Search

SiC monoliths containing 5 wt.% Al2O3-Y2O3 additive were joined using a thin Ti3AlC2, TiC, or Ti filler. After joining at 1900 °C for 5 h under 3.5 MPa, the joint properties were compared in terms of the microstructure, phase evolution, joining strength, and possible elimination of the joining layer. Although all samples showed a sound joint, the microstructure differed according to the filler. SiC joined with Ti3AlC2 filler showed an indistinguishable joining interface due to the filler decomposition followed by solid-state diffusion into the SiC base, whereas TiC filler remained at the interface without showing decomposition or diffusion. In contrast, the Ti filler showed a possible elimination of the joining layer because of the diffusion of Ti and the formation of TiC. The mean joining strengths for the Ti3AlC2, TiC, and Ti fillers were 300, 234, and 248 MPa, respectively, which were comparable to that of the base SiC material (250 MPa).

A new effective oxidative solution for titanium (Ti) surface etching was recently developed. The present in vitro study was aimed at determining the influence of shorter (than 240 min) treatment time on the surface characteristics of the Ti nano/micro hierarchical structures. Cylinder-shaped Ti grade 5 alloys were etched for 30, 60, 120, and 240 min at room temperature and cleaned successively with acetone, ethanol, and distilled water in an ultrasonic bath. The micro- and nanostructures, surface roughness, dynamic wettability, and the surface elemental composition of the etched surfaces were evaluated. Nano/micro hierarchical structures, composed of micro-pits and nano-channels, were formed on the Ti surface through simple immersion in the oxidative solution. The findings suggest that the 120-min immersion yielded significant enhancement in the roughness and wettability of the Ti surfaces.

This study compared the microstructures and mechanical properties of nickel–chromium–molybdenum (Ni–Cr–Mo) alloys prepared from a single alloy with an identical composition using two new digital processes (selective laser melting (SLM) and soft metal milling (SMM)) and conventional lost-wax casting (LWC). Disc specimens were used to study the microstructures via various analytical methods, while dumbbell-shaped specimens were subjected to tension to determine the mechanical properties (n = 6). The SLM and SMM alloys showed a higher number of large and small pores, respectively, than the LWC alloy. A face-centered cubic (γ)-phased matrix was indexed for all three resultant alloys. The SLM and SMM alloys also showed more homogeneously distributed elements and finer grains (in particular, ultrafine grains in the SLM alloy) when compared to the LWC alloy. Meanwhile, the LWC alloy showed a statistically higher yield strength than the other two alloys (p &lt, 0.001). Notwithstanding, all three resultant Ni–Cr–Mo alloys satisfied the ISO 22674 standard criteria for type 5 materials (yield strength: &gt, 500 MPa, percentage elongation: &gt, 2%, and elastic modulus: &gt, 150 GPa).

The eutectic Mg2Si phase in as-cast Mg-1.3Si alloys appears as a needle or Chinese-script-type morphology. However, when 0.5 wt% Ce is added to a Mg-1.3Si alloy, the morphology of the eutectic Mg2Si phase changes to very fine fibers. Previous studies found that explaining the effects of Ce addition on the modified Mg2Si phase in Mg alloys is challenging. In this study, a new mechanism for modifying the Mg2Si phase in Ce-containing Mg-Si alloys was considered based on microstructure-correlated crystallographic analyses. When Mg2Si phases are grown during solidification, Ce solutes pile up in front of the solid/liquid interface layer and react with Mg, Si, and Ce to form the CeMg2Si2 phase. Tetragonal CeMg2Si2 phases were investigated by high-resolution transmission electron microscopy (TEM) and they were found to be located on one side or on both of the edges of the modified Mg2Si phase. In addition, an analysis of the automated crystal orientation and phase mapping in TEM showed that thin nanorods such as those in the CeMg2Si2 and refined Mg2Si phases are oriented vertically in preferred growth directions 0 0 1 > and 1 1 1 ¯ > for CeMg2Si2 and Mg2Si, respectively. Thus, CeMg2Si2 phases are responsible for the restricted growth of Mg2Si phases.

In this study, we investigated the effect of sintering temperature (1300, 1350, or 1400 °C) and holding time (1 or 2 h) on the mechanical properties of a cobalt-chromium (Co-Cr) alloy (Soft Metal) produced by milling/post-sintering, using a tensile test (n = 6). Prior to the test, the different nanostructures arising from the sintering conditions were also analyzed. The phase ratio of γ (face-centered cubic) phase to ɛ (hexagonal close-packed) phase increased mainly with increasing temperature. The formation of Cr23C6 carbide was greatest in the 1350 °C groups when compared to the other temperature groups. The 1400 °C groups had a substantially greater grain size than the 1300 °C and 1350 °C groups, together with a significant number of annealing twins inside the matrix phases. Overall, the 1350 °C groups showed the most superior properties. The 1400 °C groups showed a mean 0.2% yield strength under 500 MPa. The holding times did not significantly affect the mechanical properties (p > 0.05).

