Selected Area Electron Diffractometry Research Articles

Syntheses and characterizations of GO/Mn3O4 nanocomposite film electrode materials for supercapacitor applications

We have, in this study; used simple, in-expensive and environmentally-friendly successive ionic layer adsorption and reactions (SILAR) deposition procedure to successfully grow GO/Mn3O4 thin film electrode materials. The deposited films were examined for their surface morphology using scanning electron microscopy (SEM) while its morphology and structure was confirmed using transmission electron microscopy (TEM) and selected area electron diffractometry (SAED) respectively. X-ray diffraction (XRD) was used to study their structural properties while their supercapacitive studies were obtained using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques. All deposited films were scanned in 1 M solution of Na2SO4 electrolyte. The SEM images of the deposited films revealed highly porous interconnected morphology with Mn3O4 densely dispersed among graphene oxide (GO). Individual peaks of Mn3O4 and GO compounds indicating uniform spread of Mn3O4 inside the porous matrix of GO were observed from the XRD. Mn3O4 nanograins well-dispersed on the surface were further confirmed through the TEM images while bright concentric rings confirming the polycrystalline nature of the films were observed from SAED images. The film deposited at 40 cycles yielded the maximum specific capacitance of 532.54 Fg−1at 5 mVs−1 scan rate. The results of the electrochemical studies show that the GO/Mn3O4 composite films synthesized by SILAR could be a promising material for supercapacitors.

Influence of Nd3+ Doping on the Structure, Thermal Evolution and Photoluminescence Properties of Nanoparticulate TiO2 Xerogels

Undoped and Nd3+-doped xerogels (Nd3+-dopant content in the range 0.5–10 mol%) were obtained from colloidal sols in turn prepared by a “green sol-gel route” in aqueous media. The as-synthesized xerogels were characterized by X-ray diffractometry (XRD), high resolution electron microscopy (HREM) together with selected area electron diffractometry (SAED), and Raman spectroscopy (RS), finding that they crystallize as tiny nanocrystals of anatase with traces of brookite and rutile. The thermal stability of the as-synthesized xerogels was next studied in-situ by X-ray thermo-diffractometry (XRTD) as well as ex-situ by XRD, HREM/SAED, and RS on xerogels calcined at different temperatures (400–900 °C), concluding that Nd3+ doping results in the formation of substitutional solid solutions with enlarged unit-cell volume that (i) stabilizes the anatase phase retarding the onset of its transformation to rutile to ever higher temperatures and (ii) provides the anatase nanocrystals with superior resistance to crystal growth. It was also found that Nd4Ti9O24 eventually precipitates at high temperatures when the Nd3+-dopant content is equal to or higher than 3 mol%, which leaves the still-existing anatase nanocrystals without stabilizer cations therefore causing their immediate transformation to rutile. Finally, the photoluminescence (PL) behaviour of the Nd3+-doped TiO2 xerogels with both anatase and rutile crystal structures was investigated and critically compared, observing that the PL emission (i) increases with increasing crystallinity of the host nanocrystals, (ii) decreases above a certain optimal Nd3+-dopant content due to concentration quenching, and (iii) is much greater for rutile host matrices. In this scenario, the 3 mol% Nd3+-doped rutile xerogel maximized the PL emission, emitting at both ∼915 and 925 nm due to the existence of two distinct local crystal fields for the Nd3+ cations.

Synthesis of Superparamagnetic ZnFe₂O₄-Core/Ag-Deposited ZnO-Shell Nanodiscs for Application as Visible Light Photocatalyst.

