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Emission of greenhouse gases and infectious diseases caused by improper agro-waste disposal has gained significant attention in recent years. To overcome these hurdles, agro-waste can be valorized into valuable bioactive compounds that act as reducing or stabilizing agents in the synthesis of nanomaterials. Herein, we report a simple circular approach using Citrus reticulata Blanco (C. reticulata) waste (peel powder/aqueous extract) as green reducing and capping/stabilizing agents and Zn nitrate/acetate precursors to synthesize ZnO nanoparticles (NPs) with efficient antimicrobial and photocatalytic activities. The obtained NPs crystallized in a hexagonal wurtzite structure and differed clearly in their morphology. UV-vis analysis of the nanoparticles showed a characteristic broad absorption band between 330 and 414 nm belonging to ZnO NPs. Fourier transform infrared (FTIR) spectroscopy of ZnO NPs exhibited a Zn-O band close to 450 cm-1. The band gap values were in the range of 2.84-3.14 eV depending on the precursor and agent used. The crystallite size obtained from size-strain plots from measured XRD patterns was between 7 and 26 nm, with strain between 16 and 4%. The highly crystalline nature of obtained ZnO NPs was confirmed by clear ring diffraction patterns and d-spacing values of the observed lattice fringes. ZnNPeelMan_400 and ZnNExtrMan showed good stability, as the zeta potential was found to be around −20 mV, and reduced particle aggregation. Photoluminescence analysis revealed different defects belonging to oxygen vacancies (VO+ and VO+2) and zinc interstitial (Zni) sites. The presence of oxygen vacancies on the surface of ZnAcExtrMan_400 and ZnAcPeelMan_400 increased antimicrobial activity, specifically against Gram-negative bacteria Escherichia coli (E. coli) and Salmonella enteritidis (S. enteritidis). ZnNExtrMan with a minimal inhibitory concentration of 0.156 mg/mL was more effective against Gram-positive bacteria Staphylococcus aureus (S. aureus), r

Pure, samarium (Sm3+) and zirconium (Zr4+) doped titanium dioxide (TiO2) nanofibers were synthesized using the electrospinning method followed by calcination at 500 °C for 1 h. The structure, morphology and optical properties of the obtained nanofibers were investigated as a function of different Sm3+ and Zr4+ contents (0.5–5 mol%). XRD and FTIR analysis showed that addition of Sm or Zr suppressed the transformation of anatase to rutile. After calcination all fibers were smooth, fragile and randomly oriented. HRTEM analysis revealed that doping with Sm didn’t affect the TiO2 crystal lattice whilst Zr4+ ions replaced the substitutional sites in the anatase crystalline lattice. The effects of Sm3+ and Zr4+-dopant content and different doses of photocatalyst on the photodegradation of methylene blue (MB) were monitored under UV-light illumination. TiO2:0.5%Sm3+ and TiO2:1.0%Zr4+ nanofibers have shown the highest photocatalytic activity of 97% and 98% due to red shifting of the band gap towards visible light in the case of Sm and suppressed electron-hole recombination shown in recorded PL spectra in the case of Zr.

In this work, titanium dioxide (TiO2) nanofibers doped with 0.5–5 mol% zirconium ions (Zr4+) were synthesized by combining the sol-gel process and electrospinning method, and calcined at 500 °C. The morphological, structural and optical properties of pure and Zr-doped TiO2 nanofibers were investigated. According to the XRD and FTIR analyses, the addition of Zr as a dopant suppressed the transformation of anatase to rutile phase. Scanning electron microscopy showed that all fibers were smooth, fragile and randomly oriented after the calcination process. HRTEM analysis revealed that Zr4+ ions were incorporated at the substitutional sites in the anatase TiO2 crystalline lattice. The photocatalytic efficiency for degradation of methylene blue (MB) was examined for both pure and Zr-doped TiO2 samples. Nanofibers doped with 1% of Zr4+ ions have shown the highest photocatalytic activity of 98%, wich can be explained by considering lower PL intensity in the PL spectrum of this sample, indicating suppressed electron-hole recombination.

