Inorganic Dielectrics Research Articles

Mechanically Durable Organic/High-k Inorganic Hybrid Gate Dielectrics Enabled by Plasma-Polymerization of PTFE for Flexible Electronics.

To achieve both the synergistic advantages of outstanding flexibility in organic dielectrics and remarkable dielectric/insulating properties in inorganic dielectrics, a plasma-polymerized hafnium oxide (HfOx) hybrid (PPH-hybrid) dielectric is proposed. Using a radio-frequency magnetron cosputtering process, the high-k HfOx dielectric is plasma-polymerized with polytetrafluoroethylene (PTFE), which is a flexible, thermally stable, and hydrophobic fluoropolymer dielectric. The PPH-hybrid dielectric with a high dielectric constant of 14.17 exhibits excellent flexibility, maintaining a leakage current density of ∼10-8 A/cm2 even after repetitive bending stress (up to 10000 bending cycles with a radius of 2 mm), whereas the HfOx dielectric degrades to be leaky. To evaluate its practical applicability to flexible thin-film transistors (TFTs), the PPH-hybrid dielectric is applied to amorphous indium-gallium-zinc oxide (IGZO) TFTs as a gate dielectric. Consequently, the PPH-hybrid dielectric-based IGZO TFTs exhibit stable electrical performance under the same harsh bending cycles: a field-effect mobility of 16.99 cm2/(V s), an on/off current ratio of 1.15 × 108, a subthreshold swing of 0.35 V/dec, and a threshold voltage of 0.96 V (averaged in nine devices). Moreover, the PPH-hybrid dielectric-based IGZO TFTs exhibit a reduced I-V hysteresis and an enhanced positive bias stress stability, with the threshold voltage shift decreasing from 4.99 to 1.74 V, due to fluorine incorporation. These results demonstrate that PTFE improves both the mechanical durability and electrical stability, indicating that the PPH-hybrid dielectric is a promising candidate for high-performance and low-power flexible electronics.

Facile preparation of nano-SiO2 composites with excellent high-temperature thermal insulation performance

Inorganic thermal insulation materials can greatly reduce heat loss from high-temperature equipment, thereby supporting energy-saving technologies. Among these nano-SiO2 composites have promising application potential, which is limited by their existing preparation methods. This study aims to develop a low-cost high-performance thermal insulator. Nano-SiO2 composites were prepared by the wet impregnation of glass fibre felt with nano-SiO2 aqueous slurry and ambient pressure drying. The density of the composite linearly increased from 0.17 to 0.24 g/cm3 when the solid content of the slurry was increased from 5% to 15%. As the density of the composite increased, the thermal conductivity at 300–700 °C decreased. The introduction of SiC to the composites significantly improved their thermal insulation performance. The composite with SiC exhibited a thermal conductivity of 0.1334 W/(m·K) at 700 °C, which is better than its commercial counterpart of SiO2 aerogel felt. The rear surface temperatures of the composites at 700 °C with different pressures of 0.01–0.1 MPa were investigated to comprehensively understand the thermal insulation performances. Overall, a facile, efficient, safe, and eco-friendly preparation for nano-SiO2 composites have good prospect in the field of industrial energy saving.

Organic–Inorganic Hybrid Thermal Insulation Materials Prepared via Hydrosilylation of Polysilsesquioxane Having Hydrosilyl Groups and Triallylisocyanurate

Organic–Inorganic Hybrid Thermal Insulation Materials Prepared via Hydrosilylation of Polysilsesquioxane Having Hydrosilyl Groups and Triallylisocyanurate

Social and Economic Analysis of Project Management for Foam Glass Production Company Establishment

Currently, much attention is paid to the development of new thermal insulation materials in the production of building materials suitable for use in industrial and residential premises. Foam glass is one of the most popular inorganic thermal insulation materials. Foam glass is considered as one of the most high-quality and durable heat-insulating materials. It has a number of strength characteristics, among which are resistance to deformation, compressive strength, and resistance to environmental influences. Foam glass products are resistant to heat and aggressive chemicals, they do not undergo a combustion process, do not form smoke and do not emit toxic combustion products, and are also resistant to low temperatures. The material is easy to process, which allows you to get products of any desired shape. In this regard, this article discusses the relevance of an enterprise establishment for the production of foam glass: they performed the review of the material properties, environmental friendliness, production methods, and technologies, and analyzed the presence of competitors in the Republic of Tatarstan. The main conclusions on scheduling and social and economic analysis of the planned production are also presented. The purpose of the work is the creation of an enterprise for the production of foam glass. To achieve this goal, it is necessary to analyze the Russian market of heat-insulating materials, research the sales market and draw up a marketing plan, develop a schedule for an enterprise establishment, calculate the economic justification for the proposed production effectiveness, analyze the risks of a project for an enterprise establishment using the sensitivity analysis method.