Nanodiscs with ZnFe₂O₄ core and Ag-deposited ZnO shell have been synthesized by hydrothermal method. Scanning electron microscopy (SEM) shows the morphology as nanodiscs. X-ray diffractometry (XRD), selected area electron diffractometry (SAED) and Raman spectroscopy reveal cubic ZnFe₂O₄, hexagonal ZnO and face centered cubic Ag as the constituents of the synthesized nanodiscs. Energy dispersive X-ray spectroscopy (EDS) provides the atomic percentage of Ag as 0.6. High resolution transmission electron microscopy (HRTEM) displays the core-shell structure of the synthesized nanodiscs. The specific surface area, pore volume and pore radius of the nanodiscs are 26.83 m² g-1, 0.082 cm³ g-1 and 4.88 nm, respectively. The charge-transfer resistance (RCT) of precursor ZnFe₂O₄ nanoparticles, determined by solid state impedance spectroscopy, is very much smaller than that of pristine ZnO and ZnFe₂O₄/Ag-ZnO and the RCT of ZnFe₂O₄/Ag-ZnO is larger than that of ZnO. The capacitance (C) of ZnFe₂O₄/Ag-ZnO is very much smaller than that of ZnFe₂O₄ and ZnO and the C of ZnFe₂O₄ is much larger than that of ZnO. ZnFe₂O₄/Ag-ZnO nanodiscs as well as ZnFe₂O₄ nanopowder are superparamagnetic. ZnFe₂O₄/Ag-ZnO exhibits surface plasmon resonance (SPR) in the visible region. The emission spectrum of ZnFe₂O₄/Ag-ZnO is similar to that of pristine ZnO and shows violet, blue, blue-green and green emissions due to different crystal defects in ZnO lattice. The synthesized nanodiscs display visible light photocatalysis, degrade dye completely and are reusable visible light photocatalyst. The mechanism of visible light photocatalysis is addressed.

CdO-Intercalated TiO2 Nanosphere-Clusters: Synthesis and Electrical, Optical and Photocatalytic Properties

Nanocrystalline TiO2, owing to its optical and electrical properties and chemical stability, is a technologically and industrially important semiconductor material. Modification of its optoelectronic characteristics by implanting CdO nanocore enables to retain its non-toxicity as well as stability and this cannot be achieved by Cd2+-doping or depositing CdO. CdO-intercalated TiO2 forms type III heterojunction and its synthesis and optoelectronic properties are unexplored. Nanocrystalline CdO was obtained by precipitation method and CdO-intercalated anatase TiO2 nanosphere-clusters synthesized by sol-gel technique. The scanning electron micrographs reveal the size of nanospheres forming the clusters as 115–165 nm. The energy dispersive X-ray spectrum confirms the presence of the constituent elements. Selected area electron diffractometry along with transmission electron microscopy shows intercalation of CdO nanocore in TiO2 anatase lattice. While the charge transfer resistance of the synthesized sample is larger than that of pristine TiO2 the band gap of the obtained nanospheres does not differ from that of pristine TiO2. However, the intercalation suppresses the deep level emission. The synthesized nanosphere-cluster is an efficient photocatalyst. The photocatalytic activities of CdO-intercalated TiO2 and pristine TiO2 have been analyzed in terms of their optical and electrical properties.

Synthesis of mesoporous worm-like ZrO 2 –TiO 2 monoliths and their photocatalytic applications towards organic dye degradation

Abstract The current article reports on the synthesis of a thermally stable mesoporous worm-like ZrO 2 doped TiO 2 monolith materials through a neutral templating route. The controlled thermal treatment facilitates clean removal of organic templates, resulting in a stable and well-defined porous framework. The ZrO 2 doped TiO 2 monoliths serve as an efficient and reusable photocatalyst materials for the photodegradation of Naphthol Green B (NG-B), a widely employed organic dye stain, within 10 min of irradiation time frame. The synthesized monoliths are characterized using techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDAX) spectroscopy, selected area electron diffractometry (SAED), UV–vis diffuse reflectance spectrophotometry (UV–vis–DRS), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), photoluminescence spectroscopy (PLS), and Brunauer–Emmett–Teller (BET) adsorption isotherm. The XRD analysis confirms the retention of anatase phase by the ZrO 2 doped TiO 2 monoliths and also the mesoporous structure. The DRS and PLS analysis indicate that the ZrO 2 doped TiO 2 monoliths exhibit band gap narrowing in comparison to pure TiO 2 monoliths, with improved quantum yield and photocatalytic efficiency. The BET analysis reveals a surface area and pore volume value of 80.2 m 2 /g and 8.1 nm, respectively, for ZrO 2 -TiO 2 monolith materials. We have also investigated on the influence of solution pH, dye concentration, dopant stoichiometry, photocatalyst dosage and photo-additives on the photocatalysis process.

