Improving structural and magnetic properties of zinc stannate thin films through nickel doping via sol-gel method.

Ternary oxides are currently emerging as promising materials for optoelectronic devices and spintronics, surpassing binary oxides in terms of their superior properties. Among these, zinc stannate (Zn2SnO4) stands out due to its stability and attractive physical characteristics. However, despite its outstanding attributes, there is a need to further develop its magnetic properties for spintronic applications. In this study, Ni-doped Zn2SnO4 thin films were synthesized using the sol-gel method, and their magnetic characteristics were investigated for the first time. X-ray diffraction analysis confirmed the high crystallinity of the synthesized samples, even after the incorporation of Ni dopants, without any secondary phases. SEM imaging revealed the cubic structure morphology of the thin films. An increase in the bandgap, dependent on the Ni dopant concentration, was observed for doped zinc stannate, suggesting potential for tailored electronic properties. FTIR spectroscopy confirmed the presence of functional groups within the material. Notably, the magnetic properties of the thin films were analyzed using a vibrating sample magnetometer (VSM), revealing diamagnetic behavior for pure zinc stannate and ferromagnetic properties for Ni-doped Zn2SnO4, which increased with dopant concentration. Overall, the results highlight the excellent structural, optical, and ferromagnetic properties of Ni-doped Zn2SnO4 thin films, positioning them for diverse applications, particularly in optoelectronic and spintronic technology.

Nitrogen-Doped Carbon Encapsulated Partial Zinc Stannate Nanocomposite for High-Performance Energy Storage Materials.

As a bimetal oxide, partial zinc stannate (ZnSnO3) is one of the most promising next-generation lithium anode materials, which has the advantages of low operating voltage, large theoretical capacity (1,317 mA h g-1), and low cost. However, the shortcomings of large volume expansion and poor electrical conductivity hinder its practical application. The core-shell ZnSnO3@ nitrogen-doped carbon (ZSO@NC) nanocomposite was successfully obtained by coating ZnSnO3 with polypyrrole (PPy) through in situ polymerization under ice-bath conditions. Benefiting from this unique compact structure, the shell formed by PPy cannot only effectively alleviate the volume expansion effect of ZnSnO3 but also enhance the electrical conductivity, thus, greatly improving the lithium storage performance. ZSO@NC can deliver a reversible capacity of 967 mA h g-1 at 0.1 A g-1 after 300 cycles and 365 mA h g-1 at 2 A g-1 after 1,000 cycles. This work may provide a new avenue for the synthesis of bimetal oxide with a core-shell structure for high-performance energy storage materials.

Regulation of Photovoltaic Response in ZSO-Based Multiferroic BFCO/BFCNT Heterojunction Photoelectrodes via Magnetization and Polarization.

Multiferroic devices have attracted renewed attention in applications of photovoltaic devices for their efficient carrier separation driven by internal polarization, magnetization, and above-bandgap generated photovoltages. In this work, Zn2SnO4-based multiferroic Bi6Fe1.6Co0.2Ni0.2Ti3O18/Bi2FeCrO6 (BFCNT/BFCO) heterojunction photoelectrodes were fabricated. Structural and optical analyses showed that the bandgap of the spinel Zn2SnO4 is ∼3.1 eV while those of Aurivillius-type BFCNT and double-perovskite BFCO are 1.62 and 1.74 eV, respectively. Under the simulated AM 1.5G illumination, the as-prepared photoelectrodes delivered a photoconversion efficiency (η) of 3.40% with a short-circuit current density (Jsc), open-circuit voltage (Voc), and fill factor (FF) of 10.3 mA·cm-2, 0.66 V, and 50.4%, respectively. Analyses of adjustment of an applied electric and magnetic field on photovoltaic properties indicated that both magnetization and polarization of multiferroics can effectively tune the built-in electric field and the transport of charge carriers, providing a new idea for the design of future high-performance multiferroic oxide photovoltaic devices.

The Potential for Bio-Sustainable Organobromine-Containing Flame Retardant Formulations for Textile Applications-A Review.

