Alumina Pillared Research Articles

Long-distance interface diffusion induced non-volume-conserved deformation in self-supported submicron-sized aluminum pillars

The plastic deformation of a solid generally conserves the local mass/volume of the sample. Here, we show that under elevated temperature and low strain rate, this may not hold for the widely used compression test geometry with self-supported aluminum pillars in the submicron range. Plastic flow can instead proceed with continuous shortening, while the overall diameter and shape remain constant. This apparent non-conservation results from a rarely-reported interface-diffusion-mediated deformation, when interface diffusion between the metal and the native oxide layer is rejuvenated to mediate mass relocation spreading over an interfacial area far exceeding the dimensions of the self-supported pillar, thus providing large continuous plastic strain.

Electroplated Aluminum Pillars for Ultrasonic Flip Chip Bonding

Flip chip bonding is a widely used method in 3D integration. In this study, the use of electroplated Aluminum as pillar structure for ultrasonic flip chip bonding is demonstrated for the first time. Al pillars were deposited from a chloroaluminate ionic liquid on a 6 inch silicon wafer. The influences of ultrasonic bonding parameters (bonding time, ultrasonic power and bonding force) were investigated at room temperature. Al pillar bonding was performed successfully in less than 1 s. High bonding forces are recommended as more pillars get mechanical contact to the substrate, thus, ultrasonic energy can be transferred to the interface causing bonding.

Functionalized Clays for Radionuclide Sequestration: A Review

Performance assessment of nuclear waste disposal options requires implementation of effective buffer materials. Buffer materials must meet longevity requirements and scavenge challenging radioisotopes, e.g., iodine-129 (I-129) and technetium-99 (Tc-99), both long-lived, highly mobile, anionic species in oxic environments. In many proposed nuclear waste repositories, heat generating radioactive waste will be surrounded by clay buffer material, which swells to fill the gap between the waste package and the host geology, restricting radionuclide transport to diffusive processes for several hundred years. The clay can be functionalized to further the limit release of Tc-99, as pertechnetate (TcO4–), and I-129, as iodate (IO3–) and iodide (I–). Here, we review clay buffer functionalization and the potential to enhance sequestration of anionic radionuclides that have an increased risk of leaching out of a disposal facility. Functionalization with quaternary amines, nanosilver, bismuth-based materials, silane, and aluminum pillars have been demonstrated to improve the removal of targeted contaminants from solution. This review defines key research questions that remain: (i) can functionalized clay immobilize TcO4–, IO3–, and I– to the same extent as the reactive components themselves? (ii) Does functionalization affect the ability of the clay barrier to perform its safety functions of protecting the waste canister and limiting radionuclide transport? In addition to radionuclide retention, a multimodal analytical approach is required to assess functionalized clay performance, and recommended techniques are reviewed here. The key parameters that can influence radionuclide sequestration by functionalized clay are also evaluated. Theoretical approaches, including both density functional theory calculations and molecular dynamics simulations, can inform the energetics and kinetics of radionuclide interactions with functionalized clays. This combined experimental and theoretical approach can link atomistic and microscopic processes to predict the macroscopic physical properties of the functionalized clays.

Enhanced Adsorption of Methyl Orange by Mongolian Montmorillonite after Aluminum Pillaring

This article studies the enhancement of methyl orange (MO) adsorption by Mongolian montmorillonite (MMt) modified by the intercalation of the Keggin Al13 complex, followed by calcination during the pillaring process. The properties of MMt, Al-intercalated MMt (P-MMt), and Al-pillared MMt (P-MMt-C) were determined using X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface-area analysis, and a field emission scanning electron microscope (FE-SEM). The MO adsorption by modified MMt was subsequently evaluated. The XRD basal distance (d001) and the specific surface area (SSA) increased after the modification of MMt. The TGA results revealed that P-MMt and P-MMt-C had better thermal stability than MMt. The Al-pillared MMt obtained after calcination (e.g., P-MMt-C400) showed a larger basal distance and surface area than that without pillaring. The MO adsorption process of P-MMt-C400 was supposed to be dominated by chemisorption and heterogeneous multilayer adsorption, according to the kinetic and isotherm studies. The maximum adsorption capacity of P-MMt-C400 is 6.23 mg/g. The MO adsorption ability of Al-pillared MMt was contributed by the Keggin Al13 complex attracting MO and the increase in the surface area of macro-, meso- and micro-pores (>1.2 nm). The Al-pillared MMt in this study could be applied as an adsorbent in a water purification system to remove MO or other dye elements.

