Search

Nanocomposites of 20% and 30% Co-doped Ni/NiO were synthesized using a microwave-assisted sol-gel auto-combustion method. The 30% Co-doped Ni/NiO nanocomposite exhibited negative magnetoresistance (M-R) at various temperatures, including 2 K, 10 K, 80 K, 100 K, and 250 K. This behavior is interpreted as indicative of a Kondo-like scattering effect. The resistivity ρ ( T ) upturn observed at low temperatures in the 30% Co-doped Ni/NiO nanocomposite can be accurately described by a power series equation combined with a Kondo term. Furthermore, this sample demonstrated a metal-insulator transition around the Kondo temperature T ≈ 29.8(5) K, with noticeable resistivity changes at magnetic fields of 0 T, 1 T, 5 T, and 8 T. Additionally, a hump in resistivity at approximately 212 K, 170 K, 243 K, 251 K, and 209 K for magnetic fields of 0 T, 0.05 T, 1 T, 5 T, and 8 T, respectively, is attributed to the charge ordering of Co K ≈ 29.8(5) K, with noticeable resistivity changes at magnetic fields of 0 T, 1 T, 5 T, and 8 T. Additionally, a hump in resistivity at approximately 212 K, 170 K, 243 K, 251 K, and 209 K for magnetic fields of 0 T, 0.05 T, 1 T, 5 T, and 8 T, respectively, is attributed to the charge ordering of Co 3+ and Co 4+ ions within the Ni/NiO lattice, contributing to a further metal-insulator transition., Competing Interests: The author declares no competing interests., (This journal is © The Royal Society of Chemistry.)

In this study, we explored the gas-sensing capabilities of MoS 2 petaloid nanosheets in the metallic 1T phase with the commonly investigated semiconducting 2H phase. By synthesizing SnS 2 nanoparticles and MoS 2 petaloid nanosheets through a hydrothermal method, we achieve notable sensing performance for NO 2 gas at room temperature (27 °C). This investigation represents a novel study, and to the best of our knowledge no, prior similar investigations have been reported in the literature for 1T@2HMoS 2 /SnS 2 heterostructures for room temperature NO 2 gas sensing. The formed heterostructure between SnS 2 nanoparticles and petaloid MoS 2 nanosheets exhibits synergistic effects, offering highly active sites for NO 2 gas adsorption, consequently enhancing sensor response. Our sensor demonstrated a remarkable sensing response ( R a / R , rapid response time of 54 s, baseline recovery in 345 s, good selectivity and long-term stability, underscoring its potential for practical gas-sensing applications.g = 7.49) towards 1 ppm of NO 2 , rapid response time of 54 s, baseline recovery in 345 s, good selectivity and long-term stability, underscoring its potential for practical gas-sensing applications., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

The development of better electrode materials for lithium-ion batteries has been intensively investigated both due to their fundamental scientific aspects as well as their usefulness in technological applications. The present technological development of rechargeable batteries is hindered by fundamental challenges, such as low energy and power density, short lifespan, and sluggish charge transport kinetics. Among the various anode materials proposed, heterosite FePO 4 (h-FP) has been found to intercalate lithium and sodium ion hosts to obtain novel rechargeable batteries. The h-FP has been obtained via the delithiation of triphylite LiFePO 4 (LFP), and its structural and electronic properties have been investigated with different crystallite sizes. The synchrotron XRD measurements followed by Rietveld refinement analysis reveal lattice expansion upon the reduction of crystallite size of h-FP. In addition, the decrease in the crystallite size enhances surface energy contributions, thereby creating more oxygen vacancies up to 2% for 21 nm crystallite size. The expansion in the lattice parameters is reflected in the vibrational properties of the h-FP structure, where the red-shift has been observed in the characteristic modes upon the reduction of crystallite size. The local environment of the transition metal ion and its bonding characteristics have been elucidated through soft X-ray absorption spectroscopy (XAS) with the effect of crystallite size. XAS unequivocally reveals the valence state of iron 3d electrons near the Fermi level, which is susceptible to local lattice distortion and uncovers the detailed information on the evolution of electronic states with crystallite size. The observed local lattice distortion has been considered to be as a result of the decrease in the level of covalency between the Fe-3d and O-2p states. Further, we demonstrate the structural advantages of nanosized h-FP on the transport properties, where an enhancement in the polaronic conductivity with decreasing crystallite size has been observed. The polaronic conduction mechanism has been analyzed and discussed on the basis of the Mott model of polaron conduction along with an insightful analysis on the role of the electronic structure. The present study provides spectroscopic results on the anode material that reveal the evolution of electronic states for fingerprinting, understanding, and optimizing it for advanced rechargeable battery operations., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The present finding illuminates the physics of the formation of interfaces of metal based hetero-structures near layer continuous limit as an approach to develop high-efficiency W/B 4 C multilayer (ML) optics with ML periodicity varying d = 1.86-1.23 nm at a fixed number of layer pairs N = 400. The microstructure of metal layers is tailored near the onset of grain growth to control the surface density of grains resulting in small average sizes of grains to sub-nanometers. This generates concurrently desirable atomically sharp interfaces, high optical contrast, and desirable stress properties over a large number of periods, which have evidence through the developed ML optics. We demonstrate significantly high reflectivities of ML optics measured in the energy range 10-20 keV, except for d = 1.23 nm due to quasi-continuous layers. The reflectivities at soft gamma-rays are predicted., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