This review considers the challenge of developing sustainable organobromine flame retardants (BrFRs) and alternative synergists to the predominantly used antimony III oxide. Current BrFR efficiencies are reviewed for textile coatings and back-coatings with a focus on furnishing and similar fabrics covering underlying flammable fillings, such as flexible polyurethane foam. The difficulty of replacing them with non-halogen-containing systems is also reviewed with major disadvantages including their extreme specificity with regard to a given textile type and poor durability.The possibility of replacing currently used BrFRs for textiles structures that mimic naturally occurring organobromine-containing species is discussed, noting that of the nearly 2000 such species identified in both marine and terrestrial environments, a significant number are functionalised polybrominated diphenyl ethers, which form part of a series of little understood biosynthetic biodegradation cycles.The continued use of antimony III oxide as synergist and possible replacement by alternatives, such as the commercially available zinc stannates and the recently identified zinc tungstate, are discussed. Both are effective as synergists and smoke suppressants, but unlike Sb203, they have efficiencies dependent on BrFR chemistry and polymer matrix or textile structure. Furthermore, their effectiveness in textile coatings has yet to be more fully assessed.In conclusion, it is proposed that the future of sustainable BrFRs should be based on naturally occurring polybrominated structures developed in conjunction with non-toxic, smoke-suppressing synergists such as the zinc stannates or zinc tungstate, which have been carefully tailored for given polymeric and textile substrates.

Potential Synergism between Novel Metal Complexes and Polymeric Brominated Flame Retardants in Polyamide 6.6.

While environmental concerns have caused polymeric brominated primary flame retardants (PolyBrFRs) to be effective replacement monomeric species, few alternatives for antimony trioxide (ATO) have been developed beyond the zinc stannates (ZnSs). Previous research, which explored the interactions of aluminium (AlW), tin (II) (SnW) and zinc (ZnW) tungstates with several phosphorus-containing flame retardants in polyamide 6.6 (PA66), is extended to two PolyBrFRs: brominated polystyrene (BrPS), and poly(pentabromobenzyl acrylate) (BrPBz). On assessing the effect of each tungstate on the thermal degradation and flammability in combination with each PolyBrFR using TGA, UL94, LOI, cone calorimetry and TGA-FTIR, only ZnW and SnW showed significant increases in LOI (>26 vol.%). Both ZnW-BrPS- and ZnW-BrPBz-containing formulations yielded average UL94 ratings ≥ V-2 and TGA char residues (corrected for metals content at 500 °C) in air > 15 wt.%. BrPS-containing samples, especially those containing ZnW and SnW, generated peak heat release rates approximately 50% lower than the equivalent BrPBz samples. These reductions did not correlate with respective increases in LOI, suggesting that tungstate-PolyBrFR combinations influence pre-ignition differently to post-ignition behaviour. Calculated synergistic effectivities indicate that ZnW functions as a synergist in both pre- and post-ignition stages, especially with BrPS. TGA-FTIR and char analyses showed that, in addition to the vapour-phase activity normally associated with PolyBrFRs, condensed-phase processes occurred, especially for the ZnW-PolyBrFR combinations. Additionally, ZnW demonstrated significant smoke-suppressing properties comparable with zinc stannate (ZnS).

Hydrothermal growth of Zn2 SnO4 :Eu,Ca for red emission.

Zinc stannate (Zn2 SnO4 ) and Zn2 SnO4 codoped with Eu3+ and Ca2+ (ZTO:Eu,Ca) were synthesized by hydrothermal method and characterized with X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDAX), Raman spectrometer, field emission scanning electron microscopy (FESEM), ultraviolet-visible (UV-vis) and photoluminescence (PL) spectrophotometers. PL analysis of Zn2 SnO4 gives broad defect induced emission in the region 500-750 nm. The crystal structure of Zn2 SnO4 was retained even with a nominal doping of Eu, Ca and its combination in the Zn2 SnO4 . The Eu3+ ions were found to occupy the non-centrosymmetric sites of the Zn2 SnO4 and gave emissions at 592, 615 and 702 nm. Zn2 SnO4 :Eu,Ca showed red emission at 615 nm attributed to the electronic transition from the excited state 5 D0 → 7 F2 of the 4f6 configuration of Eu3+ . Nominal codoping of Eu3+ and Ca2+ ions promoted the quenching of orange emission from Eu3+ in Zn2 SnO4 :Eu,Ca.

Effects of neonatal exposure to the flame retardant tetrabromobisphenol-A, aluminum diethylphosphinate or zinc stannate on long-term potentiation and synaptic protein levels in mice.

