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- 2019
- low-temperature electronics
- junction field-effect transistors
- differential operational amplifier
- LTspice environment
- differential stage
- common-mode rejection ratio
- class AB operation
- optimization of analog electronic circuit
- operational amplifier
- LTspice environment
- Electronic Science and Technology
- Don State Technical University
- Southern Federal University
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Magnetic, magneto-optical and specific heat studies of the low temperature anomalies in the magnetodielectric DyIG ferrite garnet
摘要： Measurements of magnetization and Cotton Mouton effect (CM) under external magnetic field (Hex) combined with specific heat experiments at Hex = 0, were performed on dysprosium iron garnet Dy3Fe5O12 (or DyIG) single crystals. From the low-temperature dependences of some magnetic, magneto-optical and thermodynamic quantities, such as spontaneous magnetization, both magnetic and CM susceptibilities and the excess specific heat due to the contribution of Dy3+ ions only, give rise to the appearance of two types of anomalies. The first one which is related to the ‘low temperature paraprocess’ effect, occurs in the region of the ‘Belov point’ TB predicted at 42 K. Whereas the second one, which is due to the previous spin reorientation transition, takes place at TSR = 15 K. The easy axis of magnetization which remains along the <111> direction above TSR, changes spontaneously below TSR and becomes aligned along the low symmetry angular <uuw> phases. The results are analyzed taking into account those reported earlier such the negative magnetodielectric effect for Hex < 10 kOe and the Schottky effect which cause anomalies respectively, in the dielectric constant at TSR and in the excess specific heat near the low temperature point TB.
关键词： Low temperature Belov point,Dy3Fe5O12,Ferrimagnetism,Field induced phase transition,Spin reorientation
更新于2025-09-23 15:23:52
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Temperature independent low firing [Ca0.25(Nd1-xBix)0.5]MoO4 (0.2 ≤ x ≤ 0.8) microwave dielectric ceramics
摘要： A scheelite structured [Ca0.25(Nd1-xBix)0.5]MoO4 (0.2 (cid:1) x (cid:1) 0.8) ceramics were prepared via solid state reaction method. All the ceramics can be well densi?ed below 780 (cid:3)C. As x value increased from 0.2 to 0.8, microwave dielectric permittivity increased from 14.0 to 27.8, Qf (Q ? quality factor ? 1/dielectric loss; f ? resonant frequency) value decreased from 42,000 GHz to 19,000 GHz, and TCF shifted from (cid:4)50 ppm/oC to t18 ppm/oC. The best microwave dielectric properties with permittivity between 23.54 and 23.56, Qf value between 24,000 GHze21,000 GHz and TCF value ~ (cid:4)8 ppm/oC in wide temperature range 25 (cid:3)Ce130 (cid:3)C were obtained in x ? 0.6 ceramic. This work showed that Bi played an important role to modify the TCF from negative to positive value in scheelite materials and this result further accelerate the application of scheelite materials in low temperature co-?red ceramics (LTCC) technology.
关键词： Microwave dielectric properties,Low temperature sintering,MoO3,Scheelite
更新于2025-09-23 15:23:52
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[IEEE 2018 7th Electronic System-Integration Technology Conference (ESTC) - Dresden, Germany (2018.9.18-2018.9.21)] 2018 7th Electronic System-Integration Technology Conference (ESTC) - Integration with Light
摘要： This paper reports the use of Laser-induced Forward Transfer (LIFT) technology for printing of multilayer flexible circuitries and the fabrication of micro-bumps for flip-chip bonding of packaged LEDs and bare die microcomponents. Bonding of passive and functional surface mount devices (SMD) on low-temperature polyethylene terephthalate (PET) foils have been demonstrated using two selective bonding techniques. Firstly, using a high intensity near-infrared (NIR) lamp, a bare die NFC chip was bonded on micro-bumps formed with LIFT printed isotropic conductive adhesive (ICA) within less than a minute. Secondly, using a high intensity Xenon lamp, passive components and packaged LEDs were bonded within 5 seconds on micro-bumps formed with conventional Sn–Ag–Cu (SAC) lead-free alloys. In the both cases, due to selective light absorption, a limited temperature increase was observed in the PET substrates allowing successful bonding of components onto the delicate polyethylene foil substrates using conventional interconnect materials.
