Deposition of silicon nitride thin films by hot-wire CVD at 100ºC and 250ºC

Silicon nitride thin films for use as passivation layers in solar cells and organic electronics or as gate dielectrics in thin-film transistors were deposited by the Hot-wire chemical vapor deposition technique at a high deposition rate (1-3 Ǻ/s) and at low substrate temperature. Films were deposited using NH3/SiH4 flow rate ratios between 1 and 70 and substrate temperatures of 100º C and 250ºC. For NH3/SiH4 ratios between 40 and 70, highly transparent (T ~ 90%), dense films (2.56 - 2.74 g/cm3) with good dielectric properties and refractive index between 1.93 and 2.08 were deposited on glass substrates. Etch rates in BHF of 2.7 Ǻ/s and 10 MV cm−1.Fundação para a Ciência e Tecnologia (FCT) - FCT/CNRS programa com o contracto no. 20798, bolsa de investigaçao e projecto PTDC-CTM-66558-200

Synchrotron X-ray studies on polyamide composites prepared by reactive injection molding

Semicrystalline polyamide 6 (PA6) and composites on its basis are among the most frequently used polymer materials for highly demanding applications. The performance of these composites depends on the crystalline structure of the PA6 matrix in which two crystalline forms most frequently coexist: α- and γ-polymorphs. This work reports on the crystalline structure of a variety of composite materials produced by in-mold reactive polymerization of caprolactam in specially designed semi-automatic equipment for reactive processing of nylons (NYRIM), carried out in the presence of particulate mineral reinforcements (natural or-ganically treated aluminum silicates and synthetic titanosilicates), PA6 oriented monofilaments and textile structures of glass fibers. The morphology and the crystalline structure of all composites were studied by syn-chrotron X-ray diffraction. Transcrystalline PA6 layer was observed in all fibrous PA6 laminates whose struc-ture fine crystalline structure was accessed.Fundação para a Ciência e Tecnologia; German Synchrotorn Radiation Source - DESY, Hambur

Photocatalytic degradation of Rhodamine B dye by cotton textile coated with SiO2-TiO2 and SiO2-TiO2-HY composites

This work is devoted to study the photocatalytic ability of cotton textiles functionalized with SiO2-TiO2 and SiO2-TiO2-HY composites to degrade a dye molecule. Coatings were prepared by sol-gel method and calcined at different temperatures in a range of 400–750 °C. FTIR confirmed the existence of SiOTi bounds and the band located in the region between 570 and 600 cm−1 was used to calculate the framework Si/Al ratio of HY in the SiO2-TiO2-HY composites. XRD confirmed the presence of nanosized TiO2 (anatase phase) in all calcined composites. Nitrogen adsorption isotherms showed a decrease in surface area and pore volume for higher calcination temperature. A simple mechanical process was used to impregnate the different composites on the cotton substrates. The photocatalytic activity of cotton textiles functionalized with SiO2-TiO2 and SiO2-TiO2-HY composites was tested via the degradation of Rhodamine B (RhB) dye under similar solar irradiation. The best catalytic performance was achieved with the SiO2-TiO2 and SiO2-TiO2-HY composites subjected to a calcination treatment at 400 °C, whereas SiO2-TiO2 presented a decolourization and mineralization around 94% and 89%, respectively, after 2 h of irradiation. Furthermore, the products of RhB degradation were analysed and identified by using HPLC-ESI–MS and ion chromatography techniques and a photocatalytic mechanism was proposed.The authors thank CAPES from Brazil for the financial support of this work. This work is also a result of project “AIProcMat@N2020 − Advanced Industrial Processes and Materials for a Sustainable Northern Region of Portugal 2020”, with the reference NORTE-01-0145-FEDER-000006 and the project BioTecNorte (operation NORTE-01-0145-FEDER-000004), supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF). This work also has been funded by ERDF through COMPETE2020 − Programa Operacional Competitividade e Internacionalização (POCI), Project POCI-01-0145-FEDER-006984 − Associate Laboratory LSRE-LCM and by national funds through FCT − Fundacão para a Ciência e a Tecnologia for project PTDC/AAGTEC/5269/2014 and Centre of Chemistry (UID/QUI/00686/2013 and UID/QUI/0686/2016).info:eu-repo/semantics/publishedVersio

Understanding the structural and optical evolution of Eu3+ and Dy3+ co-doped YVO4 phosphors across concentration series for lighting applications

