Pure Phase Research Articles

A novel method to enhance the superconducting properties of Bi2Sr2CaCu2O8+δ superconducting thin films by self-assembly NiO nanorods

The utilization of Bi-based superconductors in magnetic field environments is limited due to their anisotropic structure and lack of efficient magnetic flux pinning sites. Therefore, to enhance the performance of Bi-based superconductors in a magnetic field, this study presents the preparation of Bi2212 high-temperature superconducting thin films with varying NiO doping levels on SrTiO3 (STO) single crystal substrates with different concentrations of NiO seed layers via the self-assembly method. Additionally, phase purity, crystal structure, surface morphology, and transport properties were thoroughly analyzed. According to the results, the NiO seed layers prepared on the STO substrates presented epitaxial growth characteristics, with the NiO second phase in the Bi2212 matrix growing epitaxially along the seed layers. As NiO doping slightly broadens the phase formation temperature range of Bi2212 superconducting thin films, the self-assembly method can be utilized to prepare NiO nanorods with epitaxial growth in Bi2212 thin films. Notably, the self-assembled NiO-doped Bi2212 thin film demonstrated higher critical current carrying capacity, with its Jc reaching 6.28 × 104 A/cm2 at 10 K in self-field. This provides a technical reference for improving the performance of high-temperature superconducting thin films under a high magnetic field.

Supported LaCoO3 perovskite-like oxides for N2O decomposition: The key role of the support nature and LaCoO3 content

In this work a detailed comparison of the N2O decomposition catalytic performance of LaCoO3 perovskite-like mixed oxides supported over different commercial materials was conducted. Zirconia-, silica- and γ-alumina-based supports were studied. Zirconia-based supports turned out to be the most applicable because of the formation of the pure LaCoO3 perovskite phase on their surface. Among these supports, ZrO2-La revealed to possess the best activity owing to the highest Co2+/Co3+ (0.82) and Oads./OL (0.67) ratios on its surface. The raw of activities was as follows: LaCoO3(20 %)/ZrO2-La > LaCoO3(20 %)/ZrO2 > LaCoO3(20 %)/ZrO2-W. When the LaCoO3 content in LaCoO3/ZrO2-La was 20 wt%, the maximum of activity was observed – 94.78 mmol(N2O)/[g(cat.)·h] at 450 °C. This fact was in accordance with the highest Co2+/Co3+ (0.82) and Oads./OL (0.67) ratios at the 20 wt% LaCoO3 content. Coordinatively unsaturated Co2+, forming Lewis acid-base pairs, were proposed to be the active sites of the zirconia-based LaCoO3 catalysts in the N2O decomposition.

Dynamic optical information encryption strategy based on rare earth ions doped BaSi2O5 phosphors with adjustable trap distribution

Multi-modal strategies for optical information storage have received a lot of attention to meet the increasing security requirements. In this case, long persistent luminescence (LPL) phosphors with different dopant ions were obtained by introducing Dy3+ and Ho3+ ions into the BaSi2O5:Eu2+ phosphor to adjust the distribution and depth of the trap centers. The generation of the pure phase BaSi2O5 was confirmed by X-ray diffraction (XRD) and XRD Rietveld refinement. The peak emission of BaSi2O5: Eu2+ phosphor is about 500 nm with 313 nm excitation. Both BaSi2O5: Eu2+, Dy3+, and BaSi2O5: Eu2+, Ho3+ phosphors exhibit emission characteristics of Eu2+ ions. The trap depths of the three phosphors are different by Gaussian fitting of thermoluminescence (TL) curves, and the depth of BaSi2O5: Eu2+, Dy3+ phosphor can reach 1.070 eV. Typically, the flexible luminescent film based on BaSi2O5: Eu2+ phosphor can be written optical pattern using 365 nm ultraviolet (UV) light, such as "DL" and "fireworks" patterns, and subsequently read out by thermal or infrared light stimulus. Further, a strategy for encryption and decryption of dynamic optical information in Morse code has been developed using BaSi2O5: Eu2+, BaSi2O5: Eu2+, Dy3+, and BaSi2O5: Eu2+, Ho3+ phosphors, indicating the prospective use in optical information security.

