Physical characterization of anhydrous and hydrous forms of the hydrochloride salt of BVT.5182 a novel 5-HT(6) receptor antagonist

The physicochemical properties of 1-benzenesulfonyl-4-(piperazin-1-yl)-indole hydrochloride, a novel 5-HT₆ receptor antagonist for the treatment of obesity were characterized. Two solid state forms were identified at ambient conditions (23°C): an anhydrate form (1) and a hydrate form (2), with 1.5 moles of H₂O. The latter easily dehydrates and rehydrates without affecting the crystal morphology. Investigations of the propensity for interconversion between the two forms reveal that a) conversion of 2→1 takes place above 145°C and that b) conversion of 1→2 only occurs after crystallization from supersaturated aqueous solutions at a water activity ≥0.94 or in the presence of comparable amounts of crystals of 2 in water at ambient conditions. However, in an equimolar suspension of 1 and 2 at 37°C no phase transformation was observed. Thus, the difference in chemical potential between the two forms is small. Form 1 was shown to have overall favorable solid state properties and, hence, considered the preferred form for continued pharmaceutical development. The characterization was performed by means of light microscopy, scanning electron microscopy, powder X-ray diffraction, FTIR/NIR-spectroscopy, differential scanning calorimetry, hot stage microscopy, thermogravimetry, dynamic vapor sorption, Karl Fischer water content determination, phase stability studies of suspensions, solubility, and intrinsic dissolution rate measurements.     

Synthesis and characterization of nano-sized BaxSr1?xSO4 (0 ≤ x ≤ 1) solid solution by a simple surfactant-free aqueous solution route

A facile aqueous solution route has been employed to synthesize Ba _x Sr_1−x SO₄ (0 ≤ x ≤ 1) solid solution nanocrystals at room temperature without using any surfactants or templates. The as-synthesized products were characterized by means of X-ray diffraction (XRD), X-ray fluorescence spectrometer (XRF), scanning electron microscopy (SEM), and differential scanning calorimetry-thermogravimetry (DSC-TG). The Ba _x Sr_1−x SO₄ solid solution nanocrystals exhibit an orthorhombic structure and an ellipsoidal-shaped morphology with an average size of 80–100 nm. The lattice parameters of Ba _x Sr_1−x SO₄ solid solution crystals increase with increasing x value. However, they are not strictly coincident with the Vegard’s law, which indicates that the as-obtained products are non-ideal solid solutions. The Ba _x Sr_1−x SO₄ solid solution nanocrystals have an excellent thermal stability from ambient temperature to 1300°C with a structural transition from orthorhombic to cubic phase at about 1111°C.     

Processings of iron oxides at room temperature. I. Solid state conversion of pure α-FeOOH into distinctive α-Fe2O3

A distinct α-Fe₂O₃ variety is formed when pure synthetic α-FeOOH is dry ground at ambient temperature in a mechanically driven mortar at > 40 hr periods. XRD and IR spectroscopy indicate that its structural order is distinct from protohematite (obtained by heating α-FeOOH to ～450°C) and from well crystallized hematite. According to the changes observed in the WHH (width at half height) and So (surface area) values vs. grinding time, the broadening of α-Fe₂O₃ diffraction peaks is attributed mainly to decreasing particle size. Preferential disruption of some lattice planes occurs during the irreversible solid state conversion of α-FeOOH → defect α-Fe₂O₃. Variations in size, color and eventually in water content of the progressively formed α-Fe₂O₃ particles are observed.     

Synthesis of nanometric LaCr0.5Mn0.5O3 perovskite at low temperature by the polyvinyl alcohol gel combustion method

Nanosized LaCr_0.5Mn_0.5O₃ perovskite was synthesised with relatively high surface area (15.5 m²/g) at low temperature (650 °C) by the combustion method using polyvinyl alcohol (PVA) and corresponding metal nitrates. The perovskite was characterised by X-ray diffraction, thermogravimetric and differential thermal analysis, field emission scanning electron microscopy and Brunauer–Emmett–Teller technique. The optimal preparative conditions were PVA/metals 3:1 by mole, pH = 3–4 and 80 °C for gel formation. Perovskite exhibits a good catalytic activity in total oxidation of m-xylene at the low temperature of reaction (250 °C).     