Uticaj modifikacije gline na elektrohemijsko ponašanje hinhidrona

Montmorillonite originated from Wyoming was modified by acid activation and aluminum pillaring process. The samples of clay obtained in this manner, as well as starting clay, were applied at the surface of a glassy carbon electrode by the means of Nafion. The activity of these electrodes was investigated on the redox couple quinone/hydroquinone (Q/QH2) in buffered and unbuffered solutions. The type of clay modification influenced the activity of the electrodes and the mechanism of the redox reaction.

Interfacial Diffusion Induced Giant Plasticity in Sub-Micron Sized Aluminum Pillars

The plastic deformation of a solid generally conserves the local sample mass/volume. Here, we show that this may not hold for the widely-adopted compression test geometry, with self-supported submicron-sized pillars. Plastic flow can instead proceed with continuous shortening while keeping constant overall diameter and shape. This apparent non-conservation results from a rarely-reported interfacial-diffusion-mediated deformation, when interface diffusion between the metal and the native oxide layer is rejuvenated to mediate mass relocation spreading over an area far exceeding the dimensions of the self-supported pillar, thus providing large continuous plastic strain.

Using Frost to Promote Cassie Ice on Hydrophilic Pillars

We develop a novel approach to suspend ice in the air-trapping Cassie state without requiring any fragile hydrophobic coatings or nanostructures. First, frost was preferentially grown on the tops of hydrophilic aluminum pillars due to their sharp corners and elevation over the noncondensable gas barrier. Subsequently, Cassie ice was formed by virtue of the impacting droplets getting arrested by the upper frost tips. A scaling model reveals that the dynamic pressure of an impacting droplet causes the water to wick inside the porous frost faster than the timescale to impale between the pillars.

Efficiency of Aluminium Pillared Montmorillonite Clays of Pakistani Origin (Peshawar And Samwal) on the Adsorption of Chromium Ions in Aqueous Solutions

Efficiency of Aluminium Pillared Montmorillonite Clays of Pakistani Origin (Peshawar And Samwal) on the Adsorption of Chromium Ions in Aqueous Solutions

Acoustic beam controlling in water by the design of phononic crystal

Three-component phononic crystals line-defects composed of aluminum, rubber and water were introduced to the aluminum pillars arrayed in water for controlling of the acoustic beam. The propagation properties of self-collimation-based acoustic waves were investigated by finite element method in the designed PC structure. Results reveal that the line-defects can lead to two splitting wave beams. The beam splitter PC structure can be controlled by adjusting the radii of the rods and the coating layer in the line defects. When the acoustic speed of the coating layer changes, the splitting propagation of the acoustic wave can be changed. The output acoustic wave can be altered by controlling the phase difference of the two incident sound sources.

Modified vermiculites as effective catalysts for dehydration of methanol and ethanol

Abstract Two series of catalysts for the reactions of methanol and ethanol dehydration were obtained from vermiculite. The first series of the catalysts were obtained by treatment of raw clay with nitric acid solution. Such modification of vermiculite resulted in a significant increase of its specific surface area and also partial leaching of Al3+ and Fe3+ cations from clay layers. Acid treatment of vermiculite resulted in its activation in the processes of methanol and ethanol dehydration. The second series of the catalysts were obtained by intercalation of vermiculite with alumina pillars. Prior to the pillaring process, raw vermiculite was treated with nitric acid solution followed by complexation of Al3+ and Fe3+ cations, leached from clay layers, with oxalic acid or citric acid. Alumina pillared vermiculites, characterized by increased specific surface area, porosity and acidity, were found to be very active catalysts of alcohols dehydration. Catalytic performance of modified vermiculites was related mainly to the concentration and strength of acid sites present in the samples.

Deformation behavior of aluminum pillars produced by Xe and Ga focused ion beams: Insights from strain rate jump tests

Micro-compression testing of focused ion beam fabricated pillars is a popular technique for mechanical characterization at small scales. However, there are concerns associated with these ion-prepared samples, including irradiation damage from Ga ions and Ga segregation at grain boundaries resulting in liquid metal embrittlement. In this work, this is investigated using strain rate jump nanoindentation and micro-compression of single crystalline and ultrafine-grained aluminum with different grain boundary conditions. The extracted strain rate sensitivity and activation volume are used to study the effects of Ga and Xe ion species from fabrication and testing methods on deformation behavior of aluminum samples. Results show that the measured strain-rate sensitivity of non-equilibrium, ultrafine-grained aluminum is significantly affected by the dosage of Ga. Activation volumes suggest that the dominant deformation mechanism remains consistent despite Ga at the boundaries. Atom probe tomography reveals that Ga was observed to segregate to aluminum grain boundaries up to 2.2 at.% in the FIB prepared sample.

