Electron Glass Research Articles

Quantum Coulomb glass on the Bethe lattice

We study the Coulomb glass emerging from the interplay of strong interactions and disorder in a model of spinless fermions on the Bethe lattice. In the infinite coordination number limit, strong interactions induce a metallic Coulomb glass phase with a pseudogap structure at the Fermi energy. Quantum and thermal fluctuations both melt this glass and induce a disordered quantum liquid phase. We combine self-consistent diagrammatic perturbation theory with continuous time quantum Monte-Carlo simulations to obtain the complete phase diagram of the electron glass and to characterize its dynamical properties in the quantum liquid, as well as in the replica symmetry broken glassy phase. Tunneling spectra display an Efros-Shklovskii pseudogap upon decreasing temperatures, but the density of states remains finite at the Fermi energy due to residual quantum fluctuations. Our results bear relevance to the metallic glass phase observed in Si inversion layers.

Highly disordered VO2 films: appearance of electronic glass transition and potential for device-level overheat protection

In this work, the phase transition of a highly disordered amorphous VO2 film is studied. It is found that the electronic transport behavior follows the Arrhenius or Vogel–Tammann–Fulcher model, showing different thermal sensitivity under different thicknesses. Based on it, the concept of a prototype device with overheating protection capability is demonstrated. The results, reflecting the relationship between phase transition and structural disorder, open up a unique pathway to understand the metal insulator transition in strongly correlated electronic systems and to its functionality in electronic devices.

Dwelling deep into the anisotropic transport of Zintl Ca3Sb2

Phonon-glass-electron-crystal (PGEC) is a class of materials that exert electron crystal like pronounced electronic conduction and glass like supressed thermal conduction leading to astonishing thermoelectric (TE) performance. The density functional theory based investigation of Zintl Ca3Sb2 is presented. We find that a narrow band gap of 0.35 eV and the spatially dispersed phonon branches of Ca3Sb2 result in improved power factor and ultra-low thermal conductivity. Comparing with conventional TE materials PbTe, Bi2Te3 and Mg3Sb2, the Ca3Sb2 possesses significantly low average thermal conductivity (κL) of 0.26 Wm-1K−1 at 300 K. The root-cause of such a feeble κL is reciprocated in terms of the acoustic modes with supressed vibrational frequency that when coupled with lower lying optic phonon modes, results in significantly high phonon scattering rates and phonon anharmonicity. Interestingly, the thermal conduction along the cross-plane direction is found to be much more supressed than the in-plane direction suggesting appreciable anisotropy. The TE efficiency of Ca3Sb2 is envisaged from the temperature dependent profile of figure of merit ZT which is found to attain magnitude of ∼ 0.72 (in z-direction) within temperature range 300 K-600 K for both charge carriers. Besides providing in-depth insight to the thermal conduction, the study provides motivation to investigate this yet-to-be-synthesized potential Zintl compound.

Electron glass signatures up to room temperature in disordered insulators

This paper describes the observation of non-equilibrium field effects at room temperature in four disordered insulating systems: granular Al, discontinuous Au, amorphous NbSi and amorphous indium oxide thin films. The use of wide enough gate voltage ranges and a cautious analysis of the data allow us to uncover memory dips (MDs), the advocated hallmark of the electron glass, in the four systems. These MDs are found to relax slowly over days of measurements under gate voltage changes, reflecting the impossibility for the systems to reach an equilibrium state within experimentally accessible times. Our findings demonstrate that these electrical glassy effects, so far essentially reported at cryogenic temperatures, actually extend up to room temperature.

Mechanical and physical characteristics of hybrid particles/fibers-polymer composites: A review

Hybrid composites containing polymeric matrix materials and saturated with strengtheners and particles in the form of molecules are found to be of great interest to researchers, technicians, and scientists because of the technological, mechanical and physical characterization required for important engineering applications. Advances in the mechanical behavior of polymeric hybrid materials have a great impact on motivating researchers to develop new materials. This review deals with the study of the effect of reinforcement hybrid fibers/particles on polymer hybrid compounds in terms of mechanical and physical characteristics. From this study, it was concluded that the fibers have become an alternative to mineral materials. Synthetic fibers including (carbon fibers, electronic glass, Kevlar fibers) and natural fibers (bamboo fibers, Jute fibers, sisal fibers) with the different particles such as (alumina, graphene, titanium oxide and silicon carbide) were the most widely used and effective, which led to a significant improvement in the mechanical and physical characteristics of polymer materials.