Mechanochemical synthesis and heating-induced transformations of a high-entropy Cr-Fe-Co-Ni-Al-Ti alloy

An amorphous-crystalline two-phase (amorphous phase + BCC solid solution) powder alloy has been produced by mechanochemical synthesis (MS): by grinding an equiatomic mixture of Cr, Fe, Co, Ni, Al, and Ti metals in a Fritsch (P-7) ball mill at a powder-to-ball weight ratio of 1: 8. Using X-ray diffraction, X-ray microanalysis, and scanning electron microscopy, we have determined the sequence of reaction steps during milling of the mixture. In the early stages of milling (2 h), we observed the formation of an ordered phase (B2), Al + Ni → NiAl, and the Co_HCP → Co_FCC polymorphic transformation. Milling for 3 h led to the formation of a BCC solid solution. Further milling produced an amorphous phase (AP). In the range 6–25 h of milling, the percentage of the AP increased and that of the BCC solid solution decreased. The phase transformations induced by heating the alloy to 1200°C after MS have identified using differential thermal analysis and X-ray diffraction: \(MS (FCC + AP)\xrightarrow{{450^ \circ C}}(B2)\xrightarrow{{650^ \circ C}}(L2_1 + BCC)\xrightarrow{{850^ \circ C}}L2_1 + \sigma - phase\) (FeCr structure). Prolonged milling has been shown to stabilize the metastable BCC solid solution at temperatures of ?650°C.     

Effect of sintering temperature on the phase composition and microhardness of WC-8 wt % Co cemented carbide

The effect of sintering temperature (800–1600°C) on the phase composition, density, and microhardness of WC-8 wt % Co cemented carbide has been studied using x-ray diffraction, scanning electron microscopy, optical microscopy, and density measurements. The results indicate that, during sintering of the starting powder mixture, containing not only WC and Co but also the lower carbide W₂C and free carbon, W₂C reacts with cobalt metal to form Co₃W. At sintering temperatures from 900 to 1200°C, the reaction intermediate is the ternary carbide phase Co₆W₆C. During sintering at 1300°C, this phase reacts with carbon to form Co₃W₃C. Sintering at 1000°C and higher temperatures is accompanied by the formation of a cubic solid solution of tungsten carbide in cobalt, β-Co(WC). The density and microhardness of the sintered samples have been measured as functions of sintering temperature, and the optimal sintering temperature has been determined.     

Micro-structure of graphite-intercalated tin oxide and its influence on SnO2-based gas sensors

A nano-scaled graphite oxide (GO) was prepared with a micro-layer structure for intercalation. Graphite-intercalated SnO₂ was obtained at temperatures lower than 100°C. The morphology, microstructure, crystalline phases and thermal property of this intercalative composite were studied by atomic force microscopy (AFM), field-emission scanning electron microscopy (FE-SEM), X-ray diffractometry (XRD) and differential scanning calorimetry-thermogravimetry (DSC-TG) doped with a proper amount of graphite-intercalated composites (GITs), GIT-SnO₂ composite was obtained after heat treatment. This combined gas sensor reveals low resistance and high sensitivity to butane between 200°C and 300°C. Translated from Journal of Materials Science & Engineering, 2006, 24(4): 582–587 (in Chinese)     

Synthesis of LiMn2O4 via high-temperature ball milling process

Spinel LiMn₂O₄ powder was prepared by a novel process of high-temperature ball milling. For comparison, the spinel LiMn₂O₄ powder was also synthesized by the traditional method of solid state reaction. It was found that high-temperature ball milling significantly decreased the synthesis temperature and time. LiMn₂O₄ with pure spinel phase could be successfully synthesized only by 2?h high-temperature ball milling at 500°C and 600°C. However, pure spinel LiMn₂O₄ could not be completely synthesized by 2?h solid state reaction at 800°C. The LiMn₂O₄ particles prepared by high-temperature ball milling are nano-sized (<100?nm) and much smaller than that prepared using solid state reaction. The electrochemical tests results indicated that the as-synthesized LiMn₂O₄ by 2?h high-temperature ball milling at 600°C showed a favorable initial discharge capacity of 124.2 mAh g^?1 at current rate of 0.1 C and still retained a capacity of 119.8 mAh g^?1 at 0.1 C after 80 continuous cycles from 0.1 to 2.0 C.     

