Sealed Quartz Tube Research Articles

A new one-dimensional strontium vanadium tellurite, Sr7V4Te12O41.

Vanadium tellurites display a rich structural chemistry with interesting physical properties, such as second harmonic generation (SHG). Tellurites, i.e. Te(4+)Ox, are often observed in unusual structures and form various structural motifs, including isolated clusters, chains, layers, and three-dimensional networks. Similarly, vanadates, i.e. V(5+)Ox, show rich structural features, such as VO4 tetrahedra, VO5 square pyramids or trigonal bipyramids, and VO6 octahedra. Strontium vanadium tellurite, Sr7V4Te12O41, was obtained from the melt of the solid-state reaction of SrTeO4 and VO2 in a sealed quartz tube as it cooled from 973 K. The crystal structure exhibits a one-dimensional latticework along the a axis comprised of paired Sr3Te3Ox units, namely Sr6Te6O2x+1, with corner-shared TeO4 polyhedra - and specifically the Te lone-pair electrons - facing outward in the bc plane. The Sr6Te6O2x+1 latticework is helical and is layered in the b-axis direction against sheets of corner-shared VO4 tetrahedra, and is linked in the c-axis direction via individual corner-shared SrO8 square prisms.

Effect of solid carburization on surface microstructure and hardness of Ti-6Al-4V alloy and (TiB+La2O3)/Ti-6Al-4V composite

Solid carburization was employed to improve the hardness of Ti-6Al-4V alloy and (TiB+La2O3)/Ti composite. The samples wrapped in graphite powder were placed in sealed quartz tubes, followed by solid carburization at 1227 K for 24 h. Microstructure and phase analysis indicated that TiC reinforcements and Ti-C solid solutions were introduced after solid carburization. Moreover, the volume fraction of equiaxed α-Ti phase in diffusion layer decreased obviously with increasing sample depth. Hardness testing results indicated that both the carburized surfaces performed significant improvement of about 100% in micro-hardness compared with untreated materials. The variation of carbon contents with increasing sample depth resulted in a hardened layer of 300 μm in the carburized samples. Meanwhile, slight influence on the internal microstructure and hardness indicated that solid carburization was an effective method in strengthening the surface of titanium alloy and titanium matrix composite.

Effects of yttrium doping in ordered double perovskite Sr2CrReO6

Solid-state reactions carried out in a sealed quartz tube showed that the yttrium solubility limit in the ordered double perovskite Sr2YxCrReO6 is x = 0.2. Using X-ray diffraction analysis and Rietveld refinement, it was possible to confirm the existence of a solid solution with a maximum yttrium (at.%) content of 10%. The compound obtained, Sr1.8Y0.2CrReO6, exhibited a microstructure with grain sizes similar to those of Sr2CrReO6. However, it was noticed that the volume of the unit cell had increased by 0.2%. The compound Sr1.8Y0.2CrReO6 also exhibited an increase in magnetization of 10% with respect to that of Sr2CrReO6 without there being a change in the critical temperature (∼640 K) and with the characteristics of a structured crystalline solid solution being maintained. This suggested that Sr1.8Y0.2CrReO6 can be used for the development and fabrication of spintronics devices.

Two new lanthanide members of francisite family Cu3Ln(SeO3)2O2Cl (Ln = Eu, Lu)

Two new lanthanide compounds, Cu3Ln(SeO3)2O2Cl, Ln = Eu and Lu, with mineral francisite structure were synthesized under vacuum in sealed quartz tubes. The Rietveld refinement of the structure results in orthorhombic unit cell, space group Pmmn. The arrangement of magnetically active Cu2+ ions in francisite structure corresponds to buckled kagomé type lattice. Both compounds were characterized in measurements of ac-magnetic susceptibility, dc-magnetization, X-band electron spin resonance and specific heat in the range 2–320 K under magnetic field up to 9 T. The ferromagnetic interactions dominate in both compounds at elevated temperatures. The Eu (Lu) francisite manifests antiferromagnetic order at TN = 36 (38) K and undergoes the field-induced metamagnetic transition into canted ferrimagnetic state at BC = 2.6 (3.0) T. The magnetization loops of both compounds evidence hysteretic behavior above BC.

ChemInform Abstract: Anionic Ordering in Ba15V12S34O3, Affording Three Oxidation States of Vanadium and a Quasi‐One‐Dimensional Magnetic Lattice.

AbstractPolycrystalline Ba15V12S34O3 is prepared by solid state reaction of a 12:3:12:22 molar mixture of BaS, BaO, V, and S under 200 mbar Ar (corundum crucible in sealed quartz tube, 1.

