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Spectral analysis and temperature measurement during flash sintering under AC electric field
摘要： In-situ diffraction experiments were used to study the change in peak profiles of 8YSZ during conventional sintering and flash sintering under AC electric field. Using calibration from a conventionally heated standard, the lattice expansion of 8YSZ under flash conditions was correlated to actual specimen temperature, indicating temperature comparable to that required for conventional sintering. At higher current densities, a temperature rise greater than 2000 °C was reached, which resulted in abnormal grain growth and temperature instability. Microstructural analysis demonstrated that finer grain size can be achieved by limiting the current in order to avoid high specimen temperatures. Experiments varying the thickness of the green compact resulted in higher heat loss due to thermal conduction and corresponding reduction in final density. A replacement to the blackbody radiation model was successfully used to fit the data and explain all effects based on Joule heating as well as provide a flash sintering processing map incorporating furnace temperature, power dissipation, and sample geometry.
关键词： 8YSZ,processing map,fast firing,flash sintering,energy dispersive diffraction
更新于2025-11-21 11:01:37
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[ACM Press the 14th IEEE/ACM International Symposium - Athens, Greece (2018.07.17-2018.07.19)] Proceedings of the 14th IEEE/ACM International Symposium on Nanoscale Architectures - NANOARCH '18 - Signal Synchronization in Large Scale Quantum-dot Cellular Automata Circuits
摘要： Quantum-dot fabrication is a well-established nanotechnology, which have many applications in many different scientific fields. By placing four quantum-dots on the corners of a square, a cell is formed, in which the digital information can be stored. This cell serves as the structural device of Quantum-dot Cellular Automata (QCA) circuits. After QCA presentation, several digital circuits and systems have been designed and proposed in the literature. However, one of the biggest problems QCA designers have to face to pave the successful design of functional and large scale QCA circuits is signal synchronization. In this paper, a novel approach of the aforementioned problem is presented. This approach is inspired by the well known computational problem of Firing Squad Synchronization (FSS). FSS problem has many similarities with large scale QCA circuits synchronization problem. In addition, FSS problem has been studied by many researchers and many efficient solutions have been proposed in the literature.
关键词： Synchronization,Firing Squad Synchronization problem,Quantum-dot Cellular Automata (QCA),Large Scale Circuits,Nanoelectronics
更新于2025-09-23 15:22:29
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Firing voltage reduction in thermally annealed Gea??Asa??Te thin film with ovonic threshold switching
摘要： Recently, chalcogenide materials have exhibited ovonic threshold switching characteristics, improving their suitability as selector devices to effectively depress the sneak current in the cross-point array (CPA) structures. However, chalcogenides must be subjected to a firing process before they can exhibit the threshold switching behavior. The firing process causes operation problems with respect to the memory operation process in the case of the CPA structure. Although the firing process is expected to be related to Joule heating with a high electric current, the physical nature of the changes during the firing process remains unclear. In this study, selector devices are fabricated by sandwiching amorphous Ge–As–Te thin films between the TiN and W layers. Furthermore, the authors examine the microstructure of the Ge–As–Te thin films before and after the electric firing process using transmittance electron microscopy (TEM, JEOL JEM-F200). The TEM analysis of the pristine Ge–As–Te thin films denotes the uniform contrast of the image, which implies the uniform chemical composition of the film. However, the Ge–As–Te thin films exhibit nonuniform contrast due to the effects of Joule heating after the electric firing process. The Ge–As–Te thin films were thermally annealed at 150 and 250 °C for 1 min via the rapid thermal annealing process to verify the effects of thermal treatment on the firing process in chalcogenide thin films. The effect of thermal annealing on the threshold switching behavior was also investigated by studying the compositional stability. Their results showed that the thermal annealing process caused the uniform compositions on the pristine Ge–As–Te films to be fluctuated with decreasing firing voltage for threshold switching.
