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The inverse perovskite BaLiF <sub/>3</sub> : single-crystal neutron diffraction and analyses of potential ion pathways
摘要： Doped barium lithium tri?uoride has attracted attention as component for scintillators, luminescent materials and electrodes. With lithium and ?uoride, it contains two possibly mobile species, which may account for its ionic conductivity. In this study, neutron diffraction on oxide-containing BaLiF3 single-crystals is performed at up to 636.2(cid:2)C. Unfortunately, ion-migration pathways could not be mapped by modelling anharmonic ion displacement or by inspecting the scattering-length density that was reconstructed via maximum-entropy methods. However, analyses of the topology and bond-valence site energies derived from the high-temperature structure reveal that the anions can migrate roughly along the edges of the LiF6 coordination octahedra with an estimated migration barrier of (cid:3)0.64 eV (if a vacancy permits), whereas the lithium ions are con?ned to their crystallographic positions. This ?nding is not only valid for the title compound but for ion migration in all perovskites with Goldschmidt tolerance factors near unity.
关键词： bond-valence energy landscape,topological analysis,high-temperature neutron diffraction,maximum-entropy methods,fluoroperovskite
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE ISAF-FMA-AMF-AMEC-PFM Joint Conference (IFAAP) - Hiroshima (2018.5.27-2018.6.1)] 2018 IEEE ISAF-FMA-AMF-AMEC-PFM Joint Conference (IFAAP) - Bi<inf>4</inf>Ti<inf>3</inf>O<inf>12</inf>/SrTiO<inf>3</inf>Sol-Gel Composite for Ultrasonic Transducers
摘要： In this study, lead-free new sol-gel composite, Bi4Ti3O12(BiT)/SrTiO3(ST) was developed. 100μm thick films were fabricated on 3mm thick titanium substrates by sol-gel spray technique. Polarization process was carried out at room temperature and 400°C. Samples were set onto a hot plate and ultrasonic response in pulse-echo mode was recorded by a digital oscilloscope from room temperature to 500°C. As a result, each samples showed reflected wave at 500°C. Therefore, BiT/ST sol-gel composite have high temperature endurance up to 500°C. In addition, BiT/ST films was able to polarize at room temperature.
关键词： ultrasonic transducer,high temperature,nondestructive testing,sol-gel composite
更新于2025-09-10 09:29:36
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Visualization of a Berezinskii–Kosterlitz–Thouless Topological Phase Transition in a Josephson Medium: Detection of an Anomalous Temperature Dependence of the Magnetoresistance of YBa2Cu3O7–δ Granular High-Temperature Superconductors
摘要： The possibility of implementing a Berezinskii–Kosterlitz–Thouless topological phase transition in a Josephson medium of two-level high-temperature superconductors induced by a magnetic field has been studied. The effect of temperature and external magnetic field on the transport properties of the YBa2Cu3O7 – δ granular high-temperature superconductor considered as a model object is studied experimentally. For the first time, an anomalous behavior of the magnetoresistance isotherms is detected in a narrow range of temperature and external magnetic field indicating a topological phase transition in the Josephson medium of granular high-temperature superconductors.
关键词： YBa2Cu3O7 – δ,high-temperature superconductors,magnetoresistance,Josephson medium,Berezinskii–Kosterlitz–Thouless topological phase transition
更新于2025-09-10 09:29:36
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Increased nitrogen-vacancy centre creation yield in diamond through electron beam irradiation at high temperature
摘要： The nitrogen-vacancy (NV) centre is a fluorescent defect in diamond that is of critical importance for applications from ensemble sensing to biolabelling. Hence, understanding and optimising the creation of NV centres in diamond is vital for technological progress in these areas. We demonstrate that simultaneous electron irradiation and annealing of a high-pressure high-temperature diamond sample increases the NV centre creation efficiency from substitutional nitrogen defects by up to 117% with respect to a sample where the processes are carried out consecutively, but using the same process parameters. This increase in fluorescence is supported by visible and infrared absorption spectroscopy experiments. Our results pave the way for a more efficient creation of NV centres in diamond as well as higher overall NV densities in the future.
关键词： diamond,nitrogen-vacancy centre,high temperature,fluorescence,absorption spectroscopy,electron beam irradiation
更新于2025-09-10 09:29:36
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Microstructure and thermoelectric properties of In2O3/ITO thin film thermocouples with Al2O3 protecting layer
摘要： In2O3/ITO thin film thermocouples (TFTCs) with alumina protecting layer were fabricated on alumina substrates. The effects of protecting layer on their performance at higher temperature and long term service were investigated accordingly. In2O3 and ITO thin films were prepared by radio frequency magnetron sputtering methods, while the alumina protecting layer was prepared by traditional spin-coating methods. Microstructural and thermoelectric properties of the In2O3/ITO TFTCs with and without alumina (Al2O3) protecting layer were investigated as a function of sintering time from 2 to 10 h at 1250 °C. The results show that, the existence of alumina protecting layer can effectively increase the performance capabilities of thermocouples at high temperatures by inhibiting the volatilization of the thin film. In2O3/ITO TFTCs with protecting layer can work normally over 10 h at 1250 °C while Seebeck coefficient is 131.7 μV/°C. The drift rate can reach 3.05 °C/h, which is much better than those without protecting layer.