Sublimation of volatiles from H2O:CO2 bulk ices in the context of comet 67P/Churyumov-Gerasimenko

Context. Comets are considered to be remnants from the formation of the Solar System. ESA’s Rosetta mission targeted comet 67P/Churyumov-Gerasimenko and was able to record high-quality data on its chemical composition and outgassing behaviour, including low abundances of N2 that are observed to be correlated with H2O and CO2 in approximately a 63:37 ratio. Aims. In this work, the thermal desorption behaviour of N2 in H2O:CO2 ices was studied in the laboratory to investigate the co-desorption behaviour of N2 within the two most abundant cometary ices in 67P and to derive desorbing fractions in different temperature regimes. Methods. H2O:CO2:N2 ices of various ratios were prepared in a gas mixing system and co-deposited at 15 K onto a copper sample holder. Sublimation of the ice was measured using temperature programmed desorption mass spectrometry. Quantitative values were derived for the fraction of N2 co-desorbing with CO2 and H2O respectively. To validate the results, H2O:CO2:13CO ices were prepared as well. Results. The experiments show that the co-desorption of N2 with CO2 in H2O:CO2:N2 ices depends on the bulk amount of CO2 present in the ice. The fraction of N2 trapped in H2O reduces as more N2 and CO2 are added to the mixture. CO behaves qualitatively similar to N2, but more CO is found to co-desorb with CO2. To reproduce the ratio of N2 desorbing with H2O over that of CO2 (N2(H2O)/N2(CO2)), our ice analogues need to contain ≥15% CO2, while 67P contains ≤7.5% CO2. Large fractions of N2 can be removed from the ice due to heating up to 70 K, but for ice that most closely resembles that of 67P, the loss fraction of pure phase N2 is expected to be ≤20%. Therefore, N2 is suggested to be a minor carrier of nitrogen in the comet.

Synthesis, crystal structure and thermal properties of a new polymorphic modification of diisothiocyanatotetrakis(4-methylpyridine)cobalt(II)

The title compound, [Co(NCS)2(C6H7N)4] or Co(NCS)2(4-methylpyridine)4, was prepared by the reaction of Co(NCS)2 with 4-methylpyridine in water and is isotypic to one of the polymorphs of Ni(NCS)2(4-methylpyridine)4 [Kerr & Williams (1977). Acta Cryst. B33, 3589–3592 and Soldatov et al. (2004). Cryst. Growth Des. 4, 1185–1194]. Comparison of the experimental X-ray powder pattern with that calculated from the single-crystal data proves that a pure phase has been obtained. The asymmetric unit consists of one CoII cation, two crystallographically independent thiocyanate anions and four independent 4-methylpyridine ligands, all located in general positions. The CoII cations are sixfold coordinated to two terminally N-bonded thiocyanate anions and four 4-methylpyridine coligands within slightly distorted octahedra. Between the complexes, a number of weak C—H...N and C—H...S contacts are found. This structure represent a polymorphic modification of Co(NCS)2(4-methylpyridine)4 already reported in the CCD [Harris et al. (2003). NASA Technical Reports, 211890]. In contrast to this form, the crystal structure of the new polymorph shows a denser packing, indicating that it is thermodynamically stable at least at low temperatures. Thermogravimetric and differential thermoanalysis reveal that the title compound starts to decomposes at about 100°C and that the coligands are removed in separate steps without any sign of a polymorphic transition before decomposition.