YVO4 nanoparticles co-doped with Eu3+ and Dy3+ ions were successfully synthesized using a conventional coprecipitation method. The resulting phosphors exhibited a single-phase trigonal YVO4 structure, with nanoparticles averaging approximately 60 nm in size, obtained by measurements carried out with scanning electron microscope images. UV–visible diffuse reflectance spectroscopy analysis reveals that the direct band gaps of our samples fall within the range of 3.6–3.75 eV. After a thorough analysis, the optimal doping concentration was identified as 2 at% Eu3+ and 2 at% Dy3+ ions co-doping, exhibiting the strongest up-conversion emission intensity under 310 nm excitation. YVO4:x (Eu3+, Dy3+) phosphors exhibit distinct bands corresponding to transitions of Dy3+ and Eu3+ ions from their 4F9/2 and 5D0 excited states, respectively. The energy transfer from Dy3+ to Eu3+ is validated through electric dipole–dipole interaction, with a critical distance of 15.63 A. YVO4 nanoparticles codoped with Eu3+ and Dy3+ ions exhibit wide-range control over their photoluminescence color by regulating the concentration of both dopants. These findings suggest great potential for applications in current industrial settings.This work was supported by the European Structural and Investment Funds in the FEDER Component through the Operational Competitiveness and Internationalization Programme (COMPETE 2020) under Advanced Decision Making in productive systems through Intelligent Networks (ADM.IN) Project 055087 (POCI-01–0247-FEDER-055087), and partially supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020

High performance ternary solid polymer electrolytes based on high dielectric poly(vinylidene fluoride) copolymers for solid state lithium-ion batteries

The Supporting Information is available free of charge at: https://pubs.acs.org/doi/10.1021/acsami.3c03361Renewable energy sources require efficient energy storage systems. Lithium-ion batteries stand out among those systems, but safety and cycling stability problems still need to be improved. This can be achieved by the implementation of solid polymer electrolytes (SPE) instead of the typically used separator/electrolyte system. Thus, ternary SPEs have been developed based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene), P(VDF-TrFE-CFE) as host polymers, clinoptilolite (CPT) zeolite added to stabilize the battery cycling performance, and ionic liquids (ILs) (1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN])), 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([PMPyr][TFSI]) or lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), incorporated to increase the ionic conductivity. The samples were processed by doctor blade with solvent evaporation at 160 °C. The nature of the polymer matrix and fillers affect the morphology and mechanical properties of the samples and play an important role in electrochemical parameters such as ionic conductivity value, electrochemical window stability, and lithium-transference number. The best ionic conductivity (4.2 × 10–5 S cm–1) and lithium transference number (0.59) were obtained for the PVDF-HFP-CPT-[PMPyr][TFSI] sample. Charge–discharge battery tests at C/10 showed excellent battery performance with values of 150 mAh g–1 after 50 cycles, regardless of the polymer matrix and IL used. In the rate performance tests, the best SPE was the one based on the P(VDF-TrFE-CFE) host polymer, with a discharge value at C-rate of 98.7 mAh g–1, as it promoted ionic dissociation. This study proves for the first time the suitability of P(VDF-TrFE-CFE) as SPE in lithium-ion batteries, showing the relevance of the proper selection of the polymer matrix, IL type, and lithium salt in the formulation of the ternary SPE, in order to optimize solid-state battery performance. In particular, the enhancement of the ionic conductivity provided by the IL and the effect of the high dielectric constant polymer P(VDF-TrFE-CFE) in improving battery cyclability in a wide range of discharge rates must be highlighted.The authors thank the Fundação para a Ciência e Tecnologia (FCT) for financial support under the framework of Strategic Funding UIDB/04650/2020, UID/FIS/04650/2020, UID/EEA/04436/2020, and UID/QUI/00686/2020 and under Projects MIT-EXPL/TDI/0033/2021, POCI-01-0247-FEDER-046985, and 2022.03931.PTDC funded by national funds through FCT and by the ERDF through the COMPETE2020─Programa Operacional Competitividade e Internacionalização (POCI). The authors also thank the FCT for financial support under Grant SFRH/BD/140842/2018 (J.C.B.) and FCT Investigator Contracts 2020.02915.CEECIND (D.M.C), CEECIND/00833/2017 (R.G.), and 2020.04028.CEECIND (C.M.C.). This study forms part of the Advanced Materials program and was supported by MCIN with funding from European Union NextGenerationEU (Grant PRTR-C17.I1) and by the Basque Government under the IKUR program. The authors are thankful for technical and human support provided by SGIker (UPV/EHU/ERDF, EU)

Influence of solvent evaporation temperature on the performance of ternary solid polymer electrolytes based on poly(vinylidene fluoride-co-hexafluoropropylene) combining an ionic liquid and a zeolite

