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Blocking and remanence properties of weakly and highly interactive cobalt ferrite based nanoparticles
摘要： We compare both magnetic blocking properties and remanence curves for dilute ferrofluid and powder samples of ferrite magnetic nanoparticles. Low field DC magnetization, AC susceptibility, isothermal remanent magnetization and DC demagnetization techniques are employed to investigate the role of interparticle magnetic interactions on the superparamagnetic relaxation, the magnetic anisotropy and on the super-spin-glass state in closely packed particles. The samples used herein are 3 nm sized spinel-type nanocrystals made of a cobalt ferrite core covered by a layer of maghemite on its outermost surface and can be obtained as aqueous colloidal dispersions thanks to this core-shell strategy. They show large anisotropy attributed to an enhanced surface contribution and the blocking temperature is shifted towards higher values as interparticle distance decreases. For all investigated diluted liquids and powder samples the frequency dependency of the peak temperature is well accounted by a Vogel-Fulcher law, with the insertion of a phenomenological temperature associated to the magnitude of interparticle dipolar interactions. The fractional change of the peak temperature per decade of frequency enlights the presence of interactions between particles in dilute liquids and of a spin-glass-like state in powder samples. The remanence curves always show global demagnetizing behavior, attributed to the combination of both spin surface disorder and interparticle dipolar interactions, the former being predominant in isolated nanoparticles and the latter in powder samples. However, in the most compacted powder, exchange interaction between surface ions of different particles becomes more pronounced and promotes an additive magnetizing effect.
关键词： cobalt ferrite nanoparticles,superparamagnetism,magnetic interactions,blocking temperature,spin-glass state,remanence curves
更新于2025-09-19 17:15:36
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Research on a 3D Encapsulation Technique for Capacitive MEMS Sensors Based on Through Silicon Via
摘要： A novel three-dimensional (3D) hermetic packaging technique suitable for capacitive microelectromechanical systems (MEMS) sensors is studied. The composite substrate with through silicon via (TSV) is used as the encapsulation cap fabricated by a glass-in-silicon (GIS) reflow process. In particular, the low-resistivity silicon pillars embedded in the glass cap are designed to serve as the electrical feedthrough and the fixed capacitance plate at the same time to simplify the fabrication process and improve the reliability. The fabrication process and the properties of the encapsulation cap were studied systematically. The resistance of the silicon vertical feedthrough was measured to be as low as 263.5 m?, indicating a good electrical interconnection property. Furthermore, the surface root-mean-square (RMS) roughnesses of glass and silicon were measured to be 1.12 nm and 0.814 nm, respectively, which were small enough for the final wafer bonding process. Anodic bonding between the encapsulation cap and the silicon wafer with sensing structures was conducted in a vacuum to complete the hermetic encapsulation. The proposed packaging scheme was successfully applied to a capacitive gyroscope. The quality factor of the packaged gyroscope achieved above 220,000, which was at least one order of magnitude larger than that of the unpackaged. The validity of the proposed packaging scheme could be verified. Furthermore, the packaging failure was less than 1%, which demonstrated the feasibility and reliability of the technique for high-performance MEMS vacuum packaging.
关键词： vertical interconnect,capacitive,glass reflow,MEMS,3D encapsulation
更新于2025-09-19 17:15:36
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Application of Judd-Ofelt Theory Upon Chlofluorophosphate Glass Doped with Erbium
摘要： A series of erbium doped glasses chlorofluorophosphates were prepared and characterized. The absorption spectra were analyzed to determine the Judd-Ofelt parameters. The optical performance of these doped glasses suggesting the relevance of these glasses for optical fiber/ wave guide lasers and optical amplifiers.
关键词： and optical amplifier,rare earth,Judd-Ofelt parameters,glass doped,laser,erbium
更新于2025-09-19 17:15:36
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Structures of silicate glasses with varying sodium and fixed iron contents
摘要： Silicate glasses have been synthesised with a fixed 8 mol% of Fe3O4 and sodium oxide varying from 12 mol% to 20 mol%. The environment of the Fe ion was examined by Extended X-ray Absorption Fine structure and M?ssbauer spectroscopy which have shown tetrahedral coordination of oxygen around Fe regardless of the oxidation state of iron. M?ssbauer data indicate increasing; distortion of these tetrahedral units and Fe3+ to Fe2+ ratios, with increasing sodium concentration. Raman spectroscopic studies have shown the presence of Qn linkages for n = 0 to n = 4. For the sodium silicate glass without iron, the single most common linkage is Q3 (~ 50%) suggesting the role of the alkali to be disruptive to the continuity of the silica random network. For the iron containing glasses, the main linkage is Q2 (~ 65%). However, in the latter glasses the fraction of Q3 linkages although considerably less (~10% to ~20%) than Q2 is shown to increase with alkali content due to the concomitant rise of Fe3+ ions which are known to be network formers.