A brilliant equation and dipole-relaxation dynamics in tuned BiFeO3−BaTiO3−MgFe2O4 triphasic composites mediated using spinel phase contents

The integration of perovskite and spinel materials into multifunctional composites offers diverse technological applications due to their unique properties. This study explores the detailed multifunctional characteristics of tri-phasic composites with general formula (1−x)(0.6BiFeO3 + 0.4BaTiO3) + xMgFe2O4 (0 ≤ x ≤ 0.1), synthesized using a straightforward two-step process. X-ray diffraction confirmed the high crystallinity and phase purity of the composites. Subsequent observations using field emission scanning electron microscopy revealed a highly porous morphology with varying grain sizes. Electrically, the composite with x = 0.08 exhibited notable dielectric impedance, and modulus characteristics, aligning well with the requirements for efficient energy storage. Magnetically, the material displayed a gradual reduction in coercivity values, reaching 199.59 Oe at x = 0.10, alongside a peak magnetization of 5.140 emu/g and a remanent magnetization-to-saturation magnetization (Mr/Ms) ratio of 0.173. These features underscore the material’s potential for magnetic memory applications. Detailed dielectric response analysis across wide frequency range highlighted suitability of as synthesized composites for advanced energy storage devices.

The development and application of Cu@TiO2@SAPO-34 as better photocatalyst towards degradation of various pollutants

The study developed a novel Cu@TiO2@SAPO-34 nanocomposite for photocatalytic mortification of organic pollutants using modified hydrothermal synthesis. The material was characterized using XRD, BET, XPS, SEM, TEM, UV–vis, and Photoluminescence spectroscopy, confirming high pollutant absorption and photocatalytic capability. The structural analysis identified the emergence of monoclinic CuO and pure anatase phase TiO2, with ligands matching the formation of SAPO-34 at various planes of 2theta degrees. Also, species of Cu-SAPO-34 (35.43 and 65.88°) and TiO2-SAPO-34 (25.56°) were identified. The BET analysis indicated a narrow pore size distribution of 5.59 nm for Cu@TiO2@SAPO-34, with a high surface area to volume ratio of 145.7868 m2. g−1. The optical property analysis revealed that TiO2 exhibited light absorption mainly in the visible region, while Cu@TiO2@SAPO-34 exhibited early adsorption in the ultraviolet region and extended to the visible regions. This was accompanied by a concomitant decrease in band gap energy from 3.09 eV for TiO2 to 2.61 eV for Cu@TiO2@SAPO-34. The Photodegradation experiment demonstrated that TiO2 nanoparticles achieved 83 % degradation of methylene blue (MB) dye solution after 120 minutes under ultraviolet irradiation, while the Cu@TiO2@SAPO-34 composite achieved 98 % within 30 minutes. The novel nanocomposite material was further tested for real wastewater treatment, self-cleaning of the coated film, and nature of wettability, which all confirmed that the novel Cu@TiO2@SAPO-34 composite is superhydrophilic and a better photocatalyst for degrading organic contaminants. The study details the Photodegradation reaction mechanism for the Cu@TiO2@SAPO-34 nanocomposite, comparing it to TiO2 under UV–vis irradiation, and proposes a chabazite-related structure using Biovia Materials Studio 2020.

Exploring Defect-Engineered Metal-Organic Frameworks with 1,2,4-Triazolyl Isophthalate and Benzoate Linkers.

Synthesis and characterization of DEMOFs (defect-engineered metal-organic frameworks) with coordinatively unsaturated sites (CUSs) for gas adsorption, catalysis, and separation are reported. We use the mixed-linker approach to introduce defects in Cu2-paddle wheel units of MOFs [Cu2(Me-trz-ia)2] by replacing up to 7% of the 3-methyl-triazolyl isophthalate linker (1L2-) with the "defective linker" 3-methyl-triazolyl m-benzoate (2L-), causing uncoordinated equatorial sites. PXRD of DEMOFs shows broadened reflections; IR and Raman analysis demonstrates only marginal changes as compared to the regular MOF (ReMOF, without a defective linker). The concentration of the integrated defective linker in DEMOFs is determined by 1H NMR and HPLC, while PXRD patterns reveal that DEMOFs maintain phase purity and crystallinity. Combined XPS (X-ray photoelectron spectroscopy) and cw EPR (continuous wave electron paramagnetic resonance) spectroscopy analyses provide insights into the local structure of defective sites and charge balance, suggesting the presence of two types of defects. Notably, an increase in CuI concentration is observed with incorporation of defective linkers, correlating with the elevated isosteric heat of adsorption (ΔHads). Overall, this approach offers valuable insights into the creation and evolution of CUSs within MOFs through the integration of defective linkers.