Solid polymer electrolytes (SPEs) will allow improving safety and durability in next-generation solid-state lithium-ion batteries (LIBs). Within the SPE class, ternary composites are a suitable approach as they provide high room-temperature ionic conductivity and excellent cycling and electrochemical stability. In this work, ternary SPEs based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as a polymer host, clinoptilolite (CPT) zeolite, and 1-butyl-3-methylimidazolium thiocyanate ([Bmim][SCN])) ionic liquid (IL) as fillers were produced by solvent evaporation at different temperatures (room temperature, 80, 120, and 160 °C). Solvent evaporation temperature affects the morphology, degree of crystallinity, and mechanical properties of the samples as well as the ionic conductivity and lithium transference number. The highest ionic conductivity (1.2 × 10-4 S·cm-1) and lithium transference number (0.66) have been obtained for the SPE prepared at room temperature and 160 °C, respectively. Charge-discharge battery tests show the highest value of discharge capacity of 149 and 136 mAh·g-1 at C/10 and C/2 rates, respectively, for the SPE prepared at 160 °C. We conclude that the fine control of the solvent evaporation temperature during the preparation of the SPE allows us to optimize solid-state battery performance.The authors thank the Fundação para a Ciência e Tecnologia (FCT) for financial support under the framework of Strategic Funding UIDB/04650/2020, UID/FIS/04650/2020, UID/EEA/04436/2020, and UID/QUI/0686/2020 and under projects MIT-EXPL/TDI/0033/2021, 2022.03931.PTDC, and POCI-01-0247-FEDER-046985 funded by national funds through FCT and by the ERDF through the COMPETE2020─Programa Operacional Competitividade e Internacionalização (POCI). The authors also thank the FCT for financial support under Grant SFRH/BD/140842/2018 (J.C.B.) and FCT investigator contracts 2020.02915.CEECIND (D.M.C.), CEECIND/00833/2017 (R.G.), and 2020.04028.CEECIND (C.M.C.). This study forms part of the Advanced Materials program and was supported by MCIN with funding from European Union NextGenerationEU (PRTR-C17.I1) and by the Basque Government under the IKUR program. The authors are thankful for technical and human support provided by SGIker (UPV/EHU/ERDF, EU)

Influence of ionic liquid characteristics on the performance of ternary solid polymer electrolytes with poly(vinylidene fluoride-co-hexafluoropropylene) and zeolite

Solid polymer electrolytes (SPEs) are the necessary step towards solid-state lithium-ion batteries (LIBs). Their function as separator and electrolyte allows to increase the safety of energy storage devices by the elimination of the liquid components. In this work, three-component SPEs based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) as host polymer, clinoptilolite zeolite, and different ionic liquids (ILs) (1-ethyl-3-methylimidazolium thiocyanate ([EMIM][SCN]), 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]), 1-ethyl-3-methylimidazolium dicyanamide ([EMIM][NCN2]) and 1-butyl-3-methylimidazolium dicyanamide ([BMIM][NCN2]) were produced and characterized. The influence of the nature of the IL anion and cation on the morphology, degree of crystallinity, mechanical properties, ionic conductivity, and battery cycling performance were studied. It is demonstrated that the [SCN]- anion is the most suitable if SPE applications are envisaged. The ionic conductivity depends on the IL type. At room temperature, a maximum value of 1.3 × 10−5 S cm−1 was obtained for the SPE doped with [BMIM][NCN2]. Regarding battery performance, the best value of discharge capacity was observed for the SPE based on [BMIM][SCN], which for an initial discharge capacity of 135 mAh.g−1 yielded a capacity loss below 30% after 30 cycles at room temperature. Thus, it is concluded that proper selection of the IL (cation chain length and anion size) allows tailoring battery performance of solid-state batteries based on three-component SPEs.The authors thank the Fundação para a Ciência e Tecnologia (FCT) for financial support under the framework of Strategic Funding UIDB/04650/2020, UID/FIS/04650/2020, UID/EEA/04436/2020, and UID/QUI/0686/2020 and under projects POCI-01-0145-FEDER-028157, MIT-EXPL/TDI/0033/2021, POCI-01-0247-FEDER-046985 and 2022.03931.PTDC funded by national funds through FCT and by the ERDF through the COMPETE2020—Programa Operacional Competitividade e Internacionalização (POCI). The authors also thank the FCT for financial support under Grant SFRH/BD/140842/2018 (J.C.B.) and FCT investigator contracts 2020.02915.CEECIND (D.M.C), CEECIND/00833/2017 (RG) and 2020.04028.CEECIND (C.M.C.). This study forms part of the Advanced Materials program and was supported by MCIN with funding from European Union NextGenerationEU (PRTR-C17.I1) and by the Basque Government under the IKUR and ELKARTEK programs. The authors thank for technical and human support provided by SGIker (UPV/EHU/ERDF, EU)

Simple shape-selective control of germanium pyroxene crystals

Molecular recognition at interfaces is essential approach for growth of crystals with selectively exposed facets. In general, this process is guided by impurities or solvents that favor the development of surfaces with particular reticular density. However, the specific agents that direct the crystal habit of one system often remain irrelevant for another, and thus, the control of crystal surface of many materials is still poorly known. Here we show selective resizing of prismatic crystal facets of germanium clinopyroxene (NaFeGe2O6) only by a simple switch between nitrate (Fe3+), chloride (Fe3+), and sulfate (Fe2+) sources of iron. The observed effect is explained by the combination of different rates of ion transport to the crystal surface and binding affinity of the hydrolyzed derivatives of the iron precursors that cap the crystal surface during the crystallization. Furthermore, this work reveals the first mild hydrothermal synthesis of germanium clinopyroxeneThis work was supported by the Fundaçã̧o para a Ciência e a Tecnologia (FCT) − “Investigador 2013 (IF/01516/2013)”