Superparamagnetic core/shell Fe2O3/ZnO nanosheets as photocatalyst cum bactericide

Core/shell Fe2O3/ZnO nanosheets have been synthesized hydrothermally and characterized by high resolution scanning and transmission electron microscopies, X-ray and selected area electron diffractometries, Raman spectroscopy and vibrating sample magnetometry. The core/shell nanosheets are superparamagnetic and absorb strongly at 3.2eV. Their emission is similar to that of pristine ZnO. The photocatalytic activity is far larger than that of Fe2O3 and is not less than that of ZnO. The nanosheets are reusable and photostable. Although the composite constitutes type-I core/shell band alignment the presence of Fe2O3 core does not suppress the photocatalytic activity. The lifetime of charge carriers in core/shell Fe2O3/ZnO does not differ significantly from that of ZnO. The bactericidal activity of Fe2O3/ZnO is larger than that of ZnO. Thus the synthesized composite nanosheets are magnetically recoverable efficient bactericide cum photocatalyst for environmental remediation.

Tri-functional Fe2O3-encased Ag-doped ZnO nanoframework: magnetically retrievable antimicrobial photocatalyst

Fe2O3-encased ZnO nanoframework was obtained by hydrothermal method and was doped with Ag through photoreduction process. Energy dispersive x-ray spectroscopy, transmission electron microscopy (TEM), high resolution TEM, selected area electron diffractometry, x-ray diffractometry and Raman spectroscopy were employed for the structural characterization of the synthesized material. While the charge transfer resistance of the prepared nanomaterial is larger than those of Fe2O3 and ZnO the coercivity of the nanocomposite is less than that of hydrothermally obtained Fe2O3 nanostructures. Although Fe2O3/Ag–ZnO exhibits weak visible light absorption its band gap energy does not differ from that of ZnO. The photoluminescence of the fabricated nanoframework is similar to that of ZnO. The radiative recombination of charge carriers is slightly slower in Fe2O3/Ag–ZnO than in ZnO. The synthesized Fe2O3-encased Ag-doped ZnO, under UV A light, exhibits sustainable photocatalytic activity to degrade dye and is magnetically recoverable. Also, the Fe2O3/Ag–ZnO nanocomposite disinfects bacteria effectively in absence of direct illumination.

Ohmic Contact Fabrication Using a Focused-ion Beam Technique and Electrical Characterization for Layer Semiconductor Nanostructures

Layer semiconductors with easily processed two-dimensional (2D) structures exhibit indirect-to-direct bandgap transitions and superior transistor performance, which suggest a new direction for the development of next-generation ultrathin and flexible photonic and electronic devices. Enhanced luminescence quantum efficiency has been widely observed in these atomically thin 2D crystals. However, dimension effects beyond quantum confinement thicknesses or even at the micrometer scale are not expected and have rarely been observed. In this study, molybdenum diselenide (MoSe2) layer crystals with a thickness range of 6-2,700 nm were fabricated as two- or four-terminal devices. Ohmic contact formation was successfully achieved by the focused-ion beam (FIB) deposition method using platinum (Pt) as a contact metal. Layer crystals with various thicknesses were prepared through simple mechanical exfoliation by using dicing tape. Current-voltage curve measurements were performed to determine the conductivity value of the layer nanocrystals. In addition, high-resolution transmission electron microscopy, selected-area electron diffractometry, and energy-dispersive X-ray spectroscopy were used to characterize the interface of the metal-semiconductor contact of the FIB-fabricated MoSe2 devices. After applying the approaches, the substantial thickness-dependent electrical conductivity in a wide thickness range for the MoSe2-layer semiconductor was observed. The conductivity increased by over two orders of magnitude from 4.6 to 1,500 Ω(-) (1) cm(-) (1), with a decrease in the thickness from 2,700 to 6 nm. In addition, the temperature-dependent conductivity indicated that the thin MoSe2 multilayers exhibited considerably weak semiconducting behavior with activation energies of 3.5-8.5 meV, which are considerably smaller than those (36-38 meV) of the bulk. Probable surface-dominant transport properties and the presence of a high surface electron concentration in MoSe2 are proposed. Similar results can be obtained for other layer semiconductor materials such as MoS2 and WS2.

Enhanced Field Emission Properties of Ag Nanoparticle-Decorated ZnO Nanorods Under Ultraviolet Illumination

In this paper, pure ZnO and Ag nanoparticle (NP)-decorated ZnO nanorods (NRs) were successfully synthesized via a low-temperature hydrothermal method. The as-prepared samples were characterized through high-resolution transmission electron microscopy and selected-area electron diffractometry. The enhanced field emission (FE) behavior of the Ag NP-decorated ZnO NRs along the [0002] crystal $c$ -axis and their single-crystalline hexagonal structures were characterized with surface-protruding Ag NPs. The resulting FE in the dark and under ultraviolet illumination had low turn-ON electric fields of 3.93 and 2.04 $ \rm V\,\cdot \mu m^{-2}$ , whereas the enhanced field enhancement factors were 1593 and 57 872, respectively.