Effect of air-annealing on the structure, surface morphology, and supercapacitive properties of the 2D-BiOCl nanosheets

Upright-standing nanosheets of bismuth oxychloride (BiOCl), synthesized via a facile chemical synthesis method and air-annealed from 50 to 600 ℃ temperatures (named BOC-50–600), are envisaged as electrochemical supercapacitor electrodes. These electrodes are initially screened for their surface morphology, elemental configuration, phase purity, and binding energy by various means. Due to changes in the surface morphology, phase, charge transfer resistance, and binding energy, the one annealed at 150 ℃ i.e., BOC-150 has offered targeted supercapacitive performance due to quasi-faradaic redox reactions in 6 M KOH electrolyte solution. The specific capacitance of the BOC-150 electrode, measured at 1.40–5.0 A/g current densities, varies from 264.6 to 95 F/g. The as-assembled BOC-150//BOC-150 symmetric supercapacitor device (SSD) demonstrates an efficient supercapacitive performance with a maximum 86.87 Wh/kg energy density and 3735 W/kg power density. Additionally, the as-designed SSD endows an admirable capacity retention of 81.6% for 5000 charge-discharge cycles, approving moderate chemical stability and considerable mechanical robustness for use in commercial electronic items.

Synthesis of N-vinylcarbazole from acetylene by a continuous high-pressure liquid-phase process with inherent safety

In this study, a continuous high-pressure liquid-phase acetylene microreaction process is rationally designed and successfully realized by employing the strategy of decoupling the acetylene dissolution and successive reaction. As the acetylene reaction is operated in a pure liquid phase with high acetylene concentration, the safety and efficiency of the acetylene conversion process are greatly improved. As a result, N-vinylcarbazole (NVC) is continuously synthesized from dissolved acetylene at 165 °C and 4.5 MPa. Compared to the conventional batch process, the reaction time is reduced to 5–20 min from 5 to 6 h, the amount of catalyst is reduced by 14.8 times, and the specific activity (g carbazole /g KOH /min) is increased by 220 times. To further increase the yield of NVC, 4-tert-butylcatechol (TBC) is added to the feedstock as a polymerization inhibitor, which improves the yield of NVC to 88 %. Several other vinyl compounds, in addition to NVC, are also continuously synthesized from acetylene using this method, which suggests that the process decoupling reaction strategy is widely applicable to acetylene-involved reactions.

Photocatalytic performance of ZnO and ZnO/Zn3(PO4)2 coatings formed by plasma electrolytic oxidation of zinc

In this study, plasma electrolytic oxidation (PEO) of zinc in a water solution containing 10 g/L Na3PO4⋅12H2O + 2 g/L KOH, was used for the preparation oxide of coatings for application in photocatalysis for degradation of organic dyes. Degradation of methyl orange (MO) as a model of organic dyes under simulated sunlight was used. In coating formed after 2 min of PEO, the pure phase hexagonal wurtzite ZnO was identified, while in coatings formed for a long time of PEO (up to 5 min) monoclinic phase of Zn3(PO4)2 was identified together with ZnO (ZnO/Zn3(PO4)2 coatings). ZnO/Zn3(PO4)2coatings show better photocatalytic activity (PA) than ZnO coating. The ZnO/Zn3(PO4)2 coating with the highest PA was formed after 4 min. Coupling ZnO with Zn3(PO4)2 reduce the recombination rate of photo-generated electron/hole pairs in ZnO which leads to an increase in PA of ZnO/Zn3(PO4) coatings compared to pure ZnO coating. This is confirmed by photoluminescent measurements. According to photocatalytic and photoluminescence measurement mechanism of the light-induced degradation of MO over ZnO/Zn3(PO4)2 coatings is suggested.