Direct fabrication of unsupported inclined aluminum pillars based on uniform micro droplets deposition

In order to investigate forming directly complex parts without support materials or structures by uniform micro droplets deposition technique, the present work focus on fabricating the unsupported inclined aluminum pillars through offset deposition. An experimental system is developed to produce and deposit uniform molten aluminum droplets. A model is introduced to describe the inclined angle of the droplet deposition at different offset ratios. A one dimensional heat transfer model is proposed to help select the initial temperature parameters of the impinging droplet and the previous solidified droplet to ensure that the fusion occurs. No melting, partial melting and excessive melting region at different offset ratios are determined. The correspondence between offset ratio and inclined angle is considered to be a simple cosine function, and the hypothesis is verified by experiments. The influence of deposition error on an inclined angle of pillars is studied. Internal microstructure of droplet fusion is observed in order to ensure good metallurgical bonding. All of these studies show the feasibility of fabricating directly unsupported inclined aluminum pillars in the limited angle range by using uniform micro droplets.

Nanoporous Copper Doped Aluminium Pillared Montmorillonite for Dye-containing Wastewater Treatment.

Copper doped aluminium pillared montmorillonite (Cu-Alpill-MMT) was prepared by adding Cu2+ into the suspension of aluminium pillared montmorillonite (Alpill-MMT) using high power ultrasonic treatment and calcining to CuO at 500 °C. The XRD and XRF data revealed that the doped CuO partially occupied both internal and external surfaces of the Alpill-MMT. The N2 adsorption/desorption analysis showed that the Cu-Alpill-MMT consisted of slit-like mesopores with two ranges of pore diameter, i.e. ~3.8 nm and ~6-30 nm. The Cu-Alpill-MMT exhibited the superior adsorption capacity for Basic Yellow 1 (BY1), however, it hardly adsorbed Reactive Orange 16 (RO16). The decolorization of RO16 was achieved when the H2O2 or H2O2/UV was introduced into the treatment system together with the Cu-Alpill-MMT, acting as heterogeneous catalyst for Fenton or photo-Fenton oxidation processes, respectively. The Cu-Alpill-MMT could exhibit the antibacterial activity after intimate contact with Escherichia coli ATCC®25922 under JIS L 1902: 1998 (Qualitative) test method.

Preparation of Alumina Pillared Montmorillonite Clays Employing Ultrasonics and Their Catalytic Properties

<p>An accelerated diffusion of alumina precursor species in-between the gallery region of montmorillonite clays by the use of ultrasonic technique is described. This method offers a faster, efficient and attractive route for the synthesis of alumina-pillared clay catalysts. Out of the several preparative parameters studied, the role of pre-exchanged cations influenced the optimum duration of ultrasonic agitation and treatment for the pillaring process. By comparing ultrasonic route and conventional preparation procedure, it is revealed that uniform spacing of alumina pillars in the clay means homogeneously distributed acid centers. The influence of calcination temperature on the acidity and hence the catalytic activity is described. The choice of three different montmorillonite clays with different cation exchange capacities enables one to tune the pore dimensions of the pillared clays. The catalytic applications include studies on cumene cracking, dehydration of propan-2-ol and alkylation of benzene with linear olefins. </p>

Synthesis, Characterization and Aplication of TiO2 Alumina Pillared Montmorillonite Photocatalyst

Dispersion of TiO2 on montmorillonite pillared aluminium has been done successfully. The photocatalyst were prepared by intercalation of Al13 onto natural montmorillonite and then calcined at 500oC. Titania dispersion onto aluminium pillared montmorillonite was carried out by impregnation method at the theoritic concentration of 0.4, 0.8, 1 and 3% titania. The photocatalyst then characterized by XRD, porosimetry, SEM and Diffuse Reflectance Visible methods. Results of characterization showed that the basal spacing and specific surface area as well as total pore volume were decreased after dispersion of TiO2 on PILM, meanwhile SEM image exhibited that beside in the pores of PILM, the TiO2 was also dispersed on the surface of PILM. DR UV characterization result indicated that the band gap of TiO2 dispersed PILM for Ti/PILM 0,8%, Ti/PILM 1% and Ti/PILM 3% was 3.66, 3.19 and 3.19 eV respectively. Photodegradation optimum of methyl orange was found to be at Ti/PILM 1% Keywords : montmorillonite, pillarization, photocatalyst, methyl orange, TiO2

Experimental Investigation on Composite Phase-Change Material (CPCM)-Based Substrate