An emerging technology of active packaging enables prolongation of food shelf life by limiting the oxygen transfer and the reactivity of free radicals, which both destruct food freshness. In this work, Fe2TiO5 nanoparticles were synthesized using a modified sol–gel method and evaluated as an enforcement of alginate food packaging film. Pure phase Fe2TiO5 nanoparticles had an average particle size of 44 nm and rhombohedral morphology. Fe2TiO5 nanoparticles induce no cell damage of human Caco-2 epithelial cells and show no inhibitory effect towards growth of a panel of bacterial strains, suggesting good biocompatibility. Films obtained by incorporation of Fe2TiO5 nanoparticles into alginate using the solvent casting method show no migration of iron or titanium ions from films to food simulants again suggesting their safety as a packaging material. Fe2TiO5 nanoparticles also showed strong antioxidant efficiency as determined using the DPPḢ assay, and confirmed further in a preservation test on fresh fruit.

Problems that countries all over the world have in common are dependence of economy and energy production on fossil fuels. There is a growing need for energy production and storage routes that are safe for the environment, renewable, efficient and cheap. One of the directions in which science is moving forward is discovering materials suitable for use in batteries and supercapacitors to improve their operating potential, electrical capacity or biocompatibility. The objective is also to synthesize materials for batteries or supercapacitors that are cheap, consist of earth abundant elements and have high electrochemical activity.In this work, mixed nickel-magnesium ferrites NixMg1−xFe2O4, with x being 0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1, were synthesized via sol-gel combustion synthesis with citric acid used as fuel and nitrate ions used as oxidizing agents. Combusted powders were calcined at 700 °C. The structure and morphology of the powders were characterized with X-ray diffraction method (XRD), field emission scanning electron microscopy (FESEM), Raman and FTIR spectroscopy. The band gap was calculated by using UV/Vis diffuse reflectance spectroscopy (DRS). Samples were cast on nickel foam and tested as energy storage materials in a three-electrode setup in 3 M KOH aqueous solution as electrolyte. The methods used were cyclic voltammetry (CV) and constant current chronopotentiometry to obtain galvanostatic charge-discharge (GCD) curves. Results show that all of the synthesized materials show battery-type charge storage in alkaline electrolyte due to the formation of metal cation oxyhydroxides. With increasing nickel content, electrochemical activity drops. The highest value of capacity, 34.3 mA h g-1 at the current density of 500 mA g-1 is ascribed to magnesium ferrite, MgFe2O4.

Nickel manganite nanocrystalline fibers were obtained by electrospinning and subsequent calcination at 400 °C. As-spun fibers were characterized by TG/DTA, Scanning Electron Microscopy and FT-IR spectroscopy analysis. X-ray diffraction and FT-IR spectroscopy analysis confirmed the formation of nickel manganite with a cubic spinel structure, while N2 physisorption at 77 K enabled determination of the BET specific surface area as 25.3 m2/g and (BJH) mesopore volume as 21.5 m2/g. The material constant (B) of the nanocrystalline nickel manganite fibers applied by drop-casting on test interdigitated electrodes on alumina substrate, dried at room temperature, was determined as 4379 K in the 20–50 °C temperature range and a temperature sensitivity of −4.95%/K at room temperature (25 °C). The change of impedance with relative humidity was monitored at 25 and 50 °C for a relative humidity (RH) change of 40 to 90% in the 42 Hzπ1 MHz frequency range. At 100 Hz and 25 °C, the sensitivity of 327.36 ± 80.12 kΩ/%RH was determined, showing that nickel manganite obtained by electrospinning has potential as a multifunctional material for combined humidity and temperature sensing.