Nonquenching of charge carriers by Fe3O4 core in Fe3O4/ZnO nanosheet photocatalyst.

Fe3O4-implanted ZnO and pristine ZnO nanosheets have been synthesized hydrothermally. High-resolution scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, elemental mapping, selected area electron diffractometry, powder X-ray diffractometry, Raman spectroscopy, vibrating sample magnetometry, solid state impedance spectroscopy, UV-visible diffuse reflectance spectroscopy, and photoluminescence spectroscopy show implantation of Fe3O4 in ZnO nanosheets. Fe3O4 core with ZnO shell is of type I core/shell heterostructure which is to quench charge carriers and suppress photocatalysis. But the photocatalytic activity is not suppressed on implantation of Fe3O4 in ZnO nanosheets, and time controlled single photon counting lifetime spectroscopy shows that the photogenerated charge carriers are not quenched by the Fe3O4 core in the ZnO nanosheets. The composite nanosheets are photostable, reusable, and magnetically recoverable, revealing potential application in mineralization of organic pollutants.

Synthesis of Nanoparticulate In‐Doped BiVO4 for Enhanced Visible‐Light Photocatalytic Degradation of Dye

Indium (2.9, 3.5, and 4.9 at. %)‐doped and pristine monoclinic BiVO4 nanoparticles were synthesized by hydrothermal method. They were characterized by high‐resolution scanning electron, field emission scanning electron, transmission electron and high‐resolution transmission electron microscopies, powder X‐ray and selected‐area electron diffractometries, energy‐dispersive X‐ray, Raman, UV‐visible diffuse reflectance, photoluminescence, and solid‐state impedance spectroscopies. The band gap and near‐band‐gap emission of 4.9% In‐doped BiVO4 nanoparticles are larger than those of the rest of the nanomaterials. The charge‐transfer resistance of 4.9% In‐doped BiVO4 is the least. In‐doping enhances visible‐light photocatalytic activity.

Enhanced visible light-photocatalysis by hydrothermally synthesized thallium-doped bismuth vanadate nanoparticles

Thallium-doped (1.5, 2.3 and 19.3at%) bismuth vanadate (BiVO4) and pristine BiVO4 nanoparticles were hydrothermally synthesized. They were characterized by powder X-ray and selected area electron diffractometries, high resolution scanning electron and transmission electron microscopies, and energy dispersive X-ray, Raman, UV–visible diffuse reflectance and photoluminescence spectroscopies. Tl-doping reduces the band gap energy and recombination of charge carriers. The visible light photocatalytic activity of 19.3% Tl-doped BiVO4 nanoparticles is larger than those of the other Tl-doped BiVO4 and pristine BiVO4 nanoparticles. The synthesized Tl-doped BiVO4 nanoparticles displaying enhanced photodegradation of dye could find potential applications as visible light photocatalyst for the abatement of various organic pollutants.

Synthesis of luminescent SnO2:Eu3+ nanorods via a salt-assisted solution combustion process.

SnO2:Eu3+ nanorods have been successfully synthesized by annealing products from microwave-induced KCl-assisted solution combustion reaction, which uses tin (IV) chloride pentahydrate and europium nitrate as cationic source, ethyl glycol as fuel and ammonium nitrate as combustion-supporting agent. The structural and photoluminescent properties of SnO2:Eu3+ nanorods were investigated by high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), selected area electron diffractometry (SAED), X-ray diffractometry (XRD) and photoluminescence spectroscopy. The phase transformation in the synthetic process was observed by X-ray diffraction pattern. Accordingly, the growth mechanism of SnO2:Eu3+ nanorods was discussed. The results showed that the SnO2:Eu3+ nanorods were rutile-structured single crystals with 10-15 nm in diameter and 200-250 nm in length. Proper addition of KCl into redox mixture solution is critical to the formation of SnO2:Eu3+ nanorods. The doped Eu3+ concentration has obvious effect on the photoluminescence of SnO2:Eu3+ nanorods. The approach is convenient, inexpensive and efficient for the high yield preparation of SnO2:Eu3+ nanorods.