This paper manifests an A 3 -coupling strategy assisted by novel hydromagnesite sheets impregnated with cobalt ferrite (CoFe 2 O 4 -HMS) magnetic nanoparticles (MNPs) as an environmentally benign nanocomposite to synthesize imidazo[1,2- a ]pyridine scaffolds under ultrasonication. The synthesis of these biologically active derivatives was achieved through A 3 -coupling employing 2-aminopyridines derivatives, pertinent aryl aldehydes, and phenylacetylene in the presence of polyethylene glycol 400 (PEG 400) as a green solvent under aerobic conditions. Based on its high product yield (up to 94%) in a short reaction time, with a modest catalyst loading, excellent catalyst, and solvent recyclability without substantial loss of operation (up to five synthetic cycles), as demonstrated by the high ecological compatibility and sustainability factors, this strategy follows the principles of green chemistry. The synthesized nanocomposite was characterized via several spectroanalytical techniques, including PXRD, FE-SEM, HR-TEM, EDAX, ICP-AES, FT-IR, Raman spectroscopy, CO 2 -TPD, TGA-DTA-DTG analyses, magnetic studies, and nitrogen porosimetry. Furthermore, the structures of synthesized compounds were confirmed based on FT-IR, 1 H NMR, 13 C NMR, mass spectroscopy, and elemental analysis data., Competing Interests: The authors declare no conflicts of interest., (This journal is © The Royal Society of Chemistry.)

Li + incorporated tunable Y 2 O 3 :Eu 3+ red-emitting nanophosphors were synthesized using a wet chemical method. The effect of Li + on structural and luminescence properties of the nanophosphors were studied in detail. The structural results exhibited that nanophosphors have a body-centered cubic (I) phase with point group symmetry m 3̄. No additional impurity peaks were observed within the range of the XRD pattern due to the Li + ion. FTIR spectra reveal the formation of the pure and crystalline structure of the nanophosphors. TEM results show the prepared nanophosphors were highly crystalline and polycrystalline in nature. PL studies show the highly enhanced emission band due to the flux effect, greatly improved crystallinity caused by the Li + ion, and the different excitation wavelengths. The most intense luminescence band was observed at 612 nm for red emission ascribed to the 5 D 0 → 7 F 2 transition of Eu 3+ ion upon 254, 393, and 465 nm excitations in the C 3i and C 2 symmetry site of Y 2 ions. The chromaticity color coordinates, CCT values, were tuned in the red region of the color space. Hence, the results indicate that the prepared nanophosphor can be used as a red component to construct the white light for light-emitting diode applications.3 respectively. The highly enhanced emission band was observed under excitation at 254 nm and is 6.9 and 3.67 times higher than the emission band excited at 393 and 466 nm, respectively. The average lifetime also varies with different concentrations of Li + ions. The chromaticity color coordinates, CCT values, were tuned in the red region of the color space. Hence, the results indicate that the prepared nanophosphor can be used as a red component to construct the white light for light-emitting diode applications., Competing Interests: The author declares there is no conflicts of interest in the current research., (This journal is © The Royal Society of Chemistry.)

