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Crystal and X-ray powder diffraction data are presented for the Al3Ho2Si2 ternary compound. The powder pattern was indexed and refined on a monoclinic cell with the Al3Y2Si2 structure type with space group C12/m1, a = 10.1096(2) Å, b = 4.020(6) Å, c = 6.5734(6) Å, β = 100.848(2)°, V = 262.37 Å3, Z = 2ρx = 5.910 g cm−3, F30 = 142.8(0.006, 35), and RIR = 0.91.
Open pore metal foams may be of interest as regenerators because of their large specific surface area and their high porosity. In this experiment, three aluminum foam samples (pore size 2–2.36 mm and around 65% porosity) were manufactured by the replication process. The volumetric heat transfer coefficient and number of transfer units (NTU) of the foams and a packed bed of steel ball bearings (2 mm diameter) were determined using a single-blow transient technique over the range 500 < Rem < 1400. The NTU values of the foams and ball bearings both reduced with increasing Reynolds number (flow velocity). The pressure drop across the matrices increased with the velocity, though the values for the metal foams were much lower than that of the ball bearings, indicating that they may have potential for this type of application.
The 3D morphological evolution of titanium foams as they undergo a two-step fabrication process is quantitatively characterized through x-ray micro- and nano-tomography. In the first process step, a Cu–Ti–Cr–Zr prealloy is immersed in liquid Mg, where Cu is alloyed with Mg while a skeleton of crystalline Ti–Cr–Zr is created. In the second step, the Mg–Cu phase is etched in acid, leaving a Ti–Cr–Zr foam with submicron struts. 3D images of these solidified Ti–Cr–Zr/Mg–Cu composites and leached Ti–Cr–Zr foams are acquired after 5, 10, and 30 min exposure to liquid Mg. As the Mg exposure time increases, the Ti–Cr–Zr ligaments grow in size. The tortuosity loosely follows the Bruggeman relation. The interfacial surface distribution of these Ti-foams is qualitatively similar to other nano-porous metal prepared by one-step dealloying. The characteristic length of the Mg–Cu phase and pores are also reported.
Copper (I) oxide (Cu2O) is a direct band gap semiconductor with p-type conductivity and is a potential candidate for multi-junction solar cells. In this work, incoherent light source based photo-assisted metal-organic chemical vapor deposition (MOCVD) was used to deposit high quality Cu2O thin films on n-type <100> silicon and quartz substrates. X-ray diffraction studies reveal that crystalline Cu2O is deposited. UV-Vis-NIR spectroscopy results indicated a band gap of 2.44 eV for Cu2O thin films. Transmission electron spectroscopy results show that the Cu2O film grows in the form of three-dimensional islands composed of smaller nanocrystalline grains in the range of 10–20 nm. I–V measurements indicate that the Cu2O/n-Si device fabricated using the MOCVD process has a lower dark current density than other devices reported in the literature.
Hyperbranched copper phthalocyanine (CuPc) with uniform spherical morphology has been firstly obtained by ethylene glycol solvothermal synthetic route. The highly dispersed spherical CuPc aggregates with a diameter of ∼500 nm. X-ray diffraction indicated that the molecules were stacked into one-dimensional b-axis aggregate. In addition, the split Soret band together with the broadened and blue-shifted Q-bands in the optical spectra suggested the H (face-to-face) type of interactions in the arrangement of macrocycles in a dense-packed structure. Due to its good symmetrical structure and unique morphology, the hyperbranched spherical CuPc showed excellent broadband microwave absorption behaviors in a frequency of 2–18 GHz. Over an absorber of 5 mm thickness, an absorption bandwidth of 12 GHz corresponding to reflection loss below −10 dB can be obtained. The high value of microwave reflection about −50 dB at the frequency of 16.5 GHz also suggested that the hyperbranched spherical CuPc can be used as promising microwave absorbing materials.
Morphological and crystallographic effects of a high magnetic field on the primary Al6Mn phase formed during the solidification of hypereutectic Al–3.25wt%Mn were investigated. Without the field, the primary Al6Mn crystals are mainly concentrated in the lower part and reveal a dispersed needle-like shape. In three dimension, the needles are in the form of a quadrangular prism (laterally bound by {110} and preferentially growing along <001>). When the magnetic field is applied, they tend to be distributed homogenously and show some extra agglomerate- or chain-like forms (preferentially extending along <100>). Furthermore, they also tend to preferentially orient with <100> parallel to the field direction. The homogenous distribution is caused by the magnetic viscosity resistance force. The “agglomerates” or “chains” are the result of a “bifurcation effect” due to the breakdown at the sharp edges of the quadrangular prisms. The preferential orientation should be attributed to the magnetocrystalline anisotropy of Al6Mn.
Four-layer multiwalled carbon nanotube (MWNT) thin films were deposited via dropcasting (1 mg/mL MWNTs and 10 mg/mL SDBS) onto filter papers that vary in pore size (1, 5, 25, and 40 µm) to determine the effect of the underlying substrate structure on the in-plane properties of the films. The films (<100 nm thick) were dried using vacuum filtration, and drying in a 65 °C heater with and without a ceramic heating board. DC resistance of the films ranged from 6 × 103 to 9.3 × 109 Ω. Impedance spectroscopy analysis revealed a low and a high frequency inductive response and two parallel R–C circuits for the more conducting thin films. High resistance films were fit by a single RC circuit with a constant-phase element. The differences in the in-plane electrical responses of the different MWNT films can be explained by the degree of carbon nanotube surface coverage, obtained as a result of using different pore size filter papers. The drying method utilized also affected the CNT network formation and its resultant electrical properties.