Nanocrystalline Zn2SnO4/SnO2 powder was obtained by a solid state reaction of ZnO and SnO2 nanopowders mixed in the molar ratio 1:1. The phase composition of the obtained powder was studied by XRD and Raman spectroscopy, morphology and texture were characterized by FESEM, TEM, BET and Hg porosimetry, while XPS and FTIR spectroscopy were used to determine the surface chemistry. The influence of humidity on complex impedance was monitored on bulk samples in the relative humidity (RH) range 30–90% in a climatic chamber in the frequency range 42 Hz- 1 MHz at working temperatures of 25 and 50 °C. Change in RH had a significant influence on impedance reduction, especially noticeable in the lower frequency range, indicating potential application of this nanocomposite as a humidity sensing material. Increase in RH led to an increase in AC conductivity that changed with frequency according to the Jonscher power law. The frequency exponent decreased with increase in RH and sample temperature indicating that the correlated hopping barrier model is the dominant conduction mechanism. Complex impedance was analyzed using an equivalent circuit consisting of a parallel resistance and constant phase element, showing the dominant influence of grain boundaries at both working temperatures (25 and 50 °C). The resistance decreased, while the capacitance and relaxation frequency increased with increase in RH. At high humidity an added Wartburg element enabled modeling of the charge diffusion process

Nanostructured Fe2TiO5 (pseudobrookite), a mixed metal oxide material holds significant promise for utilization in energy and environmental applications. However, its full application is still hindered due to the difficulty to synthesize monophasic Fe2TiO5 with high crystallinity and a large specific surface area. Herein, Fe2TiO5 nanofibers were synthesized via a versatile and low-cost electrospinning method, followed by a calcination process at different temperatures. We found a significant effect of the calcination process and its duration on the crystalline phase in the form of either pseudobrookite or pseudobrookite-hematite-rutile and the morphology of calcined nanofibers. The crystallite size increased whereas the specific surface area decreased with an increase in calcination temperature. At higher temperatures, the growth of Fe2TiO5 nanoparticles and simultaneous coalescence of small particles was noted. The highest specific surface area was obtained for the sample calcined at 500 degrees C for 6 h (S-BET = 64.4 m(2) g(-1)). This work opens new opportunities in the synthesis of Fe2TiO5 nanostructures using the electrospinning method and a subsequent optimized calcination process for energy-related applications.

Nanostructured Fe2TiO5 (pseudobrookite), a mixed metal oxide material holds significant promise for utilization in energy and environmental applications. However, its full application is still hindered due to the difficulty to synthesize monophasic Fe2TiO5 with high crystallinity and a large specific surface area. Herein, Fe2TiO5 nanofibers were synthesized via a versatile and low-cost electrospinning method, followed by a calcination process at different temperatures. We found a significant effect of the calcination process and its duration on the crystalline phase in the form of either pseudobrookite or pseudobrookite–hematite–rutile and the morphology of calcined nanofibers. The crystallite size increased whereas the specific surface area decreased with an increase in calcination temperature. At higher temperatures, the growth of Fe2TiO5 nanoparticles and simultaneous coalescence of small particles was noted. The highest specific surface area was obtained for the sample calcined at 500 °C for 6 h (SBET = 64.4 m2 g−1). This work opens new opportunities in the synthesis of Fe2TiO5 nanostructures using the electrospinning method and a subsequent optimized calcination process for energy-related applications.

Samarium and zirconium-doped TiO2 nanofibers (3 and 5 wt.%) were synthesised by a simple modified electrospinning method. The effects of calcination temperature on the size of the as-spun doped titania fibers was investigated. As-spun nanofibers were studied and characterized through thermal gravimetric analysis (TG-DTA), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning electron microscopy (SEM), while the structure and morphology of calcined fibers was studied by X-Ray Diffraction (XRD), Field Emission Electron Microscopy (FESEM) and spectroscopic techniques (FT-IR and DRS UV-vis). The influence of dopant type and amount on the photocatalytic degradation of Methylene blue (MB) was investigated.

