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This article focuses on structural, optical, magnetic, and dielectric behavior of Ni-substituted CeO 2 quantum dots synthesized by efficient chemical precipitation technique. Synthesized nanopowders were analyzed by XRD, FESEM, TEM, FT-IR, UV, PL, dielectric, electrochemical, and magnetic behavior. X-ray diffraction technique stipulated the nanopowders that exhibit FCC structure and don't have any unwanted phases. FESEM and TEM analyses showed that the particles are in the nanometer range and the microstructure alternation evidenced from spherical to the nanorods. The functional group and compositional study confirmed the substitution of Ni within CeO 2 . The UV–Vis absorption spectrum approved the blue shift in absorption and increase in bandgap from 3.39 to 4.20 eV. The photoluminescence study confirmed the strong blue emission with the increase of Ni concentration. VSM analysis demonstrated that the Ni-doped CeO 2 quantum dots are ferromagnetic nature and the magnetization increased. The electrochemical analysis confirmed the increase of supercapacitance property of CeO 2 nanoparticles with Ni at a low scan rate. The dielectric analysis suggested that the CeO 2 : Ni can be utilized for the capacitor application.

In the present work, pure and copper composite zirconium oxide nanoparticles with a different percentages of copper (0.02, 0.04, 0.06 and 0.08%) were successfully synthesized by a low cost sol–gel technique. It was found that as-prepared samples of copper-composite (zirconium oxide) ZrO 2 nanoparticles are in monoclinic phase. The copper-doped zirconium oxide (ZrO 2 ) NPs are present as spherical morphology and highly agglomeration confirmed by scanning electron microscopy and high resolution transmission electron microscope analyses. The synthesis samples exhibited two bandgap energy at 3.6 eV and 2.6 eV, 3.57 eV and 2.4 eV, 3.55 eV and 2.14 eV, and 3.5 eV and 2.1 eV. The presence of functional groups and the chemical bonding is confirmed by FT-IR spectra. PL spectra of the pure and Cu-doped ZrO 2 nanoparticles exhibited oxygen vacancies. Voltage–current characteristics of pure and composite ZrO 2 nanoparticles are studied at vary incident light intensity that show the negative photoconductivity.

In this paper, we report that hafnium oxide nanoparticles with different copper contents (0.00, 0.02, 0.04, and 0.06%) are successfully synthesized by sol–gel technique. The influence of the copper concentration and observed the morphological and structural changes of the obtained nanoparticles. For characterization, XRD observed that the crystalline structure depends on the doping content. The synthesis samples are undoped hafnium and copper-doped hafnium oxide nanoparticles, which crystallographic change from cubic to monoclinic phase with increasing doping concentration. The presence of Hf, Cu, and O in the synthesis sample was confirmed by EDS analysis. Energy gaps of the synthesized samples were estimated from the ultraviolet–visible absorption spectrum as well as Tauc’s plot which infers that the energy gap decreases with the increase of Cu content. Fourier transform infrared spectrum confirms the cadmium dopant through peak shifting from 538 to 650 cm −1 . PL showed an emission peak at 360 nm that strongly confirmed the UV region and intensity of emission peak increase with increase dopant. SEM and TEM study reveal that the synthesized samples consist of spherical morphology and the particle size varies between 34 and 43 nm. The electrical resistivity decreases from 28 to 16Ω with doping content increasing which indicates that the conductivity of the nanomaterial is improved.

The present study discusses the synthesis and characterization of Co-doped CeO 2 quantum dots obtained via the chemical precipitation technique. The crystalline nature, optical properties, nanostructure, and magnetic behavior of the prepared samples have been investigated using various experimental techniques. The face-centered cubic structure of the Co-doped CeO 2 quantum dots was demonstrated by the structural confirmation. The crystallite size was observed to decrease from 10.11 to 5.84 nm when the cobalt dopant concentration increased from 0 to 6%. Optical analysis revealed a significant blue shift in the UV absorption spectrum from 246 to 220 nm, resulting in a bandgap increase from 5.04 to 5.64 eV. The photoluminescence analysis indicates that the added Co dopant decreased the emission intensity. The peak shift from 512 to 532 cm −1 in Fourier transform infrared spectra confirmed the cobalt ion doping. The displacement of the Raman peak from 462 to 441 cm −1 further confirmed the space group Fm 3 ¯ m of CeO 2 . TEM images revealed that the CeO 2 samples without Co were spherical, but those with Co were nanorods. Energy-dispersive x-ray spectrum and x-ray photoelectron spectra confirmed the Co dopant. The vibrating sample magnetometer study confirmed the magnetic transition from weak to strong ferromagnetic transition due to Co dopant. Electron spin resonance spectra established the ferromagnetic character of undoped and Co-doped cerium oxide quantum dots.

This work reports the synthesis and characterization of Sr doped ZnO nanoneedles prepared by the chemical precipitation method. Studying the outcome of Sr doping on crystallite size, microstructure, optical and magnetic properties, synthesized nanoparticles were examined by using an x-ray diffractometer, a vibrating sample magnetometer, an ultraviolet–visible spectrometer, a field emission scanning electron microscope, and a photoluminescence spectrometer. The XRD investigation confirmed the increase in average crystallite size from 16 to 33 nm with the increase in Sr content up to 5% and then decreased to 26.23 for 10% of Sr content. The UV–Vis spectra confirmed the bandgap variation from 3.53 to 3.33 eV with Sr doping. FTIR spectra confirmed the substitution of Sr in ZnO through the slight shift of vibrational bonds at 570 cm −1 towards the higher wavenumber. UV emission at 395 nm observed in PL spectra confirmed the formation of ZnO nanoparticles. A microstructural analysis established the morphology transformation from nanoflakes to nanoneedles at a higher amount of Sr. Magnetization behaviour confirmed the weak ferromagnetism in undoped and Sr doped ZnO nanoparticles. The saturation magnetization, retentivity, and coercive field of 3% Sr doped ZnO are 0.30 emu g −1 , 0.034 emu g −1 , and 0.064 T, correspondingly. The enhancement of coercivity and magnetization is attributable to the replacement of Zn 2+ by Sr ions. A cyclic voltammetry study suggested that Sr doped ZnO nanoflakes may be a promising substantial electrode for supercapacitor development.