Broad Band Electromagnetic Interference (EMI) Shielding Properties of Polyaniline/ Polyvinyl Alcohal/ Fly Ash/ MnO2 Free Standing Films

Microwave absorbing material (MAM) is a kind of functional material that can absorb electromagnetic wave effectively and convert electromagnetic energy into heat or make electromagnetic wave disappear by interference. These types of materials are gaining much attention in the field of civil and military applications. The present work is the report of our effort in studying the EMI-Shielding properties of conducting polyaniline (PANI) and their composites. The wet dark green precipitate and varied weight percentage (wt %) of cenosphere particles were transferred directly to the 5% polyvinyl alcohol (PVA) solution. The resulting mixture was stirred continuously for 1 hour for homogeneous distribution of the particles. The mixture was poured on to the glass plate and allowed to dry at room temperature to get freestanding PANI/FA/MnO2/PVA polymer matrix. The electromagnetic wave absorption, reflection and EMI Shielding Effectiveness (EMI SE) of the composites has been measured at X-band (8-12 GHz) micro wave frequencies. The experimental results indicate that the absorption dominated EMI SE of the composites is influenced by the fly ash weight percentage. The study suggests the prospects of the composites as effective shielding materials for a broad range of micro wave frequency

Enhanced Humidity Sensing Response in Eu³⁺-Doped Iron-Rich CuFe₂O₄: A Detailed Study of Structural, Microstructural, Sensing, and Dielectric Properties

The CuFe(2−x)EuxO4 (where x = 0.00, 0.01, 0.02, 0.03) nanoparticles are synthesized by solution combustion method. The influence of Eu3+ on the structural, morphological, dielectrical, and humidity sensing study is recorded. The XRD pattern peaks of the as-prepared CuFe(2−x)EuxO4 (where x = 0.00, 0.01, 0.02, 0.03) nanoparticle confirm the polycrystalline spinel cubic structure with a small amount of CuO impurity phase at 38.87° and 48.96°. Surface morphology of the samples was studied by scanning electron microscope (SEM) images of the nanoparticles, and their respective average grain size was estimated using Image software. Chemical composition of all prepared samples was analyzed by EDS spectra. The dielectric parameters of AC conductivity, electric modulus, and impedance of the samples were measured over a range of frequencies from 0.1 KHz to 1 MHz at room temperature. Europium-doped copper ferrite samples showed good humidity sensing response, response and recover times, and stability over a %RH range of 11–91%. These types of samples are very useful for sensor application, battery applications, electronic applications, and automotive applications

Nano porous Al2O3-TiO2 thin film based humidity sensor prepared by spray pyrolysis technique

The nano porous surface structured TiO2 and Al2O3-TiO2 thin films were prepared using spray pyrolysis technique at 350°C. The XRD pattern of Al2O3-TiO2 film shows anatase phase and mixed phase of Al2TiO5. The surface morphology of films show a uniformly distributed nano porous structure. The elemental analysis through EDAX shows good stoichiometry. The sensitivity for humidity sensing were determined for both films of TiO2 and Al2O3-TiO2 and corresponding values are found to be 74.2% and 84.02%, this result reveal that Al2O3-TiO2 films shows higher sensing percent than the TiO2 due to the nano porous surface nature. The Al2O3-TiO2 film shows fast response time and long recovery time than the TiO2 film, this may be due to the meso-porous morphology of these films

Структурні, оптичні та електричні властивості легованих Ce наночастинок SnO2, підготовлених методом горіння гелю з додаванням поверхнево-активних речовин

Нанокристалічні чисті та леговані Ce порошки оксиду олова (SnO2) синтезували методом горіння гелю з додаванням поверхнево-активних речовин (CTAB і PEG), використовуючи сечовину як паливо. Підготовлені зразки характеризували PXRD, FESEM, UV-Vis, FTIR та імпедансним аналізатором. Аналіз PXRD виявив тетрагональну рутильну фазу SnO2. Розмір зерна оцінювали за допомогою рівняння Дебая-Шеррера та методу Вільямсона-Холла. Параметри елементарної комірки були знайдені за допомогою уточнення Рітвельда та графіка Нельсона-Ріллі. На фотографіях FESEM було показано утворення наночастинок майже сферичної форми. Спектр FTIR виявив смуги завдяки фундаментальним гармонікам та комбінації з'єднань Sn-O та Sn-O-Sn. У спектрах UV-Vis показано зменшення ширини забороненої зони із вмістом Ce внаслідок збільшення дефектів. Вплив легування Ce на електричні властивості вивчали при кімнатній температурі. Діелектричні параметри ε' і tanδ були максимальними для зразка чистого SnO2. Варіювання діелектричних властивостей та змінної провідності з частотою зумовлено міжфазною поляризацією типу Максвелла-Вагнера.Nanocrystalline pure and Ce doped tin oxide (SnO2) powders were synthesized through surfactant (CTAB and PEG) assisted gel combustion method using urea as a fuel. Prepared samples were characterized by PXRD, FESEM, UV-Vis, FTIR and Impedance analyzer. The PXRD analysis revealed the tetragonal rutile SnO2 phase. The grain size was estimated using the Debye-Scherrer equation and Williamson-Hall method. The cell parameters were found using Rietveld refinement and Nelson-Rieley plot method. The FESEM pictures showed the formation of nanoparticles of almost spherical shape. FTIR spectrum revealed the bands due to the fundamental overtones and combination of Sn-O and Sn-O-Sn entities. The UV-Vis spectra showed the decrease in band gap with Ce content due to an increase in defects. The effect of Ce doping on the electrical properties was studied at room temperature. The dielectric parameters, ε' and tanδ were maximum for pure SnO2 sample. The variation of dielectric properties and ac conductivity with frequency is due to the Maxwell-Wagner type of interfacial polarization