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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Heat flux and temperature measurements on glass envelope and bellows of parabolic trough receivers
摘要： This paper reports heat flux measurements on parabolic trough receivers, which are integrated to calculate the receiver overall heat loss. Integrated heat fluxes yield an overall heat loss value which agrees with DLR ThermoRec heat loss measurements within ± 5 %, in the simplified case of assuming a homogeneous heat flux distribution around the receiver circumference. Heat flux measurements also allow separating glass envelope and shielded bellow heat loss terms for receiver thermal modelling. Shielded bellows only represent 3 to 4 % of the receiver total length at ambient temperature, however heat flux measurements show that their contribution to the overall receiver heat loss ranges from 5 to 15 %, depending on the shield construction and the absorber temperature. The receiver specific heat loss thus tends to lie above the glass envelope specific heat loss. Almost homogeneous heat flux values are measured along the glass envelope length (variation below 5 %), while more inhomogeneous heat flux values are observed over circumference of the glass envelope (variation between top and side of 17 %). The measurement setup analysis shows a good repeatability, although a proper mounting of heat flux sensors is important in order to avoid systematic biases.
关键词： heat loss,parabolic trough receivers,heat flux measurements,glass envelope,shielded bellows
更新于2025-09-04 15:30:14
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Deposition of pure Cu films on glass substrates by decomposition of Cu complex pastes at 250 °C and additional Cu plating
摘要： Pure Cu film strongly adherent to glass substrates was deposited by printing Cu(COOH)2-containing paste and decomposing it at 250 °C in nitrogen atmosphere. The complete transformation of Cu(COOH)2 into Cu required 30 min and generated a low sheet resistance of 0.167 Ω/sq (volume resistivity: 15.0 μΩ·cm). Maximum adhesion between the Cu film and substrate was attained at the Cu complexes:α-terpineol mixing ratio of 6:4 by weight. The spike-shaped microstructure at the Cu/glass interface was determined to be the main cause for the outstanding adhesion properties. The resistance further decreased to 0.084 Ω/sq by increasing the thickness and modifying the surface of the Cu film via electroless Cu plating.
关键词： Cu complex paste,Cu film,Glass substrate,Decomposition,Adhesion
更新于2025-09-04 15:30:14
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Low-Temperature Process for Direct Formation of MoS2 Thin Films on Soda-Lime Glass Substrates
摘要： To obtain molybdenum disulfide (MoS2) patterns without any mechanical problems caused by the transfer process, direct current (DC) sputtering and rapid thermal processing (RTP) were used to form MoS2 instead of the conventional chemical vapor deposition (CVD) process. To form MoS2 on a soda-lime glass substrate at temperatures below 600 °C, MoS2 films were deposited at various DC sputtering powers and annealed at various temperatures from 400 °C to 550 °C. From the scanning electron microscope (SEM) and atomic force microscope (AFM) results, the surface morphologies of the MoS2 films can be observed, depending on the sputtering power and the film thickness. The Raman spectrum results showed that the E1 2g and A1 g mode peaks appeared at approximately 372 cm?1 and 400 cm?1, respectively, and the MoS2 surface was crystallized in the in-plane direction. The X-ray photoelectron spectroscopy (XPS) results showed noticeable S 2p (2p 1/2, 2p 3/2) peaks and Mo 3d (3d 3/2, 3d 5/2) peaks at stable binding energies after RTP at temperatures below 600 °C. The high mobilities and carrier densities of all the MoS2 films can be investigated from the Hall measurements.
关键词： DC Sputtering,Low Temperature,Molybdenum Disulfide (MoS2),Rapid Thermal Processing (RTP),Soda-Lime Glass
更新于2025-09-04 15:30:14
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High Pressure effect on fluorescence lifetime <i>τ</i> for magnetic dipole <sup>5</sup> D <sub/>0</sub> → <sup>5</sup> F <sub/>1</sub> transitions in YAG:Eu <sup>3+</sup>
摘要： The fluorescence lifetime for magnetic dipole 5D0→7F1 transition in yttrium aluminum garnet doped with Eu3+ (YAG:Eu3+) crystal was studied under the pressure of up to 10.4 GPa at room temperature. The fluorescence lifetime τ (5D0→7F1 transition) slowly decreased with pressure. The pressure effect on τ (5D0→7F1 transition) was explained with a model which considered pressure effect on line position: inter-ionic distance, ion volume, molecular volume, ion polarizability, molecular polarizability, sample refractive index, and surrounding hydrostatic medium refractive index. The fluorescence lifetime τ calculated by the presented model was in close correspondence with the experimental values.