Dynamic white-light interferometry via multiwavelength tilt iteration and sliding local least squares.

The growing interest in microprofile measurements for advanced semiconductor manufacturing and electronic glass screens has stimulated the demand for in situ dynamic white-light interferometry (DWLI). However, it is challenging to perform vibration-insensitive measurements because of the broad-spectrum interference. In this Letter, we report a vertical scanning DWLI using multiwavelength tilt iteration and sliding local least squares. Numerical simulations and comparative experiments were conducted to verify the principle and performance of the proposed method. To the best of our knowledge, this is the first time such a DWLI has been proposed to achieve excellent vibration-resistant performance without using complex photoelectric compensation systems.

Superhydrophobic surface of glass powder derived from wet milling with aliphatic chemicals modification

Glass frit has emerged recently as a promising material for incorporation in adhesive of electronic components owing to its high sealing density, environmental stability and easy processing. This requires the glass surface to be hydrophobic to ensure high dispersity, grinding uniformity, and high-temperature sintering performance of the glass frit. However, the glass surface is usually hydrophilic. In this work, we developed a wet milling method to effectively produce hydrophobic glass powder by using aliphatic chemicals modification. We employed a series of aliphatic chemicals containing nucleophilic functional groups to prepare ultrafine lead aluminosilicate electronic glass powders. The nucleophilic substitution reaction of amino groups, carboxylic acid groups, hydroxyl groups and phosphoric acid groups reduces the hydroxyl content on the surface of the glass powder to 0.10 mg/m2, and generates steric hindrance and hydrophobicity (contact angle: 153.0°) through the long carbon chain. The obtained powder therefore shows a uniform particle size distribution, anti-agglomerated property, and maximum 25 °C lower hemispheric point temperature compared to powder prepared by conventional hydrophilic milling method. This work provides a versatile method to simultaneously control the structural and surface properties of glass powders at their formation stage.

Engineered Ceria Slurries for Electronic Glass Substrate CMP Application

Glass substrates have gradually gained more attention as the media platters in hard disk drives (HDD) used in laptops, data centers, and cloud storage due to its advantageous properties. Particularly, advanced technologies like Heat Assisted Magnetic Recording (HAMR) in HDD and Through-Glass-Via (TGV) in 3D packaging applications all require the use of glass substrates with precisely controlled surface properties. Glass substrate’s advantages include lower weight, improved flatness, less flutter at high RPM’s and lower thermal expansion as compared to aluminum / NiP substrates. This lower expansion when exposed to heat makes it ideal for HAMR technology, which will be the key to creating hard disk drives with growing storage capacity. Chemical mechanical polishing (CMP) is a method to eliminate surface defects induced by grinding & lapping to meet final requirements of HAMR or TGV for glass substrates with surface finishes down to a few angstrom level or less. Key performance targets include removal rate, surface roughness, TTV, FSW, ceria residue / particle content (cleanability) on glass disks as well as recyclability. In this study, slurries for CMP are investigated utilizing engineered ultra-pure ceria particles which are known to have high material removal rate (MRR) on glass substrates. Various particle sizes, morphology, and chemical additives were evaluated. Results of systematic CMP tests including MRR, surface roughness, recyclability, and most importantly, ease of ceria residue removal from the glass substrate will be reported. Morphology of ceria particles was found to play a critical role in MRR. An optimized combination of ceria morphology and additive chemistries enables high MRR together with improved Ceria residue / cleanability performance. Figure 1

Towards Higher Electric Conductivity and Wider Phase Stability Range via Nanostructured Glass-Ceramics Processing.