In the context of biology and medicine, nanotechnology encompasses the materials, devices, and systems whose structure and function are relevant for small length scales, from nanometers through microns. The purpose of this study was to compare the microstructures and resultant biocompatibility of three commercially available soft milled cobalt–chromium (Co–Cr) alloys (Ceramill Sintron, CS; Sintermetall, SML; and Soft Metal, SM). Disc-shaped specimens were prepared by milling the soft blanks and subsequent post-sintering. The crystal and microstructures of the three different alloys were studied using optical microscopy, X-ray diffractometry (XRD), energy dispersive X-ray spectroscopy, and electron backscatter diffraction. The amounts of Co, Cr, and molybdenum (Mo) ions released from the alloys were evaluated using inductively coupled plasma-mass spectroscopy. The effect of ion release on the viability of L929 mouse fibroblasts was evaluated by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The SML alloy showed a finer grain size (approx. 5 μm) and a larger pore size (approx. 5 μm) than the CS and SM alloys, and its XRD pattern exhibited a slightly higher ε phase peak intensity than that of the γ phase. In the CS and SML alloys, the average crystallite sizes of the nano-sized Cr23C6 carbide were 21.6 and 19.3 nm, respectively. The SML alloy showed higher concentrations of Cr and Mo in the grain boundaries than the other two alloys. The SML alloy showed significantly higher Co and Mo ion releases (p < 0.001) and significantly lower cell viability (p < 0.05) than the CS and SM alloys. The combined results of this in vitro study suggest that the three soft milled Co–Cr alloys had different crystal and microstructures and, as a result, different levels of in vitro biocompatibility.

Self-assembled nano-layering resulting from combined ionic and hydrogen-bonding interactions of phosphate functional monomers with zirconia have been proposed. The purpose of this study was to investigate the bond strengths of two phosphate monomer-containing adhesive resin cements (Panavia F 2.0 and RelyX U200) to a conventional tetragonal zirconia (Lava Plus, LP) and a new cubic zirconia (Lava Esthetic, LE), with three different shade zones, after air-abrasion. The structures of the zirconia surfaces were examined with scanning electron microscopy (SEM) and X-ray diffractometry (XRD). Vickers hardness and fracture toughness of the surfaces were also evaluated using a hardness tester. After air-abrasion (with 50 µm Al2O3 at a pressure of 0.25 MPa), the surface roughness was measured using confocal laser scanning microscopy (CLSM) and the resin cements were bonded (diameter: 2.38 mm) to the surfaces. All bonded specimens were stored in water at 37 °C for 24 h before performing the shear bond strength (SBS) test (n = 15). In the SEM images, the LP group showed a finer grain size than the LE groups. The XRD patterns confirmed that LP and LE had tetragonal and cubic phases, respectively. Although there were no significant differences in Vickers hardness among the four groups (p = 0.117), the three LE groups revealed inferior fracture toughness to the LP group (p < 0.001). However, neither the surface roughness of the air-abraded zirconia surfaces nor SBS values of each resin cement bonded to them were significantly different (p > 0.05). In conclusion, no significant difference in SBS value was detected between the tetragonal and cubic zirconia within each resin cement used, probably due to the similar surface roughness of the air-abraded zirconia ceramics.

Recently, a simple surface modification treatment of titanium (Ti) was developed to produce nano-and micro-scale features on the surfaces via simple immersion in an oxidative aqueous solution (30% hydrogen peroxide/5% sodium bicarbonate). However, this treatment method of Ti surfaces requires a relatively long immersion time (4 h) in the oxidative solution. In this study, we investigated whether an increase in the temperature of the oxidative etching solution can shorten the immersion time of Ti effectively. Polished grade 5 dental Ti (Ti-6Al-4V) discs were immersed in the oxidative aqueous solution either for 30 or 60 min. The temperature of the etching solution was maintained at 25 (similar to room temperature), 35, or 45 °C during etching. The etched surfaces were studied in terms of micro- and nano-structures, surface roughness, and wettability (surface energy). The increase in the temperature of the solution accelerated the etching effect of Ti and created both micro- and nano-structures on the surfaces more effectively. In particular, immersion for 60 min at the solution temperature of 35 °C significantly increased the surface roughness and wettability, although the etching effect was enhanced further at the solution temperature of 45 °C.

Against a general consensus regarding the high toxicity and low biocompatibility of cast nickel–chromium (Ni–Cr) alloys, the in vitro biocompatibility of selective laser melting (SLM)-fabricated Ni–Cr alloys was investigated and compared with that of cast alloy. Using a single Ni–Cr alloy powder, two SLM alloys with high (SLM_a) and low (SML_b) porosity were prepared by adjusting the laser process parameters in addition to a cast alloy. The alloys were studied in terms of their microstructure, metal ion release, and cell response. All three alloys were composed of only the γ (face-centered cubic) phase. However, both SLM alloys showed more homogeneous dispersion of Ni, Cr, and molybdenum elements and finer grain formation than the cast alloy. Immersion test results indicated that both SLM alloys (in particular, SML_b) exhibited a significantly lower Ni ion release than the cast alloy (P