关键词： rare earth,fluorescence lifetime,YAG:Eu3+,optical properties,glass ceramics,High pressure
更新于2025-09-04 15:30:14
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Electrical characteristics of PbO–CaO–TiO2–SiO2–B2O3 glass ceramics doped with germanium
摘要： Various glass samples in the compound 55[(PbxCa1?x)O?TiO2]-44[2SiO2?B2O3]-1Ge (0 ≤ x ≤ 0.7) were fabricated by using the melt-quenching technique and their glass ceramics (GC) were obtained by controlled crystallization of the glass samples. The identification of phase and crystal structure with measurement of cell parameters was carried out using X-ray diffractometer (XRD). XRD results revealed the presence of the single phase formation of rutile (TiO2). The surface morphology of the synthesized GC samples was evaluated using a scanning electron microscope (SEM). The electrical behaviour of three selected GC samples with x = 0.0, 0.3 and 0.7 was being widely studied using impedance and immittance spectroscopy. The lead free GC sample, x = 0.0 possesses a high dielectric constant, 91,252 at low frequency (50 Hz) and high temperature (500 °C) due to space charge polarization that was ascertained by impedance spectroscopy of the tested samples. The fitting of impedance spectra with a modelled equivalent circuit was performed and different values of resistance and capacitance were calculated.
关键词： Dielectric constant,Rutile TiO2,Glass ceramics,Impedance spectroscopy,Space charge polarization
更新于2025-09-04 15:30:14
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A new design of the YIG/MTC joint brazed by bismuth-based glass
摘要： The paper uncovers an underlined mechanism of joining Yttrium Iron Garnet (YIG) and Magnesium Titanate Ceramic (MTC) with a bismuth-based glass braze. The proposed joint design has not been investigated until present. The central hypothesis is as follows. The brazed bismuth-based glass microstructure and the resulting mechanical strength of a YIG/MTC joint design support favorably a good bonding of the interface domains. The supporting evidence includes the following: (i) the bismuth-based glass features good wettability on YIG and MTC, (ii) the sequence of the coefficients of thermal expansions (YIG, bismuth-based glass, MTC) is in a favorable succession. The study reveals that the interface reactions form: (i) a lamellar phase and YBO3 whiskers at the YIG/Bi25 interface, (ii) both MgFe2O4, and Bi4Ti3O12 whiskers in addition to Zn2Ti3O8 reaction layer at the MTC/Bi25 interface, and (iii) Fe2O3 phase along the brazing seam. The mechanical integrity of joints has been studied as well.
关键词： Magnesium titanate ceramic,Whiskers,Microstructure,Bismuth-based glass braze,Yttrium iron garnet ferrite
更新于2025-09-04 15:30:14
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Structure, dielectric properties of low-temperature-sintering BaTiO <sub/>3</sub> -based glass–ceramics for energy storage
摘要： The 0.85BaTiO3–0.15Bi(Mg2/3Nb1/3)O3 (BTBMN) ceramics with low-melting-temperature B2O3–Na2B4O7–Na2SiO3 (BNN) glass addition were prepared by the solid state method. The composition of the glass–ceramics was BTBMN–x wt.% BNN (x = 0, 1, 3, 5, 7, 9, 12, 15; abbreviated as BG). The sintering characteristics, phase structure, microstructure, dielectric properties and energy storage properties were systematically investigated. The sintering temperature of BTBMN ceramics was greatly reduced by the addition of BNN glass. The second-phase BaTi(BO3)2 was observed in the BG system until the glass content reached 15 wt.%. The addition of BNN glass significantly reduces the grain size of BTBMN ceramics. With the increase of BNN glass content, dielectric constant of BG glass–ceramics at 1 kHz gradually decreased, the maximum dielectric constant (εm) of BG glass–ceramics gradually decreased, while the temperature corresponding to the maximum dielectric constant (Tm) increased, the ferroelectric relaxation behavior decreased and the temperature stability of the dielectric constant gradually improved. As the BNN glass content increased, the breakdown electric field strength (BDS) of BG glass–ceramics increased first and then decreased, and the polarization values reduced gradually, while the trend of energy storage performance is similar to BDS. When the BNN glass content was 3 wt.%, the energy storage properties of the BG glass–ceramics were optimal, and a recoverable energy storage density (Wrec) of 1.26 J/cm3 and an energy storage efficiency (η) of 80.9% were obtained at the electric field strength of 220 kV/cm. The results showed that BG glass–ceramics were promising for energy storage capacitors.