This review article presents recent studies on nanostructured glass-ceramic materials with substantially improved electrical (ionic or electronic) conductivity or with an extended temperature stability range of highly conducting high-temperature crystalline phases. Such materials were synthesized by the thermal nanocrystallization of selected electrically conducting oxide glasses. Various nanostructured systems have been described, including glass-ceramics based on ion conductive glasses (silver iodate and bismuth oxide ones) and electronic conductive glasses (vanadate-phosphate and olivine-like ones). Most systems under consideration have been studied with the practical aim of using them as electrode or solid electrolyte materials for rechargeable Li-ion, Na-ion, all-solid batteries, or solid oxide fuel cells. It has been shown that the conductivity enhancement of glass-ceramics is closely correlated with their dual microstructure, consisting of nanocrystallites (5–100 nm) confined in the glassy matrix. The disordered interfacial regions in those materials form “easy conduction” paths. It has also been shown that the glassy matrices may be a suitable environment for phases, which in bulk form are stable at high temperatures, and may exist when confined in nanograins embedded in the glassy matrix even at room temperature. Many complementary experimental techniques probing the electrical conductivity, long- and short-range structure, microstructure at the nanometer scale, or thermal transitions have been used to characterize the glass-ceramic systems under consideration. Their results have helped to explain the correlations between the microstructure and the properties of these systems.

Lifetimes of local excitations in disordered dipolar quantum systems

When a strongly disordered system of interacting quantum dipoles is locally excited, the excitation relaxes on some (potentially very long) timescale. We analyze this relaxation process, both for electron glasses with strong Coulomb interactions - in which particle-hole dipoles are emergent excitations - and for systems (e.g., quantum magnets or ultracold dipolar molecules) made up of microscopic dipoles. We consider both energy relaxation rates ($T_1$ times) and dephasing rates ($T_2$ times), and their dependence on frequency, temperature, and polarization. Systems in both two and three dimensions are considered, along with the dimensional crossover in quasi-two dimensional geometries. A rich set of scaling laws is found.

Context-sensitive smart glasses monitoring wear position and activity for therapy compliance-A proof of concept.

PurposeTo improve the acceptance and compliance of treatment of amblyopia, the aim of this study was to show that it is feasible to design an electronic frame for context-sensitive liquid crystal glasses, which can measure the state of wear position in a robust manner and detect distinct motion patterns for activity recognition.MethodsDifferent temple designs with integrated temperature and capacitive sensors were developed to realize the detection of the state of wear position to distinguish three states (correct position/wrong position/glasses taken off). The electronic glasses frame was further designed as a tool for accelerometer data acquisition, which was used for algorithm development for activity classification. For this purpose, training data of 20 voluntary healthy adult subjects (5 females, 15 males) were recorded and a 10-fold cross-validation was computed for classifier selection. In order to perform functional testing of the electronic glasses frame, a proof of concept study was performed in a small group of healthy adults. Four healthy adult subjects (2 females, 2 males) were included to wear the electronic glasses frame and to protocol their activities in their everyday life according to a defined test protocol. Individual and averaged results for the precision of the state of wear position detection and of the activity recognition were calculated.ResultsContext-sensitive control algorithms were developed which detected the state of wear position and activity in a proof of concept. The pilot study revealed an average of 91.4% agreement of the detected states of wear position. The activity recognition match was 82.2% when applying an additional filter criterion. Removing the glasses was always detected 100% correctly.ConclusionThe principles investigated are suitable for detecting the glasses’ state of wear position and for recognizing the wearer´s activity in a smart glasses concept.

Experimental investigation on concrete partially replaced with waste glass powder and waste E-plastic

Waste Electronic Plastic (WEP) and Waste Glass Powder (WGP) are found to be available in abundance due to their extensive production with single utilisation policy. Researchers have been evolving various methods to utilize these waste materials as substitute ingredients in concrete. This research work is aimed at investigating the combined effect of these two waste products in concrete. Experimental investigations were carried out in order to use WGP as a replacement to cement with 5%, 10%, 15% and 20%, and WEP as a replacement to coarse aggregate with 5%, 10%, 15% and 20%, on volume basis. Different blends were made with the combination of WGP and WEP too. Basic mechanical tests were carried out. Further, durability performance of concrete was evaluated using water absorption, acid attack, sulphate attack, and rapid chloride penetration tests (RCPT). Micro Structural analysis was also evaluated using Scanning electron microscope (SEM) and X-ray diffraction method (XRD). The fresh concrete property obtained with the replacement up to 20% WGP and up to 15% WEP showed better slump and density results. WGP filled the pores that were developed due to the replacement of WEP and this was inferred with less porosity of matrix. Hardened concrete property results showed that the combination of WGP and WEP increased the compressive strength up to 25% beyond which the strength was decreased.

