showed absorption in the UV light region, while the absorption of Eu-doped CTO samples exhibited the blue shift owing to the presence of Eu³⁺. Moreover, the photocatalytic activities of samples for decomposing dyes were reverse to the sequence of PL intensities. The PL properties and photocatalytic activity of the Eu³⁺-doped CTO nanoparticles were thus discussed in detail from the viewpoints of the microstructures and charge transfer-related processes.

The intensive up-conversion (UC) photoluminescence and temperature sensing behavior of Er³⁺-doped Bi₇Ti₄NbO₂₁(BTN) ferroelectric ceramics prepared by a conventional solid-state reaction technique have been investigated. The X-ray diffraction and field emission scanning electron microscope analyses demonstrated that the Er³⁺-doped BTN ceramics are single phase and uniform flake-like structure. With the Er³⁺ ions doping, the intensive UC emission was observed without obviously changing the properties of ferroelectric. The optimal emission intensity was obtained when Er doping level was 15 mol.%. The temperature sensing behavior was studied by fluorescence intensity ratio (FIR) technique of two green UC emission bands, and the experimental data fitted very well with the function of temperature in a range of 133–573 K. It suggested that the Er³⁺-doped BTN ferroelectric ceramics are very good candidates for applications such as optical thermometry, electro-optical devices and bio-imaging ceramics.

Photochromic (PC) luminescent ferroelectric materials have aroused great interest because of their potential applications in optical information memories, optical switches and bio-imaging. However, those materials are basically opaque. In this work, we prepared a PC luminescent ${\text{K}}_{0.5}$${\text{Na}}_{0.5}$NbO₃-based ferroelectric transparent ceramic by modifying with ${\text{Eu}}^{3+}$, ${\text{Ba}}^{2+}$, ${\text{Ti}}^{4+}$ and ${\text{Sr}}^{2+}$, which not only have good optical transmittances ($\sim$60% at 900nm), moderate ferroelectric properties and down-conversion photoluminescence (PL) properties, but also exhibit reversible PC behavior. After the illumination by xenon lamp, the colors of the ceramics change from pale green to gray, and then reversibly recover to their initial state via thermal stimulus (200^∘C for 10min). Interestingly, both the optical transmittances and PL intensities can be effectively tailored by controlling the PC reaction process. The results suggest that the ferroelectric transparent ceramics are promising for the modulation of photoenergy and the design of optoelectronic devices.

Solid solutions of the lead-free 0.88(${\text{Na}}_{0.5}$${\text{Bi}}_{0.5})$TiO₃-0.12(${\text{Ba}}_{1-x}$${\text{Sm}}_x)$TiO₃ (NBT-BT: $x$Sm) ferroelectric ceramics were synthesized by solid state reaction. The doping of Sm promotes the structure of the ceramics to transform toward morphotropic phase boundary, and it decreases the grain size of the ceramics. With the increase of Sm content, the ferroelectric properties are improved gradually, where the ferroelectric polarization increases and the coercive field decreases. Sm doping induces a dielectric anomaly with obvious frequency dispersion at a low temperature, exhibiting the transition from the ferroelectric to relaxor state. Moreover, the photoluminescence spectra of NBT-BT:$x$Sm ceramics exhibit a strong orange emission upon blue light excitation of the 400nm to 500nm. The emission intensities are strongly dependent on the Sm doping concentration, which reached the optimal value as the doping concentration is 0.7%. These results suggest that the NBT-BT:$x$Sm ceramics may have significant technological promise in novel multifunctional devices.