关键词： Structure,Silicate,Iron,Glass,Sodium
更新于2025-09-19 17:15:36
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On the Adherence of Chemically Deposited CdS Films to Common Inorganic Substrates: Effect of Cd <sup>2+</sup> Concentration in Solution, Substrate Surface Chemistry, and Reaction Temperature
摘要： The bad adherence to the substrate of chemical-solution-deposited chalcogenide films in alkaline solution is a current technological problem. However, this issue is belittled since is commonly solved by employing pre-sensitized substrates or by empirically changing the deposition parameters until 'finding' the 'proper' chemical formulation. For these reasons, the issue of the adherence has not been previously studied. The present research aims to properly discuss the issue of adherence by taking as example CdS. As a substrate, we used float glass sheets to take advantage of this interesting flat glass (different tin content). It was found that both the surface chemical composition of the substrate and the concentration of Cd2+ in the reaction solution play important roles in the adherence of the CdS thin films; an important effect of temperature was also found. The results were also consistent for indium tin oxide and silicon wafer surfaces. We propose a general surface reaction scheme which considers both the surface reactive sites and the hidroxo–cadmium–thiourea complexes of the reaction solution, as well as the formation of a surface intermediate entity which dissociates into a CdS molecule bonded to the surface and byproducts. The adherence depends on the quantity of surface intermediate entities formed, and therefore, the conditions that promote their formation contribute to the adherence: high reagent concentration, high-reactive surface sites, and low reaction temperature.
关键词： Float Glass,X-Ray Photoelectron Spectroscopy (XPS),Chemical Bath Deposition,Film Adherence,Tin Oxide
更新于2025-09-19 17:15:36
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Fabrication of branched-TiO2 microrods on the FTO glass for photocatalytic reduction of Cr(VI) under visible-light irradiation
摘要： It is important to prepare a visible-light responsive photocatalyts, which has enhanced absorbance in the range of visible-light. In addition, metal nanoparticles deposited on TiO2 induced the localized surface plasmon resonance (LSPR) effect of Au nanoparticles (AuNPs), and thus enhanced the photocatalytic activity. Herein, TiO2 microrods with nano-branch (B-TiO2) on the fluorine-doped tin oxide glass (FTO) was prepared by hydrothermal method, and AuNPs was deposited on the B-TiO2. Its photocatalytic activity was evaluated by reduction of toxic Cr(VI) to less-toxic Cr(III) under visible-light irradiation. AuNPs/B-TiO2/FTO was successfully photocatalytic reduced target ions and Cr(III) ions were also removed from aqueous phase.
关键词： reduction of Cr(VI),TiO2,Photocatalyst,FTO glass,visible-light-driven
更新于2025-09-19 17:15:36
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Virtual fluoroscopy during transbronchial biopsy for locating ground-glass nodules not visible on X-ray fluoroscopy
摘要： Background: Virtual fluoroscopy (VF) is a novel guided technique that provides ray summation images of target lesions similar to X-ray fluoroscopy. Endobronchial ultrasound with a guide sheath (EBUS-GS) is a useful modality for imaging ground-glass nodules (GGNs) but is not ideal for GGNs that cannot be detected on X-ray fluoroscopy. We evaluated whether the addition of VF to EBUS-GS improved the diagnostic yield. Methods: Consecutive patients who had undergone diagnostic bronchoscopy for GGNs that were not detected on X-ray fluoroscopy between September 2012 and January 2016 were retrospectively enrolled. The patients were divided into two groups: a non-VF group [performed using conventional thin-section computed tomography (CT), X-ray fluoroscopy, EBUS-GS, and virtual bronchoscopy for reference], and a VF group (performed using additional VF to non-VF group). We then compared the diagnostic yields between the two groups and performed a multivariate analysis to identify factors associated with an increased diagnostic yield. Results: A total of 74 patients (VF, 35 patients; non-VF, 39 patients) were enrolled and were included in the analysis. The diagnostic yield was significantly higher in the VF group (77.1%) than in the non-VF group (51.2%, P=0.030). There were no clinically significant complications in either group. In the multivariate analysis, a positive bronchus sign [odds ratio (ORs), 5.41; 95% confidence interval (CI), 1.36–21.40] and the use of VF (odds ratio, 3.68; 95% confidence interval, 1.16–11.60) were significantly associated with successful bronchoscopic diagnosis. Conclusions: The addition of VF to EBUS-GS helped to identify GGNs that were not visible on X-ray fluoroscopy.
