Fluoride-ion conductors show promise for next-generation solid-state ionics, but achieving high room-temperature conductivity and strong thermal stability remains a significant challenge, especially in rareearth fluoride systems, where vacancy formation, clustering, and microstructure intricately influence ion transport. Here, we show that mechanochemical synthesis followed by moderate hot pressing within the effective temperature range of 200-300 °C yields a tysonite-type Ca-doped rare-earth fluoride with high room-temperature conductivity. Within the low-temperature processing route, vacancy topology, c-axis lattice expansion, and grain-boundary structure are collectively optimized, resulting in a 5-orderof-magnitude increase in room temperature (RT) fluoride-ion conductivity to approximately 10 −4 S cm −1 , while also lowering the activation energy to approximately 0.4 eV. Thermogravimetric analysis, combined with time-resolved Electrochemical Impedance Spectroscopy (EIS) data, indicates that fluctuations in conductivity can be attributed to changes in defect chemistry, particularly the formation of vacancies at the fluorine site. Hot pressing at 400 °C results in vacancy clustering, c-axis collapse, the formation of intergranular glassy phases, and a sharp decrease in conductivity to approximately 10 −9 S cm −1 , highlighting a trade-off among processing, structure, and ion transport. Notably, pellets pressed at 300 °C show slow conductivity relaxation over approximately 30 days under ambient conditions, indicating metastable defect dynamics and long-term stabilization. We demonstrate that near singlecrystal ion conductivity in polycrystalline tysonite fluorides can be attained not via densification or equilibrium defect optimization, but by kinetically stabilizing an anisotropic defect network through low-temperature thermomechanical processing.

Antimony sulfide (Sb2S3), an emerging photovoltaic material, is desirable for efficient, cost-effective solar cells, attributed to its capability to achieve highly crystallized Sb2S3 films by nonvacuum techniques, favoring the design of all-solution-processed photovoltaics. A high-performance Sb2S3 solar cell often constitutes hydrophobic hole-transporting layers, creating a surface energy mismatch with hydrophilic solution-processed, effective transparent conductors (TCs) like silver nanowires (AgNWs). Therefore, the realization of an efficient, all-solution-processed Sb2S3 solar cell remains challenging. Herein, a completely solution-processed Sb2S3 solar cell is achieved by designing an effective AgNW-based TC by intermixing an AgNW solution with 27 vol % poly(3-hexylthiophene) (P3HT). An interaction between isopropyl alcohol, a polar solvent in the AgNW solution, and P3HT results in the aggregation of the polymer, enhancing adhesion between the AgNWs and the glass/FTO/TiO2/Sb2S3/P3HT surface. This technique enables a reduction in the sheet resistance of AgNW-based TCs by 88%. The Sb2S3-based solar cells with modified AgNW-based TCs provide an efficiency of 2.1% and a consistent open-circuit value of 0.7 V for up-scaled devices. The adaptation of TCs allows the device to work in bifacial mode with a see-through feature, evidenced by an average visible light transmittance of 11.7%. The developed all-solution-processed Sb2S3-based semitransparent photovoltaics would be advantageous for photovoltaic-integrated product applications.

This study presents the synthesis and characterisation of cellulose long chain fatty acid ester films using a novel distillable ionic liquid (IL), 5-methyl-1,5,7-triaza-bicyclo-[4.3.0] non-6-enium acetate [mTBNH][OAc] in combination with DMSO as a cosolvent. The cellulose esters cellulose diacetate (CDA), cellulose laurate (CL), and cellulose palmitate (CP) were fabricated through an evaporation-induced phase separation method (EIPS) and dried under two conditions: conventional oven drying (RO) and vacuum oven drying (VO). The influence of drying conditions on the structural, thermal, and surface properties of the films was evaluated using XRD, TGA, SEM, AFM, and contact angle measurement techniques. XRD confirmed an amorphous structure in all films, with no significant effect on the drying conditions. TGA revealed consistent thermal degradation profiles across all samples, with ester group decomposition accruing between 140 and 250 °C and main cellulose backbone degradation near 350 °C. The SEM cross-section showed a uniform film, devoid of cavities and layered structures. AFM analysis demonstrated that VO-dried films had smoother surfaces compared to RO-dried films, correlating with increased contact angles and enhanced hydrophobicity. A strong inverse relationship between surface roughness and hydrophobicity was observed, particularly in VO-dried samples, although this was not statistically significant due to data variability. Overall, the drying method had minimal impact on the internal structure and thermal stability; it significantly influenced surface morphology and wettability.

