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We report on the fabrication of p-Si/n-CdO and p-Si/n-CdIn2O4 junction diodes using chemically prepared pure CdO and In 5–20 wt.%-doped CdO nanoparticles. The cadmium oxide (CdO) and indium-doped cadmium oxide (ICO) nanoparticles were characterized using x-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, energy dispersive analysis, high-resolution transmission electron microscopy (HRTEM), UV-Vis analysis, photoluminescence (PL) and electrical conductivity measurements. The strongest orientation along the (111) plane for CdO indicates a fcc crystal system. The average particle size of ICO nanoparticles vary from 26 nm to 41 nm. The FTIR bands for ICO samples at 508–511 cm−1 was strongly remodeled while increasing the doping concentration of In at 15 wt.%. HRTEM revealed a clear spherical morphology ~16.28 nm of average particle size for the ICO with 20 wt.% In. Moreover, a maximum electrical conductivity of 15.084 × 10−10 S cm−1 with higher transmittance range of about 76.11% was achieved. The photosensitivity of the p-Si/n-CdIn2O4 diode varied from 103 to 104 %. Also, high quantum efficiency ~225.92% and specific detectivity 5.1952×1011 Jones were found for p-Si/n-CdIn2O4 photodiode. These outcomes suggest that the developed p-Si/n-CdIn2O4 diode is suitable one in the fabrication of UV photodetector and solar cell devices for electronic communication. [ABSTRACT FROM AUTHOR]

Abstract: Nanocrystalline KHo(WO4)2 (KHW) particles were successfully synthesized via conventional Pechini sol–gel method. Prepared precursor gel was calcined at 250, 550, 600, 650 and 700°C, and the resulting samples were analyzed with TG–DTA, powder X-ray diffraction, FT-IR, Raman, FESEM, TEM, UV–Vis-NIR (diffuse reflectance spectrum (DRS)), fluorescence and vibrating sample magnetometer (VSM). Thermal degradation of derived gel was observed up to 400°C and phase formation starts from 550°C. The product phase formation at higher annealing temperature was investigated by means of powder XRD. Organic liberation in the samples with respect to temperature was analyzed using FT-IR spectrum. Raman spectrum reveals the formation of tungsten ribbons as well as the quality of the samples while increasing the calcination temperature. The nano size of the synthesized particles was confirmed with FESEM and TEM micrographs. Reflectance and emission studies reveal the corresponding absorption and emission properties of trivalent state holmium ion. Paramagnetic behavior of the derived KHW was confirmed with VSM results. [Copyright &y& Elsevier]

Abstract: Dysprosium (Dy) doped potassium gadolinium tungstate single crystals were grown by top seeded solution growth using K2WO4 as solvent. Two different concentrations of laser active ions were doped in the crystal. Crystals grown with lower growth rate using K2WO4 as solvent yielded better quality than that grown by K2W2O7 as solvent. Growth conditions, like cooling rate and the rotation rate were optimized. Absorption studies confirm dominant absorption peaks in the visible as well as in near infrared regions. Photoluminescence reveals a strong yellow emission for the doped samples and the emission intensity of 3% Dy doped sample is 1.4 times higher than that of 1% Dy concentration in KGW. Raman spectra indicate the characteristic vibrational modes corresponding to the tungstate anion. The intensity of peaks in Raman spectra are increased with increase in concentration of Dy, in addition to a slight shift in Raman frequency. [ABSTRACT FROM AUTHOR]