Graphene-nanostructured systems, such as graphene quantum dots (GQDs), are well known for their interesting light-emitting characteristics and are being applied to a variety of luminescence-based applications. The emission properties of GQDs are complex. Therefore, understanding the science of the photophysics of coupled quantum systems (like quantum clusters) is still challenging. In this regard, we have successfully prepared two different types of GQD clusters, and explored their photophysical properties in detail. By co-relating the structure and photophysics, it was possible to understand the emission behavior of the cluster in detail. This gave new insight into understanding the clustering effect on the emission behaviour. The results clearly indicated that although GQDs are well connected, the local discontinuity in the structure prohibits the dynamics of photoexcited charge carriers going from one domain to another. Therefore, an excitation-sensitive dual emission was possible. Emission yield values of about 18% each were recorded at the blue and green emission wavelengths at a particular excitation energy. This meant that the choice of emission color was decided by the excitation energy. Through systematic analysis, it was found that both intrinsic and extrinsic effects contributed to the blue emission, whereas only the intrinsic effect contributed to the green emission. These excitation-sensitive dual emissive GQD clusters were then used to sense Fe 3+ and Cr 6+ ions in the nanomolar range. While the Cr 6+ ions were able to quench both blue and green emissions, the Fe 3+ ions quenched blue emission only. The insensitivity of the Fe 3+ ions in the quenching of the green emission was also understood through quantum chemical calculations., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

We synthesized mesoporous cobalt titanate (CTO) microrods via the sol-gel method as an outstanding working electrode for the supercapacitor. The mesoporous CTO microrods were amassed in hexagonal shapes of an average width of ∼670 nm, and were composed of nanoparticles of average diameter ∼41 nm. The well crystalline CTO microrods of the hexagonal phase to the R 3̄ space group possessed an average pore size distribution of 3.92 nm throughout the microrod. The mesoporous CTO microrods with increased textural boundaries played a vital role in the diffusion of ions, and they provided a specific capacitance of 608.4 F g -1 and a specific power of 4835.7 W kg -1 and a specific energy of 9.77 W h kg -1 in an aqueous 2 M KOH electrolyte, which was remarkably better than those of Ti, La, Cr, Fe, Ni, and Sr-based perovskites or their mixed heterostructures supplemented by metal oxides as an impurity. Furthermore, the diffusion-controlled access to the OH - ions (0.27 μs) deep inside the microrod conveyed high stability, a long life cycle for up to 1950 continuous charging-discharging cycles, and excellent capacitance retention of 82.3%. Overall, the mesoporous CTO shows its potential as an electrode for a long-cycle supercapacitor, and provides opportunities for additional enhancement after developing the core-shell hetero-architecture with other metal oxide materials such as MnO 2 , and TiO 2 ., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Polycrystalline samples of Ba 0.96 Ca 0.04 Ti 0.91 Fe 0.09 O 3 were prepared using a conventional solid state reaction route with different Fe starting precursors (Fe 2 O 3 , Fe 3 O 4 ). The Rietveld refined XRD data confirmed the phase purity and tetragonal crystal structure of both the samples. The average grain size measured using SEM was ≈0.40 μm in both the samples. XPS analysis confirmed the presence of only Fe 2+ and both Fe 2+ /Fe 3+ in Fe 2 O 3 and Fe 3 O 4 doped BCT samples. The P r and M r values have been measured to be 1.34 μC cm -2 , 2.88 μC cm -2 and 0.0015 emu g -1 and 0.135 emu g -1 in Fe 2 O 3 and Fe 3 O 4 doped BCT samples, respectively. The Fe 3 O 4 doped samples exhibit much better M-E coupling (≈22%) as compared to Fe 2 O 3 doping in BCT is better suited for multiferroic applications.3 O 4 doping in BCT is better suited for multiferroic applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Considering the significant impact of magnetically retrievable nanostructures, herein, Fe 3 O 4 and Ce-doped Fe 3 O 4 nanoparticles were employed as scaffolds for the removal of the Reactive Black 5 (RB5) azo dye. We synthesized the Ce-doped Fe 3 O 4 nanoparticles via hydrothermal treatment at 120 °C for 10 h with varying cerium concentrations (1.5-3.5%) and characterized them using basic techniques such as FTIR and UV-visible spectroscopy, and XRD analysis. The retention of their magnetic behaviors even after cerium amalgamation was demonstrated and confirmed by the VSM results. FESEM and EDX were used for the morphological and purity analysis of the synthesized nanoabsorbents. XPS was carried out to determine the electronic configuration of the synthesized samples. The porosity of the magnetic nanoparticles was investigated by BET analysis, and subsequently, the most porous sample was further used in the adsorption studies for the cleanup of RB5 from wastewater. The dye adsorption studies were probed via UV-visible spectroscopy, which indicated the removal efficiency of 87%. The prepared Ce-doped Fe 3 O 4 nanoabsorbent showed the high adsorption capacity of 84.58 mg g -1 towards RB5 in 40 min. This is attributed to the electrostatic interactions between the nanoabsorbent and the dye molecules and high porosity of the prepared sample. The adsorption mechanism was also analyzed. The kinetic data well-fitted the pseudo-first-order model, and the adsorption capability at different equilibrium concentrations of the dye solution indicated monolayer formation and chemisorption phenomena. Furthermore, the magnetic absorbent could be rapidly separated from the wastewater using an external magnetic field after adsorption., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