The efficiency of TiO2-based dye-sensitized solar cells (DSSCs) has been limited because charge transfer is not fully achieved, and the injected electrons always recombine with the acceptor species before the electrode can collect them. The novel device architecture of offering graded bands into the TiO2 photoanode network of DSSCs is presented to enhance the power conversion efficiency (PCE). Mono (x %) as well as graded (w–x–y–z %) W-doped TiO2 films are prepared to form intermediate bands in the bandgap of TiO2. A significant enhancement in the PCE is achieved when mono x % W-TiO2 films are tested as the photoanode of the DSSCs. Furthermore, DSSCs with band-engineered W-TiO2 cascade layer exhibit significant photovoltaic performance showing graded carrier transport to current collector. In particular, a graded 1–5–7–9 W cascade film exhibits the highest photovoltaic performance of 11.30% without decreasing the open-circuit voltage, which is 48% higher than pristine DSSCs without a blocking layer. This ...

We report microstructural evaluation in proton-irradiated SiCf/SiC up to a fluence level of 1018 p+/m2 (E = 20 MeV) performed at the Korea Multi-purpose Accelerator Complex (KOMAC). To fabricate the SiCf/SiC, a SiC-based matrix with two different sintering additives, Sc-nitrate and Al2O3-Y2O3, were infiltrated into the Tyranno® SiC preform by electrophoretic deposition and subsequent hot pressing. Scanning (SEM) and high resolution (HREM) electron microscopy was used to probe crack formation, pore generation and surface amorphization upon irradiation. SiC matrix was comparatively more crack-resistant in the SiCf/SiC with Sc-nitrate than that with Al2O3-Y2O3. Subsurface porosity evolved in the form of continuous bands for Al2O3-Y2O3 and discrete pockets for Sc-nitrate additives. Selective leaching of Si from the grain surface leads to the formation of a graded structure and surface amorphization. Irradiation-induced roughness on the fibers facilitates easy debonding at the SiCf-PyCcoating interface but no significant changes in the flexural behavior were observed.

In this work, the effective degradation of methyl orange as a model of azo dyes which are the common industrial pollutants by Er-doped Mn2O3 nanomaterials was introduced. Erbium (Er3+)-substituted nanocrystalline Mn2O3 (Mn2−xErxO3) was obtained by oxidation of Mn(NO3)2 at ambient conditions under ultrasound sonication in basic solution. Er3+ substitution into the structure of Mn2O3 resulted in a material with new physical properties, composition and morphology. The SEM, XRD, EDX, TEM, HRTEM, XPS techniques were used for characterization of prepared material. Increasing the amount of Er3+ ions during synthesis did not increase significantly the percent substitution in the final product beyond 6%. The influence of substitution of Er3+ ions into Mn2O3 caused a red shift in the absorbance and a decrease in the band gap from 2.01 to 1.92 eV in the case of 6% Er-doped Mn2O3. The as-synthesized compounds were used for sonocatalytic degradation of Methyl Orange (MO). 6% Er-doped Mn2O3 displayed the elevated sonocatalytic activity considering various amounts of erbium. Considering radical scavengers, the sequence of inhibitory effect was 1, 4 Benzoquinone > I− > SO32− > t-BuOH > C2O42−. The influence of various specifications like catalyst amount, primary dye concentration, and ultrasonic power was explored. Furthermore, 92% degradation of the dye in 70 min under ultrasonic irradiation suggests that 6% Er-doped Mn2O3 is a promising sonocatalyst for environmental remediation.

Barium europium(II) aluminate (BaxEu1−xAl2O4) powders were prepared by a solid-state reaction among barium carbonate (BaCO3), europium oxide (Eu2O3), and alumina (Al2O3) powders at 1400 °C for 3 h under a mixed gas flow of H2 and N2. The powders were characterized by powder X-ray diffraction (XRD), infrared and Raman spectroscopy, and photoluminescence (PL). With increasing Ba2+ content in BaxEu1−xAl2O4, the structure of BaxEu1−xAl2O4 changed from a monoclinic (P21) to hexagonal (P63) phase. The hexagonal (P6322) phase was also observed between the two phases. The XRD pattern of a single Ba0.6Eu0.4Al2O4 phase, which has not been reported in the literature, was refined by the Rietveld method and its structure was confirmed by selected-area electron diffraction. With increasing x value, the emission peak in the PL spectra of BaxEu1−xAl2O4 became weaker (x = 0–0.4) and then more intense (x = 0.6–0.98), and its position showed a blue shift from 520 to 498 nm.