CoxMg1-xFe2O4 (where x was 0.0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1) spinel ferrites were synthesized by the sol-gel combustion method using citric acid as fuel, following the rules of propellant chemistry. Amorphous powders were then calcined at 700 degrees C for 3 h. Structural analysis by X-Ray diffraction (XRD), FTIR and Raman spectroscopy confirmed the formation of a cubic spinel structure where the cation distribution and inversion degree depended on the Co2+ and Mg2+ ion content. Accordingly, the lattice parameter varied between 8.3703 angstrom (MgFe2O4) and 8.3919 A (Co-0.9 Mg0.1Fe2O4) as did the crystallite size, from 34 nm (Co0.1Mg0.9Fe2O4) to 48 nm (Co0.9Mg0.1Fe2O4). Scanning electron microscopy (SEM) showed the formation of multigrain agglomerates. Determined values of the maximal and remanent magnetization, as well as coercive field, depended on the Co2+ and Mg2+ ion content and increased with substitution of diamagnetic Mg2+ ions with magnetic Co2+ ions. Most impressive is the increase of the coercive field from 74 Oe for MgFe2O4 to 1000 Oe for CoFe2O4, as well as an increase of magnetization in the field of 10 kOe from 27.4 emu g(-1) to 75.7 emu g(-1). The determined optical band gaps from UV/Vis DRS measurements showed a strong dependence on cation content, morphology, and crystallite size, decreasing from 2.09 eV for MgFe2O4 to 1.42 eV for CoFe2O4. The photocatalytic efficiency of as-synthesized ferrites was investigated by monitoring photocatalytic degradation of Methylene Blue (MB) under natural sunlight, and artificial light source emitting visible light. Different conditions of MB degradation such as photocatalyst loading, molar concentration of MB, and pH values were investigated. Results have shown that under both visible light and natural sunlight, excessive amounts of cobalt retarded the photocatalytic process. Co0.9Mg0.1Fe2O4 showed considerable activity (74.5% after 4 h) that is unexpected but possibly connected to structural anomalies. The best

The growth of thin oxide coatings on the aluminum substrate in water-based sodium tungstate electrolyte by plasma electrolytic oxidation (PEO) is discussed and experimentally illustrated. The growth is carried out using a distinctive ultra-low duty cycle pulsed direct current (DC) power supply. During the PEO processing elements present in micro-discharges are identified using standard optical emission spectroscopy (OES) technique. The spectral line shape analysis of the first two hydrogen Balmer lines shows the presence of two types of micro-discharges. Obtained coatings are also characterized with respect to their morphology and chemical and phase composition. It is shown that coatings are composed of Al, O, and W, featuring low roughness and porosity. Partial crystallization of the coatings resulted in identification of WO3, W3O8, and gamma-Al2O3 crystalline phases.

Nanostructured Fe2TiO5 (pseudobrookite), a mixed metal oxide material holds significant promise for utilization in energy and environmental applications. However, its full application is still hindered due to the difficulty to synthesize monophasic Fe2TiO5 with high crystallinity and a large specific surface area. Herein, Fe2TiO5 nanofibers were synthesized via a versatile and low-cost electrospinning method, followed by a calcination process at different temperatures. We found a significant effect of the calcination process and its duration on the crystalline phase in the form of either pseudobrookite or pseudobrookite-hematite-rutile and the morphology of calcined nanofibers. The crystallite size increased whereas the specific surface area decreased with an increase in calcination temperature. At higher temperatures, the growth of Fe2TiO5 nanoparticles and simultaneous coalescence of small particles was noted. The highest specific surface area was obtained for the sample calcined at 500 degrees C for 6 h (S-BET = 64.4 m(2) g(-1)). This work opens new opportunities in the synthesis of Fe2TiO5 nanostructures using the electrospinning method and a subsequent optimized calcination process for energy-related applications.