Polaronic effect of a metal layer on variable range hopping

We investigate the effect of a metal plate on the variable range hopping (VRH) conductivity of a two dimensional electron-glass (EG) system. The VRH conductivity is known to have a stretched exponential dependence on temperature, with an exponent $p$ that depends on the shape of the EG's single particle density of states (DOS). For constant DOS $p=1/3$ and for linear DOS $p=1/2$, also known as Mott's and Efros-Shklovskii's VRH respectively. The presence of the plate causes two effects on the EG system, static and dynamic. The well known static effect accounts for the additional screening of the Coulomb repulsion in the EG and for the partial filling of the Coulomb gap in the DOS. This in turn causes an increase of the conductivity at very low temperatures. Here we investigate the complementary dynamical effect, which is related to the polaronic phenomena. Our main result is the dynamical suppression of the standard phonon assisted hopping and, thus, suppression of the conductivity in a much wider range of temperatures as compared to the low temperature static effect. The relation to experiments is discussed.

Partial replacement of Ordinary Portland cement by LCD glass powder in concrete

This paper represents the properties of concrete with partial replacement of cement by LCD glass powder derived from discarded gadgets. This end of life LCD glass powder was obtained from electronic glass scrap and is used in this work after grinding to a particle size of 45 µm or less. X-ray Fluorescence spectroscopy (XRF) test indicates SiO2, Al2O3, CaO and MgO as the major oxides in the LCD glass powder. The fresh state, hardened state and durability properties of concrete show significant improvement with inclusion of waste LCD glass powder in concrete. 5% replacement of cement by waste LCD glass powder is considered as the optimal replacement level with respect to the strength studies. The compressive strength of 5% replacement is obtained as 20%, 28% and 36% higher than control specimen after 7 days, 28 days and 56 days respectively with regard to chloride ion penetration and sorptivity of concrete, 5% substitution of cement shows optimal results while 20% of partial replacement with LCD glass powder gives the better results on sulphate resistance and acid attack. In concrete, replacement of cement with pozzolanic materials such as waste LCD glass powder may be a viable option in mitigating environmental pollution through a reduction in cement consumption as well as by accommodating solid waste.

Thermal energy converters based on granular silicon

The use of granular silicon (GS) makes it possible to create a system like “electronic crystal-phonon glass” and reduce the cost of materials. With GS from silicon slurry, it is possible to obtain values of the Zeebeck coefficient of ∼500 μV/deg and to reduce the thermal conductivity by 7-9 times as compared to single-crystal silicon. The GS high conductivity is proposed to be achieved by resonant tunneling of current carriers through a nanosized SiO2 layer covering the GS particles.

Ionization waves in the PK-4 direct current neon discharge

The PK-4 system is a micro-gravity dusty plasma experiment currently in operation on-board the International Space Station. The experiment utilizes a long DC discharge in neon or argon gases. We apply our 2D particle-in-cell with Monte Carlo collisions discharge simulation to compute local plasma parameters that serve as input data for future dust dynamics models. The simulation includes electrons, Ne+ ions, and Ne m metastable atoms in neon gas and their collisions at solid surfaces including secondary electron emission and glass wall charging. On the time scale of the on-board optical imaging, the positive column appears stable and homogeneous. On the other hand, our simulations show that on microsecond time scales the positive column is highly inhomogeneous: ionization waves with phase velocities in the range between 500 m s−1 and 1200 m s−1 dominate the structure. In these waves, the electric field and charged particle densities can reach amplitudes up to 10 times of their average value. Our experiments on ground-based PK-4 replica systems fully support the numerical findings. In the experiment, the direction of the DC current can be alternated, which has been found to favor dust particle chain formation. We discuss possible mechanisms for how the highly oscillatory plasma environment contributes to the dust particle chain formation.