关键词： Ge–As–Te thin films,chalcogenide materials,thermal annealing,ovonic threshold switching,firing process
更新于2025-09-23 15:21:01
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Low-temperature co fired ceramic materials with three different dielectric constants
摘要： A new type of low-temperature co-fired ceramic (LTCC) material with a medium dielectric constant was developed in this study (MK, εr = 20.9). MK can be co-fired with a high-dielectric-constant material (HK, εr = 44.5) and a low-dielectric-constant material (LK, εr = 8.1) previously reported. Glass and ceramic materials similar to HK and LK were used. The compositions of glass and ceramic materials for MK were designed to set the adequate dielectric constant and low-temperature coefficient of the dielectric constant (τεr). The coefficient of thermal expansion (CTE) was matched with those of both the previous materials. MK was confirmed to match well electrically with both the previous materials, had no mechanical defects, and showed minimal inter-diffusion. With the addition of MK, the three types of LTCC material system contribute to the enhancement of the performance and the downsizing of electronic components for high-frequency communication.
关键词： electronic components,high-frequency communication,dielectric constant,co-firing,low-temperature co-fired ceramic
更新于2025-09-23 15:21:01
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Effect of Firing Temperature and Duration on Fused Silica Investment Shell Strength at Room Temperature
摘要： Fused silica is widely used in investment casting shell molds as ?our, stucco and binder for its superior properties, such as low linear thermal expansion coef?cient and high thermal shock resistance. Investment shell molds are usually ?red after the de-wax process to remove the residue pattern material, and to improve shell strength through sintering. The ?ring temperatures are generally high enough to affect the phase constituent and microstructure of the shells, which further in?uences the shell strength. Firing duration at ?ring temperature is another important factor having an impact on the shell strength due to grain coarsening, but it is often overlooked by investment foundries. In this article, the room temperature moduli of rupture of investment shells ?red at different conditions were determined. The crystallinity of fused silica shells was determined using X-ray diffraction. The differences on the shell strength were discussed and correlated with the microstructure and phase constitution in the shells after different ?ring processes.
关键词： phase transformation,modulus of rupture,firing duration,firing temperature,investment shell
更新于2025-09-19 17:15:36
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High-Efficiency p-Type Si Solar Cell Fabricated by Using Firing-Through Aluminum Paste on the Cell Back Side
摘要： Firing-through paste used for rear-side metallization of p-type monocrystalline silicon passivated emitter and rear contact (PERC) solar cells was developed. The rear-side passivation Al2O3 layer and the SiNx layer can be effectively etched by the firing-through paste. Ohmic contact with a contact resistivity between 1 to 10 m?·cm2 was successfully fabricated. Aggressive reactive firing-through paste would introduce non-uniform etching and high-density recombination centers at the Si/paste interface. Good balance between low resistive contact formation and relatively high open-circuit voltage can be achieved by adjusting glass frit and metal powder content in the paste. Patterned dot back contacts formed by firing-through paste can further decrease recombination density at the Si/paste interface. A P-type solar cell with an area of 7.8 × 7.8 cm2 with a Voc of 653.4 mV and an efficiency of 19.61% was fabricated.
关键词： contact formation,open-circuit voltage,firing-through paste,PERC
更新于2025-09-19 17:13:59
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Application Of Artificial Neural Networks In Modeling Of Manufactured Front Metallization Contact Resistance For Silicon Solar Cells
摘要： This paper presents the application of artificial neural networks for prediction contact resistance of front metallization for silicon solar cells. The influence of the obtained front electrode features on electrical properties of solar cells was estimated. The front electrode of photovoltaic cells was deposited using screen printing (SP) method and next to manufactured by two methods: convectional (1. co-fired in an infrared belt furnace) and unconventional (2. Selective Laser Sintering). Resistance of front electrodes solar cells was investigated using Transmission Line Model (TLM). Artificial neural networks were obtained with the use of Statistica Neural Network by Statsoft. Created artificial neural networks makes possible the easy modelling of contact resistance of manufactured front metallization and allows the better selection of production parameters. The following technological recommendations for the screen printing connected with co-firing and selective laser sintering technology such as optimal paste composition, morphology of the silicon substrate, co-firing temperature and the power and scanning speed of the laser beam to manufacture the front electrode of silicon solar cells were experimentally selected in order to obtain uniformly melted structure well adhered to substrate, of a small front electrode substrate joint resistance value. The prediction possibility of contact resistance of manufactured front metallization is valuable for manufacturers and constructors. It allows preserving the customers’ quality requirements and bringing also measurable financial advantages.
