23 research outputs found
Sol-gel derived nanostructured γ-alumina porous spheres as an adsorbent in liquid chromatography
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Hydrolysis of aluminium metal, synthesis of nano alumina and sol-gel processing of monoliths
No full textABSTRACTHigh purity alumina is usually prepared using various intermediate aluminium compounds such as aluminium nitrate, aluminium alkoxides etc., as precursors. In fact the above mentioned intermediate aluminium compounds themselves are produced from aluminium metal. The present investigation is concerned with examining the feasibility of using aluminium hydroxides prepared by hydrolyzing aluminium metal, for sol gel processing. The study assumes added significance in view of the claims of Alcoa that it is possible to produce high purity aluminium metal in large quantities economically.During the present investigation sols were prepared by using various hydroxides, ie., bayerite, gibbsite and boehmite. Sol gel transition was observed only in the case of boehmite sol and this was gelated by either forced gelation method to prepare powder or controlled gelation method to prepare monoliths.Transparent Xerogels (boehmite) could be prepared by controlled gelation method but the presence of a thin layer of bayerite often resulted in translucency. Crack free monoliths could be prepared by heating the xerogels at a low heating rate(< 1 °C/min). It was found that sol gel processed boehmite transformed to alpha alumina at a relatively lower temperature (∼ 1080 °C ) than the as prepared boehmite which transformed at about 1200 °C.</jats:p
Investigation of magnetoelectric effect in novel multiferroic thin films for MEMS applications
No full textCharacterization of multiferroic thin films directly deposited on silicon for novel device applications
No full textwe have investigated the multiferroic and dielectric properties in Dy modified BiFeO(3) thin films deposited directly on silicon using pulsed laser deposition (PLD) technique. The results support the usability of these films in multiferroic based MEMS devices as well as gate dielectrics for future CMOS applications
The Study of Ferroelectric, Magnetic and Magnetoelectric Properties of Multiferroic Pb(Fe0.5Ti0.5)O3 Nanoparticles
No full textAbstractMultiferroic Pb(Fe0.5Ti0.5)O3 is a system which has coupled co-existence of ferroelecticity and ferromagnetism at room temperature. We have been successful in synthesizing multiferroic Pb(Fe0.5Ti0.5)O3 nanoparticles of average size 36nm using wet chemical route and studied the ferromagnetic, ferroelectric and multiferroic properties of this system. It is observed that the nanoparticles also possess ferroelectricity, ferromagnetism and menetoelectric coupling at room temperature. This study could be useful in small scale devices employing multiferroicity, for example multi-state memory devices
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Jetting, In-Nozzle Meniscus Motion and Nozzle-Plate Flooding in An Industrial Drop-on-Demand Print Head
No full textThe state of the ink film at and near the nozzles of a drop-ondemand(DoD) print head during jetting has a direct impact on
printing performance and reliability. We have developed highspeed imaging apparatus and analytical techniques to investigate
the ink film dynamics on an industrial print head nozzle-plate in real-time. In addition to a direct correlation between the jet
emergence velocity and drive voltage, drive-dependent variations in the oscillation of the ink meniscus in adjacent nozzles were also observed. Using a ray-tracing model to analyze the meniscus shape, the meniscus oscillations for both printing and nonprinting nozzles were found to be complex and involve elements such as pre-oscillation and high-order surface waves. The flooding of non-firing nozzles, deliberately caused by the application of maximum drive voltage to a neighboring nozzle, has been recorded and analyzed dynamically. The build-up of fluid in an annulus around the nozzle (flooding rate) has been characterized and compared with models for the net ink flow
through the nozzle
A novel ZnO piezoelectric microcantilever energy scavenger: Fabrication and characterization
No full textThis novel piezoelectric zinc oxide (ZnO) thin film microcantilever was fabricated by micromachining technique. To release the cantilever, wet anisotropic etching of Silicon (Si) was performed by tetramethyl ammonium hydroxide (TMAH). The transverse piezoelectric coefficient d31 of the ZnO film, obtained from the deflection of the cantilever with influence of applied voltage, was calculated as 3.32 pC/N. The observed dynamic characterization of the novel piezoelectric microcantilever had linear response with the applied driving voltage. The obtained values of Young Modulus and Hardness were 208 ± 4 GPa and 4.84 ± 0.1 GPa respectively. This inexpensive novel method provides additional design flexibility to fabricate vibrational energy harvesters. The easy steps of fabrication and cost effectiveness of this method may be preferred it over DRIE. The voltage induced due to deformation of ZnO cantilever were measured ~230 mV. This microcantilever energy scavenger may be used to power the nano devices and sensors for medical and agricultural applications as a replacement of traditional bulky batteries. Keywords: ZnO, Tetramethyl ammonium hydroxide (TMAH), Energy scavengers, Piezoelectri