ChemInform Abstract: Crystal Structure, Electronic Structure, and Photocatalytic Activity of Oxysulfides: La2Ta2ZrS2O8, La2Ta2TiS2O8, and La2Nb2TiS2O8.

AbstractThe title compounds are synthesized by solid state reactions using La2O3, La2S3, Ta2O5, ZrO2, Nb2O5, TiS2, and S as starting materials (sealed quartz tubes, 1100 °C, 48 h).

A facile route to large‐scale synthesis MoO2 and MoO3 as electrode materials for high‐performance supercapacitors

MoO3 and MoO2 materials have been successfully synthesized by thermal decomposition of ammonium paramolybdate in air and a sealed quartz tube, respectively. The microstructure of as‐synthesized MoO3 is composed of irregular lamellar plates with a plate thickness around 100 nm and MoO2 has the larger grain size with lamellar plates connected with each other. A maximum specific capacitance of 318 F/g at 0.5 A/g is obtained for MoO2 prepared in a closed environment. On the other hand, the sample MoO3 exhibits excellent rate capacity with specific capacitances of 218, 209, 196, 188, 176, and 160 F/g at current densities of 0.5, 1, 2, 3, 4, and 5 A/g, respectively. These results pave the way to consider MoO3 and MoO2 as prospective materials for energy‐storage applications.

Anionic Ordering in Ba15V12S34O3, Affording Three Oxidation States of Vanadium and a Quasi-One-Dimensional Magnetic Lattice

Polycrystalline Ba15V12S34O3 is prepared by solid state reaction of a 12:3:12:22 molar mixture of BaS, BaO, V, and S under 200 mbar Ar (corundum crucible in sealed quartz tube, 1.

Zirconium Trisulfide as a Promising Cathode Material for Li Primary Thermal Batteries

In this work ZrS3 has been synthesized by solid state reaction in a sealed quartz tube and investigated as a candidate cathode material in Li thermal batteries. The structure of ZrS3 before and after cell testing has been studied using powder X-ray diffraction. A new spinel related material, LiZr2S4, has been identified as the product of the electrochemical process, which can be indexed to a = 10.452(8) Å cubic unit cell. The electrochemical properties of the batteries were investigated at 500°C against Li13Si4 by galvanostatic discharge and galvanostatic intermittent titration technique (GITT). In a thermal Li cell at 500°C a single voltage plateau of 1.70 V at a current density of 11 mA/cm2 was achieved with capacity of 357 mA h g−1. Therefore ZrS3 material has some promise as a cathode for Li thermal batteries.

ChemInform Abstract: Detection and Characterization of Compounds in the Mn‐W‐Cl System Through a Combined Thermal Scanning ‐ XRD Approach.

AbstractThermal scanning of the Mn—W—Cl system reveals the formation of four new compounds, MnxWCl6 (I), MnW2Cl10 (II), (Mn,W)1‐xCl2 (III), and MnW6Cl14 (IV) upon progressive reactions of WCl6 and Mn powder (sealed quartz tube, 125—500 °C, 2—21 d).

피션트랙 검출기법에 의한 고체 및 액체상태 지질물질의 우라늄 정량과 그 적용성

피션트랙 검출에 의해 고체 및 액체상태 지질물질 내 우라늄을 정밀정량하는 최적기법을 제안하고 그 적용성을 검증하였다. 우라늄 정량은 중성자 조사에 의해 유도시킨 <TEX>$^{235}U$</TEX>의 핵분열 흔적을 트랙 디텍터에 기록하여 고배율 현미경 하에서 계수함으로써 이루어진다. 우라늄-친화력이 좋은 암석(예: 화강암, 석탄)을 분말 펠릿시료로 만들어 건식 검출하면, 그다지 높지 않은 우라늄함량(<5 ppm, 즉 <TEX>${\mu}g\;g^{-1}$</TEX>)에서도 빈번하게 함유된 함-우라늄광물에 기인한 트랙 군집현상으로 인해 시료의 전체평균 함량 결정이 쉽지 않았으며, 트랙 균질부와 군집부를 별도로 검토해야 한다. 시료의 균질성이 유지된다면 백운모-Lexan 디텍터에 의한 중복 측정과 여러 차례 중성자 조사에 의한 반복 측정에서 높은 재현성이 확인되었다. 건고 액체시료 경우에 <TEX>$10^1ppm$</TEX> 수준 및 그 이상의 우라늄함량에서 흔히 나타나는 불균질 현상을 극복하기 위해, 진공 석영튜브를 이용한 습식 검출법을 제안한다. 습식 검출에서 우라늄 균질성은 <TEX>$10^0ppm$</TEX> 수준 이하에서 회복되며, 측정하한은 <TEX>$10^2ppb$</TEX> (i.e. <TEX>$ng\;g^{-1}$</TEX>) 수준까지 무난한 것으로 입증되었다. The fission track registration techniques for accurate determinations of uranium in solid- and liquid-state geological materials were recommended and their applicability were examined. The determination of uranium can be achieved by optical counting of neutron-induced fission tracks of <TEX>$^{235}U$</TEX> registered on solid-state track detectors under high magnification. In a dry registration method using powdered pellets of rocks (e.g., granite and coal) showing good uranium-affinity, it was not easy to decide an overall mean concentration over the total sample owing to track-clusters caused by frequent presence of uranium-bearing minerals. Separate scanning for homogeneous and track-clustered parts may be an alternative choice. Assuring the homogeneity over the whole sample, high reproducibilities were confirmed both from duplicate detections using mica and Lexan polycarbonate detectors and from multiple measurements at different thermal neutron fluences. The wet registration method using sealed quartz tubes is recommended to overcome the common heterogeneity in uranium concentrations of <TEX>$10^1ppm$</TEX> and more. Adopting the wet registration, the uranium homogeneity was recovered below the <TEX>$10^0ppm$</TEX> level and the lower detection limit was proved to reach without difficulty the <TEX>$10^2ppb$</TEX> (i.e. <TEX>$ng\;g^{-1}$</TEX>) level.