Nanocrystalline nickel manganite (NiMn2O4) powder with a pure cubic spinel phase structure was synthesized via sol-gel combustion and characterized with XRD, FT-IR, XPS and SEM. The powder was mixed with sodium alginate gel to form a nano-biocomposite gel, dried at room temperature to form a thick film and characterized with FT-IR and SEM. DC resistance and AC impedance of sensor test structures obtained by drop casting the nano-biocomposite gel onto test interdigitated PdAg electrodes on an alumina substrate were measured in the temperature range of 20-50 degrees C at a constant relative humidity (RH) of 50% and at room temperature (25 degrees C) in the RH range of 40-90%. The material constant obtained from the measured decrease in resistance with temperature was determined to be 4523 K, while the temperature sensitivity at room temperature (25 degrees C) was -5.09%/K. Analysis of the complex impedance plots showed a dominant influence of grains. The decrease in complex impedance with increase in temperature confirmed the negative temperature coefficient effect. The grain resistance and grain relaxation frequency were determined using an equivalent circuit. The activation energy for conduction was determined as 0.45 eV from the temperature dependence of the grain resistance according to the small polaron hopping model, while the activation energy for relaxation was 0.43 eV determined from the Arrhenius dependence of the grain relaxation frequency on temperature.

Nickel manganite nanocrystalline fibers were obtained by electrospinning and subsequent calcination at 400 degrees C. As-spun fibers were characterized by TG/DTA, Scanning Electron Microscopy and FT-IR spectroscopy analysis. X-ray diffraction and FT-IR spectroscopy analysis confirmed the formation of nickel manganite with a cubic spinel structure, while N-2 physisorption at 77 K enabled determination of the BET specific surface area as 25.3 m(2)/g and (BJH) mesopore volume as 21.5 m(2)/g. The material constant (B) of the nanocrystalline nickel manganite fibers applied by drop-casting on test interdigitated electrodes on alumina substrate, dried at room temperature, was determined as 4379 K in the 20-50 degrees C temperature range and a temperature sensitivity of -4.95%/K at room temperature (25 degrees C). The change of impedance with relative humidity was monitored at 25 and 50 degrees C for a relative humidity (RH) change of 40 to 90% in the 42 Hz pi 1 MHz frequency range. At 100 Hz and 25 degrees C, the sensitivity of 327.36 +/- 80.12 k omega/%RH was determined, showing that nickel manganite obtained by electrospinning has potential as a multifunctional material for combined humidity and temperature sensing.

The aim of this work was to synthesize semiconducting oxide nanoparticles using a simple method with low production cost to be applied in natural sunlight for photocatalytic degradation of pollutants in waste water. Iron titanate (Fe2TiO5) nanoparticles with an orthorhombic structure were successfully synthesized using a modified sol–gel method and calcination at 750°C. The as-prepared Fe2TiO5 nanoparticles exhibited a moderate specific surface area. The mesoporous Fe2TiO5 nanoparticles possessed strong absorption in the visible-light region and the band gap was estimated to be around 2.16 eV. The photocatalytic activity was evaluated by the degradation of methylene blue under natural sunlight. The effect of parameters such as the amount of catalyst, initial concentration of the dye and pH of the dye solution on the removal efficiency of methylene blue was investigated. Fe2TiO5 showed high degradation efficiency in a strong alkaline medium that can be the result of the facilitated formation of OH radicals due to an increased concentration of hydroxyl ions.

Nanocrystalline iron manganite powder was synthesized using the sol–gel combustion process, with glycine as fuel. It was further calcined at 900 °C for 8 h, resulting in the formation of a loose cubic FeMnO3 powder with a small specific surface area, net-like structure and plate-like particles as confirmed by XRD, N2 physisorption, FESEM and TEM analyses. The metal ion release was studied by ICP-OES and showed that less than 10 ppb of Fe or Mn ions were released by leaching in water, but 0.36 ppm Fe and 3.69 ppm Mn was found in LB (Luria–Bertani) bacterial medium. The generation of reactive oxygen species (ROS) was monitored in distilled water and bacterial medium and showed that FeMnO3 particles do not generate O2˙− ions with or without UV irradiation, but synthesize H2O2 and show an antioxidative effect. Besides the higher stability of FeMnO3 particles in aqueous solution they showed an inhibitory effect on Bacillus subtilis growth in LB medium even at low concentrations (0.01 mg ml−1), but not in BHI medium even at 1 mg ml−1. This study points out that the mechanism of antibacterial action of engineered metal oxides needs continued investigation and specific experimental controls.