Low Temperature Sealing Process and Properties of Kovar Alloy to DM305 Electronic Glass

The low temperature sealing of Kovar alloy to DM305 electronic glass was realized by using lead-free glass solder of the Bi2O3-ZnO-B2O3 system in atmospheric environment. The sealing process was optimized by pre-oxidation of Kovar alloy and low temperature founding of flake glass solder. The effects of sealing temperature and holding time on the properties of sealing joint were studied by means of X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), etc. The results showed that the pre-oxidized Kovar alloy and DM305 electronic glass were successfully sealed with flake glass solder at the sealing temperature of 500 °C for 20 min. Meanwhile, the joint interface had no pores, cracks, and other defects, the shear strength was 12.24 MPa, and the leakage rate of air tightness was 8 × 10−9 Pa·m3/s. During the sealing process, element Bi in glass solder diffused into the oxide layer of Kovar alloy and DM305 electronic glass about 1 μm, respectively.

Tradisi Ruwatan Wayang Bagi Umat Hindu Jawa

<p>The existence of wayang for Javanese society is something that has become a cultural tradition. The existence of the Wayang Tradition is evidenced by the continued emergence of dalang who perform wayang in certain areas with progressive artistic creativity. Wayang is a performance culture that is used as a medium or a means of transferring a particular science as well as entertainment. In the end, the function of wayang shows<br />evolved from media guidance, spectacle, information delivery tools, to the promotion of certain products such as those that often appear on electronic glass screen media.<br />The existence of Wayang Kulit is a Javanese traditional art in particular, which is closely related to the levels of human life or the life cycle. Humans in their lives will be bound by the norms or value systems adopted by their society. The norms that are still valid in Javanese society include the Ruwatan ceremony which contains elements of salvation or cleansing humans from existing sin and calamity. Some people belonging to sukerta<br />(dirty, sin) according to Javanese people’s beliefs must be meruwat. Because if it is not diruwat it will become prey to Batara Kala. Then through Ruwatan by performing the wayang show Murwakala story and reading the Ruwatan mantras the Javanese people believe they will not be afraid and unlucky in their future lives.</p>

Gafas electrónicas con sensores ultrasónicos para personas no videntes

El objetivo de esta investigación fue desarrollar un prototipo tecnológico de gafas electrónicas que le permite a las personas no videntes a movilizarse en el entorno que los rodea, el cual les evita accidentes. La importancia de este proyecto consta en darles una calidad de vida a las personas no videntes, con el cumplimiento de los objetivos planteado se desarrolló este estratégico prototipo, en el que se detalla las funciones y característica técnicas de los diferentes componentes electrónicos que se utilizaron. Se realizó un análisis de la movilidad de las personas no videntes al momento de desplazarse de un lugar a otro, en el cual se detectaron dificultades que no les permitieron la movilidad. Se utilizaron métodos de investigación científica como, Historio-lógico, inducción-deducción, encuestas, observación y estadístico –matemático, permitieron las pautas necesarias para el proceso del estudio y el desarrollo de unas series de preguntas que se basa en encuestas y entrevistas que son primordiales para la validación de la investigación. Los resultados manifestaron los cambios significativos que se producen en la vida de las personas no videntes al utilizar las gafas electrónicas que responden a sus necesidades y disminuye los accidentes por los diferentes obstáculos, les brinda confianza para desplazarse independientemente, lo que los motiva a utilizarlas diariamente. Se concluyó con la implementación de un prototipo de gafas electrónicas con el sistema de comunicación electrónico, permite detectar obstáculos que provocan accidentes, de esta forma el usuario tiene confianza y comodidad.

Electron glass effects in amorphous NbSi films

We report on non equilibrium field effect in insulating amorphous NbSi thin films having different Nb contents and thicknesses. The hallmark of an electron glass, namely the logarithmic growth of a memory dip in conductance versus gate voltage curves, is observed in all the films after a cooling from room temperature to 4.2~K. A very rich phenomenology is demonstrated. While the memory dip width is found to strongly vary with the film parameters, as was also observed in amorphous indium oxide films, screening lengths and temperature dependence of the dynamics are closer to what is observed in granular Al films. Our results demonstrate that the differentiation between continuous and discontinuous systems is not relevant to understand the discrepancies reported between various systems in the electron glass features. We suggest instead that they are not of fundamental nature and stem from differences in the protocols used and in the electrical inhomogeneity length scales within each material.