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- 2019
- Mach Zehnder Interferometer
- Convolution code
- Lithium Niobate
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- Electro-optic
- Optoelectronic Information Science and Engineering
- DIT University
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Effect of the synthesis method on the properties of lithium doped graphene oxide composites with tin oxide nanoparticles: Towards white luminescence
摘要： Graphene oxide (GO) based composites functionalized with nanoparticles are emerging as potential candidates for multifunctional devices. As the synthesis route can strongly influence the way in which the nanoparticles are anchored to GO and the resulting properties, different routes have been employed and evaluated in this work for the preparation of composites formed by GO and undoped or Li doped SnO2 nanoparticles. Promotion of synergetic effects, as well as changes in the structural and luminescent properties of the composites have been also analyzed. In comparison with GO, composite samples synthesized in this work involve enhanced luminescence while retaining nearly white emission, which could lead to wider applicability of GO based composites in free standing and emitting and sensing devices. Aspects, such as GO reduction, stabilization of different Sn-based oxides, variation in the concentration of oxygen related functional groups, changes in the sp2 domain sizes, incorporation of lithium and enhancement of the luminescence, have been analyzed in this work by means of x-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), energy dispersive x-ray spectroscopy (EDS), Raman spectroscopy, x-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) characterizations.
关键词： Nanoparticles,Lithium,Tin oxide,Nanomaterials,Luminescence,Composite
更新于2025-09-23 15:23:52
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Probing Lithium Carbonate Formation in Trace-O <sub/>2</sub> -Assisted Aprotic Li-CO <sub/>2</sub> Batteries Using in Situ Surface-Enhanced Raman Spectroscopy
摘要： A trace O2-assisted aprotic Li-CO2 battery represents a promising approach for CO2 recycling. However, cathode passivation and large overpotential are frequently observed for current Li-CO2 batteries because of the insolubility and non-conductivity of the discharge product of lithium carbonate (Li2CO3). Toward maximizing the energy capabilities of the Li-CO2 electrochemistry, it is crucially important to have a fundamental understanding of the Li2CO3 formation mechanism in Li-CO2 batteries. In this report, the discharge reaction of a trace O2-assisted Li-CO2 battery has been interrogated with in-situ surface enhanced Raman spectroscopy (SERS). It was found that in high donor number (DN) solvents Li2CO3 formation proceeds primarily via an 'electrochemical solution route' with peroxodicarbonate (C2O6^2-) as the key intermediate; while in low DN solvents Li2CO3 forms via a chemical reaction of Li2O2 and CO2 on the cathode surface, namely a 'chemical surface route'. It is notable that during discharge the trace O2 acts as a 'pseudo-catalyst' to activate CO2 in high DN solvents, but not in low-DN solvents. The mechanistic study presented here will assist to tailor-design better electrolyte systems and enable more energetic electrochemistry operating far away from the poison of Li2CO3.
关键词： surface enhanced Raman spectroscopy,lithium carbonate,O2-assisted aprotic Li-CO2 battery
更新于2025-09-23 15:23:52
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Luminescent Electrochromic Devices for Smart Windows of Energy-Efficient Buildings
摘要： To address the challenges of the next generation of smart windows for energy-efficient buildings, new electrochromic devices (ECDs) are introduced. These include indium molybdenum oxide (IMO), a conducting oxide transparent in the near-infrared (NIR) region, and a NIR-emitting electrolyte. The novel electrolytes are based on a sol-gel-derived di-urethane cross-linked siloxane-based host structure, including short chains of poly (ε-caprolactone) (PCL(530) (where 530 represents the average molecular weight in g mol?1). This hybrid framework was doped with a combination of either, lithium triflate (LiTrif) and erbium triflate (ErTrif3), or LiTrif and bisaquatris (thenoyltri?uoroacetonate) erbium (III) ([Er(tta)3(H2O)2]). The ECD@LiTrif-[Er(tta)3(H2O)2] device presents a typical Er3+ NIR emission around 1550 nm. The ?gures of merit of these devices are high cycling stability, good reversibility, and unusually high coloration ef?ciency (CE = ?OD/?Q, where Q is the inserted/de-inserted charge density). CE values of ?8824/+6569 cm2 C?1 and ?8243/+5200 cm2 C?1 were achieved at 555 nm on the 400th cycle, for ECD@LiTrif-ErTrif3 and ECD@LiTrif-[Er(tta)3(H2O)2], respectively.