关键词： high temperature,thermoelectric properties,Al2O3 protecting layer,long term service,In2O3/ITO thin film thermocouples
更新于2025-09-10 09:29:36
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Performance comparison of high temperature sensor based on non-adiabatic silica microfiber and single mode-multimode-single mode fiber structure
摘要： A fiber-based temperature sensor operating at high temperature was demonstrated using multimode interference effect and its performance was compared with that of two different probes based on a non-adiabatic microfiber and singlemode-multimode-singlemode (SMS) fiber structure. Interference fringes of the output red-shifted as the temperature increased due to the change in the effective refractive index of the multiple modes inside both structures. The sensor probes were able to measure the temperature variation up to 400°C with a linearity of more than 90%. The temperature sensitivity of the microfiber and SMS sensors is 6.0 PM/°C and 11.1 PM/°C, respectively. Our proposed sensors are simple, relatively cheap to be fabricated, and could operate at high temperatures above 300°C.
关键词： Interference filter,Fiber-optic sensor,high temperature sensor
更新于2025-09-10 09:29:36
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High Temperature, Transparent, Superhydrophobic Teflon AF-2400/Indium Tin Oxide Nanocomposite Thin Films
摘要： The outstanding properties of Teflon AF-2400—chemical, optical, etc.—inspired us to make modifications to enhance its hydrophobicity. We prepared an AF-2400/Indium Tin Oxide Nanocomposite by a spin coating technique at room temperature, using the AF-2400 polymer as the matrix and indium tin oxide (ITO) nanoparticles as the filler. Different ITON concentrations ranging from 3 mg/ml to 30 mg/ml were prepared to study the effect of nanoparticle loading on the films’ properties and superhydrophobicity. The effect of spin speed and annealing temperature was also studied. Atomic force microscopy, x-ray photoelectron spectroscopy, and UV-vis analysis were employed to characterize the prepared films. The results indicate that the film’s low surface energy and nano/micro-features made it superhydrophobic. Increasing the ITON concentration to 15 mg/ml improved the superhydrophobicity of the composite film by increasing the surface roughness. The coating showed superhydrophobic behavior with a static contact angle around 152o and contact angle hysteresis less than 2o. The nanocomposite films also exhibited excellent thermal stability sustaining temperature as high as 240°C without losing its superhydrophobic behavior. Three models, Wenzel, Cassie-Baxter, and Shuttleworth-Bailey, were used to predict the static contact angle. The results confirmed that the latter model gave the best prediction. In addition to superhydrophobicity, the AF-2400/ITON films coated on a glass substrate showed very high transparency—around 95% in the visible and infrared range. An effective medium theory, the Bergman representation, was used to simulate the transmittance of the AF-2400/ITON nanocomposites. The measured and simulated transmittance values were in good agreement in the visible range. Based on our results, this coating may be highly useful for many practical applications, including solar cell coatings, chemical resistance protective coatings, and more.
关键词： High Temperature,Superhydrophobic,Nanocomposite,Indium Tin Oxide,Transparent,Teflon AF-2400
更新于2025-09-10 09:29:36
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Synthesis of TiO <sub/>2</sub> (B) and High-temperature Stable Anatase TiO <sub/>2</sub> Nanowires by Hydrothermal Method and Investigation of Photocatalytic Activity
摘要： In this study, TiO2 nanowires (TNWs) were synthesized through hydrothermal method and were characterized using X-Ray diffraction (XRD), transmission electron microscopy (TEM) and BET techniques. Monoclinic TiO2 (B) is the dominant phase of TNWs up to 600 ℃ which is completely transformed into a highly crystalline anatase phase at 800 ℃. The photocatalytic activity of TNWs, prepared at various calcination temperatures, was investigated in the removal of Rhodamine B (RhB) as an organic model pollutant. The results indicated that the photocatalytic activity of TNWs, prepared at 800 ℃ calcination temperature (TNWs-800), was better than that of other samples and even TiO2-P25 nanoparticles.
关键词： Anatase TiO2 nanowires,Photocatalytic activity,TiO2 (B),Hydrothermal method,High-temperature
更新于2025-09-10 09:29:36
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Photoluminescence characteristics of Pr3+ doped PbGdB7O13 as a new red emitting phosphor
摘要： A red phosphor Pr3+ doped PbGdB7O13 was synthesized by high temperature solid state reaction. The effect of Pr3+ doped concentration on the luminescent properties of the phosphor was investigated. The emission spectrum includes an apex at about 607 nm, corresponding to the 3P0→3H6 transition of the Pr3+ ion activator. For PbGd1-xB7O13:xPr3+, the emission peak intensity first increases with the increase of Pr3+ concentration, and reaches the maximum when the Pr3+ concentration is 0.02, and then decreases with the increase of Pr3+ concentration. The CIE coordinates of the PbGdB7O13:0.02Pr3+ phosphor was calculated to be (0.6332, 0.3651), falling into the red color. Therefore, there is a potential application on display, indication or illumination.
关键词： Photoluminescence,High temperature solid state reaction,CIE,Borate
更新于2025-09-10 09:29:36
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High-rate deposition of silicon films in a magnetron discharge with liquid target
摘要： Silicon coatings have been deposited on substrates made of low-carbon and high-carbon steels and tungsten in a magnetron discharge with liquid target at substrate bias voltages ranging from +100 V to -600 V. The structure of obtained coatings was examined by a scanning electron microscopy. The strong influence of substrate bias voltage on the coating structure was observed. The corrosion resistance of coated steel samples was examined in concentrated sulphuric, hydrochloric and nitric acids and their solutions. The resistance of coated tungsten samples against high-temperature oxidation was examined by their exposure to O2 gas at a pressure of 0.2 Pa and a temperature of 1073 K. The coatings deposited under bias voltages of +100 V and -600 V had dense structures and showed the best protective properties among all deposited coatings.
关键词： high-temperature oxidation,silicon coatings,liquid target,corrosion resistance,magnetron discharge
更新于2025-09-10 09:29:36