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Lithium chloride (LiCl) incorporated MCM-41 has been synthesised by sol-gel method using tetraethyl orthosilicate as a precursor in basic medium. 5, 10, 15, 20, 25, 30 and 35 wt% of LiCl were incorporated in mesoporous silica to investigate the humidity sensing. With increasing wt% of LiCl broadening of O–H peak is observed in the Fourier Transform Infrared spectra, indicating greater adsorption of hydroxyl groups on porous silica. The surface area of the MCM-41 circular discs was determined by Brunauer−Emmett−Teller (BET). Scanning electron microscopy images suggest that incorporation of LiCl leads to coalescence of grains in mesoporous silica. 25 wt% LiCl incorporated MCM-41 showed a wide range linear response of impedance change for 11%–90% RH exhibiting 3.5-order drop in impedance at a 1 kHz frequency. The Nyquist plots for all compositions showed increased ionic conduction with increasing relative humidity. [ABSTRACT FROM PUBLISHER]

Abstract: Co x Zn y Fe3−x−y O4 ferrite (x=1 to 0; y=0 to1) nanocrystals have been synthesized by reverse microemulsion method. The nanocrystals are then comprehensively characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Field emission transmission electron microscopy (FETEM), and magnetic properties were measured by using Vibrating sample magnetometer. X-ray analysis showed that all the crystals were cubic spinel. The lattice constant increased with the increase in Zn substitution. FETEM reveals that particle size varies in the range from 3 to 6nm. As the concentration of Zn increases the magnetic behavior varies from ferromagnetic at y=0 and 0.2 to superparamagnetic to paramagnetic at y=1. The Curie temperature decreases with increasing concentration of Zn. [Copyright &y& Elsevier]

Abstract: Co0.5Zn0.5Fe2O4/PANI nanocomposites with bimodal size distribution were synthesized via reverse microemulsion method. Structural characterization was done by Fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy. Vibrating sample magnetometer measurement confirmed the ferromagnetic behavior of nanocomposite with saturation magnetization of 3.95emu/g and low coercive force (39Oe). It was observed that on nanocomposite formation with PANI nanofibers, Co0.5Zn0.5Fe2O4 ferrite nanocrystals undergo transition from being superparamagnetic to ferromagnetic. A mechanistic description of the process has also been presented in view that the process could be extended for the fabrication of other bimodal nanocomposites. [Copyright &y& Elsevier]

The present study describes the synthesis of mesoporous metal oxide–α-Fe 2 O 3 nanocomposites and investigation of their gas-sensing performance. Mesoporous Li 2 O-doped Fe 2 O 3 and SnO 2 –Fe 2 O 3 nanocomposites were synthesized employing a nanocasting technique using KIT-6 as the structure guiding template. The structural features of synthesized mesostructures were analyzed using X-ray diffraction, Brunauer–Emmett–Teller studies and Fourier transform infrared spectroscopy. The morphological features of metal oxide–Fe 2 O 3 nanocomposites were observed by scanning electron microscopy and transmission electron microscopy. Thin films of mesoporous metal-oxide nanocomposites were prepared and studied as sensors toward formaldehyde (HCHO) and ethanol (C 2 H 5 OH) over the operating temperature range of 25–200 °C. The SnO 2 –Fe 2 O 3 sensor showed maximum sensing response toward HCHO at 150 °C after attainment of sufficient ordering of structure at high temperatures. However, Li 2 O-doped Fe 2 O 3 exhibited very high response of 6.08 and 5.82 for HCHO and C 2 H 5 OH, respectively, at room temperature (25 °C). Gas-sensing behaviors of nanocomposites along with the sensing phenomenon were explained on the basis of their mesostructures and crystallinity. Image 1 • Mesoporous Li 2 O-doped Fe 2 O 3 and SnO 2 –Fe 2 O 3 nanocomposites synthesized via nanocasting. • Sensing tested toward formaldehyde and ethanol at various operating temperatures. • Temperature-dependent sensitivity of composites was studied. • Highest sensitivity at 25 °C for both the volatile gases for Li 2 O-doped Fe 2 O 3. • SnO 2 –Fe 2 O 3 showed sensing characteristics at higher temperatures when sufficient crystallinity attained. [ABSTRACT FROM AUTHOR]