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This work evaluated bacterial cellulose (BC) as a possible biodegradable soft electronics substrate in comparison to polyethylene terephthalate (PET), while also focusing on evaluating hybrid MXene/BC material as potential flexible electronic sensor. Material characterization studies revealed that the BC material structure consists of nanofibers with diameters ranging from 70 to 140 nm, stacked layer-by-layer. BC samples produced are sensitive to post-treatment with isopropanol resulting in a change of structural and mechanical properties. The viscoelastic properties of the BC substrates have been studied experimentally in comparison with the PET film. Aged BC substrate showcased similar viscoelastic properties stability, while exhibiting better properties above 70 °C, with total storage modulus change of −15% and loss modulus change of 21%. MXenes prepared using the Minimally Intensive Layer Delamination (MILD) method were screen-printed onto BC substrates and PET films to form MXene/BC (MX/BC) and MXene/PET (MX/PET) devices. The electrical properties results showcased different resistive behavior on both BC and PET substrate samples with different impedance moduli. MX/PET presented lower sheet resistance of around 156 Ω ·sq−1, while MX/BC was 2733 Ω ·sq−1. Finally, the MX/BC and MX/PET devices were subjected to repeatable quasi-static load tests and the piezoresistive sensing behavior of the devices has been reported. [ABSTRACT FROM AUTHOR]

In this work, the structure of silica thin films synthesized with three different SiO2 precursors and obtained by the sol–gel method and dip coating technique was studied. Additionally, the influence of Ag addition on the obtained silica sols and then gel structure was investigated. Silica coatings show antireflective properties and high thermal resistance, as well as hydrophobic or hydrophilic properties. Three different silica precursors, TEOS (tetraethylorthosilicate), DDS (dimethyldietoxysilane) and AerosilTM, were selected for the synthesis. DDS added to silica sol act as a pore size modifier, while Ag atoms are known for their antibacterial activity. Coatings were deposited on two different substrates: steel and titanium, dried and annealed at 500 °C in air (steel substrate) and in argon (titanium substrate). For all synthesized films, IR (infrared) spectroscopic studies were performed together with GID and XRD (Grazing Incidence Diffraction, X-ray Diffraction) measurements. The topography and morphology of the surface were traced by SEM and AFM microscopic methods, providing information on the samples' roughness, particle sizes and thickness of the particular layers. The wetting angle values were also measured. GID and XRD measurements pointed to the distinct contribution of an amorphous phase in the samples, allowing us to recognize the crystalline phases and calculate the silver crystallite sizes. The FTIR spectra gave information on the first coordination sphere of the studied samples. [ABSTRACT FROM AUTHOR]

Understanding the thermal properties of zeolites is crucial for their industrial applications. This study explores the thermal stability and dehydration process of clinoptilolite using high-temperature X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Clinoptilolite's thermal decomposition was monitored from 25 °C to 1200 °C, with results analyzed based on its crystal structure. Principal components analysis (PCA) of the DRIFT spectra indicated progressive water removal and dehydration upon heating, leading to the formation of hydrogen bonds. Thermogravimetric analysis (TGA) revealed a two-step endothermic weight loss: initially, physically adsorbed water was lost up to 100 °C, followed by the removal of tightly bound water and hydroxyl groups until 800 °C. Clinoptilolite remained the dominant phase up to 800 °C, after which albite and cristobalite took over. Rietveld refinement showed that the sample initially contained 70% clinoptilolite, 24% albite, and 6% cristobalite. Above 800 °C, clinoptilolite disappeared, leaving 93% albite and 7% cristobalite. FT-IR spectra changes due to water loss were evident: drying of adsorbed water occurred up to 75 °C and minimal changes were observed from 75 °C to 135 °C, followed by further dehydration until 240 °C. Complete dehydration was confirmed by the disappearance of OH stretching vibration bands by 395 °C, consistent with TGA findings. [ABSTRACT FROM AUTHOR]

Transparent Yb3+/Er3+ glass-ceramic was successfully obtained by the extrusion method. The extrusion of oxyfluoride tellurite-germanate glass co-doped with Yb3+ and Er3+ ions at 520 ℃ resulted in the formation of Ba0.75Er0.25F2.25 nanocrystals, leading to an increase in the upconversion (UC) emission intensity of 35 times in glass-ceramic with respect to the glass. The glass to glass-ceramic transition was confirmed by X-ray diffraction (XRD) and Transmission electron microscope (TEM). Also, the structural changes that occurred during crystallization were assessed using Fourier-transform infrared (FTIR) spectroscopy. Furthermore, the pump power and temperature UC emission dependence of glass and glass-ceramic under 976 nm laser excitation were investigated in detail. The assessments showed that i) two-phonons are involved in the UC process and ii) the temperature has a significant influence over it. The Yb3+/Er3+ codoped glass-ceramic shows relatively high Sa and Sr values in a wide temperature range from 300 to 573 K, presenting the maximal Sa value of 3.50 × 10-3 at 573 K and the maximal Sr value of 6.30 × 10-3 at 364 K. These results suggest that the glass-ceramic is a good candidate for optical applications such as luminescent thermometry. [ABSTRACT FROM AUTHOR]

Titania dioxide (TiO2) layers were synthesized via the acid-catalysed sol-gel route using titania (IV) ethoxide, and then annealed at temperatures varying in the range of 150-700 °C. The research concerned the effect of annealing temperature on the structure of TiO2 layers, their surface morphology, and their optical properties. Further, X-ray diffractometry, and Raman spectroscopy were used to determine the structure of TiO2 layers. Scanning electron and atomic force microscopy were used to study the surface morphology of TiO2 layers. Transmittance, reflectance, absorption edge, and optical homogeneity were investigated by UV-VIS spectrophotometry, while the refractive index and thicknesses of TiO2 layers were measured using a monochromatic ellipsometer. Chromatic dispersion characteristics of the complex refractive index were determined using spectroscopic ellipsometry. Structural studies have shown that the TiO2 layers annealed at temperatures up to 300 °C are amorphous, while those annealed at temperatures exceeding 300 °C are polycrystalline containing only anatase nanocrystals with sizes increasing from 6 to 20 nm with the increase of the annealing temperature. Investigations on the surface morphology of TiO2 layers have shown that the surface roughness increases with the increase in annealing temperature. Spectrophotometric investigations have shown that TiO2 layers are homogeneous and the width of the indirect optical band gap varies with annealing temperature from 3.53 eV to 3.73 eV. [ABSTRACT FROM AUTHOR]