Tubular alumina as a key component of new thermally stable ceramic materials

Using scanning electron microscopy and X-ray diffraction, we have examined processes that occur in tubular alumina during heating in air to temperatures in the range 1100–1200°C. The results demonstrate that, starting at temperatures between 600 and 700°C, α-Al₂O₃ (corundum) is formed in the solid material. Heating the tubular material to 1000°C converts some of the starting alumina into χ-Al₂O₃ and some into α-Al₂O₃. The samples calcined for 2–10 h at 1100°C contain α-Al₂O₃ and æ-Al₂O₃. Heating to 1000–1300°C has no effect on the shape of the tubular particles. The ceramics obtained in this way are stable in contact with water. When tubular alumina with a SiCl₄ vapor hydrolysis product deposited on its surface is heat-treated at temperatures in the range 1100–1300°C, we observe the formation of mullite (Al₂O₃ · 2SiO₂) on the surface of the tubular particles.     

Catalytic conversion of Kraft lignin to bio-multilayer graphene materials under different atmospheres

Kraft lignin was catalytic graphitized by iron at 1000 °C in argon, hydrogen, CO₂, methane, and natural gas atmospheres, respectively. The effect of atmospheric agent types on product distribution (gas, liquid, and solid carbon yields) was analyzed. The solid products were characterized by scanning electron microscopy, Raman, high-resolution transmission electron microscopy, and X-ray diffraction. Experimental results have shown that the degree of graphitization of Kraft lignin depends not only on the highest temperature, but also the type of ambient gas phase during heat treatment. Methane and natural gas in the ambient gas phase seem to accelerate the formation of multilayer graphene materials with a range of 2–30 layers, and hydrogen and carbon dioxide have an etching effect on solid carbon species during the catalytic graphitization process, while multilayer graphene-encapsulated iron nanoparticles were the main products in the case of argon.     

Evolution of M23C6 phase in HR3C steel aged at 650 °C

The evolution of the morphology, composition, and particle size of the M₂₃C₆ phase in HR3C steel aged at 650 °C was analysed, by means of metallographic microscopy, scanning electron microscopy, and transmission electron microscopy. The results showed that the Cr/Fe ratio in the M₂₃C₆ phase, in the form of irregular square and long strip, increased with the ageing time. Fe was gradually replaced by Cr in the M₂₃C₆ lattice. The M₂₃C₆ phase gradually evolved and then became stable after ageing for 2000 h.     

Preparation of NixTiy compound via Ni plating followed by thermal treatment of Ti powder

In this research, Ni_xTi_y compound was prepared by thermal treatment of Ni-plated Ti powder. For this purpose, Ti powder was plated in an electroless Ni bath for various times (120, 225, 300, and 720?min). Hydrazine hydrate was used as a reductant for the deposition of pure Ni on the Ti particles. The plated powder (225?min) was heat treated under argon atmosphere to achieve Ni_xTi_y powder. Finally, the heated/plated powder was pressed by CIP followed by sintering at 980°C for prepare the Ni_xTi_y bulk sample. The plated powders as well as sintered one were characterized using scanning electron microscopy, energy dispersive spectrometer, X-ray fluorescence, X-ray diffraction and differential scanning calorimetric. The NiTi₂, NiTi, and Ni₃Ti phases were detected in the XRD patterns of heated/plated Ti powder. According to DSC data, the heated/plated Ti powder showed reversible martensitic transformation at temperature range of ?38.0°C to +38.1°C, while sintered/heated/plated Ti powder displayed reversible transformation at temperature range of 16.0°C–15.4°C.     