This study evaluated the in vitro biocompatibility of nickel–chromium (Ni–Cr) alloys produced via three different manufacturing techniques (casting, selective laser melting [SLM], and soft milling [SM]) from a single alloy with the same elemental composition. The microstructure, ion release, and cell viability of the alloys were studied. The Ni-based γ phase was identified for the three alloys. A segregation of the Cr and molybdenum (Mo) was observed in the cast alloy. The SLM and SM alloys exhibited a more homogeneous elemental dispersion and a finer grain formation than the cast one. Extensive porosity as well as (Mo,Cr)C carbide were generated in the SM alloy. The SLM alloy showed the lowest release of Ni ion, followed by the SM alloy (p

The lithiation of tungsten bronze oxide β-SrTa 2 O 6 was accomplished by the solid state ion exchange of Sr 2+ → 2Li + , which led to a solid solution of Li x Sr 1−0.5 x Ta 2 O 6 ( x = 0–0.31). For the above conversion, β-SrTa 2 O 6 was reacted with various amounts of Li 2 CO 3 at 600 °C in air. With increasing x in Li x Sr 1−0.5 x Ta 2 O 6 , an orthorhombic-to-tetragonal symmetry transition was observed along with a gradual decrease in lattice volume. As observed from scanning electron microscopy and transmission electron microscopy, the grains of Li x Sr 1−0.5 x Ta 2 O 6 phases with x = 0.17 and 0.25 were formed from columnar bundles aligned along the c -axis. Solid state 7 Li nuclear magnetic resonance (NMR) spectroscopy revealed the presence of two different Li environments in Li x Sr 1−0.5 x Ta 2 O 6 , and their respective populations. The ionic conductivity of Li x Sr 1−0.5 x Ta 2 O 6 was measured by ac impedance spectroscopy as functions of the temperature and composition x . Regardless of the composition, the conductivity of Li x Sr 1−0.5 x Ta 2 O 6 displayed an Arrhenius type temperature dependence, and the highest Li + conductivity was found from x ≈ 0.17. At temperatures between 75 and 268 °C, the Li + ionic conductivity of Li 0.17 Sr 0.92 Ta 2 O 6 increased from 10 −8.8 S/cm to 10 −5.0 S/cm with an activation energy of 0.74 eV.

This paper reports a facile hydrothermal synthesis of hierarchical coral-like ZnCo2O4 nanostructures comprised of necklace type nanowires without the use surfactants. The hierarchical coral structure is composed of an interconnected necklace-type nanowire arrangement on the nanoscale, facilitating charge transportation. In addition, the coral-like ZnCo2O4 nanowires were mesoporous (29.36 m2 g− 1 and 18.96 nm), leading to large electrochemical active sites for the redox reaction and fast ion transport within the ZnCo2O4 nanowires. When used in electrochemical supercapacitors, the interconnected necklace type, coral-like ZnCo2O4 nanowires exhibited a significantly high specific capacity (694 F g− 1 at a current density of 2 A g− 1), high rate capability (264 F g− 1 at 10 A g− 1), and excellent cycling stability (capacitance retention of ∼ 85% even after 2000 cycles at a charge-discharge current density of 10 A g− 1). These results suggest that hierarchical coral-like ZnCo2O4 nanowires are a promising electrode material for energy storage applications in high-performance pseudocapacitors.

The purpose of this study was to evaluate metal ion release of a cobalt–chromium (Co–Cr) alloy produced by using both the new milling/post-sintering (MPS) and traditional casting (CAST) techniques and the influence of ion release on cell response. The concentration of released ions from the specimens immersed in artificial saliva (pH 5.3 and 2.3) and cell culture medium was measured by inductively coupled plasma-mass spectroscopy. Cell (L929 mouse fibroblasts) response to the specimens was evaluated by water-soluble tetrazolium salt-8 assay (1, 3, and 7 days). The microstructure of the MPS specimen was characterized by fine grain size and predominant e (hexagonal close-packed) phase. The MPS specimens showed consistently significantly smaller releases of Co ions than the CAST specimens (P

HoxCd1−xS (0 ≤ x ≤ 0.12) nanoparticles with different Holmium contents were successfully synthesized via hydrothermal method. The prepared samples were characterized by X-ray diffraction, scanning electron microscopy, Energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and UV–Vis diffuse reflectance spectroscopy techniques. Photocatalytic efficiency of pure and HoxCd1−xS samples was evaluated by monitoring the decolorization of RRed 43 in aqueous solution under visible light irradiation. 8 % Ho-doped CdS nanoparticles indicated the highest decolorization among the different amounts of dopant agent used. The effect of operational parameters including doping level, catalyst dosage, initial dye concentration and radical scavengers on the photocatalytic activity were evaluated. The Langmuir–Hinshelwood (L–H) model was evaluated for the photocatalytic process.

We report the fabrication of self-organized titania (TiO2) nanotubes (TNTs) with controlled pore diameters (140–20 nm) by anodization for the application of electrochemical capacitor electrodes. The areal capacitances obtained for 140 nm TNTs as 0.23/0.13 mF cm–2 at a scan rate of 1/5 mV s–1 and it is enhanced to 5.5/2.9 mF cm–2 (at the same scan rates) by controlling the pore diameter to 20 nm. In this study, role of pore diameter in the capacitance behavior of TNTs is explained on the basis of effective surface area and presence of oxygen vacancies/titanium interstitials. With a decrease in the pore diameter, the surface area-to-volume ratio (and hence, active surface sites) increases, which leads to greater dissociation of Ti4+ into Ti3+ under high temperature annealing and thus brings more nonstoichiometric defects like Ti3+ interstitials and oxygen deficiency within the lower dimensional TNTs. This manifests higher charge conductivity and greater electrochemical performance of TNTs with lower diamete...