Cellulose, as a sustainable raw material, holds a promising future as a thermoplastic material. This work focused on fabricating cellulose ester thin films by using both controlled vacuum oven drying and conventional oven drying by the evaporation induced phase separation method (EIPS). A novel distillable ionic liquid (IL) 5-Methyl-1,5,7-triaza-bicyclo- [4.3.0]non-6-enium acetate [mTBNH][OAc]with high dissolving capability of cellulose along with dimethylsulfoxide (DMSO) as a co-solvent are used. The drying methods were compared to investigate their influence on the Cellulose ester films morphological and wettability properties. Based on the results, with increasing the drying rate in the vacuum oven the films have a smoother surface (with CP having 2.14nm RMS value) than the other samples, also indicating higher contact angles of 124 for CP under vacuum drying conditions with denser films.

Photocatalysis is a green and cost-effective approach to environmental remediation. While TiO2 is considered one of the benchmark photocatalysts, alternative materials such as Bi2O3 have recently attracted increasing scientific attention as prospective visible light photocatalysts. This study aimed to develop a strategy for Bi2O3 thin film deposition via ultrasonic spray pyrolysis and systematically study process variables for the deposition of β-Bi2O3 thin films for photocatalytic applications. To achieve the aim, the precursor solution concentration as well as deposition and annealing temperature were optimised. The structural, optical, morphological, chemical and wettability properties of the obtained Bi2O3 thin films were investigated with respect to the effect on the photocatalytic oxidation of 10 ppm methyl orange (MO). The highest photocatalytic activity (48% in 5 h) under UV-A was recorded for the β-Bi2O3 film deposited using 0.1 M precursor solution at 300 °C and heat-treated for 1 h in air at 350 °C. Deposition at 300 °C resulted in an amorphous film structure, whereas annealing at 350 °C led to the formation of the β-Bi2O3 phase with the dominant facet orientation (220). These results show the suitability of spray pyrolysis for the deposition of Bi2O3 thin films with promising results for MO dye degradation, expanding the range of suitable photocatalytic materials.

The study proposes using the distillable ionic liquid 5-methyl-1,5,7-triaza-bicyclo-[4.3.0]non-6-enium acetate, [mTBNH][OAc], for cellulose dissolution, making it an environmentally friendly alternative to conventional solvents in the transesterification of cellulose with vinyl esters. This ionic liquid (IL) has high dissolving power for cellulose and durability for recycling. However, its high viscosity limits cellulose concentration and its expensiveness hinders commercialization. The addition of naturally derived, low-cost, and low-viscous co-solvents can reduce overall cost and viscosity. In this study, various green co-solvents, including γ-valerolactone (GVL), dimethyl isosorbide (DMI), sulfolane (SLF), and N,N′-dimethylpropyleneurea (DMPU), were mixed with [mTBNH][OAc] to test their ability to enhance cellulose transesterification. Cellulose esters with a degree of substitution (DS) up to 1.6 have been synthesized. The chemical composition of the materials was confirmed by FTIR and NMR. Green co-solvents alter the solubility and flow activation energy of cellulose in binary solvents. The produced cellulose esters become more amorphous, and their viscosity and complex moduli decrease because of the DS changing in the following order: DMPU < SLF < DMI < GVL. The efficiency of internal plasticization of cellulose esters was studied through melt flow rheology, which indicated that it increases with increasing DS. All tested cellulose esters have almost identical degradation temperatures, as detected by TGA.

