Structural changes of cerium doped copper ferrites during sintering process and magneto-electrical properties assessment

Crystalline CuCe_xFe_2-xO₄ nanoparticles with different rare earth metal content (x = 0.00, 0.03, 0.05, 0.08 and 0.10) were synthesized using a co-precipitation technique that involves a 600 °C calcination treatment. The newly obtained powders were pressed into pellets and heated up to 950 °C in order to form a compact and less porous material, ideal for dielectric measurements. X-ray investigations revealed a structural modification from typical cubic system to a tetrahedral spinel form, accompanied by Ce³⁺ cations exclusion and formation of secondary phases. The amount of phases and cations distribution were determined by Rietveld refinement method. A degradation process of cerium doped copper ferrite was proposed based on X-ray analysis and Rietveld refinement. Furthermore, the magnetic behavior of both 600 °C and 950 °C samples was investigated from the hysteresis loops recorded from a vibrating sample magnetometer (VSM) in a ±10 kOe range. Room temperature dielectric values for the 950 °C samples were determined using the parallel-plate capacitor configuration in a frequency range of 10 Hz – 1 MHz.     

Synthesis and photocatalytic properties of layered intercalated materials HTaWO6/(Pt,Cd0.8Zn0.2S)

HTaWO₆/(Pt, Cd_0.8Zn_0.2S) was fabricated by successive intercalation reactions. The intercalation material shows a broad reflection over 300–580 nm and possess excellent photocatalytic capability under the irradiation of visible light. The photocatalytic activity of HTaWO₆/Cd_0.8Zn_0.2S is superior to that of unsupported Cd_0.8Zn_0.2S and is enhanced by co-incorporation of Pt.     

Enhanced opto-electronic properties of X-doped (X = Al,Ga, and In) CuO thin films for photodetector applications

Recent trends in optoelectronics still need a highly efficient photodetector based on p-type metal oxide semiconductors. This work stands with the improvement in the performance of CuO thin films via doping with different metals into the thin films. The CuO thin films were successfully doped with 1 wt% of X (X?=?Al, Ga, and In) by spray pyrolysis method. The prepared doped CuO thin films were characterized to interpret the structural, morphological, and elemental characteristics using advanced techniques. These doped CuO thin films were subjected to study the photodetection ability by analyzing optoelectronic properties. The doping also tuned the optical and electrical properties. Among the fabricated photodetectors, the Al-doped CuO detector shows a maximum photocurrent. The CuO:Al (1.0%) thin film exhibits a high photocurrent of 2.59 × 10^?6 A, the responsivity of 2.82 × 10^??1 AW^??1, the external quantum efficiency of 66%, and the detectivity of 1.45 × 10¹⁰ Jones. Compared to the other thin films, Al doping has remarkably reduced the bandgap and shows a good photosensing activity that may be due to an increase in charge carriers. These outcomes provide a way to assemble good photodetectors and tune their properties in a wide range.

     

CAN catalyzed synthesis of β-amino carbonyl compounds via Mannich reaction in PEG

Ceric ammonium nitrate (CAN) in PEG was used as an efficient and recyclable solvent system for one pot, three component Mannich reaction of acetophenone with aromatic aldehydes and aromatic amines. This protocol has advantages of high yield, mild reaction conditions, no environmental pollution and simple work up procedure.     

Building organic assemblies with 2-pyridone and dicarboxylic acids: relating molecular conformation and synthon stability to crystal structure

The syntheses and crystal structures of five cocrystals; 2-pyridone oxalic acid (2/1), 2-pyridone succinic acid (2/1), 2-pyridone adipic acid (2/1) dihydrate, 2-pyridone suberic acid (2/1), and 2-pyridone sebacic acid (2/1), are reported. The competition between two similar self-complementary hydrogen-bonded synthons (carboxylic acid and 2-pyridone) are examined systematically in this series of cocrystals. In each case, the crystal structure contains planar dimers of 2-pyridone which are bridged by a dicarboxylic acid via a combination of C–H ⋯ O and O–H ⋯ O hydrogen bonds to generate infinite 1-D ribbons. The orientation of these ribbons is determined by changes in molecular shape and conformational flexibility of the dicarboxylic acid.     