ChemInform Abstract: Magnetically Frustrated Double Perovskites: Synthesis, Structural Properties, and Magnetic Order of Sr2BOsO6 (B: Y, In, Sc).

AbstractSr2BOsO6 (B: Y, In, and Sc) are prepared by solid state reaction of stoichiometric mixtures of the respective binary metal oxides (corundum crucible in sealed quartz tubes under Ar, 950‐960 °C, 100 h).

Biocompatibility and compressive properties of Ti-6Al-4V scaffolds having Mg element

Porous scaffolds of Ti-6Al-4V were produced by mixing of this alloy with different amount of magnesium (Mg) powders. The mixtures were compacted in steel die by applying uniaxial pressure of 500MPa before sintering the compacts in sealed quartz tubes at 900°C for 2h. Employing Archimedes׳ principle and Image Tool software, the total and open volume percentages of porosities within the scaffolds were found to be in the range of 47–64% and 41–47%, respectively. XRD results of titanium before and after sintering showed that no contamination, neither oxides nor nitrides formed during processes. Compressive properties of the scaffolds were studied using an Instron machine. The observed compressive strength and Young׳s module of the scaffolds were in the range of 72–132MPa, and 37–47GPa, respectively. Cell attachment and proliferation rate of MG-63 on porous samples were investigated. The results showed that proliferation rate increased with increasing Mg content. However no clear differences were observed between samples regarding cell attachment, so that bridges were observed in all cell gaps within the scaffolds.

ChemInform Abstract: Crystal Structure and Orbital‐Singlet State of AgxVP2O7.

AbstractPolycrystalline samples of AgxVP2O7 (0.7 ≤ x ≤ 0.9) are prepared by solid state reaction of mixtures of composition 2xAg3PO4, 4xVPO4, 3(1‐x)VPO5, and (3‐x)V(PO3)3 (sealed quartz tubes, 1073 K, 12 h).

Synthesis, characterization and time dependent phase transformation of Li0.4WO3 bronze

Abstract Lithium tungsten bronzes with a nominal composition of Li0.4WO3 were synthesized by solid state reactions in silica tubes at 973 K and various low pressures. Samples were characterized using X-ray single crystal and powder diffraction, and neutron powder diffraction. The air pressure inside the sealed quartz tubes played roles for the formation of Li0.4WO3 phases with different symmetries. Whereas using a pressure of 10–7 MPa a pure body centered cubic (Im 3 ¯ $\bar 3$ ) tungsten bronze was formed, at higher pressures (&gt;10–7 MPa) a mixture of Im 3 ¯ $\bar 3$ and primitive cubic (Pm 3 ¯ $\bar 3$ m) perovskite tungsten bronzes were observed with pressure dependent phase fractions. While keeping the synthesized samples under open atmospheric conditions the Im 3 ¯ $\bar 3$ phase gradually transformed into a tetragonal perovskite (P4/nmm) tungsten bronze. The slow cubic into tetragonal phase transformation has been explained in terms of the mobility of lithium within two different crystallographic sites.