Synthesis and photocatalytic activity of Eu3+-doped nanoparticulate TiO2 sols and thermal stability of the resulting xerogels

The synthesis of nanoparticulate TiO2 sols without and with Eu3+ doping (1, 2, or 3 mol%) by the colloidal sol–gel method in aqueous media was investigated, with emphasis on the effect of the Eu3+ doping on the peptization time and rheological properties of the sols. It was found that the addition of Eu3+ increasingly retards the peptization process, and also results in sols with greater aggregate sizes which are therefore more viscous, although in all cases the distributions of aggregate sizes are unimodal and the flow behavior is Newtonian. The shifting of the isoelectric point of the sols toward greater pH with increasing Eu3+ doping indicates that the aforementioned trends are due to the chemical adsorption of europium ionic complexes in the form of solvated species. Furthermore, the effect of Eu3+ doping on the ultraviolet–visible spectrum and photocatalytic activity of the peptized sols was also explored. It was found that the Eu3+ doping increasingly shifts slightly the absorption edge from the ultraviolet to the visible range, and that its effect on the photocatalytic activity is certainly complex because this is enhanced only if the Eu3+ cations have some electronic transition (charge transfer transition or transitions between the ground state and the excited states) at the wavelength of the incident radiation, in which case the photocatalytic activity first increases with increasing Eu3+ content and then decreases perhaps due to occurrence of Eu–Eu interactions or simply to the greater aggregation state. Finally, the influence of the Eu3+ doping on the thermal stability of the nanoparticulate xerogels resulting from the drying of the peptized sols was also examined by X-ray thermo-diffractometry together with transmission electron microscopy, selected area electron diffractometry, and X-ray energy-dispersive spectrometry. It was found that although the xerogels crystallize all as anatase phase, this is increasingly more thermally stable with increasing Eu3+ doping, displaying a slowed down nanocrystallite growth, delayed onset temperature of the anatase-to-rutile phase transformation, and extended retention temperature of anatase phase.

Solvothermal Synthesis of CeO2–TiO2 Nanocomposite for Visible Light Photocatalytic Detoxification of Cyanide

A CeO2–TiO2 nanocomposite was synthesized solvothermally using ascorbic acid (A), urea (U), or polyvinylpyrrolidone (PVP). Powder X-ray and selected area electron diffractometries and Raman spectroscopy confirm the anatase phase of TiO2 and face-centered cubic lattice of CeO2. Energy dispersive X-ray spectroscopy confirms the purity of the synthesized composites and provides their compositions. Scanning electron, field emission scanning electron, and transmission electron microscopies give the sizes and shapes of the synthesized nanoparticles. UV–visible diffuse reflectance spectroscopy shows the optical absorption edges of CeO2–TiO2 (A), CeO2–TiO2 (U), and CeO2–TiO2 (PVP) as 510, 441, and 410 nm, respectively. The blue, blue-green, and green emissions shown by the three nanocomposites indicate the existence of defects such as oxygen vacancies in the crystal lattices. All three composites differ in their electrical properties, obtained by solid-state impedance spectroscopy. Furthermore, solid-state impeda...

Effect of Er3+ doping on the thermal stability of TiO2 nanoparticulate xerogels

The effect of Er3+ doping on the thermal stability of TiO2 nanoparticulate xerogels prepared by a colloidal sol–gel route was investigated. It was found that the as-synthesized xerogels crystallize as anatase phase with crystallite sizes in the low nanoscale range ( 100 ± 5 m2/g). Nevertheless, it was also found that the Er3+ cations are deposited on the surface of TiO2 nanocrystallites thus resulting in xerogels with smaller and more uniform nanoaggregates. Most importantly, detailed analyses using X-ray thermo-diffractometry together with selective analyses by transmission electron microscopy, selected area electron diffractometry, and X-ray energy-dispersive spectrometry showed that the thermal stability of these TiO2 nanoparticulate xerogels increases with increasing Er3+ doping. Specifically, the nanocrystallite growth is slowed down, the onset temperature of the anatase-to-rutile phase transformation is delayed, and the anatase phase is retained up to greater temperatures as the Er3+ content increases, which are all phenomena attributable to the formation at low temperatures (i.e. ~200 °C) of solid solutions with Er3+ solutes within the TiO2 host. Moreover, these solid solutions also have lower thermal expansion coefficient than the undoped crystal structure. Finally, Er3+ doping increasingly promotes the precipitation at high temperatures of Er2Ti2O7 from the rutile TiO2 solid solution, with the precipitation temperature decreasing with increasing Er3+ doping content.