关键词： erbium β-diketonate complex,poly(ε-caprolatone)/siloxane hybrids,erbium triflate,lithium triflate,NIR-transparent IMO,sol–gel,zero-energy buildings,electrochromic devices
更新于2025-09-23 15:23:52
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Easy preparation of nanoporous Ge/Cu3Ge composite and its high performances towards lithium storage
摘要： Nanoporous Ge/Cu3Ge composite is fabricated simply through selective dealloying of GeCuAl precursor alloy in dilute alkaline solution. The as-made Ge/Cu3Ge is characterized by three dimensional (3D) bicontinuous network nanostructure which comprises of substantial nanoscale pore voids and ligaments. Owing to the 3D porous architecture and the introduction of well-conductive Cu3Ge, the lithium storage performances of Ge are dramatically enhanced in terms of higher cycling stability and superior rate performance. Nanoporous Ge/Cu3Ge anode delivers steady capacities above 1000 mA h g-1 upon cycling for 70 loops at 400 mA g-1. In particular, after 300 cycles at the high rate of 3200 mA g-1 the capacity retention for Ge/Cu3Ge is able to reach a maximum of 99.3%. On the contrary, the pure nanoporous Ge encounters severe capacity decay. In view of the outstanding energy storage performances and easy preparation, nanoporous Ge/Cu3Ge exhibits great application potential as an advanced anode in lithium storage related technologies.
关键词： dealloying,anode,lithium ion batteries,nanoporous,germanium
更新于2025-09-23 15:23:52
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Effect of Different Inorganics on Polyimide-based Bragg Grating Humidity Sensor
摘要： Effect of activated carbon and lithium chloride on polyimide-based fiber Bragg Grating relative humidity sensor has been experimentally investigated. Through dip coating process, organic-inorganic hybrid coatings were deposited on fiber Bragg grating to form different relative humidity sensors. Experimental results show that the addition of activated carbon or lithium chloride alone could increase the humidity sensitivity (1.67 times and 1.61 times, respectively), but the structure which contains both lithium chloride and activated carbon increases the sensitivity most (3.9 times). In the 14-day stability test, the fluctuation of pure polyimide sensor is ± 6.5%, while the ones of activated carbon sensor, lithium chloride sensor, activated carbon and lithium chloride sensor are ± 3%, ± 8%, and ± 1.6%.
关键词： lithium chloride,fiber Bragg grating,activated carbon,polyimide,humidity sensor
更新于2025-09-23 15:22:29
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Electronic transition dipole moment and radiative lifetime calculations of lithium dimer ion-pair states
摘要： We present here a computational study of the lifetimes of the ion-pair n1Rt g , n = 3–6, states of lithium dimer. The lifetimes are calculated using ab initio electronic transition dipole moment functions and combination of experimental and ab initio potential curves. The ab initio calculations are carried out using the full configuration-interaction method. The lifetime calculations include the radiative contributions of all the allowed bound–bound and bound-free transitions to lower electronic states. In addition, to test the computational methods used in this work, we have calculated the lifetimes of levels of the lowest excited singlet, A1Rt u , state of lithium dimer.
关键词： Electronic transition dipole moment,Lithium dimer,Lifetime,Ion-pair states
更新于2025-09-23 15:22:29
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GeO <sub/>2</sub> Encapsulated Ge Nanostructure with Enhanced Lithium-Storage Properties
摘要： Germanium (Ge)-based nanostructures, especially those with germanium dioxide (GeO2), have drawn great interest for applications in lithium (Li)-ion batteries due to their ultrahigh theoretical Li+ storage capability (8.4 Li/Ge). However, GeO2 in conventional Ge(s)/GeO2(c) (where (c) means the core and (s) means the shell) composite anodes with Ge shell outside GeO2 undergoes an irreversible conversion reaction, which restricts the maximum capacity of such batteries to 1126 mAhg?1 (the equivalent of storing 4.4 Li+). In this work, a porous GeO2(s)/Ge(c) nanostructure with GeO2 shell outside Ge cores are successfully fabricated utilizing the Kirkendall effect and used as a lithium-ion battery anode, giving a substantially improved capacity of 1333.5 mAhg?1 at a current density of 0.1 Ag?1 after 30 cycles and a stable long-time cycle performance after 100 cycles at a current density of 0.5 A g?1. The enhanced battery performance is attributed to the improved reversibility of GeO2 lithiation/delithiation processes catalyzed by Ge in the properly structured porous GeO2(s)/Ge(c) nanostructure.