Solid state synthesis and characterization of bulk β-FeSe superconductors

Polycrystalline FeSe0.88 was synthesized by solid-state reaction method in sealed quartz tube at different heat heating cycles. The identification and characterization of FeSe0.88 samples were determined by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDX). The electrical transport, magnetic and thermal transport properties of the obtained samples were also investigated. The results showed that the sensitivity of resistivity and magnetic susceptibility depends on heating cycles while the structural formation of samples does not. The upper critical field Hc2(0) has been determined with the magnetic field parallel to the sample surface and yielding a maximum value of 23.2T. At the zero field coherence length, ξ, value was calculated to be 3.33nm. Calculated μ0Hc2(0)/kBTc rate indicated comparably higher value (3.17T/K) than the Pauli limit (1.84T/K) and obtained results were suggested unconventional nature of superconductivity in our samples.

ChemInform Abstract: Synthesis and Crystal Structure of the Quaternary Compound AgFe2GaTe4.

AbstractThe title compound is synthesized from a stoichiometric mixture of the elements in an evacuated and sealed quartz tube heated to 1500 °C for 48 h, followed by annealing at 600 °C for 30 d.

Influence of atmosphere on redox structure of BaCe0.9Y0.1O2.95 – Insight from neutron diffraction study

High-resolution neutron powder diffraction data were collected at different temperatures and pressure under hydrogen or oxygen under high and low humidities. The samples were loaded in sealed quartz tubes in dry or wet conditions at 0.33 atm pressure and 295 K temperature, and heated up to 973 K during measurements. Rietveld refinement of neutron diffraction data showed that the structure changed from primitive orthorhombic (space group Pbnm) to body centred orthorhombic (Imma) to rhombohedral (R-3c) on heating from room temperature to 973 K. At 623 K temperature and 0.71 atm pressure, the unit-cell volume is higher in wet hydrogen and oxygen atmosphere than dry atmosphere due to proton uptake. Oxygen site occupancies were directly determined as functions of temperature for dry and wet conditions in both oxidising and reducing conditions in order to probe actual oxygen/hydroxyl contents under the conditions relevant to most fuel cell or transport studies.

Fullerene peapods: In-situ conductivity study during synthesis

We report in-situ measurement of the conductivity during the synthesis of C60-filled single-walled carbon nanotubes (SWNTs), so-called fullerene peapods. The synthesis was performed in a sealed quartz tube at 773 K by using the sublimation of C60 into the hollow space of the SWNTs. The change in the resistance in the SWNT buckypaper was monitored during the C60-filling process, and the temperature dependence of the resistance was compared to that for empty SWNTs and fullerene peapods. The SWNT networks became more metallic due to the encapsulation of C60, and a reduced temperature dependence of the resistivity was observed in the peapods, with an overall decrease in the resistivity. The interaction between the SWNT and C60 molecules, changing the electronic properties of SWNTs, can provide a way to functionalize the SWNTs.

Formation of the PGE Reef Horizon in the Sonju Lake Layered Mafic Intrusion by Thermal Migration Zone Refining

Thin horizons of sulfide minerals enriched in platinum group elements (PGEs), known as PGE “reefs,” are a feature of many layered mafic intrusions, including the Sonju Lake intrusion (Midcontinent rift, Minnesota). In traditional petrologic models, PGE reefs are thought to form during upward accumulation of mineral deposits, either by downward settling of immiscible sulfides through a silicate melt (the orthomagmatic model) or by concentration during upward flow and deposition in a fluid (the hydromagmatic model). While each model explains some of the observations from reefs, neither provides a consistent explanation for both the overall PGE distribution and evidence for offsets in peak concentrations of PGEs and base metals. If, alternatively, layered intrusions form by a top-down process of sill injection and reaction (thermal migration zone refining) as postulated in Lundstrom et al. (2011a), then PGE reefs could form as a moving sulfide band passes downward through a mineral-melt mush at the particular temperature of sulfide saturation. A simple temperature gradient experiment in a sealed quartz tube illustrates how sulfide moves and aligns parallel to a temperature gradient. Thus, while silicates form in a mush zone and remain immobile, the immiscible sulfide liquid position is controlled by the temperature of sulfide saturation and thus moves down relative to the silicates as new sills underplate previous ones; effectively, all PGE derived from the upper portion of the intrusion (above the reef) partition into this layer resulting in the enriched reef layer, consistent with observed distribution and mass balance in the Sonju Lake intrusion. The higher sulfide-silicate mineral partition coefficients for the PGE relative to Cu as sulfides move relative to the silicates results in Cu being chromatographically separated from PGEs during the process. Thus, the mechanism can account for the two major observations, the overall distribution of PGEs in layered intrusions and the chromatographic separation of PGEs from Cu, perhaps better than existing models. The model provides a sharp alternative to current models, with its predictive aspects potentially improving future exploration for PGE deposits.