Deposition and structural characterization of nanostructured RuO2 on rutile-TiO2/sapphire(100) templates by reactive radio frequency magnetron sputtering

We report the deposition and structural characterization of nanostructural RuO2 on rutile (R)-TiO2/sapphire(100) templates by reactive radio frequency magnetron sputtering. The micrographs of field-emission scanning electron microscopy and X-ray diffraction patterns of RuO2/R-TiO2 heteronanostructures indicated the growth of vertically aligned RuO2 (001) nanotubes (NTs) and/or V-shaped RuO2(101) nanowedges (NWs) on top of R-TiO2 nanorods (NRs). Transmission electron microscopy and selected-area electron diffractometry characterizations of the vertically aligned RuO2 NTs showed that the hollow RuO2 NTs with square cross section have open-end morphology with long axis directed along the [0 0 1] direction, while the V-shaped RuO2 NWs revealed that the nanowedges are crystalline RuO2 with twin plane of (101) and twin direction of 1¯01 at the V-junction. The probable mechanisms for the formation of well-aligned RuO2 nanocrystals on top of R-TiO2 NRs were discussed.

Growth and Characterization of Well-Aligned RuO2/R-TiO2 Heteronanostructures on Sapphire (100) Substrates by Reactive Magnetron Sputtering

We report the growth of well-aligned RuO2/R-TiO2 heteronanostructures on sapphire (100) substrates by reactive magnetron sputtering using Ti and Ru metal targets under different conditions. The surface morphology and structural properties of the as-deposited heteronanostructures were characterized using field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and selected-area electron diffractometry (SAED). The FESEM micrographs and XRD patterns indicated the growth of vertically aligned RuO2(001) nanotubes and twinned V-shaped RuO2(101) nanowedges (NWs) on top of R-TiO2 nanorods under different sputtering pressures. TEM and SAED characterizations of the V-shaped RuO2 NWs showed that the NWs are crystalline RuO2 with twin planes of (101) and twin direction of [ 01] at the V-junction.

Micaceous iron oxide prepared from pyrite cinders by hydrothermal method

Micaceous iron oxide (MIO) with a hexagonal flaky shape was prepared by hydrothermal method. The ferric hydroxide used as precursor was obtained by an acidic leaching solution of pyrite cinders reacting with ammonia solution. The optimal experimental conditions for preparing micaceous iron oxide were investigated by orthogonal experiments. Micaceous iron oxide can be successfully prepared when optimal parameters of total iron concentration of 2.0 mol/L, pH value of 8, n(Fe2+)/n(Fe3+) of 0.1, mass of seed crystal of 1 g, reaction temperature of 260 °C and reaction time of 30 min are applied. X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffractometry (SAEM) were adopted to characterize the hydrothermal products prepared under optimal conditions. The results indicate that highly crystallized α-Fe2O3 hexagonal flakes, about 1.0–1.5 μm in diameter and 0.1 μm in thickness, are prepared. Furthermore, the quality of micaceous iron oxide prepared can meet the required characteristics of micaceous iron oxide pigments for paints (ISO10601—2007).

Fabrication of a Nacre-Like Aragonite/PAA Multilayer Film on a Nacre Substrate

We devised a new process for fabricating an artificial nacreous structure on a natural nacre substrate. A film of alternating layers of natural nacre-like aragonite (CaCO3) and poly(acrylic acid) (PAA) was fabricated directly on an aragonitic nacre substrate from a solution at room temperature. Alternate repetition of aragonite growth in a CaCl2 solution and PAA drop coating gave a multilayer inorganic/organic nanocomposite film of alternating aragonite nanostacks and porous PAA. The microstructure and nanostructure of the film were characterized by field-emission scanning electron microscopy. The degree of orientation of deposited aragonite was determined by examination of fabricated aragonite-type strontianite (SrCO3) nanostacks. Analysis by X-ray diffractometry shows that the crystallographic c axis of the nanostacks is oriented perpendicular to the substrate surface. Analysis by transmission electron microscopy selected-area electron diffractometry shows that the a and b axes of the strontianite nanos...