关键词： Co-firing in the furnace,Screen printing,Computational material science,Artificial neural networks,Selective laser sintering,Silicon solar cell
更新于2025-09-16 10:30:52
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Preparation of Ultra-low Temperature Sintering Ceramics with Ultralow Dielectric Loss in Na <sub/>2</sub> O-WO <sub/>3</sub> Binary System
摘要： A series of new microwave dielectric ceramics with ultralow dielectric loss in Na2O-WO3 binary system were prepared by the modified solid-state reaction method at ultra-low sintering temperatures. Three stable phases, namely Na2WO4, Na2W2O7 and Na2W4O13, were formed in the system. Their stability in the air, phase composition, compatibility with metal electrodes, microstructures and microwave dielectric properties were investigated. In this binary system, the cubic structure Na2WO4 ceramic sintered at 565?C exhibited the best microwave dielectric properties with a permittivity of 5.6, a Q × f value of 124 200 GHz and a temperature coefficient of -63 ppm/?C at a frequency of 13.1 GHz. The Na2WO4 ceramic is chemically compatible with Ag and Al electrodes. Besides, the Na2WO4 ceramic has favorable stability in the air. Due to the excellent dielectric properties and favorable stability in the air, the Na2WO4 ceramic is a great candidate for LTCC devices.
关键词： Ultra-low dielectric loss,Microwave dielectric ceramics,Ultra-low firing
更新于2025-09-04 15:30:14
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Noncontact Electrical Probe for Monitoring Cellular Processes in Primary Retinal Explants
摘要： Quantitative assessment involving noncontact electrical methods without the need for microscopy can enable a remote user to monitor the cell growth and development at different stages. In this line of pursuit, the utility of ultrahigh impedance, air-suspended capacitively coupled electric potential sensors to monitor electrically active cells is examined. Standard cell lines and chick retinal explants on a variety of optoelectronically active polymer substrates are utilized to demonstrate the utility of this sensor placed in proximity without physical contact. Burst firing in developing chick retina in the early stage when photoreceptors are not developed can be observed via the photoexcitation of optoelectronic substrates using this noncontact sensing method.
关键词： noncontact sensor,burst firing,optoelectronic polymers
更新于2025-09-04 15:30:14
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Approaching 23% with large‐area monoPoly cells using screen‐printed and fired rear passivating contacts fabricated by inline PECVD
摘要： We present n‐type bifacial solar cells with a rear interfacial SiOx/n+:poly‐Si passivating contact (‘monoPoly’ cells) where the interfacial oxide and n+:poly‐Si layers are fabricated using an industrial inline plasma‐enhanced chemical vapor deposition (PECVD) tool. We demonstrate outstanding passivation quality with dark saturation current density (J0) values of approximately 3 fA/cm2 and implied open‐circuit voltage (iVoc) of 730 mV at 1‐sun conditions after firing in an industrial belt furnace. Using a simple solar cell process flow that can be easily adapted for mass production, a peak cell efficiency of 22.8% with a cell open circuit voltage (Voc) of 696 mV is achieved on large‐area, screen‐printed, Czochralski‐silicon (Cz‐Si) solar cells using commercial fire‐through metal pastes.
关键词： silicon wafer,screen‐printed,industrial process,passivated contacts,industrial firing,PECVD,solar cells,large‐area
更新于2025-09-04 15:30:14