Water pollution is one of the main global concerns affecting humans and numerous people die annually because of the diseases inflicted by contaminated water. Due to the toxicity and carcinogenic potential of the dyes in effluent, it is necessary to attain an efficient method for wastewater treatment using the highly active and reusable photocatalyst. This study presents a promising green approach for the preparation of heterogeneous catalytic nanoparticles by investigating the synergistic effect of metal ions in spinel structure to enhance their photocatalytic activity. Herein, Mg0.5Zn0.5FeMnO4 magnetic nanoparticles (MNPs) were prepared by a green sol-gel process and thoroughly characterized by X-ray Photoelectron Spectroscopy (XPS), powder X-ray diffraction (XRD), Electrochemical Impedance Spectroscopy (EIS), field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX), transmission electron microscope (TEM), Brunauer Emmett Teller (BET), Fourier transform infrared spectroscopy (FT-IR), high-solution transmission electron microscopy (HRTEM) images and selected area electron diffraction (SAED), Differential reflectance spectroscopy (DRS), vibrating sample magnetometer (VSM), and elemental mapping. XRD pattern confirmed the spinel structure of Mg0.5Zn0.5FeMnO4 MNPs which displayed good photocatalytic performance for the decolorization of Reactive Blue 21 (RB21) dye under ambient conditions and at natural pH (pH = 6) wherein 96% of dye was degraded in 30 min and total organic carbon removal followed in 30, 60, and 120 min. Mechanistic aspects of the photodegradation were ascertained in presence of scavenger agents and the degradation products were studied by Gas chromatography–mass spectrometry (GC-MS) with identification of smaller ensuing fragmented molecules. Magnetic nanoparticles could be recycled by applying an external magnet, and their efficiency was maintained intact even after five cycles while retaining their structural integrity as attested by XRD, and FESEM analysis after reuse.

Pure and Sm-doped ZnO nanoparticles were synthesized applying a simple sonochemical method. The nanocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) techniques which confirmed the successful synthesis of the doped sonocatalyst. The sonocatalytic degradation of Acid Blue 92 (AB92), a model azo dye, was more than that with sonolysis alone. The 6% Sm-doped ZnO nanoparticles had a band gap of 2.8 eV and demonstrated the highest activity. The degradation efficiency (DE%) of sonolysis and sonocatalysis with undoped ZnO and 6% Sm-doped ZnO was 45.73%, 63.9%, and 90.10%, after 150 min of treatment, respectively. Sonocatalytic degradation of AB92 is enhanced with increasing the dopant amount and catalyst dosage and with decreasing the initial AB29 concentration. DE% declines with the addition of radical scavengers such as chloride, carbonate, sulfate, and tert-butanol. However, the addition of enhancers including potassium periodates, peroxydisulfate, and hydrogen peroxide improves DE% by producing more free radicals. The results show adequate reusability of the doped sonocatalyst. Degradation intermediates were recognized by gas chromatography-mass spectrometry (GC-MS). Using nonlinear regression analysis, an empirical kinetic model was developed to estimate the pseudo-first-order constants (kapp) as a function of the main operational parameters, including the initial dye concentration, sonocatalyst dosage, and ultrasonic power.

Although many techniques are available to assess enamel erosion in vitro, a simple, non-destructive method with sufficient sensitivity for quantifying dental erosion is required. This study characterized the bovine dental enamel erosion induced by various acidic beverages in vitro using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Deionized water (control) and 10 acidic beverages were selected to study erosion, and the pH and neutralizable acidity were measured. Bovine anterior teeth (110) were polished with up to 1 200-grit silicon carbide paper to produce flat enamel surfaces, which were then immersed in 20 mL of the beverages for 30 min at 37 °C. The degree of erosion was evaluated using ATR-FTIR spectroscopy and Vickers' microhardness measurements. The spectra obtained were interpreted in two ways that focused on the ν1, ν3 phosphate contour: the ratio of the height amplitude of ν3 PO4 to that of ν1 PO4 (Method 1) and the shift of the ν3 PO4 peak to a higher wavenumber (Method 2). The percentage changes in microhardness after the erosion treatments were primarily affected by the pH of the immersion media. Regression analyses revealed highly significant correlations between the surface hardness change and the degree of erosion, as detected by ATR-FTIR spectroscopy (P

Novel high-efficiency visible-light-sensitive Nd-doped CdTe nanoparticles were prepared with various doping concentrations of neodymium ion by a facile hydrothermal method. The reaction products were analyzed via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoelectron spectroscopy (XPS), and UV-Vis diffuse reflectance spectroscopy techniques. Red shift was seen in the absorption band edge peak in the UV-Vis absorbance spectrum with increasing Nd content. The XRD and XPS results confirmed that Nd ions successfully replaced Cd atoms and were incorporated into the crystal lattice of CdTe. SEM and TEM images indicated spherical structure and high crystallinity. Even at a very low Nd/CdTe molar ratio of 2 mol.%, Nd doping could greatly enhance the photocatalytic activity of CdTe. The photocatalytic activity of Nd-doped CdTe nanoparticles was evaluated by monitoring the decolorization of RRed 43 in aqueous solution under visible-light irradiation. The color removal efficiency of Nd0.08Cd0.92Te and pure CdTe were 83.14% and 14.32% after 100 min of treatment, respectively. Among different amounts of the doping agent, 8 mol.% Nd indicated the highest decolorization. The presence of radical scavengers such as Cl−, CO32−, SO42−, and buthanol was found to reduce the decolorization efficiency.

