Abstract: In this article, isolated percolative Cu-doped NiO nanoflakes were manufactured through an advanced chemical synthesis method. The powder materials were sintered at 300 °C, 350 °C, and 400 °C to pursue the effectuation of phase and band gap adaptation from X-ray diffractometry, Fourier Transform Infrared spectroscopy, and Raman spectroscopy. The optical study for nanoparticles was effectuated by Ultraviolet–Visible spectrophotometer, and Photoluminescence spectroscopy confirm the quantum confinement effect. Morphology and elemental conformation were surveyed by Field Emission Scanning Electron Microscope, High-Resolution Transmission Electron Microscope, and Energy Dispersive X-ray depiction and confirmed the nanostructure of our sample. The frequency and temperature dependence dielectric constant, loss tangent (tanδ), ac conductivity (σac); and the Nyquist plot were also premeditated. Finally, the larger ionic radii and higher valency of the dopant yields a subsequently high dielectric constant and ac conductivity along with low loss paving the empowerment of Cu-impregnated NiO nanoparticles in optoelectrical automation.

Abstract: Bi(Zn1/2Nb2/5)O3-modified BaTiO3 ceramics were designed with formula (1‒x)BaTiO3‒xBi(Zn1/2Nb2/5)O3 (0 ≤ x ≤ 0.15) and fabricated using conventional solid-state route. With increasing Bi(Zn1/2Nb2/5)O3 concentration, grain volume increased and phase structure was transformed from tetragonal to pseudo-cubic. Dielectric properties changed from temperature-dependent to temperature-insensitive and curves were flattened. Additionally, higher pseudo-cubic phase content induced slim P-E loop and low Pr. Therefore, 0.94BaTiO3‒0.06Bi(Zn1/2Nb2/5)O3 ceramic achieved energy storage density of 1.85 J/cm3 and high energy efficiency of 91.2% under electric field of 230 kV/cm. This energy storage density was 5 times higher than that of pure BT ceramic. Meanwhile, energy storage properties of this ceramic exhibited excellent thermal stability in the range of 30–120 °C and good frequency stability over 10–100 Hz. This work provides promising alternative option in energy storage materials.

Abstract: Herein, a CuS/CoS electrode material was synthesized using a one-step hydrothermal method as an efficient electrocatalyst for a non-enzymatic glucose sensor. The nanocomposites were characterized by Field emission scanning electron microscope (FE-SEM), Transmission electron microscope (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The CuS/CoS composite loaded glassy carbon electrode was used to investigate electrochemical properties using cyclic voltammetry (CV) and chronoamperometry (CA). The results showed 314.85 μA mM−1 cm−2 sensitivity and 1.71 μM detection limit. Selectivity of the sensor was examined over potential interfering species that exhibits the distinct increased current response on addition of glucose before and after addition of interfering species evident the selectivity of CuS/CoS electrode material. Moreover, the CuS/CoS composite-based non-enzymatic glucose sensor revealed considerable stability, selectivity over interfering species, and viability for glucose determination in diluted human serum samples, which provide efficient and cost-effective strategy to develop non-enzymatic electrochemical glucose sensing platform.

Abstract: Optical thermometry based on the fluorescence intensity ratio technology between the thermally coupled energy levels of Er3+ has become a research hotspot, but it is often limited by excitation conditions, which reduces its universality and reliability. In this work, Nd3+/Yb3+/Er3+ triply-doped LaNbO4 phosphor with excellent up-conversion (UC) luminescence characteristic and reliable temperature sensing sensitivity has been prepared by solid-state reaction method. Intense green and weak red UC emissions were gained under 808 nm and 980 nm excitations. The temperature dependent UC luminescence property and temperature sensing behavior of the sample has been investigated. The results demonstrated that the intensity ratio of the two green emissions was insensitive to the excitation wavelength and pumping power of the lasers, and the maximum absolute sensitivity was derived to be 0.91 % K−1 at 481 K. This work provides a new material with reliable and high temperature sensing sensitivity for optical thermometers.