Many high-power electronic devices such as high-power light-emitting diodes and aerial devices work intermittently. If some of the heat generated by the chips could be stored in the thermal storage medium during the working time and then be released to the ambient in the nonworking time, the heat dissipation load of the heat sinks could be diminished and a better thermal characteristic could be achieved. Inspired by this idea, we proposed a thermal storage substrate and investigated its thermal storage properties by experiment in this study. First, the composite phase-change material (CPCM) was prepared as the thermal storage medium. Second, the thermal and phase-transition properties of the CPCM were studied through differential scanning calorimeter tests. Third, the thermal conductivity of the CPCM was measured for the analysis of thermal performance. Afterward, the CPCM-based substrate was fabricated and several experiments were conducted to examine its thermal storage performance. The results showed that the thermal storage substrate could store the heat, as much as 55,773.80 J, which accounts for 32% of the heat generated by the heat source approximately. With so much heat stored in the CPCM, the temperature of the heat source went up much more slowly. To accelerate the heat conduction inside the CPCM, five aluminum pillars were added into the substrate. As a result, the temperature of the heat source and the substrate wall decreased by 3.5°C and 4.5°C, respectively.

Synthesis and Application of Alumina Pillared Bentonite Catalyst for Esterification of Acetic Acid with Different Alcohols

Synthesis and Application of Alumina Pillared Bentonite Catalyst for Esterification of Acetic Acid with Different Alcohols

Improvement in the Adsorption of Anionic and Cationic Dyes from Aqueous Solutions: A Comparative Study using Aluminium Pillared Clays and Activated Carbon

The aim of this work was to evaluate the adsorption properties of anionic dye Reactive Black 5 (RB5) and cationic dye Methylene Blue (MB) from salted aqueous solution using natural clay, aluminum pillared clay (Al-PILC), and activated carbon. The textural properties of the materials were obtained by N2 adsorption at 77 K and the structural properties of natural and pillared clays were determined by X-ray diffraction. The effect of pH, contact time, initial concentration of dye, and influence of the addition of NaCl were evaluated by batch adsorption. Adsorption isotherms of Al-PILC, in different salt concentration were compared with natural clay and activated carbon. The adsorption isotherms were well fitted by the Langmuir and Langmuir-Freundlich models. The process of pillaring only improved the adsorption of the anionic dye RB5. Depending on the system adsorbent/adsorbate analyzed, the salt concentration can either help or hinder dye adsorption. We found that a special morphology formed during the process of pillaring greatly increased adsorption of the MB cationic dye in the range of high salt concentrations. This unexpected result may help in developing new pillarization strategies to treat effluents with high salt content.

Investigation of structure and thermal stability of surfactant-modified Al-pillared montmorillonite

For combining the properties of organoclays and pillared clays, inorganic–organic clays have attracted much attention in recent years. In this study, Al Keggin cation pillared montmorillonites (Al-Mts) were first prepared and parts of Al-Mts were calcined at different temperatures (C-Al-Mts). The inorganic–organic montmorillonites were synthesized by intercalating Al-Mts and C-Al-Mts with the cationic surfactant, hexadecyltrimethyl ammonium bromide (HDTMAB). The products were characterized by X-ray diffraction, X-ray fluorescence, and simultaneous thermogravimetric analysis. For HDTMAB-modified uncalcined Al Keggin cation pillared montmorillonites (H-Al-Mts), the basal spacing increased with the increment of surfactant loading level, but the Al content of H-Al-Mts decreased simultaneously, indicating that the intercalated surfactant replaced some Al Keggin cations in the interlayer space. However, in the case of C-Al-Mts, the interlayer spaces could not be further expanded after surfactant modification, implying that the neighboring montmorillonite layers were “locked” by the aluminum pillars which were formed by dehydroxylation of Al Keggin cation pillars during thermal treatment. The thermal stability of HDTMAB-modified C-Al-Mts (H-C-Al-Mts) was much better than that of H-Al-Mts. The major mass loss of H-C-Al-Mts occurred at ca. 410 °C, corresponding to decomposition of intercalated surfactant cations. In contrast, H-Al-Mts displayed two mass loss temperatures at ca. 270 and 410 °C, corresponding to the evaporation of surfactant molecules and the decomposition of surfactant cations in the interlayer space, respectively.

Tuning of a hypersonic surface phononic band gap using a nanoscale two-dimensional lattice of pillars

We present experimental and theoretical evidence of a phononic band gap in a hypersonic range for thermally activated surface acoustic waves in two-dimensional (2D) phononic crystals. Surface Brillouin light scattering experiments were performed on the (001) surface of silicon, loaded with a 2D square lattice of 100- or 150-nm-high aluminum pillars with a spacing of $500\phantom{\rule{0.16em}{0ex}}\phantom{\rule{0.16em}{0ex}}\mathrm{nm}$. The surface Brillouin light scattering spectra revealed a different type of surface mode, related to the modulation of the lattice structure and the mechanical eigenmodes of the pillars. The experimental data were in excellent agreement with theoretical calculations performed using the finite-element method.