关键词： LIFT,low temperature bonding,NIR curing,conductive adhesive,lead-free SAC solder,photonic soldering,flip-chip bonding,laser printing
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE Industry Applications Society Annual Meeting (IAS) - Portland, OR, USA (2018.9.23-2018.9.27)] 2018 IEEE Industry Applications Society Annual Meeting (IAS) - Design and Optimization of a Solar Power Conversion System for Space Applications
摘要： This manuscript details a design method for a 500kW solar power based microgrid system for space applications. The design method utilizes multi-objective optimization with the Genetic Algorithm considering four parameters that characterize solar power based microgrids (battery voltage, PV maximum power, PV maximum power point voltage, and number of panels per string). The final optimization metric is the ratio of daily average deliverable power to total system mass (W/kg) metric. The microgrid system is composed of a number of modular DC-DC micro-converters, of which four topologies (buck, boost, buck-boost and non-inverting buck-boost) are evaluated and compared. The non-inverting buck-boost converter is determined to be the best candidate, and the optimal system characteristics are provided and analyzed. The final system design achieves a specific power of 35.56W/kg, with optimized result of 743.7V battery voltage, 439.5W PV maximum power, 182.7V PV maximum voltage, and three panels per string. Based on the optimizations results, a prototype is designed, tested, and analyzed in terms of efficiency and low temperature reliability. The converter achieved a peak efficiency of 98.4%, a power density of 3.54W/cm3, a specific power of 3.76W/g, and operated for over 267 hours of 11-minute low temperature cycles from 0oC to -140oC.
关键词： wide band gap semiconductors,microgrids,non-inverting buck-boost,maximum power point trackers,space exploration,photovoltaic systems,design optimization,DC-DC power converters,system-level design,low temperature testing
更新于2025-09-23 15:23:52
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Nonlinear transmittance of a diffusion-doped single crystal ZnSe:Fe <sup>2+</sup> at a wavelength of 2940?nm at low and room temperature
摘要： The nonlinear transmittance of a single crystal ZnSe:Fe2+ sample was measured at low and room temperature during the action of a laser pulse with a wavelength of 2940 nm. It was found that in a strong field (fluence 1.3 J cm?2, a laser pulse duration of 320 ns, a peak intensity of 4.1 MW cm?2), the sample transmittance is about 70% at room and 77% at low temperature. In a single crystal ZnSe:Fe2+ sample at a fluence of 1.3 J cm?2 and a spot diameter of high-power radiation of about 0.54 mm, at the temperature ?168 °C lasing was observed along the surface of the sample, when feedback was provided by scattering from the matted surface of the sample. This effect should be taken into account when nonlinear transmittance measurements are fulfilled of a diffusion doped a single crystal ZnSe:Fe2+.
关键词： nonlinear transmittance,ZnSe:Fe2+,low temperature
更新于2025-09-23 15:22:29
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[IEEE 2018 International Flexible Electronics Technology Conference (IFETC) - Ottawa, ON, Canada (2018.8.7-2018.8.9)] 2018 International Flexible Electronics Technology Conference (IFETC) - Low Temperature (80 °C) Sinterable Particle Free Silver Ink for Flexible Electronics
摘要： For the emerging field of flexible printed electronics, ink compatibility with substrate is always required. However, most of the commercial silver nanoparticle-based inks are not compatible with flexible substrates, as they need high- sintering temperatures (~150-250 0C). In addition, silver nanoparticle-based inks have several serious problems such as a complex synthesis protocol, high cost, particle aggregation, nozzle clogging, reduced shelf life, and jetting instability. These shortcomings in conductive inks are barriers for their wide spread use in practical applications. In this work, we demonstrate a silver-organo-complex (SOC) based particle free silver ink which can decompose at 80 0C and becomes conductive at this low temperature. The inkjet-printed film from this ink exhibits not only high conductivity but also excellent jetting and storage stability. To demonstrate the suitability of this ink for flexible electronics, an inkjet-printed film on flexible polyimide substrate is subjected to bending and crushing tests. The results before and after flexing and crushing are very similar, thus verifying the excellent tolerance against bending and crushing for this ink as compared to the commercial nanoparticles based ink.
关键词： low-temperature sintering,silver-organo-complex (SOC) ink,bending and crushing test,inkjet-printing,flexible
更新于2025-09-23 15:22:29
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Design and Optimization of a Solar Power Conversion System for Space Applications
摘要： This manuscript details a design method for a 500kW solar power based microgrid system for space applications. The design method utilizes multi-objective optimization with the Genetic Algorithm considering four parameters that characterize solar power based microgrids (battery voltage, PV maximum power, PV maximum power point voltage, and number of panels per string). The final optimization metric is the ratio of daily average deliverable power to total system mass (W/kg) metric. The microgrid system is composed of a number of modular DC-DC micro-converters, of which four topologies (buck, boost, buck-boost and non-inverting buck-boost) are evaluated and compared. The non-inverting buck-boost converter is determined to be the best candidate, and the optimal system characteristics are provided and analyzed. The final system design achieves a specific power of 35.56W/kg, with optimized result of 743.7V battery voltage, 439.5W PV maximum power, 182.7V PV maximum voltage, and three panels per string. Based on the optimizations results, a prototype is designed, tested, and analyzed in terms of efficiency and low temperature reliability. The converter achieved a peak efficiency of 98.4%, a power density of 3.54W/cm3, a specific power of 3.76W/g, and operated for over 267 hours of 11-minute low temperature cycles from 0oC to -140oC.