Comparative evaluation of antimicrobial activity of spinel structured transition metal ferrites supported on reduced graphene oxide against pathogenic strains of bacteria and fungi.

One of the global challenges for living things is to provide pollution and harmful microbes-free environment. In this study, magnetically retrievable spinel-structured manganese zinc ferrite (Mn0.5Zn0.5Fe2O4) (MZF) was synthesized by a facile solvothermal method. Further, the MZF with different weight percentages (10 wt%, 50 wt%, and 80 wt%) were supported on reduced graphene oxide (rGO). The phase purity and morphology of MZF and MZF/rGO nanocomposite were confirmed by x-ray diffraction technique and scanning electron microscopy, respectively. The Fourier transform infrared spectroscopy, Raman, UV-visible spectroscopy, and thermogravimetric analyses of the as-synthesized nanocomposites were examined for the detection of various chemical groups, band gap, and thermal properties, respectively. The MZF/rGO nanocomposite exhibited significant antibacterial and antifungal activity againstEggerthella lenta, Enterococcus faecalis, Klebsiella pneumonia, Pseudomonas aeruginosa,andCandida albicanscompared to bare MZF and rGO. The high surface area of rGO plays a crucible role in antimicrobial analysis. Additionally, the antibacterial and antifungal activity is compared by synthesizing various metal ferrites such as MnFe2O4, ZnFe2O4, and Fe3O4. The 50 wt% MZF/rGO nanocomposite exhibits significantly high antibacterial activity. However, 10 wt% MZF/rGO nanocomposite shows good antifungal activity than Fe3O4, MnFe2O4, ZnFe2O4, MnZnFe2O4, 50 wt%, and 80 wt% MZF/rGO nanocomposites. These findings suggest that the prepared ferrite nanocomposites hold promise for microbial inhibition.

Investigation of photoluminescence properties of Eu3+ doped La(OH)3 nanopowder synthesized by combustion method

Pure and different doping percentages of Eu 3+ ion (2, 5, and 10 wt%) doped La(OH)3 nanoparticles were produced using the urea-assisted combustion method followed by a three-hour calcination at 800 °C. A pure hexagonal phase of La(OH)3 structure is confirmed using X-ray diffraction (XRD) results. The photoluminescence (PL) investigations of Eu-doped La(OH)3 nanoparticles revealed orange and red emissions from 5D0→7F1 and 5D0→7F2 transitions of Eu3+ ions with excitation wavelength 395 nm. The CIE coordinate represents the orange and red zone of the La(OH)3 sample doped with Eu3+ions. The CCT values obtained are 2145 K, 2469 K, and 2583 K also the decay lifetime is 0.273 ns, 0.266 ns, and 0.493 ns for 2, 5, and 10 wt% of Eu3+ ions. The results confirmed among the three dopant concentrations of Eu3+ doped La(OH)3 nanoparticles, the optimal concentration of 10 wt% Eu3+ ion can be used for red and orange emitting phosphors.

Transparent high entropy garnet ceramics by SPS

High entropy or multi-principles component oxides as a new class of materials have been widely investigated for various applications due to their unique properties and multi-functionalities in recent years. In this study, a high entropy transparent ceramics ((Gd0.2Tb0.2Y0.2Lu0.2Yb0.2)3Al5O12) has been fabricated by spark plasma sintering (SPS) using co-precipitation synthesized powders. The powder preparation process was studied by TAG-DSC and FTIR. The phase structure, morphology, and element distribution of the obtained powder and ceramic samples are explored by XRD, SEM, and EDS mapping. It shows that the high entropy oxide (HEO) ceramic powder has a pure garnet phase, nanoparticle size, and homogenous elements distribution. The sintered ceramic exhibits the highest in-line transmittance in the visible and IR range of approximately 52 % at 700 nm and 74 % at 3.6 μm, respectively. In addition, characteristic optical properties of the final ceramics were demonstrated by photoluminescence spectroscopy. This work indicated that high-entropy garnet transparent ceramics with multi-wavelength emissions will provide more possibilities for multifunctional optical applications in the future.