关键词： bronchoscopy,virtual bronchoscopy (VB),radial endobronchial ultrasound with a guide sheath (EBUS-GS),ground-glass nodule (GGN),Lung cancer,virtual fluoroscopy (VF)
更新于2025-09-19 17:15:36
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[Laser Institute of America ICALEO? 2016: 35th International Congress on Applications of Lasers & Electro-Optics - San Diego, California, USA (October 16–20, 2016)] International Congress on Applications of Lasers & Electro-Optics - Experimental and numerical study on laser welding of glass using a CO2 laser and glass fiber as filler material
摘要： Automated laser welding with filler wires for bridging gaps and for connecting complex devices has been established for different metal materials. In spite of that, it is still a challenge to transfer this welding process to the brittle material glass. Therefore, glass welding is often realized through a manual process by heating the glass with a gas flame. In addition, welding of non-rotational components requires filler material for gap bridging between the joining partners, which is applied manually today. This work presents an experimental and numerical study on laser welding of fused silica using glass fiber as a filler material to bridge gaps. The goal was to achieve a defined weld penetration depth and heat affected zone which is important for the production of optical elements. Therefore, a CO2 laser heats up the glass components as well as the glass fiber within a temperature controlled welding process. The numerical investigations were used to identify the general process window for welding fused silica. Within the experimental study, the process parameters, such as the defined welding temperature, laser focal spot size, and feed rate were varied to investigate their impact on the welding outcome. In addition, the impact of the filler wire coating on the material composition of the welded component in the joint zone was investigated. Compared to the manual process, laser welding with glass fiber as a filling material leads to a highly reproducible process enabling a high automation level.
关键词： fused silica,temperature controlled welding,heat affected zone,laser welding,glass fiber,filler material,glass,CO2 laser,weld penetration depth
更新于2025-09-19 17:13:59
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Synthesis, structural characterization, and thermal properties of Caa?? and Laa??doped sodaa??lime glasses by laser melting
摘要： Laser melting techniques have been used in the preparation of unconventional glass compositions with high melting temperatures. Thus, we wanted to test the feasibility of using a CO2 laser in the preparation of nitrogen rich oxynitride glasses and nitride silicate glasses. Melting from oxides and metallic raw materials, we wanted to study first glass formation and possible evaporation losses of the glass components. Two glass series were prepared and studied for their structure and thermal properties, one with Ca2+- and a higher melting La3+-doped soda lime silicate series. In less than three minutes of laser melting, spheres of up to six mm diameter were successfully fabricated. The obtained glass samples were homogeneous and transparent in the visible region. X-ray diffraction and Raman spectroscopic analysis confirmed the amorphous nature of the synthesized samples. Sodium losses increase as calcium is added to the soda lime silicate glass. As expected, increasing Ca2+ or La3+ addition leady to increased depolymerization of the silicate network. Moreover, the increases in Tg with the addition of Ca2+ or La3+ ions indicating strengthening of the soda lime silicate glass by increasing strength of the M-O bonds of divalent and trivalent ions over monovalent sodium ions, weak Na-O bonds also resulting in significant evaporation loss during the short laser melting times. The thermal stability decreases upon addition of Ca2+ or La3+ ions to the soda lime silicate glasses.
关键词： Laser melting,soda lime silicate glass,thermal properties,Ca2+,glass structure,La3+
更新于2025-09-19 17:13:59
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[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Flexural and bending fatigue studies of perovskite solar cells on Willow Glass substrates
摘要： Perovskite based photovoltaic (PV) devices have gained enormous importance due to their high power conversion efficiencies and ease of fabrication (solution processing). Conventionally, flexible solar cells have been reported on substrates like PET and PEN. Corning? Willow? Glass, owing to its superior processability and oxygen and moisture barrier property, is a potential replacement for these substrates. In this work, devices fabricated on Willow Glass substrates have been subjected to bending and fatigue tests to assess their worthiness as substrates for flexible solar cells.
关键词： Willow Glass,photovoltaic,flexible,perovskite
更新于2025-09-19 17:13:59