关键词： low temperature testing,photovoltaic systems,wide band gap semiconductors,maximum power point trackers,design optimization,non-inverting buck-boost,space exploration,system-level design,DC-DC power converters,microgrids
更新于2025-09-23 15:22:29
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A Tunable Optimized Low-Temperature Sensor Based on the Hybrid Photonic Crystals (F4/Bg5/F4) and (Bg5/F4/Bg5)
摘要： In this paper, we present a novel type of low-temperature sensor based precisely on the symmetrical hybrid photonic crystals. Thanks to the two-fluid model and the transfer matrix method, we study the temperature sensitivity of the hybrid multilayers (F4/Bg5/F4) and (Bg5/F4/Bg5) where F4 represents the fourth iteration of the quasi-periodic Fibonacci sequence and Bg5 designates the multilayer Bragg mirror (HLS)5. We assume that the layers H, L, and S indicate precisely the dielectric materials of Bi4Ge3O12, SiO2, and YaBO2CuO7 superconductor one. The analysis of the transmittance spectra shows that the hybrid photonic crystal is more sensitive to the temperature than the periodic one. A higher sensibility value is reached due to the possible combination of the periodic and quasi-periodic sequences. Our investigation reveals that the photonic crystal (F4/Bg5/F4) is more sensitive to low temperature compared to (Bg5/F4/Bg5). The sensitivity is significantly affected by the position of quasi-periodic sequences. The sensitivity of such photonic crystals can be adequately controlled by applying a symmetrical chirping. The designed structures pave the way toward the achievement of a potential low-temperature sensor.
关键词： Low-temperature sensor,Tunable,Fibonacci,Photonic crystals,Chirped,TMM,Optimization
更新于2025-09-23 15:22:29
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Polymer-assisted In-situ Growth of All-Inorganic Perovskite Nanocrystal Film for Efficient and Stable Pure Red Light-emitting Devices
摘要： In the past few years, a substantial progress has been made for perovskite light-emitting devices. Both pure green and infrared thin film perovskite light-emitting devices with external quantum efficiency over 20% have been successfully achieved. However, pure red and blue thin film perovskite light-emitting diodes still suffer from inferior efficiency. Therefore, the development of efficient and stable thin film perovskite light-emitting diodes with pure red and blue emissions is urgently needed for possible applications as a new display technology and solid-state lighting. Here, we demonstrate an efficient light-emitting diode with pure red emission based on polymer-assisted in-situ growth of high quality all-inorganic CsPbBr0.6I2.4 perovskite nanocrystal film with homogenous distribution of nanocrystals in size of 20 ~ 30 nm. With this method, we can dramatically reduce the formation temperature of CsPbBr0.6I2.4 and stabilize its perovskite phase. Eventually, we successfully demonstrate a pure-red-emission perovskite light-emitting diode with a high external quantum efficiency of 6.55% and luminance of 338 cd/m2. Furthermore, the device obtains an ultra-low turn-on voltage of 1.5 V and a half-lifetime of over 0.5 hours at a high initial luminance of 300 cd/m2.
关键词： cesium-based perovskite,perovskite-polymer hybrid,Low-temperature process,pure red-emitting,perovskite LED
更新于2025-09-23 15:21:21
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Millimetre-wave low-temperature co-fired ceramic bandpass filter with independently controllable dual passbands
摘要： This study presents a detailed investigation on the frequency properties of the stub-loaded stepped-impedance resonator (SIR). For the first time, the frequency controllability of the third and fifth harmonic resonant frequencies (f3 and f5) of the SIR under different ratios of impedance and electric length is subjected to a complete theoretical analysis. It can be found that there is a length ratio which makes f3 and the voltage-null point at f3 never be affected by the change of the impedance ratio. Furthermore, the stub loaded at this voltage-null point also has no effect on f3. These features are successfully applicable to realise independent frequency control for dual-band bandpass filters (BPFs). In this situation, a new coupling path through the loaded stub can be constructed only for f5, and the coupling coefficients for the two bands can be individually varied. Accordingly, both the operational frequencies and bandwidths of the two bands can be separately adjusted. For demonstration, an independently controllable dual-band BPF operating at 27.5/33?GHz is designed and fabricated for millimetre-wave wireless applications. Good accordance is achieved between the simulated and measured results.
关键词： low-temperature co-fired ceramic,independently controllable,bandpass filter,dual passbands,millimetre-wave
更新于2025-09-23 15:21:21