Multinary chalcogenides with Kesterite structure Cu2ZnSn(S,Se)4 (CZTSSe) are a prospective material base for the enhancement of the photovoltaics industry with abundant and environmentally friendly constituents and appropriate electro-physical properties for building highly efficient devices at a low cost with a short energy pay-back time. The actual record efficiency of 13.6%, which was reached recently, is far below the current isostructural chalcopyrite’s solar cells efficiency of near 24%. The main problems for future improvements are the defects in and stability of the Kesterite absorber itself and recombination losses at interfaces at the buffer and back contacts. Here, we present an investigation into the rapid thermal annealing (RTA) of as-electrodeposited thin films of Cu2ZnSnS4 (CZTS). The treatment was carried out in a cold wall tubular reactor in dynamic conditions with variations in the temperature, speed and time of the specific elements of the process. The effect of annealing was investigated by X-ray diffractometry, Raman scattering and Scanning Electron Microscopy (SEM). The phase composition of the films depending on treatment conditions was analyzed, showing that, in a slow, prolonged, high-temperature process, the low-temperature binaries react completely and only Kesterite and ZnS are left. In addition, structural investigations by XRD have shown a gradual decrease in crystallite sizes when the temperature level and duration of the high-temperature segment increases, and respectively increase in the strain due to the formation of the phases in non-equilibrium conditions. However, when the speed of dynamic segments in the process decreases, both the crystallite size and strain of the Kesterite non-monotonically decrease. The grain sizes of Kesterite, presented by SEM investigations, have been shown to increase when the temperature and the duration increase, while the speed decreases, except at higher temperatures of near 750 °C. The set of experiments, following a scrupulous analysis of Raman data, were shown to have the potential to elucidate a way to ensure the fine manipulation of the substitutional Cu/Zn defects in the structure of CZTS thin films, considering the dependences of the ratios of Q = I287/I303 and Q′ = I338/(I366 + I374) on the process variables. Qualitatively, it can be concluded that increases in the speed, duration and temperature of RTA lead to increases in the order of the structure, whereas, at higher temperatures of near 750 °C, these factors decrease.

A wide range of mixtures of volatile organic compounds (VOCs), which are present in indoor air in low concentrations, can strongly affect human health [...]

The deposition of nickel oxide (NiO x ) thin film from an acetylacetonate source using many solution-based techniques has been avoided owing to its poor solubility in alcohol solvents. From this perspective, this work provides a systematic investigation of the development of NiO x thin film, using a combinative approach of ultrasonic spray pyrolysis (USP) and Li dopant for the synthesis and optimization of structural and optoelectronic properties of the films. An in-depth comparative analysis of nickel acetylacetonate-based precursor, employing acetonitrile and methanol as solvents, is provided. It is demonstrated that USP from acetylacetonate precursor yielded uniform, well-compact, and transparent films, with polycrystalline cubic NiO x crystal structures. By screening the deposition temperature in the range of 300–450°C, a temperature of 400°C was identified as an optimal processing temperature leading to uniform, compact, highly transparent, and p-type conductive films. At optimized deposition conditions (400°C), lithium-doped NiO x (Li:NiO x ) thin film was deposited. The shift of the main (200) XRD peak position from 43.48° (0-Li:NiO x ) to 43.56° (60-Li:NiO x ) indicated Li incorporation into the NiO x lattice. An X-ray photoelectron spectroscopy (XPS) study was employed to unravel the incorporation of Li into the deposited Li:NiO x thin films. With the deconvolution of the Ni 2p core level for the as-deposited (0, 60)-Li:NiO x films, the intensity of Ni 3+ related peak was found to increase slightly with Li doping. Furthermore, all the deposited Li:NiO x thin films showed p-type conductivity behavior, and the resistivity was reduced from 10 4 Ωcm (0-Li:NiO x ) to 10 2 Ωcm (60-Li:NiO x ). Based on these results, the deposited NiO x and Li:NiO x thin films suggested that USP-deposited Li:NiO x is highly suitable for application in inverted structure solar cells as the hole transport layer.

The development of low-material-quantity, transparent, anatase TiO2 nanoparticle free thin films as photocatalytic materials together with a profound understanding of their photocatalytic activity under ultraviolet (UV-A) and visible (VIS) light is crucial for environmentally friendly indoor air photocatalytic coatings. In this work, a TiO2 thin film modified by an increased amount of acetylacetone in the precursor solution with a material quantity of 0.2 mg cm-2 was successfully deposited on a borosilicate glass substrate by ultrasonic spray pyrolysis. VOC degradation as a single model pollutant and in mixtures under different operating conditions was studied in a multi-section continuous flow reactor. Under UV-A the reaction rate constants for heptane and toluene oxidation as individual pollutants were 1.7 and 0.9 ppm s-1, respectively. In 9 ppm VOC mixtures of acetaldehyde, acetone, heptane and toluene all the compounds were completely oxidized in a reaction time of less than 50 s. The TiO2 film showed moderately high photocatalytic activity under VIS light. The conversions of acetaldehyde, acetone, heptane and toluene in 9 ppm VOC mixtures under VIS light reached 100, 100, 78 and 31%, respectively. The synthesized TiO2 film shows promising ability in indoor air purification from VOCs. The results of this study give an extensive estimation of the thin film's photocatalytic efficiency and provide valuable data for future applications in environmental remediation.