关键词： Lead-free,glass–ceramics,relaxation,energy storage properties,BaTiO3
更新于2025-09-04 15:30:14
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Manufacture of glass and mirrors from lunar regolith simulant
摘要： Future planetary surface missions to the Moon or Mars, for example, can be augmented by the use of local materials, in order to reduce launch mass and expand mission capability. Using lunar regolith simulant and heating it within a susceptor-assisted microwave oven, it was possible to manufacture a variety of basaltic glasses. Furthermore, it was possible to shape these glasses by grinding and polishing the surface flat and smooth. Glasses manufactured from different lunar regolith simulants were coated with aluminium or silver, and the reflective properties of the resulting mirrors and uncoated surfaces were measured. It was shown that with a porous and/or smooth surface finish, mirrors could be made that reflect the incident solar light (400 nm–1250 nm) in-between 30% for the worst and 85% for the best samples. The same samples with uncoated surfaces showed to reflect less than 7% of incident solar light in the same wavelength range.
关键词： microwave heating,mirror manufacturing,ISRU,basaltic glass,lunar regolith
更新于2025-09-04 15:30:14
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Red-emission properties and crystallization behavior in Eu2O3-TeO2 glasses
摘要： Transparent glass of xEu2O3-(100-x)TeO2 binary system is obtained by using the melt-quenching method and especially studied for x = 5 in xEu2O3-(100-x)TeO2 composition. Optical properties such as transmission, excitation, and emission spectra of Eu2O3-TeO2 glass-ceramics are studied and carefully compared for the samples heated at di?erent temperatures. The one step heat-treatment a?ects the crystallinities as well as phase formation and yields cubic [Eu2Te6O15], orthorhombic [TeO2], and tetragonal [TeO2] phases depending on the heat treating temperature. Glass-ceramics of Eu3+-doped tetragonal [TeO2] shows stronger emission intensity at wavelength of 613 nm with an excitation wavelength of 394 nm compared with that from cubic [Eu2Te6O15] or Eu3+-doped orthorhombic [TeO2]. Enhancement of emission intensity in Eu3+-doped tetragonal [TeO2] is related to the local environment of Eu3+ ions substituted in tetragonal TeO2 lattice.
关键词： Tellurite glasses,Glass-ceramics,Optical property,Eu2Te6O15 crystal
更新于2025-09-04 15:30:14
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Study on structural, optical and hydrophilic properties of FTO/TiO2 tandem thin film prepared by aerosol-assisted chemical vapor deposition method
摘要： Homogeneous TiO2 thin films were prepared on fluorine-doped tin oxide (SnO2:F, FTO) substrate using aerosol-assisted chemical vapor deposition with nano-TiO2 suspension as precursors. The effects of annealing temperature on the structural, optical, electrical and hydrophilic properties have been investigated in detail. The results revealed that the nano-TiO2 precursors with averages particle size of 5 nm to 7 nm formed a uniform and smooth surface morphology on FTO substrates after annealing process. By controlling annealing temperature, the FTO/TiO2 tandem films simultaneously exhibited excellent emissivity and water contact angle with values of about 0.13 and 5°, respectively. The enhancement of the hydrophilicity was attributed to the emerging heterojunction at the FTO/TiO2 interface. The FTO/TiO2 tandem films prepared here have favorable prospective applications in the field of energy-saving coated glass for their hydrophilicity and low-emissivity performance.
关键词： Low-emissivity,Hydrophilic properties,Tandem films,Energy-saving coated glass
更新于2025-09-04 15:30:14