Nanocrystalline iron manganite powder was synthesized using the sol–gel combustion process, with glycine as fuel. It was further calcined at 900 °C for 8 h, resulting in the formation of a loose cubic FeMnO3 powder with a small specific surface area, net-like structure and plate-like particles as confirmed by XRD, N2 physisorption, FESEM and TEM analyses. The metal ion release was studied by ICP-OES and showed that less than 10 ppb of Fe or Mn ions were released by leaching in water, but 0.36 ppm Fe and 3.69 ppm Mn was found in LB (Luria–Bertani) bacterial medium. The generation of reactive oxygen species (ROS) was monitored in distilled water and bacterial medium and showed that FeMnO3 particles do not generate O2˙− ions with or without UV irradiation, but synthesize H2O2 and show an antioxidative effect. Besides the higher stability of FeMnO3 particles in aqueous solution they showed an inhibitory effect on Bacillus subtilis growth in LB medium even at low concentrations (0.01 mg ml−1), but not in BHI medium even at 1 mg ml−1. This study points out that the mechanism of antibacterial action of engineered metal oxides needs continued investigation and specific experimental controls.

Nanocrystalline Zn2SnO4/SnO2 powder was obtained by a solid state reaction of ZnO and SnO2 nanopowders mixed in the molar ratio 1:1. The phase composition of the obtained powder was studied by XRD and Raman spectroscopy, morphology and texture were characterized by FESEM, TEM, BET and Hg porosimetry, while XPS and FTIR spectroscopy were used to determine the surface chemistry. The influence of humidity on complex impedance was monitored on bulk samples in the relative humidity (RH) range 30-90% in a climatic chamber in the frequency range 42 Hz- 1 MHz at working temperatures of 25 and 50 degrees C. Change in RH had a significant influence on impedance reduction, especially noticeable in the lower frequency range, indicating potential application of this nanocomposite as a humidity sensing material. Increase in RH led to an increase in AC conductivity that changed with frequency according to the Jonscher power law. The frequency exponent decreased with increase in RH and sample temperature indicating that the correlated hopping barrier model is the dominant conduction mechanism. Complex impedance was analyzed using an equivalent circuit consisting of a parallel resistance and constant phase element, showing the dominant influence of grain boundaries at both working temperatures (25 and 50 degrees C). The resistance decreased, while the capacitance and relaxation frequency increased with increase in RH. At high humidity an added Wartburg element enabled modeling of the charge diffusion process.

The aim of this work was to synthesize semiconducting oxide nanoparticles using a simple method with low production cost to be applied in natural sunlight for photocatalytic degradation of pollutants in waste water. Iron titanate (Fe2TiO5) nanoparticles with an orthorhombic structure were successfully synthesized using a modified sol–gel method and calcination at 750°C. The as-prepared Fe2TiO5 nanoparticles exhibited a moderate specific surface area. The mesoporous Fe2TiO5 nanoparticles possessed strong absorption in the visible-light region and the band gap was estimated to be around 2.16 eV. The photocatalytic activity was evaluated by the degradation of methylene blue under natural sunlight. The effect of parameters such as the amount of catalyst, initial concentration of the dye and pH of the dye solution on the removal efficiency of methylene blue was investigated. Fe2TiO5 showed high degradation efficiency in a strong alkaline medium that can be the result of the facilitated formation of OH radicals due to an increased concentration of hydroxyl ions.

Nanocrystalline iron manganite powder was synthesized using the sol-gel combustion process, with glycine as fuel. It was further calcined at 900 degrees C for 8 h, resulting in the formation of a loose cubic FeMnO3 powder with a small specific surface area, net-like structure and plate-like particles as confirmed by XRD, N-2 physisorption, FESEM and TEM analyses. The metal ion release was studied by ICP-OES and showed that less than 10 ppb of Fe or Mn ions were released by leaching in water, but 0.36 ppm Fe and 3.69 ppm Mn was found in LB (Luria-Bertani) bacterial medium. The generation of reactive oxygen species (ROS) was monitored in distilled water and bacterial medium and showed that FeMnO3 particles do not generate O-2 & x2d9;(-) ions with or without UV irradiation, but synthesize H2O2 and show an antioxidative effect. Besides the higher stability of FeMnO3 particles in aqueous solution they showed an inhibitory effect on Bacillus subtilis growth in LB medium even at low concentrations (0.01 mg ml(-1)), but not in BHI medium even at 1 mg ml(-1). This study points out that the mechanism of antibacterial action of engineered metal oxides needs continued investigation and specific experimental controls.