For the efficient photocatalytic oxidation of organic pollutants at surfaces of semiconductors, photogenerated holes shall be separated toward the surface and transferred to reactive surface sites, whereas the transfer of photogenerated electrons toward the surface shall be minimized. In this Research Article, the identification of suitable synthesis control of charge separation combined with an in-depth understanding of charge kinetics and trapping passivation mechanisms at the related surfaces can provide tremendous opportunities for boosting the photocatalytic performance. In this work, a comprehensive transient surface photovoltage spectroscopy study of charge separation at anatase TiO2 thin films, synthesized by ultrasonic spray pyrolysis from titanium(IV) isopropoxide (TTIP)-acetylacetone (AcacH) based precursor is reported. By varying the amount of AcacH in the precursor solution, an experimental approach of synthesis control of the charge transfer toward TiO2 surface is provided for the first time. An increased amount of AcacH in the precursor promotes transition from preferential fast electron to preferential fast hole transfer toward anatase surface, correlating with a strong increase of the photocatalytic decomposition rate of organic pollutants. Suitable mechanisms of AcacH-induced passivation of electron traps at TiO2 surfaces are analyzed, providing a new degree of freedom for tailoring the properties of photocatalytic systems.

Following article describes the practical application of energy producing solar roadway in Estonia, developed by several technology companies in cooperation with Tallinn University of Technology (TalTech) laboratories and research groups. Several challenges were defeated during the research and design process: development of proper potting compound and installation methods of energy producing pavement blocks, development of a novel photovoltaic microinverter technology with shade-tolerant global maximum point tracking, etc. There are several test sites of solar roadways producing energy around Tallinn, Estonia, that can produce a considerable amount of electrical power and direct it to the grid. The test period of the system has validated the overall feasibility of the solar roadway concept and provided the scientists and engineers with valuable experience.

This paper highlights the effect of laser heat treatment on the adhesion and sliding wear of physical vapour deposited (PVD) multilayer AlxTi1-xN and nanocomposite AlxTi1-xN/alpha-Si3N4 coatings on carbon (C45E, preliminarily bulk hardened) and tool steel (Vanadis (R) 6, preliminarily bulk hardened and tempered), as well as substrate steel microstructure and hardness. The hardened zone in carbon steel generally comprises martensite and retained austenite. The hardened zone in tool steel contains martensite and retained austenite, as well as M7C3 (M = Fe, Cr) and MC (M = Fe, V) carbides. Laser heat treatment increased the average surface hardness of the carbon steel by 1.5-3.1 times and that of the tool steel by 1.1-1.2 times. The critical adhesion loads L-c1 and L-c2 enlarged by 1.22.6 times and by 1.2-1.3 times, respectively, in the case of the coatings deposited on the carbon steel. However, only slightly positive or no changes in the critical adhesion loads were observed for the tool steel case. The scratch crack propagation resistance (CPRs) of the coatings increased by 1.1-4.8 times, being more pronounced for the carbon steel substrate. The improvement of adhesion was assumed to be the result of the increased hardness (H) to Young's modulus (E) H/E and H-3/E-2 ratios of the substrate steel. Wear resistance of the coatings improved by 1.3-1.7 times. Scuffing and surface fatigue wear were the principle wear mechanisms in all the cases. However, the first mechanism was more remarkable for laser heat treated samples, and the second for the samples that remained untreated by laser. Apart from the above-mentioned increment of H/E and H-3/E-2 ratios, the improvement of wear resistance was explained by the increased CPRs values of the coatings and by the presumed precipitation of the AlN phase within them.

Reactive sintering of cemented carbides involves mechanical and thermal activation of precursor elemental powders, followed by in-situ synthesis of tungsten carbide. This approach promotes formation of ultrafine microstructure favored in many cemented carbide applications. Our study focuses on the effect of mechanical activation (high-energy milling) on the properties of powder and following thermal activation (sintering) on the microstructure characteristics and phase composition. Reactive sintering proved effective – an ultrafine grained microstructure of cemented carbides with Co and Fe binders was achieved. Formation of tungsten carbide grains was complete at low temperature during reactive spark plasma sintering, resulting in textured microstructure with anisotropic grain formation and growth.