A noticeable effect of Pr doping on key optoelectrical properties of CdS thin films prepared using spray pyrolysis technique for high-performance photodetector applications

High-quality thin film-based photodetectors containing praseodymium doped cadmium sulfide (Pr:CdS) were fabricated through spray pyrolysis and studied for various opto-electrical applications. Field emission electron microscopy (FE-SEM) revealed that the prepared films were highly compacted with an extremely fine nanostructure without any pinhole or crack. X-ray diffraction and FT-Raman spectroscopy studies confirmed the single hexagonal phase of all the films. The crystallite size was found to lie between 19 and 32 nm. Optical spectroscopy revealed that the fabricated films have low absorbance and high transmittance (in range of 70–80%). The energy gap was found to lie in the range of 2.40–2.44 eV. The PL spectra contained an intense green emission band at ~531 ± 5 nm (2.33 eV), and its intensity was enhanced by increasing the Pr doping content in CdS. The dark and photo currents of CdS increased by approximately 950 and 42 times, respectively with the addition of 5.0 wt% Pr. The responsivity (R) and specific detectivity (D*) were remarkably enhanced to 2.71 AW^-1 and 6.9 × 10¹¹ Jones, respectively, for the 5.0 wt% Pr:CdS film. The external quantum efficiency (EQE) of 5 wt% Pr:CdS films was 43 times that of pure CdS films, and the on/off ratio was 3.95 × 10² for 5.0 wt% Pr:CdS film. Its high R, D*, and EQE values, and photo-switching behavior make Pr:CdS a good contender for high quality photodetector applications.     

Synergistic effect of La+Mo addition and optimum pH on the photocatalytic dye decomposition efficiency of spray pyrolyzed ZnO thin films

This work explores the photocatalytic degradation efficiency of lanthanum (La) and molybdenum (Mo) incorporated ZnO films deposited by nebulizer spray pyrolysis onto glass slides. The influence of La and (La + Mo) doping on certain physical properties was investigated. Photocatalytic behavior of the films was studied against methyl orange (MO) and methylene blue (MB) dyes. The impacts of dye adsorption, point of zero charge, and dye solution pH on the catalytic activity of ZnO:La:Mo films were probed and compared with those of their counterparts ZnO and ZnO:La thin films. The obtained results demonstrated that ZnO:La:Mo photocatalyst exhibited greater efficiency, reaching 98% and 85% degradation after 60 min for the cationic and anionic dyes, respectively for optimum pH. The degradation reactions follow the first-order kinetics and the rate of degradation increases by adding La and (La + Mo) to ZnO. The ZnO:La:Mo thin film exhibits excellent recyclability and stability even after five runs. A possible photocatalytic mechanism has also been proposed.     

Band gap tailoring,structural and morphological behavior of Zn0.96−x Co0.04Cu x O (0 ≤ x ≤ 0.10) alloys by sol–gel method

Zn_0.96?x Co_0.04Cu _x O (0 ≤ x ≤ 0.1) nanopowders were successfully synthesized by sol–gel method. Hexagonal structure was confirmed by X-ray diffraction spectra. A new phase around 38.4° corresponding to CuO was noticed after Cu = 4 %. The reduced crystal size up to Cu = 4 % is due to the substitution of Cu²⁺ and the increasing crystal size after Cu = 4 % is due to the interference between Co and Cu metal ions. The higher absorption of Cu doped Zn_0.96Co_0.04O than undoped was due to the created charge carries. The tuning of energy gap from 3.18 to 3.69 eV by Cu-doping was discussed in terms of crystal size, the created charge carriers and the interstitial zinc atoms and oxygen deficiencies. Presence of chemical bonding and purity of the nanopowders were confirmed by Fourier transform infrared spectra.     

Synthesis and characterization of N-[4-(chlorocarbonyl)phenyl]maleimide functionalized graphene oxide and reduced graphene oxide

Functionalization of graphene oxide leads improvement in thermal stability and flame retardancy. Acid chloride terminated N-[4-(chlorocarbonyl)phenyl]maleimide (Cl-CPMI) was synthesized to decorate hydroxyl group in graphene oxide (GEO) and glycine-reduced GEO (RGEO). Structural characterization of the materials was performed using FTIR, ¹³C NMR and Raman spectroscopic methods. Interlayer distance and surface morphology were also studied using X-ray diffraction and scanning electron microscopic methods, respectively. The absence of the band for C-Cl and shortening of the O-H band in the FTIR and peak in ¹³C NMR spectra confirm the functionalization of alcoholic group on the graphitic plane with Cl-CPMI. The ratio, I_D/I_G computed from Raman study, the nature of XRD pattern and interlayer distance between the adjacent graphitic layers were not affected by the functionalization of GEO and RGEO using Cl-CPMI. The tagging of maleimide unit with the graphitic plane was also confirmed by the cloudy appearance in the SEM images.