Development of p-SnS:NiS (80:20)/n-Si photodiode for optoelectronic devices. [Display omitted] • Development of p-SnS:NiS and bare p-NiS/n-Si photodetectors are reported. • Phase optimization of NiS and fabrication of SnS/NiS nanocomposite. • Morphology evolution of NiS and SnS/NiS was studied on oleic acid addition. • The value of photosensitivity improved from 75.0% to 2168.1%. • The value detectivity varied from 1.45 × 109 to 5.99 × 1010 jones. Synthesis of metal chalcogenides nanostructures is of profound importance in obtaining desired properties for photo-sensing device fabrication. The present proposed work concentrates on the effect of oleic acid in the preparation of NiS and SnS/NiS composites, and their photodiode properties were examined. Synthesized NiS and SnS/NiS nanosystem characterized by XRD analysis, Raman analysis, Field Emission Scanning Electron Microscopy micrographs. Hexagonal structure of NiS and hexagonal and orthorhombic composite structures SnS/NiS composite was confirmed with XRD patterns. The single-phase SnS nanoparticle and SnS/NiS nanocomposite were confirmed with Raman analysis. The change in morphology while increasing oleic acid on the preparation of NiS and SnS/NiS as aggregated quasi sphere structures were verified with FE-SEM micrographs. SnS/NiS fabricated with different ratios, and oleic acid-assisted NiS composite particles show better photo-response, which is essential for photodiode application. [ABSTRACT FROM AUTHOR]

Trivalent Neodymium doped CoFe 2 O 4 was investigated as the potent photocatalyst for wastewater treatment. The CoFe 2 O 4 and Nd-doped CoFe 2 O 4 with various concentrations, such as 5, 10, and 15%, were prepared to employ the sol-gel technique. Structural characterization of the synthesized materials was done by powder X-ray Diffraction and Raman studies. The optical UV–Visible spectroscopy provides the optical properties of CoFe 2 O 4 and Nd-doped CoFe 2 O 4 and the XPS spectra, which identify the constituting elements with their oxidation states, confirm the incorporation of Nd into the CoFe 2 O 4 lattice. SEM was performed to investigate their surface morphology, showing the self-assembled microstructures of CoFe 2 O 4. The dye degradation process was investigated for the synthesized samples with methylene blue dye using UV–Visible spectroscopy, which reveals the photocatalytic performance of pure CoFe 2 O 4 and Nd doped CoFe 2 O 4 by measuring the absorbance of methylene blue at the same interval of time. The 5% Nd doped CoFe 2 O 4 exhibits enhanced photocatalytic activity with a degradation efficiency of 72% within 4 h, which is higher than the pure sample. Outcomes indicates that the synthesized material can be useful in wastewater treatment. [ABSTRACT FROM AUTHOR]

Herein, we are presenting the synthesis of pure WO 3 nanoparticles (NPs) and WO 3 /NiWO 4 nanocomposites (NCs) with improved photocatalytic activities via a simple co-precipitation process. Structural, morphological, and compositional studies approved the synthesis of the nanocomposite. Furthermore, XPS analysis confirm the chemical composition and incorporation of Ni in the final products. The Scherrer equation used to determine the crystallite size and noticed that it reduced from 34 to 21 nm on Ni added in WO 3 and also FESEM study give the average grain size of NPs around 30 nm. HRTEM and SAED studies reveals the nanocomposite phase with lattice spacing of ~0.37 nm, and ~0.29 nm, which is perfectly matched with (020) of WO 3 and (111) of NiWO 4 , respectively. FTIR analysis reveals the functional groups of the formation of WO 3 /NiWO 4 NCs. Diffused reflectance spectroscopy was employed to determine the energy gap (E g) through Kubelka-Munk relation and noticed that the E g value is reduced from 2.61 to 2.49 eV. PL emission analysis was done under 280 nm excitation and possess the intense emission peaks at 361, 383, 412, and 492 nm, among them 383 nm is high intense, which is originated from near band edge transition. The photocatalytic degradation of Methylene blue (MB) dye was investigated under UV light. The percent degradation of MB dye was observed to be ~70.83%, 71.88%, 76.39%, 86.81% and 90.63% for pure WO 3 , 5 wt% Ni, 10 wt% Ni, 15 wt% Ni and 20 wt% Ni nanocomposites, respectively. The maximum percent photodegradation of MB dye has been done ∼90.63% for 20 wt% Ni within 80 min of duration. These outcomes revealed that the prepared WO 3 /NiWO 4 NCs will be highly applicable for hazardous MB dye degradation. BET analysis, pseudo-first-order kinetic plot for photo-degradation of MB solution and elemental trapping experiment. [Display omitted] • Facile synthesis of novel WO 3 and WO 3 /NiWO 4 nanocomposites was attained via low-cost co-precipitation method. • XRD, XPS & EDX analyses confirm the synthesis of WO 3 and WO 3 /NiWO 4 nanocomposite. • TEM/HRTEM/SAED analyses confirm low dimension spherical NPs synthesis. • Energy gap systematically reduced from 2.61 to 2.49 eV on increasing the Ni concentrations in WO 3. • Highest photocatalytic degradation of MB dye was noticed for 20% Ni (WO 3 /NiWO 4) specimen. [ABSTRACT FROM AUTHOR]