A network structured carbon-doped GaN (GaN:C) nanowires (NWs) was formed by a modified metal-organic chemical vapor deposition (MOCVD) technique using Ga(CH 3 ) 3 , HCl and NH 3 as precursors. The GaN:C NWs were acquired from a non-stoichiometric ratio of Ga(CH 3 ) 3 and HCl, and the key process is believed to be the formation of polymerized GaCl x containing methyl groups. As-formed GaN:C NWs exhibited a hexagonal Wurtzite structure. The Ga to N elemental ratio was approximately 1:1, and the GaN:C NWs contained carbon with concentration of ∼5%. The GaN:C NWs showed the blue luminescence (BL) at 2.69 eV, which was conjectured to originate from the C N + – C N 0 transitions. The method developed in this study could produce a network structure of GaN:C NWs without using catalysts. Moreover, carbon doping was found to be one of the candidates to change the optoelectronic properties of GaN.

The purpose of this study was to investigate the efficacy of novel mercapto silane-based experimental primers on the resin bonding and its durability to dental noble metal–ceramic alloys in comparison with that of commercial primers. Disc-shaped gold–platinum–palladium, gold–palladium–silver, and palladium–silver alloy specimens were used as the adherents after air-abrasion. One of three commercial primers (M.L. Primer, Single Bond Universal, and All-Bond Universal) and two experimental primer systems (2-step application with γ-mercaptopropyltrimethoxysilane and then γ-methacryloxypropyltrimethoxysilane and a blend of the two silanes) was applied to each alloy. Resin cylinders with a diameter of 2.38 mm were bonded to the surfaces and light-cured. All bonded specimens were stored in water at 37 °C for 24 h and then half of them additionally water immersed for 7 days (37 °C) and then thermocycled 10,000 times before the shear bond strength test (n = 10). The surface energy parameters for unprimed a...

Hierarchical (HC) porous titania (TiO 2 ) nano-networks are developed via a two-step anodization method in a mixed viscous electrolyte of hydrofluoric acid (HF) and glycerol. An ordered imprint was generated on metallic titanium (Ti) substrate and subsequently anodized this imprint in aged HF/glycerol at different conditions to create HC nanostructures. The optimal HF/glycerol volume ratio, conductivity, and initial water/glycerol content of the electrolyte are 1:5, 10 to 12 μS/cm, and 17/83 vol%, respectively, for obtaining HC structures. Also, ruthenium-based dye adsorption analysis demonstrates better dye adsorption on HC–TiO 2 as compared to conventional TiO 2 nanotubes (TNAs), due to the enhanced active surface area of the HC nano-network.

Neodymium (Nd) ions were successfully substituted for manganese in the crystal lattice of electrolytic amorphous nanomanganese dioxide (EAMD) for the first time, by cathodic deposition from a basic aqueous solution of KMnO4 at 22 °C. The synthesized nanomaterials are characterized by XRD, SEM, TEM, HRTEM, and XPS. The Nd-doped EAMD (Nd-EAMD) produced at 5.0 V is amorphous with homogeneous size and morphology with an average particle size of 26.9 nm. The percent Nd substitution is about 0.69 at%. The as-prepared nanomaterials increase the rate of transformation of Rhodamine B (Rh B) in solution and proceed via an oxidative mechanism.

Catalytic Ni films on Si substrates were modified by NH 3 plasma, and carbon nanotubes (CNTs) were then grown on the Ni films by plasma enhanced chemical vapor deposition. The effect of the NH 3 modification power was investigated in relation to the growth of CNTs. As the modification power increased above 20 W, the structural phase of the Ni films evolved from pure Ni to Ni-silicide (Ni–Si) phase. This could be explained by the inter-diffusion of Ni and Si, due to the energetic ion bombardments, which resulted in the formation of Ni–Si layer on the Si substrate. In addition, the growth mode of as-grown CNTs changed from top-growth to base-growth mode after the formation of the Ni–Si phase. This indicated that the Ni–Si layer adhered to the Si substrate more strongly than the Ni layer and the formation of the Ni–Si layer led the change of the CNT growth mode.