关键词： porous,Kirkendall effect,nanostructures,lithium ion batteries,GeO2(s)/Ge(c)
更新于2025-09-23 15:22:29
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Fano Resonance on Nanostructured Lithium Niobate for Highly Efficient and Tunable Second Harmonic Generation
摘要： Second harmonic generation (SHG) is an important nonlinear process which is critical for applications, such as optical integrated circuit, nonlinear microscopy, laser, etc. Many challenges remain in the improvement of nonlinear conversion ef?ciency, since the typical value is of only 10?5 in nanostructures. Here, we theoretically demonstrate a periodic structure consisting of a lithium niobate (LN) bar and an LN disk, on a nanoscale (~300 nm) thin-?lm platform, which is proposed for a highly ef?cient SHG. By breaking the structure symmetry, a Fano resonance with a high Q, up to 2350 and a strong optical ?eld enhancement reaching forty-two folds is achieved, which yields a high conversion ef?ciency, up to 3.165 × 10?4. In addition to its strong second harmonic (SH) signal, we also demonstrate that by applying only 0.444 V on the planar electrode con?gurations of the nanostructured LN, the wavelength of SH can be tuned within a 1 nm range, while keeping its relatively high conversion ef?ciency. The proposed structure with the high nonlinear conversion ef?ciency can be potentially applied for a single-molecule ?uorescence imaging, high-resolution nonlinear microscopy and active compact optical device.
关键词： harmonic generation and mixing,lithium niobate,Fano resonance
更新于2025-09-23 15:22:29
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Quartz-containing glass-ceramics in the SiO <sub/>2</sub> -Li <sub/>2</sub> O-K <sub/>2</sub> O-MgO-CaO-Al <sub/>2</sub> O <sub/>3</sub> -P <sub/>2</sub> O <sub/>5</sub> system
摘要： Volume crystallization of quartz, triggered by adding P2O5, was investigated in the multicomponent SiO2–Li2O–K2O–MgO–CaO–Al2O3–P2O5 glass system. Glass‐ceramics comprising quartz as the main crystal phase besides lithium disilicate (Li2Si2O5) as a minor crystal phase were produced by controlled crystallization from the parent glass. According to quantitative crystal phase analysis by means of Rietveld refinement the mass fraction of the minor Li2Si2O5 phase decreased with increasing P2O5 content, while the fraction of quartz increased. Scanning electron microscopy revealed lath‐like Li2Si2O5 embedded in a matrix of rather globular quartz crystals forming an interlocking microstructure. Well machinable glass‐ceramics with a mean biaxial flexural strength of about 300 MPa and a fracture toughness of about 2.0 MPa × m0.5 could be realized. With mean values ≥13.6 × 10?6 K?1 the glass‐ceramics coefficient of thermal expansion is close to the one reported for low‐quartz crystals. The ease of production based on conventional glass melting and fabrication technology together with the good mechanical, optical, and machining properties enables the application of these materials in prosthodontics.
关键词： nucleation,lithium disilicate,low-quartz,glass-ceramics,quartz
更新于2025-09-23 15:22:29
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Efficacy of phototherapy with different conventional surface treatments on adhesive quality of lithium disilicate ceramics
摘要： Aim: The aim of the present study was to evaluate shear bond strength (SBS) of LDC and resin composite in combination with phototherapy and different ceramic surface treatments. Materials and Method: Forty Lithium Disilicate Glass Ceramic (LDC) disks measuring (4x4x9mm) were fabricated. The specimens were randomly divided into four groups (n=10 each) according to the surface treatment. Group 1 HF+ Silane (Control); Group 2 HF+ Ultrasonic bath + Silane; Group 3 SECP (Self etch ceramic primer) and Group 4 phototherapy (Er, Cr: YSGG) + Silane. On each ceramic disk a resin build-up was done. For SBS the specimens were subjected to increasing load with a transversal velocity of 1ml/min on a universal testing machine on a ceramic resin interface. Failure mode was evaluated using digital microscope. The failure modes were divided into adhesive, cohesive and admixed interface. Data through bond strength testing was tabulated using statistical program for social science (SPSS). Means and standard deviations were compared using analysis of variance and Tukey's post hoc test (p<0.05) Results: The maximum and minimum bond strength was observed in group 2 [19.58(1.011)] and group 1 [17.14(1.122)] respectively. The bond strength among experimental group 1 [17.14 (1.122)] and group 4 [17.48(1.145)] were found to be comparable. Specimens in Group 2 displayed significantly higher bond strength among all experimental groups. Commonly adhesive failure mode was observed in the present study, with an incidence of 60%, 100% and 70% in groups 1,2 and 3 correspondingly Conclusion: Phototherapy using laser at frequency 30Hz and 4.5 W can be used as a surface conditioner for LDC alternate to HF acid. Conditioning of LDC using Self-etch ceramic primer showed better SBS outcomes as compared to phototherapy (Er, Cr: YSGG laser).
关键词： bond strength,microleakage,Phototherapy,lithium disilicate ceramics
更新于2025-09-23 15:22:29