Abstract: This study investigated the structural and luminescent properties of rare earth (RE) ion (RE = Eu3+, Dy3+, and Er3+)-doped ASnO3 (ASnO3:RE), where A = Ca, Sr, and Ba. X-ray diffraction and Rietveld refinement analyses revealed that the lattice structures for A = Ca, Sr, and Ba were orthorhombic, pseudo-cubic, and cubic, respectively. As for the luminescent properties, the emission characteristic of each RE ion was clearly identified in our samples. Interestingly, it was commonly observed for all three RE ions that the emission intensities of the three RE ions were strongest and weakest in CaSnO3:RE and BaSnO3:RE, respectively. These results suggest the close relations of the luminescence properties of RE ions with the structural symmetry of the host material, ASnO3. In addition, the electronic structure and lattice dynamics of ASnO3:RE were investigated through theoretical calculations and optical measurements. The findings of this study provide important insights into the properties of RE ion-doped ASnO3 materials and their potential applications in optoelectronic devices.

Abstract: A series of Zr4+ doped MgFe2O4 samples (Mg1-xFe2O4: xZr (x = 0, 0.25, 0.5, 0.75, 1, 1.25 and 1.5 mol %) were synthesized using the solid-state reaction method. The XRD analysis confirms that the prepared sample has single phase cubic spinel structure with Fd-3m space group. The average crystallite size of the sample has been found to be 28.2 nm. The SEM image shows irregular cubical grains with agglomerated morphology, while the EDX spectrum confirms the presence of all essential elements. The dielectric constant and dielectric loss decrease at higher frequencies due to decreased polarization. The Complex impedance spectroscopy confirmed the existence of electrical relaxation phenomenon, and the Cole-Cole plot indicates the grain boundary contribution. The AC conductivity value remains constant at a low frequency range but shifts towards the higher value in the higher frequency region. The calculated activation energy values range from 0.27 to 0.55 eV.

Abstract: Transparent, Eu3+ doped potassium tungstate tellurite (TKWZBiEu) glass matrices were successfully synthesized via employing the traditional melt quenching method and their thermal, structural and photoluminescent characteristics were thoroughly investigated. To estimate the aggregate weight loss, glass transition temperature (Tg) and thermal stability factor (ΔT) of the prepared host glass matrix, thermogravimetric analysis-differential scanning calorimetry (TGA-DSC) were utilized. The non-crystalline character of the prepared TKWZBiEu glass was studied via XRD profile. Various vibrational functional groups were revealed via employing Fourier transform infrared (FT-IR) spectroscopy. The optical bandgap (Eopt) values for all prepared TKWZBiEu glasses have been evaluated by employing the absorption spectra. Under n-UV and blue excitations, all the prepared TKWZBiEu glasses are demonstrating reddish emission at 614 nm ascribed to the 5D0 → 7F2 transition, in which the intensity is increasing continuously with Eu3+ ion content up to 5.0 mol%. The experimental lifetime (τ) profiles demonstrate the single-exponential nature of prepared TKWZBiEu glasses under n-UV excitation. Furthermore, temperature dependent photoluminescence (TDPL) spectra indicate excellent thermal stability of the TKWZBiEu glass matrix with the highest value of activation energy (ΔE). The prototype organic epoxy resin/binder-free device has been developed using the 5.0 mol% Eu3+ doped with TKWZBi glass matrix and n-UV LED chip. All the aforementioned findings validate that the optimized TKWZBiEu glass is an auspicious candidate for the red component to fabricate organic epoxy-free w-LEDs.

Abstract: In this paper, zinc oxide (ZnO) thin films and Al-doped zinc oxide (AZO) films are prepared. The XRD results show that the addition of Al ions at the middle stage of AZO film (ms-AZO) preparation can increase the grain size and change the preferential growth orientation from (100) crystal plane to (002) crystal plane. The results of UV-VIS spectra show that the addition of Al ions at the ms-AZO preparation can greatly increase the absorption intensity in the visible light region, and the addition of Al ions at the early stage of AZO film (es-AZO) preparation can make the blue shift of the ultraviolet absorption edge. The patterns of I–V curves show that the addition of Al ions can increase the forward current of AZO/Si heterojunction, comparing to that of ZnO/Si heterojunction. Furthermore, the leakage current mechanism may dominate the carrier transport.