Single and multi-stage Y-branched TiO 2 nanotube arrays (TNAs) have been fabricated by a voltage ramping down process using potentiostatic two-step anodization in 0.5 wt% hydrofluoric acid (HF)/glycerol (1:2 volume ratio) electrolyte. Initially, the voltage is kept at 40 V for 3 h and then it is ramped down to different voltages (e.g. 30 V, 34 V, 36 V, 38 V and 39 V) at a ramping rate of either −1.0 V s −1 or −0.5 V s −1 in one time and two-time aged electrolytes. The growth mechanism of Y-branching of TNAs is modeled and explained in terms of unequal interfacial movements of the two interfaces across the barrier oxide layer (BOL) under non-steady-state growth regime. The ‘pinched off’ area of the BOL at the nanotube propagation front can be controlled effectively with the relative ramping voltage levels and electrolyte's conductivity to obtain Y-branched TNAs.

Ln x Pb 1− x Te(Ln:Nd 3+ ,Yb 3+ ) nanomaterials were synthesized using the facile hydrothermal method. The prepared samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). XRD analysis demonstrated that PbTe phase is cubic. By increasing the concentration of Ln 3+ ions, the DRS spectra of PbTe shows blue shifts instead of red shifts due to bonding changes. XPS analysis of doped PbTe samples confirms the incorporation of Yb and Nd into the lattice. The electrical conductivity of Ln-doped PbTe is shown to be higher than that of pure PbTe, and increases with temperature.

This paper reports a simple, biogenic and green approach to obtain narrow band gap and visible light-active TiO2 nanoparticles. Commercial white TiO2 (w-TiO2) was treated in the cathode chamber of a Microbial Fuel Cell (MFC), which produced modified light gray TiO2 (g-TiO2) nanoparticles. The DRS, PL, XRD, EPR, HR-TEM, and XPS were performed to understand the band gap decline of g-TiO2. The optical study revealed a significant decrease in the band gap of the g-TiO2 (E g = 2.80 eV) compared to the w-TiO2 (E g = 3.10 eV). The XPS revealed variations in the surface states, composition, Ti4+ to Ti3+ ratio, and oxygen vacancies in the g-TiO2. The Ti3+ and oxygen vacancy-induced enhanced visible light photocatalytic activity of g-TiO2 was confirmed by degrading different model dyes. The enhanced photoelectrochemical response under visible light irradiation further supported the improved performance of the g-TiO2 owing to a decrease in the electron transfer resistance and an increase in charge transfer rate. During the TiO2 treatment process, electricity generation in MFC was also observed, which was ~0.3979 V corresponding to a power density of 70.39 mW/m2. This study confirms narrow band gap TiO2 can be easily obtained and used effectively as photocatalysts and photoelectrode material.

This study evaluated the application of advanced bimetallic catalytic species of Ni and W to effectively produce hydrogen gases from ethanol steam reforming. The highest reactivity was achieved using the Ni 0.95 W 0.05/ SBA-15 catalyst. The maximum H 2 production and ethanol conversion of 90% and 85%, respectively, were obtained for 0.4 g catalyst at 600 °C after 10 h with a EtOH:H 2 O ratio of 1:3 and a gas hourly space velocity of 6000 h −1 . This highlights a synergy between the Ni and W loading on SBA-15 during ethanol steam reforming that occurs through the inhibition of Ni particle agglomeration and consequent decrease in catalytic deactivation. Additionally, the supplied W ingredients promoted CO 2 selectivity, which was generated from the CO–water gas shift reaction.

Blue emission from orthorhombic InOOH nanowires was increased dramatically by 30-fold after doping with 1 mol% Eu. This was attributed to the reduction of Eu(III) to Eu(II), which was localized on the surface and created defects. On the other hand, a larger amount of Eu-doping did not result in strong blue emission. Corundum-type rhombohedral and cubic In2O3 were obtained by post-thermal annealing of the nanowires at 400 and 700 °C, respectively. Interestingly, rhombohedral In2O3 remained stable after doping with 10 mol% Eu even upon high temperature thermal annealing at 700 °C. The morphology was changed significantly for the undoped and 1 mol% doped samples, whereas the 10 mol% doped sample showed resistance to morphological changes upon annealing at 700 °C.

In this present work, BiOI sensitized zirconia (BiOI-ZrO2) nanoparticles were fabricated using a precipitation–deposition method. The physicochemical characteristics of BiOI/ZrO2 were studied through X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), BET-surface area, X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis-DRS) and photoluminescence (PL) spectroscopy techniques. The absorption maximum of ZrO2 was shifted to the visible region after sensitization with BiOI. BET-surface area results inferred that the prepared hetero-junctions were meso-porous in nature. The photocatalytic activity of BiOI-ZrO2 for the degradation of methyl violet (MV) dye under simulated solar light irradiation was investigated in detail. 3% BiOI-ZrO2 exhibited the highest photocatalytic performance (98% of MV degradation) when compared with ZrO2 and BiOI. The enhancement in the photocatalytic activity of BiOI-ZrO2 is ascribed to the sensitization effect of BiOI, suppression of electron–hole recombination and the formation of p-n hetero-junction.