Nanocrystalline nickel manganite (NiMn2O4) was obtained by sol-gel combustion using glycine as fuel, followed by calcination at 800°C. X-ray diffraction (XRD) analysis confirmed the formation of a pure cubic spinel structure with a crystallite size of 54.5 nm. Scanning electron microscopy (SEM) of the obtained nickel manganite powder showed porous nanocrystalline morphology. The material constant (B) of the obtained nickel manganite powder applied as paste and dried at 100°C was determined as 4812 K in the temperature range 20-50°C, confirming potential application in flexible temperature sensors.

The aim of this work was to synthesize semiconducting oxide nanoparticles using a simple method with low production cost to be applied in natural sunlight for photocatalytic degradation of pollutants in waste water. Iron titanate (Fe2TiO5) nanoparticles with an orthorhombic structure were successfully synthesized using a modified sol-gel method and calcination at 750 degrees C. The as-prepared Fe2TiO5 nanoparticles exhibited a moderate specific surface area. The mesoporous Fe2TiO5 nanoparticles possessed strong absorption in the visible-light region and the band gap was estimated to be around 2.16 eV. The photocatalytic activity was evaluated by the degradation of methylene blue under natural sunlight. The effect of parameters such as the amount of catalyst, initial concentration of the dye and pH of the dye solution on the removal efficiency of methylene blue was investigated. Fe2TiO5 showed high degradation efficiency in a strong alkaline medium that can be the result of the facilitated formation of OH radicals due to an increased concentration of hydroxyl ions.

Zinc ferrite nanocrystalline powder was obtained by solid state synthesis of starting zinc oxide and hematite nanopowders. Field emission scanning electron microscopy (FESEM and transmission electron microscopy (TEM), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS) and Raman spectroscopy confirmed the formation of nanocrystalline zinc‐ferrite powder with a mixed spinel structure with small amounts of remaining zinc oxide and hematite as impurities. Thick film paste was formed and screen printed on test interdigitated PdAg electrodes on alumina substrate. Formation of a porous nanocrystalline structure was confirmed by scanning electron microscopy (SEM) and Hg porosimetry. Humidity sensing properties of zinc ferrite thick films were investigated by monitoring the change in impedance in the relative humidity interval 30‐90% in the frequency range 42 Hz – 1 MHz at room temperature (25 °C) and 50 °C. At 42 Hz at both analyzed temperatures the impedance reduced ~ 46 times in the humidity range 30‐90%. The dominant influence of grain boundaries was confirmed by analysis of complex impedance with an equivalent circuit.

In this study, pseudobrookite (Fe2TiO5) nanoparticles were fabricated by a modified sol-gel method using Fe(NO3)39H2O and Ti(OC3H7)4 as starting reagents and ethanol as solvent. Oxalic acid was used as a chelating agent while cetyltrimethyammonium bromide (CTAB) and citric monohydrate were used as surfactants. Structral and morphological characterization using X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM) analysis confirmed the formation of pseudobrookite nanoparticles. As synthetized Fe2TiO5 nanoparticles were utilized as photocatalysts for decolorisation of Methylene blue (MB) under visible light irradiation. It was observed that the adsorption of MB onto Fe2TiO5 nanoparticles is strongly dependent on the solution pH. Maximum decolorozation was observed for Fe2TiO5 nanoparticles prepared with CTAB under alcaline conditions (pH=10.5).

Nanocrystalline cobalt magnesium ferrites with varying cobalt and magnesium content (CoxMg1-xFe2O4, 0