The development of multifunctional materials with optical and electrical properties has become a research hotspot in recent years. In this work, multifunctional 0.935(Bi${}_{0.5}$Na${}_{0.5}$)TiO₃–0.065BaTiO₃ (BNT–BT)-based ferroelectric ceramics doped with small amounts of CaMAlO₄ ($\mathrm{\text{M}}=\mathrm{\text{Dy}}$, Ho) were prepared, and the effect of CaMAlO₄ on the electrostrain and photoluminescence properties of the ceramics was studied. The results showed that the CaMAlO₄ addition weakened the ferroelectric properties of the BNT–BT matrix, and promoted the improvement of the electrostrain performance. For samples doped with 1.5mol% CaMAlO₄, the unipolar strain $S_{\mathrm{\text{uni}}}$ reached the largest values, which were 0.33% ($\mathrm{\text{M}}=\mathrm{\text{Dy}}$) and 0.38% ($\mathrm{\text{M}}=\mathrm{\text{Ho}}$) under an electric field of 70kV/cm, corresponding to a large signal $d_{33}^{\ast }$ ($S_{max}∕E_{max}$) of 471pm/V ($\mathrm{\text{M}}=\mathrm{\text{Dy}}$) and 543pm/V ($\mathrm{\text{M}}=\mathrm{\text{Ho}}$), respectively. In addition, due to the existing Dy${}^{3+}$ and Ho${}^{3+}$ luminescent ions, the modified samples exhibited excellent photoluminescence performance, which exhibited bright yellow emission ($\mathrm{\text{M}}=\mathrm{\text{Dy}}$) and green emission $(\mathrm{\text{M }}=\mathrm{\text{Ho}})$ under the blue excitation. Due to their multifunctional features, these materials have potential applications as “on-off” actuators, optical-electro integration and coupling devices.

In this study, the effect of Zn doping on photoluminescence, Chromaticity and structural properties of Y₂O₃:Eu compound were studied. For this purpose, various Y₂O₃:Eu samples containing different Zn²⁺ concentration and distribution were prepared by combustion method. The resultant samples were characterized by X-ray diffractometry (XRD), Photoluminescence spectroscopy (PL) and scanning electron microscopy (SEM). The XRD patterns of samples were also examined by Rietveld refinement method and results showed that the samples had nano-sized crystallites. It has been also shown that doping of Zn²⁺ ion in structure of Y₂O₃:Eu compound can effectively enhance the PL intensity and chromaticity of Y₂O₃:Eu compound, while doping of Zn at surface of Y₂O₃:Eu powder reduces PL intensity, crystallinity and chromaticity of this compound.

The synthesis and properties of high luminescent thio-stabilized nanocrystals (NCs) in aqueous media was discussed in this paper. The sharp peaks of photoluminescence (PL) and full width at half-maximum (fwhm), were observed in the range of 50 to 70nm. The PH was 9 and the molar ratio of Cd to thiol (1:2.4) was constant during the experiment. The stabilized NCs through thioglycolic acid (TGA) show great luminosity in which the spectral of PL emission is variable with controlling the size of NCs. The size ranges of thioglycerol(TG) stabilized NCs and the spectral range of PL emission are more limited than TGA in the same condition. The concentration of thio-ligands and heating time are two factors that that will discuss in this paper to control the size of NCs.

For the first time, CeO₂ nanoparticles (NPs) were synthesized via green solution combustion method using Ocimum sanctum Linn (Tulsi) leaves extract as a reducing agent. The as-formed and calcined (500^∘C for 3h) CeO₂ NPs were characterized with different techniques. The Bragg reflections clearly indicate that the formation of cubic fluorite structure with crystallite size was found to be 10nm. The surface morphology of as-formed and calcined sample is made up of large number of irregular shaped NPs. However, agglomeration of the NPs is more in calcined sample. The estimated direct energy band gap from Tauc’s relation was found to be 2.92eV and 2.87eV for the as-formed and calcined sample, respectively. Photoluminescence spectra, CIE and CCT values clearly indicate that the present nanophosphor might find an application in display technology. Antifungal and anticancer studies show that CeO₂ NPs are noncytotoxic against fungus and cancerous cells. Whereas, electrochemical studies show that the synthesized CeO₂ NPs show redox peaks and pseudo capacitance and hence it finds importance in supercapacitor applications.