Yttrium ortho vanadate supported β-silver iodide nanoparticles (AgI–YVO4) were designed by a sono-chemical deposition method. The structural, morphological and optical properties of the as-prepared nanoparticles were investigated in detail. Transmission electron microscopy (TEM) results revealed that AgI nano-sheets were attached to YVO4 nano-grains. UV-vis-DRS results indicated that the visible light absorption ability of YVO4 was promoted by AgI modification. The photocatalytic activity was evaluated for the degradation of rhodamine-B (Rh-B) dye under simulated solar light irradiation. The photocatalytic activity of YVO4 was strongly influenced by the concentration of AgI. The photocatalyst of 10% AgI–YVO4 exhibited the best performance (98%) for the degradation of Rh-B. Moreover, the photocatalytic activity was well maintained even after four cycles. The results of this research work would be very useful for the degradation of harmful organic dyes in aqueous environments.

We synthesized hexagonal phase Pr(OH)3 nanorods by a hydrothermal method and obtained cubic phase Pr6O11 by post-thermal annealing at above 550 °C. Pr(OH)3 nanorod growth was found to occur in the [0 0 1] direction. Upon thermal annealing, the oxidation state of Pr(III) was changed to Pr(III, IV). The physicochemical properties were fully examined by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) crystallography, UV–Visible–NIR absorption, differential scanning calorimetry/thermogravimetric analysis (DSC/TGA), X-ray photoelectron spectroscopy (XPS), and temperature-programmed reduction (TPR) and CO oxidation activity tests.

Hexagonal phase Gd(OH)3 nanorods were synthesized by a hydrothermal method, and cubic phase Gd2O3 nanorods were obtained by a post-annealing treatment. Their physicochemical properties were fully examined by scanning electron microscopy, transmission electron microscopy, X-ray diffraction crystallography, differential scanning calorimetry/thermogravimetric analysis, Raman spectroscopy, FT-IR, UV–vis absorption, X-ray photoelectron spectroscopy and a temperature-programmed reduction experiment. Gd2O3 nanorods showed a hydrogen reduction peak at 790 °C. Hexagonal and cubic crystalline phases were confirmed by XRD and Raman results.

This paper reports a simple, biogenic and green approach to obtain narrow band gap and visible light-active TiO2 nanoparticles. Commercial white TiO2 (w-TiO2) was treated in the cathode chamber of a Microbial Fuel Cell (MFC), which produced modified light gray TiO2 (g-TiO2) nanoparticles. The DRS, PL, XRD, EPR, HR-TEM, and XPS were performed to understand the band gap decline of g-TiO2. The optical study revealed a significant decrease in the band gap of the g-TiO2 (Eg = 2.80 eV) compared to the w-TiO2 (Eg = 3.10 eV). The XPS revealed variations in the surface states, composition, Ti4+ to Ti3+ ratio, and oxygen vacancies in the g-TiO2. The Ti3+ and oxygen vacancy-induced enhanced visible light photocatalytic activity of g-TiO2 was confirmed by degrading different model dyes. The enhanced photoelectrochemical response under visible light irradiation further supported the improved performance of the g-TiO2 owing to a decrease in the electron transfer resistance and an increase in charge transfer rate. During the TiO2 treatment process, electricity generation in MFC was also observed, which was ~0.3979 V corresponding to a power density of 70.39 mW/m2. This study confirms narrow band gap TiO2 can be easily obtained and used effectively as photocatalysts and photoelectrode material.

Titanium nitride (TiN) was deposited on the surface of a cobalt&ndash, chromium (Co&ndash, Cr) alloy by a hot-wall type chemical vapor deposition (CVD) reactor at 850 &deg, C, and the coating characteristics were compared with those of a physical vapor deposition (PVD) TiN coating deposited on the same alloy at 450 &deg, C. Neither coating showed any reactions at the interface. The face-centered cubic (fcc) structure of the alloy was changed into a hexagonal close-packed (hcp) phase, and recrystallization occurred over at 10 &mu, m of depth from the surface after CVD coating. Characteristic precipitates were also generated incrementally depending on the depth, unlike the precipitates in the matrix of the as-cast alloy. On the other hand, the microstructure and phase of the PVD-coated alloy did not change. Depth-dependent nano-hardness measurements showed a greater increase in hardness in the recrystallization zone of the CVD-coated alloy than in the bulk center of the alloy. The CVD coating showed superior adhesion to the PVD coating in the progressive scratch test. The as-cast, PVD-coated, and CVD-coated alloys all showed negative cytotoxicity. Within the limitations of this study, CVD TiN coating to biomedical Co&ndash, Cr alloy may be considered a promising alternative to PVD technique.

Hexagonal phase Sm(OH)3 nanoroll sticks were first synthesized by hydrothermal method, and cubic phase Sm2O3 nanoroll sticks were obtained by post-annealing treatment at 450 °C. The growth of Sm2O3 nanoroll sticks was found to be [40-4] direction. Their characteristics were examined by scanning electron microscopy, transmission electron microscopy, X-ray diffraction crystallography, Raman, FT-IR, UV–Vis–NIR absorption, and temperature-programmed reduction experiment.