Brominated flame retardants such as tetrabromobisphenol-A (TBBPA) may exert (developmental) neurotoxic effects. However, data on (neuro)toxicity of halogen-free flame retardants (HFFRs) are scarce. Recent in vitro studies indicated a high neurotoxic potential for some HFFRs, e.g., zinc stannate (ZS), whereas the neurotoxic potential of other HFFRs, such as aluminum diethylphosphinate (Alpi), appears low. However, the in vivo (neuro)toxicity of these compounds is largely unknown. We therefore investigated effects of neonatal exposure to TBBPA, Alpi or ZS on synaptic plasticity in mouse hippocampus. Male C57bl/6 mice received a single oral dose of 211 µmol/kg bw TBBPA, Alpi or ZS on postnatal day (PND) 10. On PND 17-19, effects on hippocampal synaptic plasticity were investigated using ex vivo extracellular field recordings. Additionally, we measured levels of postsynaptic proteins involved in long-term potentiation (LTP) as well as flame retardant concentrations in brain, muscle and liver tissues. All three flame retardants induced minor, but insignificant, effects on LTP. Additionally, TBBPA induced a minor decrease in post-tetanic potentiation. Despite these minor effects, expression of selected synaptic proteins involved in LTP was not affected. The flame retardants could not be measured in significant amounts in the brains, suggesting low bioavailability and/or rapid elimination/metabolism. We therefore conclude that a single neonatal exposure on PND 10 to TBBPA, Alpi or ZS does affect neurodevelopment and synaptic plasticity only to a small extent in mice. Additional data, in particular on persistence, bioaccumulation and (in vivo) toxicity, following prolonged (developmental) exposure are required for further (human) risk assessment.

Controlled interfacial electron dynamics in highly efficient Zn2 SnO4 -based dye-sensitized solar cells.

Among ternary oxides, Zn2 SnO4 (ZSO) is considered for dye-sensitized solar cells (DSSCs) because of its wide bandgap, high optical transmittance, and high electrical conductivity. However, ZSO-based DSSCs have a poor performance record owing largely to the absence of systematic efforts to enhance their performance. Herein, general strategies are proposed to improve the performance of ZSO-based DSSCs involving interfacial engineering/modification of the photoanode. A conformal ZSO thin film (blocking layer) deposited at the fluorine-doped tin oxide-electrolyte interface by pulsed laser deposition suppressed the back-electron transfer effectively while maintaining a high optical transmittance, which resulted in a 22 % improvement in the short-circuit photocurrent density. Surface modification of ZSO nanoparticles (NPs) resulted in an ultrathin ZnO shell layer, a 9 % improvement in the open-circuit voltage, and a 4 % improvement in the fill factor because of the reduced electron recombination at the ZSO NPs-electrolyte interface. The ZSO-based DSSCs exhibited a faster charge injection and electron transport than their TiO2 -based counterparts, and their superior properties were not inhibited by the ZnO shell layer, which indicates their feasibility for highly efficient DSSCs. Each interfacial engineering strategy could be applied to the ZSO-based DSSC independently to lead to an improved conversion efficiency of 6 %, a very high conversion efficiency for a non-TiO2 based DSSC.

Toxicity of new generation flame retardants to Daphnia magna.

There is a tendency to substitute frequently used, but relatively hazardous brominated flame retardants (BFRs) with halogen-free flame retardants (HFFRs). Consequently, information on the persistence, bioaccumulation and toxicity (PBT) of these HFFRs is urgently needed, but large data gaps and inconsistencies exist. Therefore, in the present study the toxicity of a wide range of HFFRs to the water flea Daphnia magna was investigated. Our results revealed that four HFFRs were showing no effect at their Sw (saturated water concentration) and three had a low toxicity (EC50>10 mg L(-1)), suggesting that these compounds are not hazardous. Antimony trioxide had a moderate toxicity (EC50=3.01 mg L(-1), 95% CL: 2.76-3.25) and triphenyl phosphate and the brominated reference compound tetra bromobisphenol A were highly toxic to D. magna (EC50=0.55 mg L(-1), 95% CL: 0.53-0.55 and EC50=0.60 mg L(-1), 95% CL: 0.24-0.97 respectively). Aluminum trihydroxide and bisphenol A bis(diphenyl phosphate) caused limited mortality at Sw (26 and 25% respectively) and have a low solubility (<10 mg L(-1)). Hence, increased toxicity of these compounds may be observed when for instance decreasing pH could increase solubility. By testing all compounds under identical conditions we provided missing insights in the environmental hazards of new generation flame retardants and propose as best candidates for BFR replacements: APP, ALPI, DOPO, MHO, MPP, ZHS and ZS.

Zinc stannate nanostructures: hydrothermal synthesis.

Nanostructured binary semiconducting metal oxides have received much attention in the last decade owing to their unique properties rendering them suitable for a wide range of applications. In the quest to further improve the physical and chemical properties, an interest in ternary complex oxides has become noticeable in recent times. Zinc stannate or zinc tin oxide (ZTO) is a class of ternary oxides that are known for their stable properties under extreme conditions, higher electron mobility compared to its binary counterparts and other interesting optical properties. The material is thus ideal for applications from solar cells and sensors to photocatalysts. Among the different methods of synthesizing ZTO nanostructures, the hydrothermal method is an attractive green process that is carried out at low temperatures. In this review, we summarize the conditions leading to the growth of different ZTO nanostructures using the hydrothermal method and delve into a few of its applications reported in the literature.