Crystallization of Y3Fe5O12 thin films on silicon photonic waveguides using CO2 laser annealing

We report the local crystallization of Y3Fe5O12 (YIG) thin films grown on Si substrates, and SOI waveguides by CO2 laser annealing (LA). The effect of laser power and oxygen pressure on the crystal structure of YIG films was systematically studied. Laser power dominated the YIG film crystallinity, while oxygen partial pressure during LA strongly influenced the crystal grain size and magnetic anisotropy. Fully crystallized YIG thin films with pure garnet phases were fabricated by LA. The refractive index n and extinction coefficient k were comparable to thin films fabricated by rapid thermal annealing (RTA). Propagation loss measured at 1550 nm wavelength on YIG/SOI waveguides and YIG/SiN ring resonators were comparable to RTA annealed films, promising device development for silicon photonics.

Separation and purification of Ag and Se via vacuum thermal decomposition-volatilization of Ag2Se

In this study, theoretical and experimental investigations of the green separation and purification of Ag and Se from Ag2Se are conducted under vacuum. The vacuum separation theory calculation results indicate that the vapor pressure of Se is significantly higher than those of Ag and Ag2Se. Furthermore, the separation coefficient of the Se-Ag binary system is in the range of 104–105, and the Se content in the vapor phase exceeds 99.99 wt%. In contrast, the theoretical calculation results of vacuum thermal decomposition show that Ag2Se decomposes to Se2 (g) and Ag (l) at 1326.74 and 1488.21 K when the pressures are 1 and 10 Pa, respectively. The vacuum separation and purification experiments demonstrate that the purity of Se in the volatiles reaches 97.22 wt% at 1523 K, 50 Pa, and 480 min, and the main phase is the pure Se phase. Moreover, the purity of Ag in the residue reaches 91.88 wt%, and the main phase is the pure Ag phase. The vacuum thermal decomposition-volatilization proposed in this study can achieve environmentally friendly, short separation and purification of Ag and Se in Ag2Se.

A robust hydrothermal synthesis method of NH4Zr2(PO4)3, a precursor for HZr2(PO4)3 proton conductor

Hydrogen zirconium phosphate (HZP) is a ceramic material with the formula HZr2(PO4)3 that can potentially offer anhydrous protonic conductivity, with thermostability for the intrinsic protons up to 650 °C, and good chemical stability in aqueous environments or acid gases. Despite the attraction of these features for electrolyte applications, such as gas separation, fuel cells or electrolysers, work on this material remains in its infancy. A possible reason for this lack of attention may be related to the complexity to obtain the HZP material as a pure phase. For this reason, the current article examines a new hydrothermal synthesis method to produce the ammonium precursor, NH4Zr2(PO4)3, in its phase pure form, and consequently a refined overall route to produce the desired HZP target material. In the synthesis of the ammonium precursor, we underscore the precise control of reaction conditions that are necessary to obtain the pure NH4Zr2(PO4)3 material, both in its cubic and hexagonal structural polymorphs. For reaction times of 10 h, the cubic phase is obtained by employing a hydrothermal temperature of 150 °C and an aqueous ammonia volume of 2.1 mL, while the hexagonal phase is obtained for a hydrothermal temperature of 200 °C and an aqueous ammonia volume between 2.3 and 2.4 mL. Subsequently, we investigate the required conditions to convert hexagonal NH4Zr2(PO4)3 fully to hexagonal HZr2(PO4)3 via thermal treatment at 600 °C for 5 h, assessed by a combination of X-ray diffraction and infrared spectroscopy.In this way this article aims to open up further research on this interesting HZP material by documenting a robust route for its preparation.

