The discovery of swelling brittle mica, Na-Mica-4, has been one of the most significant advances in the pursuit for a material with high ion-exchange capacity. For technical applications, the control of the phase evolution during the synthesis is crucial. The main aim of this study was to investigate the effect of Na-Mica-4 synthesis temperature on…
Synthesis of Na-Mica-4 has been achieved by a “mix and calcine” method using sodalite and magnesium fluoride as the only precursors. Previous research found sodalite as a key intermediate reaction product in the formation of Na-Mica-4 when the NaCl melt method was employed. Similarities in structure, chemical composition and cation distribution in products using the…
Mesoporous gamma alumina fibres of high surface area, stable up to 1000 °C, were synthesized by bioreplica technique using sisal fibres as templates. Alumina formation during pyrolysis and calcination of fibres infiltrated with aluminium chloride solution has been studied, paying special attention to the interaction between the precursor and sisal fibres, using several experimental techniques…
Amorphous silicon oxynitride coatings with similar composition and different closed porosity were prepared by magnetron sputtering. Pores size, shape and distribution were evaluated by scanning electron microscopy and transmission electron microscopy. Raman and EELS analysis proved that the pores are filled with molecular nitrogen trapped during deposition. The mechanical properties evaluated by nanoindentation shows that…
The liquid-phase adsorption of thiophene from thiophene/iso-octane solutions has been investigated in batch conditions at room temperature and atmospheric pressure on MCM-22 zeolites with Si/Al in the 9–46 range. Thiophene adsorption was found to occur in two steps whatever the Si/Al ratio of the adsorbent. The presence of ferrierite besides the MCM-22 phase caused a…
MCM-22 zeolites with Si/Al in the 9–46 range were synthesised in rotating autoclave and characterised by X-ray diffraction, 1H, 29Si and 27Al magic angle spinning nuclear magnetic resonance, scanning electron microscopy and nitrogen physisorption. For the Si/Al = 21, 30 and 46 samples both X-ray diffraction and scanning electron microscopy revealed the crystallisation of pure…
The microstructure of TiO2 thin films prepared by plasma enhanced chemical vapour deposition has been assessed by using water adsorption–desorption isotherms measured by means of a quartz crystal monitor (QCM). Thin films have been deposited by using titanium tetraisopropoxide as a precursor and by changing different experimental parameters of the deposition procedure such as temperature…
Silica monospheres with a diameter of 330 nm modified with aminosilane compounds of three different basicities have been prepared. Surface coverage of the silica with an organic compound leads to an increase of the point of zero charge (PZC) of the silica surface from 2.1 to 5.1, 6.5 and 7.2 values, depending on the amine…