We describe a unique amorphous cobalt metal–organic framework derived material that acts both as a recyclable heterogeneous catalyst for organic transformations and as a trifunctional electrocatalyst.

TiO(2)thin films, modified by acetylacetone (AcacH) in solution, were deposited on glass substrate by ultrasonic spray pyrolysis and tested for photocatalytic activity in a multi-section continuous flow reactor by degradation of acetone and acetaldehyde under ultraviolet and visible light. The increase in molar ratio of AcacH in respect of titanium (IV) isopropoxide (TTIP) from 1:5 to 1:8 modified the electronic structure of the films, favoring enhanced photocatalytic activity. The photocatalytic activity was enhanced approximately twofold on the film with molar ratio 1:8 under both irradiations; the film completely oxidized 10 ppm of acetone and acetaldehyde. The photocatalytic efficacy of TiO(2)films in oxidation of air pollutants was three times higher compared to the industrial glass Pilkington Activ(TM). Moreover, all the synthesized films indicate antibacterial efficiency againstE. coliof over 99% under ultraviolet. TiO(2)film, with TTIP:AcacH molar ratio 1:8 having great possibility for its commercial use as a material for indoor air purification.

Preparation of electrocatalysts often relies on the use of multiple starting materials – inorganic salts or organometallic precursors, nanostructured carbon supports, organic additives, dopants and carbonization under modifying atmospheres (e.g. NH3 or H2) – with the examples of electrocatalysts arising from a single precursor being much less common. Herein, we have surveyed a series of heterobivalent scaffolds to identify an iron/benzimidazole-based metal– organic framework as a uniform starting material. By merging the catechol and imidazole units together, we get direct entry into a highly efficient bifunctional oxygen electrocatalyst, which alleviates the need for additional dopants and modifying conditions (ORR: Eon = 1.01 V, E1/2 = 0.87 V vs. RHE in 0.1 M KOH; OER: 1.60 V @10 mA cm–2 in 0.1 M KOH; ∆E = 0.73 V). We demonstrate that by fine-tuning the chemical nature of an organic linker, one is able modulate the electrochemical properties of a single precursor-derived electrocatalyst material.

In this study, TiO2 thin films were deposited by ultrasonic spray pyrolysis from solutions with concentrations of 0.1 and 0.2 M. The deposition temperature was adjusted at 350 °C and all samples were annealed at 500 °C for 1 h in air. The thickness of TiO2 films was changed in the range of 50 to ca. 800 nm by varying the number of spray cycles from 1 to 21 and the solution concentration. The results showed that the mean crystallite size of the anatase structure, the surface roughness, and light absorption increased with the film thickness. The effect of film thickness on the photocatalytic activity was investigated with the photodegradation of stearic acid under UV-A irradiation. The optimal thickness of TiO2 films fabricated by ultrasonic spray pyrolysis for photocatalytic self-cleaning applications was in the range of 170–230 nm, indicating a ca. 2.6 times-higher photocatalytic self-cleaning activity compared to the reference sample, Pilkington ActivTM. The photocatalytic results showed that the 190 nm-thick TiO2 film deposited from the 0.1 M solution applying seven spray cycles exhibited the finest grain structure and maximum photocatalytic activity, leading to 94% of stearic acid degradation in 180 min under UV-A light with the reaction rate constant k = 0.01648 min−1.

The economic, environmental and healthcare aspects are pushing cemented carbide industry to reduce or even avoid the usage of conventional binder metals – nickel and cobalt. Commonly, austenitic Fe-Ni alloys have been preferred choice for substituting Co. Similar to Ni, manganese acts as austenite stabilizer and studies have shown that Fe-Mn alloys offer alternative binder metal to Co and Ni in cemented tungsten carbides. In addition, Fe-Mn as a binder potentially offers improved wear resistance due to the well-known wear properties of Fe-Mn-C steels. Addition of chromium to the binder composition increases corrosion performance of composite. Cemented carbides bonded with austenitic FeCrNi binder have demonstrated promising performance. In present work the possibility of achieving austenitic binder phase through substitution of nickel by manganese as an austenite stabilizer is investigated. Structure formation, phase composition and mechanical performance of WC-FeMn and WC-FeCrMn cemented carbides are discussed.

A typical schematic for both spray pyrolysis set-up and ZrOx-based TFT device, and the corresponding electrical performance.