Aging of Cu–Be alloys with and without cobalt

Abstract

The effect of prior cold work on the decomposition of the supersaturated solid solution of Cu–Be alloys with and without cobalt addition has been studied by means of electron microscopy and hardness measurements. The results suggest that during aging from 200 to 500°C two temperature regions characterized by different aging products may be distinguished. In the lower temperature region the following continuous precipitation sequence is found: supersaturated solid solution → Guinier–Preston zones →γ′ in the higher temperature region the discontinuous precipitation reaction is: supersaturated solid solution →γ_D→γ equilibrium phase. An increase in beryllium content raises the limit of the lower temperature region, i.e. the critical temperature separating two aging regions is located between 250 and 350°C for Cu–1·5 Be and between 350 and 400°C for Cu–2Be and Cu–1·8Be–0·2Co (all in wt–%).The addition of cobalt, and the prior cold work, have a retarding effect on aging processes in the lower temperature region, but no effect has been observed in the higher region. The activation energies for formation of Guinier–Preston zones and γ′ phase were calculated and discussed in terms of the reaction of solute atoms with vacancies.

MST/242     

Synthesis of CaTiO<Subscript>3</Subscript> from calcium titanyl oxalate hexahydrate (CTO) as precursor employing microwave heating technique

Calcium titanate, CaTiO₃, an important microwave dielectric material and one of major phases in synroc (synthetic rock), a titanate ceramic with potential application for fixation of high level nuclear waste was synthesized from calcium titanyl oxalate [CaTiO (C₂O₄)₂·6H₂O] (CTO) by employing microwave heating technique. CTO heated in microwave heating system in air at 500°C for 1 h gave a perovskite, CaTiO₃. The product obtained by heating of CTO in the same system at 700°C for the same duration was however, much more crystalline. CaTiO₃ obtained by the present method was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET surface area measurement.     

Synthesis and characterization of zinc and calcium nanoferrites

In this work, Zn_(1?x)Ca_xFe₂O₄ nanoparticles (x = 0, 0.5 and 1) have been synthesized by sol–gel method followed by heat treatment at a temperature within the range of 300–700 °C. The samples with appropriate saturation magnetization (Ms), low coercivity and remanence were Zn₀Ca₁Fe₂O₄ treated at 300 °C (Ms ~ 25 emu/g), Zn₀Ca₁Fe₂O₄ treated at 400 °C (Ms ~ 40 emu/g) and Zn_0.50Ca_0.50Fe₂O₄ treated at 400 °C (Ms ~ 31 emu/g). These samples were analyzed by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and transmission electron microscopy. The heating ability of selected nanoparticles was evaluated under a magnetic field using a solid state induction heating equipment. The obtained nanoferrites showed a particle size within the range of 13–14 nm. The Zn₀Ca₁Fe₂O₄ treated at 400 °C was able to heat the nanoferrite particles/water suspension (10 mg/2 ml) at a temperature of 44 °C under the selected magnetic field (10.2 kA/m and frequency 362 kHz). Additionally, in vitro bioactivity assessment was performed by immersing samples in a simulated body fluid for different periods of time at physiological conditions of pH and temperature. The samples showed an appropriate bioactivity. These nanoferrites are highly potential materials for hyperthermia treatment.     

Oxidation of potential SOFC interconnect materials,Crofer 22 APU and Avesta 353 MA,in dry and humid air studied in situ by X-ray diffraction

Abstract

Several stainless steels have been developed for the use as interconnect materials in solid oxide fuel cells in order to reduce costs, while maintaining the required performance. The materials however, are subjected to humid air, at high temperatures up to 800°C leading to enhanced oxidation. High temperature X-ray diffraction, combined with field emission – scanning electron microscopy, has been applied to study in situ the influence of water vapour on the chromia scale formation on the ferritic Crofer 22 APU and the austenitic Avesta 353 MA alloys in comparison to their dry air oxidation behaviour. Both materials form at 800°C, during the first 100h exposure, Cr₂O₃ and MnCr₂O₄, the latter mostly in the surface region of the oxide scale. Additionally, Crofer 22 APU forms internal Al₂O₃ precipitates, while on Avesta 353 MA a SiO₂ layer is found beneath the outer oxide scale. High temperature XRD indicates stress formation and relaxation in the Cr₂O₃ scale formed in humid air, especially for Crofer 22 APU.     