(Ti,Mn)Al/Al2O3 composites were successfully synthesized by reactive hot pressing from Ti–Al–TiO2–MnO2 system. The effect of Mn coming from the Al–MnO2 reaction on the microstructure and mechanical properties of (Ti,Mn)Al/Al2O3 in situ composites was investigated in detail. The results show that the as-prepared products are mainly composed of (Ti,Mn)Al matrix (including a little of Ti3Al) and Al2O3 particles, together with a few amount of Al77.5Mn22.5 phases. The (Ti,Mn)Al matrix is refined and the in situ generated Al2O3 particles distribute uniformly on the boundaries of (Ti,Mn)Al by incorporation of Mn. The (Ti,Mn)Al/Al2O3 composite with 1.92 wt% Mn possesses the best mechanical properties. Compared with Mn-free samples obtained from Ti–Al–TiO2 system, the hardness, flexural strength, and fracture toughness are enhanced by 53.46%, 76.49%, and 64.21%, respectively. The strengthening and toughening mechanisms were also discussed specifically.
High-performance and continuous zeolite MFI membranes have been successfully fabricated, using in situ hydrothermal synthetic method, on α-Al2O3 hollow ceramic fifibers (HCFs). The CO2 separation properties of the as-prepared MFI membrane are studied by single gas permeation and binary gas permeation of CO2/N2 and CO2/CH4. The separation results show that the membrane exhibits high CO2 selectivity with separation factors of 9.2 and 6.0 for CO2/N2 and CO2/CH4, respectively. A preferred permeance for CO2 in the binary gas mixtures is about 3 × 10−7mol/(m2 s Pa). Furthermore, the supported MFI membrane possesses high mechanical strength, strong thermal stability, and high reproducibility, which are expected to have potential applications in industrial CO2 recycling.
Fusion bead method produces homogeneous samples and is suitable for analysis using fundamental-parameter (FP) method in XRF. This report describes an FP method for analysis of non-oxide samples such as metals made into fusion beads. During the fusion process, all non-oxide elements in the sample are oxidized and gain-on-ignition (GOI) occurs. Volatile elements such as carbon do not remain in the sample as a result of fusion. This process is known as loss-on-ignition (LOI). To obtain reliable analysis results of fusion beads with the FP method, weight changes as a result of LOI and GOI must be reflected accurately in software calculation. The newly developed FP method, which takes these weight changes and dilution ratios into consideration, was able to yield accurate analysis results for ferroalloys FeSi, FeMn, and SiMn, some of which have high carbon content. This method is also applicable for sulfides and carbides.
A powder X-ray diffraction method was developed and validated to measure the crystalline impurity 4-(5-cyclopentyloxy-carbonylamino-1-methyl-indol-3-ylmethyl)-3-methoxy-N-o-tolylsulfonylbenzamide hydrate in a pharmaceutical tablet ranging from 0.6 to 3% (w/w). The calibration plot was found to be linear with a correlation coefficient (r2) of 0.996, and was reproducible among operators. The detection limit was determined to be 0.6% with a signal-to-noise ratio of 3:1. The quantitation limit was determined to be 1% with a signal-to-noise ratio of 5:1. Instrument precision at the quantitation limit was 5.8%. Method precision was 6.1% at the quantitation limit and 7.4% at the detection limit. Intermediate precision at the quantitation limit was 7.3% during a 6-month study. Accuracy measurements using crystalline impurity standards prepared in an excipient mixture ranged from 89.3 to 105.5%. Accuracy measurements using tablets containing spiked quantities of crystalline impurity ranged from 72.0 to 92.7%. Accuracy measurements using spiked tablets were complicated because the crystalline impurity was lost during the manufacturing process and a correction factor was used. Ruggedness was assessed by evaluating repetitive assay, repetitive packing, sample packing, and sample stability. Repetitive assays show the exposure of standards to a relative humidity in excess of 57% caused displacement error because of an increase in sample volume and a peak-position shift. Repetitive-packing studies show the analyte was extracted from the sample at a low relative humidity because of a static-charge induction. Sample-packing studies show that two subjective packing techniques were equivalent, and that under- and over-packing samples cause changes in sample density which would not affect results within ±16%. Sample-stability studies show that the quantitation-limit standard was stable as long as the sample was exposed to a relative humidity below 57%.
A new technology to coat open-celled foams homogeneously by using a vertical centrifuge and shear-thinning slurries is presented. The technology is exemplified by a complex multilayer-coated foam for catalytic applications (Fig. 3). Furthermore, a new calculation model for the estimation of coating thickness and for quality assessment is introduced and proved by comparing the calculated and experimental data. Based on these results, various material combinations are shown, e.g., layers made of rough particles, zeolites, activated carbon, γ-Al2O3, perovskites, mullite, and yttria–alumina–garnet on SiC–, Al2O3–, or cordierite foams. Theses “functionalized foams” can be used for a wide variety of practical applications, e.g., as adsorbents and catalysts in environmental engineering, as preforms for metal matrix composites, and for special purpose applications that require corrosion and oxidation resistance.