In this work, pure tungsten oxide (WO 3) nanoparticles (NPs) and WO 3 /CoWO 4 nanocomposites (NCs) with various cobalt concentrations from 5 to 20 wt% were prepared via a co-precipitation process and subsequent annealing at 600 °C. All the synthesized samples were characterized by different techniques to study their structural, morphological, elemental, and optical properties and also to verify the conversion of WO 3 NPs to WO 3 /CoWO 4 NCs. X-ray diffraction results confirmed the existence of a stable monoclinic phase for pure WO 3 NPs and that no phase change occurs even after the formation of CoWO 4. The average crystallite sizes calculated for pure WO 3 NPs and 20 wt% WO 3 /CoWO 4 NCs were approximately 34 and 17 nm, respectively. Field-emission scanning electron microscopy revealed that pure WO 3 consists of nanoparticles as well as some nanoplates of size in the 30 nm diameter range. On Co doping of WO 3 , the size seems decrease and reveals very small NPs of size below 20 nm. Energy-dispersive X-ray spectroscopy spectra showed the persistence of chemical elements and their amount before and after the inclusion of cobalt. The chemical composition and the oxidation state of the elements on the surface of the synthesized NPs and NCs were investigated by X-ray photoelectron spectroscopy. The type of functional groups and their corresponding vibrational modes were identified by Fourier transform infrared spectroscopy. UV–visible studies were used to calculate the bandgap (E g) of pure WO 3 NPs and WO 3 /CoWO 4 NCs by means of Kubelka-Munk function plots. There was a reduction in E g from 2.61 eV for pure WO 3 NPs to 2.51 eV for 20 wt% Co NCs. In photoluminescence studies, the intensity of the emission peaks of WO 3 /CoWO 4 NCs showed a decreasing trend in comparison with pure WO 3 NPs. The formation of WO 3 /CoWO 4 NCs effectively controls the charge carrier (electron-hole) recombination. Hence, an appreciable enhancement in the photocatalytic degradation of the toxic dye methylene blue (C 16 H 18 N 3 SCl) of up to 86.5% was accomplished with WO 3 /CoWO 4 NCs (20 wt% Co sample) under irradiation with a UV-A light source. Toxic dye degradation profile of the prepared nanocomposites and proposed mechanism of dye degradation. [Display omitted] • A facile and low-cost co-precipitation method was used to prepare WO 3 nanoparticles and WO 3 /CoWO 4 nanocomposites. • Structural and compositional analyses proved the synthesis of WO 3 and WO 3 /CoWO 4 nanocomposites. • Small nanoparticles was proved via high-resolution transmission electron microscopy, and selected-area electron diffraction analysis. • A reduction in the band gap from 2.61 to 2.51 eV was found on Co doping of WO 3. • Higher photocatalytic activity for degradation of harmful methylene blue was found for WO 3 /CoWO 4. [ABSTRACT FROM AUTHOR]