Upconversion multicolor tuning in Er3+ and Yb3+ doped yttrium oxide prepared by precursor technique

The (Y0.9Er0.1-xYbx)2O3 (x = 0, 0.02, 0.05, 0.07, 0.08, 0.09) and Y1-(0.02+y)Er0.02YbyO3 (y = 0.05, 0.07, 0.09, 0.11) solid solutions have been synthesized by the precursor technique using mixed anhydrous formates. The crystal structure of ytterbium formate, Yb(HCOO)3, was established for the first time. The structural parameters and phase purity of the synthesized precursors and oxides were determined by X-ray phase analysis. The average sizes of crystallites are in the 60–80 nm range. The upconversion spectra of solid solutions exhibit a weak green and an intense red line attributed to 2H11/2,4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+ ions. The green and red emissions of (Y0.9Er0.1-xYbx)2O3 and Y1-(0.02+y)Er0.02YbyO3 oxides are caused by two-photon conversion processes. The effect of dopant (erbium and ytterbium) concentration and Er3+/Yb3+ ratio on the intensity of upconversion emission were established, the contribution of upconversion green luminescence decreases with increasing the ytterbium concentration.

Photocatalytic degradation of methylene blue using chitosan/NiO nanocomposite: A comprehensive exploration

The present research work aims to illustrate the potential power of chitosan nanoparticles and chitosan/nickel oxide (NiO) nanocomposite for the photocatalytic degradation of methylene blue (MB). Initially, chitosan nanoparticles and chitosan/NiO nanocomposite were prepared using ball milling technique, focusing on the theory of top-down preparation. It was observed that, the as-prepared chitosan/NiO nanocomposite exhibited spherical shape with small size. Meanwhile, chitosan nanoparticles were prepared with irregular shape as depicted from TEM analysis. XRD affirmed the pure phase and crystalline structure of chitosan nanoparticles as a result to the observation for two peaks at 11.3o and 20.11o. New characteristic peaks at 35.3o, 38.5o, 49o, and 63o were noticed owing to the presence of NiO blended with chitosan nanoparticles. The estimated values of optical band gap energy for chitosan nanoparticles and chitosan/NiO nanocomposite are (3.6 eV, 3.5 eV), respectively. The photocatalytic degradation of MB dye employing chitosan nanoparticles and chitosan/NiO nanocomposite achieved 21 % and 96.1 %, respectively. The enhancement of photocatalytic efficiency of MB dye was mainly attributed to the potential effect of NiO nanoparticles. The findings also demonstrated that the photocatalytic performance of both chitosan nanoparticles and chitosan/NiO nanocomposite was pH, time, and catalyst doses dependent and obey Langmuir-Hinshelwood model. The photocatalytic activity of chitosan/NiO nanocomposite lost 14.9 % of its performance after first two cycles. Therefore, chitosan/NiO nanocomposite has emerged as a pioneering agent in sustainable water treatment, promising a transformative approach to combat water pollution. This study can guide future research, industry practices, and policy decisions towards a future where water treatment is synonymous with environmental harmony and innovation.

Spontaneous time-reversal symmetry breaking by disorder in superconductors

A growing number of superconducting materials display evidence for spontaneous time-reversal symmetry breaking (TRSB) below their critical transition temperatures. Precisely what this implies for the nature of the superconducting ground state of such materials, however, is often not straightforward to infer. We review the experimental status and survey different theoretical mechanisms for the generation of TRSB in superconductors. In cases where a TRSB complex combination of two superconducting order parameter components is realized, defects, dislocations and sample edges may generate superflow patterns that can be picked up by magnetic probes. However, even single-component condensates that do not break time-reversal symmetry in their pure bulk phases can also support signatures of magnetism inside the superconducting state. This includes, for example, the generation of localized orbital current patterns or spin-polarization near atomic-scale impurities, twin boundaries and other defects. Signals of TRSB may also arise from a superconductivity-enhanced Ruderman-Kittel-Kasuya-Yosida exchange coupling between magnetic impurity moments present in the normal state. We discuss the relevance of these different mechanisms for TRSB in light of recent experiments on superconducting materials of current interest.