We observed enhanced field emission (FE) behavior for spitzer shaped ZnO nanowires synthesized via a hydrothermal approach. The spitzer shaped and pointed tipped 1D ZnO nanowires of average diameter 120 nm and length ∼5-6 μm were randomly grown over an ITO coated glass substrate. The turn-on field ( E on ) of 1.56 V μm -1 required to draw a current density of 10 μA cm -2 from these spitzer shaped ZnO nanowires is significantly lower than that of pristine and doped ZnO nanostructures, and MoS 2 @TiO 2 ) of 3924 for ZnO/ITO emitters. The enhancement in FE behavior can be attributed to the spitzer shaped nanotips, sharply pointed nanotips and individual dispersion of the ZnO nanowires. The ZnO/ITO emitters exhibited very stable electron emission with average current fluctuations of ±5%. Our investigations suggest that the spitzer shaped ZnO nanowires have potential for further improving in electron emission and other functionalities after forming tunable nano-hetero-architectures with metal or conducting materials.β FE ) of 3924 for ZnO/ITO emitters. The enhancement in FE behavior can be attributed to the spitzer shaped nanotips, sharply pointed nanotips and individual dispersion of the ZnO nanowires. The ZnO/ITO emitters exhibited very stable electron emission with average current fluctuations of ±5%. Our investigations suggest that the spitzer shaped ZnO nanowires have potential for further improving in electron emission and other functionalities after forming tunable nano-hetero-architectures with metal or conducting materials., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

We studied the conductivity relaxation originating from a glass-former composed of cations and anions, and the relation to the structural α-relaxation at temperatures above and below the glass transition temperature. The material chosen was amorphous amlodipine besylate (AMB), which is also a pharmaceutical with a complex chemical structure. Measurements were made using differential scanning calorimetry (DSC), broadband dielectric spectroscopy (BDS) and X-ray diffraction, and the characterization was assisted using density functional theory (DFT). The X-ray diffraction pattern confirms the amorphous nature of vitrified AMB. Both the ionic and dipolar aspects of the dynamics of AMB were examined using these measurements and were used to probe the nature of the secondary conductivity and dipolar relaxations and their relation to the conductivity α-relaxation and the structural α-relaxation. The coupling model predictions and quantum mechanical simulations were used side by side to reveal the properties and nature of the secondary conductivity relaxation and the secondary dipolar relaxation. Remarkably, the two secondary relaxations have the same relaxation times, and are one and the same process performing dual roles in conductivity and dipolar relaxations. This is caused by the translation-rotation coupling of the AMB molecule. Thus, AMB has both conductivity α- and β-relaxations, and application of the coupling model shows that these two relaxations are related in the same way as the structural α-relaxation and the Johari-Goldstein β-relaxation are. This important result has an impact on the fundamental understanding of the dynamics of ionic conductivity., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A thermal decomposition route with different sintering temperatures was employed to prepare non-stoichiometric nickel oxide (Ni 1- δ O) from Ni(NO 3 ) 2 ·6H 2 O as a precursor. The non-stoichiometry of samples was then studied chemically by iodometric titration, wherein the concentration of Ni 3+ determined by chemical analysis, which is increasing with increasing excess of oxygen or reducing the sintering temperature from the stoichiometric NiO; it decreases as sintering temperature increases. These results were corroborated by the excess oxygen obtained from the thermo-gravimetric analysis (TGA). X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) techniques indicate the crystalline nature, Ni-O bond vibrations and cubic structural phase of Ni 1- δ O. The change in oxidation state of nickel from Ni 3+ to Ni 2+ were seen in the X-ray photoelectron spectroscopy (XPS) analysis and found to be completely saturated in Ni 2+ as the sintering temperature reaches 700 °C. This analysis accounts for the implication of non-stoichiometric on the magnetization data, which indicate a shift in antiferromagnetic ordering temperature ( T N ) due to associated increased magnetic disorder. A sharp transition in the specific heat capacity at T N and a shift towards lower temperature are also evidenced with respect to the non-stoichiometry of the system., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)