Facile and green synthesis of (La0.95Eu0.05)2O2S red phosphors with sulfate-ion pillared layered hydroxides as a new type of precursor: controlled hydrothermal processing,phase evolution and photoluminescence

This study presents a facile and green route for the synthesis of (La_0.95Eu_0.05)₂O₂S red phosphors of controllable morphologies, with the sulfate-type layered hydroxides of Ln₂(OH)₄SO₄·2H₂O (Ln = La and Eu) as a new type of precursor. The technique takes advantage of the fact that the precursor has had the exact Ln:S molar ratio of the targeted phosphor, thus saving the hazardous sulfurization reagents indispensable to traditional synthesis. Controlled hydrothermal processing at 120 °C yielded phase-pure Ln₂(OH)₄SO₄·2H₂O crystallites in the form of either nanoplates or microprisms, which can both be converted into Ln₂O₂S phosphor via a Ln₂O₂SO₄ intermediate upon annealing in flowing H₂ at a minimum temperature of ～ 700 °C. The nanoplates collapse into relatively rounded Ln₂O₂S particles while the microprisms retain well their initial morphologies at 1 200 °C, thus yielding two types of red phosphors. Photoluminescence excitation (PLE) studies found two distinct charge transfer (CT) excitation bands of O^2? → Eu³⁺ at ～ 270 nm and S^2? → Eu³⁺ at ～ 340 nm for the Ln₂O₂S phosphors, with the latter being stronger and both significantly stronger than the intrinsic intra-f transitions of Eu³⁺. The two types of phosphors share high similarities in the positions of PLE/PL (photoluminescence) bands and both show the strongest red emission at 627 nm (⁵D₀ → ⁷F₂ transition of Eu³⁺) under S^2? → Eu³⁺ CT excitation at 340 nm. The PLE/PL intensities show clear dependence on particle morphology and calcination temperature, which were investigated in detail. Fluorescence decay analysis reveals that the 627 nm red emission has a lifetime of ～ 0.5 ms for both types of the phosphors.     

Production of MgAl2O4 – Ti(C,N) composite ceramics by aluminothermic reduction in reducing atmosphere

Abstract

In the presence of N₂ and CO gases, MgAl₂O₄ – Ti(C,N) composite has been synthesised by aluminothermic reduction. The phase characterisation and microstructure of this novel composite were investigated by powder X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The results show that the nitridation reaction begins at 1100°C. With an increase of temperature, TiC starts to appear and forms Ti(C,N) solid solution with TiN; the grain size of Ti(C,N) grows with increasing temperature and the final product is MgAl₂O₄ – Ti(C,N).     

Synthesis,characterization, and ceramic conversion of a liquid polymeric precursor to SiBCN ceramic via borazine-modified polymethylsilane

A liquid polymeric precursor to SiBCN ceramics was synthesized via dehydrogenation of polymethylsilane and borazine. The resulting precursor, its ceramic conversion, and its pyrolytic products were investigated via viscosity testing, gel permeation chromatography, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results show that Si–H bonds in polymethylsilane react with N–H or B–H bonds in borazine to form a cross-linked polymer with a viscosity of 850 mPa s. The ceramic yield of the precursor is 89 wt% after treatment at up to 1000 °C. This is 51 wt% higher than the original polymethylsilane. The polymer-ceramic conversion is complete at 800 °C and further heating at 1200 °C induces partial crystallization, which forms β-SiC crystals. The final pyrolytic product is composed of β-SiC and Si₃N₄ crystals after heat treatment at 1600 °C. The introduction of boron into the ceramic can inhibit the growth of β-SiC crystals and improve densification of the ceramic products, thus aiding the high-temperature properties of the final products. Its appropriate viscosity, good thermal curability, and high ceramic yield make this precursor appropriate for use in preparation of high-performance SiBNC ceramics for high-temperature applications.     

Synthesis of GaN nanowires by CVD method: effect of reaction temperature

GaN nanowires are fabricated on Si substrates by ammoniating Ga₂O₃/NiCl₂ thin films using chemical vapour deposition method. The influence of reaction temperature on microstructure, morphology and optical properties of GaN nanowires is characterised by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectrophotometer, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and photoluminescence. The results demonstrate that the GaN nanowires are single crystalline and exhibit hexagonal wurtzite symmetry. The best crystalline quality was achieved for an reaction temperature of 1150°C for 15?min. The growth process follows vapour–liquid–solid mechanism and Ni plays an important role as the nucleation point and as a catalyst.