Multistep inorganic synthesis and thermal insulation based on 3D THz phononic structure

In order to mitigate climate change, there is a need for new methods and technologies that will help reduce humankind's reliance on fossil fuels and this is something that scientists and researchers are integral to. At the National Institute for Materials Science (NIMS), Japan, Dr Norifusa Satoh is leading a project based on thermal insulation that has the potential to advance energy utilisation principles and techniques. Satoh has been interested in biological systems and how they can help in the development of improved inorganic materials. Currently, he is exploring methods of insulating heat at the same level as electricity. The key focus is 3D periodical structures matching the periodicity with the wavelength of THz phonons, quantised vibrations in thermal transport in materials over room temperature. Because the wavelength of THz phonons is less than 1 nm, to examine 3D THz phononic structures, he attempts to synthesise 3D periodical structures with atomic precision in a multistep manner based on the logic of chemical synthesis. Satoh intends to adapt previously developed methodologies to visualise the thermal resistivity of thermoelectric modules using heat sinks with a thermogram, which will enable him to test and validate his research findings. Ultimately, he hopes the fundamental understanding of THz phonons will contribute to energy savings in myriad ways and help pave the way towards a carbon-free future society.

Highly band-selective meta-surfaces exhibiting perfect near infrared absorption and concurrent visible band sensing: A numerical study

We report a highly band-selective, bifunctional meta-surface that serves as an ultra-wide perfect absorber for near-infrared (NIR) band and a visible-band sensor, based on a rational design strategy involving stacking and/or grating of metals, inorganic insulators, and stimuli-responsive materials. PNIPAAm-based hydrogel was utilized as a layer of stimuli-responsive insulator, which is allowed to reversibly swell and collapse in one dimension in response to stimuli such as ambient temperature and chemical environment to empower the sensing capability in the visible band, with the perfect absorption in NIR region intact. The average absorption reached an impressive 99.4% from 780 to 2500 nm, which is attributed to the synergy of localized surface plasmon (LSP), propagating surface plasmon (PSP), and cavity mode. The reported bi-functional meta-surface is particularly attractive for band-selective solar energy harvesting, naked-eye sensing, and adaptive imaging.

Polymeric Coating of Silica Microspheres for Biological Applications: Suppression of Non-Specific Binding and Functionalization with Biomolecules.

The use of micro- and nanoparticles in biological applications has dramatically grown during the last few decades due to the ease of protocols development and compatibility with microfluidics devices. Particles can be composed by different materials, i.e., polymers, inorganic dielectrics, and metals. Among them, silica is a suitable material for the development of biosensing applications. Depending on their final application, the surface properties of particles, including silica, are tailored by means of chemical modification or polymeric coating. The latter strategy represents a powerful tool to create a hydrophilic environment that enables the functionalization of particles with biomolecules and the further interaction with analytes. Here, the use of MCP-6, a dimethylacrylamide (DMA)-based ter-copolymer, to coat silica microspheres is presented. MCP-6 offers unprecedented ease of coating, imparting silica particles a hydrophilic coating with antifouling properties that is able to provide high-density immobilization of biological probes.

Polyaniline Based Field Effect Transistor for Humidity Sensor

In this present research work, we presented a new Bottom Gate P-Type Organic Field Effect Transistor (OFET) humidity sensor and its applicability towards humidity has been experimentally demonstrated. P-type organic semiconductor polyaniline (PANI) has been used in a variety of applications, including logic circuit components, electromagnetic shielding, chemical sensing, and anticorrosion. Humidity sensor can be used to monitor relative humidity (RH) in various environments. We only focus on the fabrication of conducting polymer OFETs with top contact to measure humidity and verify I-V properties. The current saturation (ISat) of p-type OFETs was 0.8 μA, while the threshold voltage VTh was 2.2 V. The results of FESEM have been perform to confirm that deposited thin film grown on the substrate is purely uniform. The Proposed sensor shows that organic gate dielectrics are a low-cost alternative to inorganic gate dielectrics with good electrical performance. The proposed OFET-based sensors have a number of benefits, such as high sensitivity, low cost, quick response, and physical flexibility.

Developing a hollow glass microsphere/geopolymer thermal insulation composite for hot metal surface coating

Manufacturing inorganic thermal insulation materials with superior properties such as low thermal conductivity (k < 0.1 W/mK) and high mechanical properties in terms of adhesion strength is critical for energy efficiency in energy-intense industries. Geopolymer-based composites composing of hollow glass microspheres (HGMs), waste fly ash (FA), and metakaolin (MK) were successfully applied on hot (T∼300 °C) metal surfaces via spray deposition technique. The effect of Si/Al and Na/Al mole ratios and HGM loading on geopolymer composites' physical, microstructural, thermal, and adhesion strength properties were explored. The best composite composition was obtained when Si/Al mole ratio, Na/Al mole ratio, and HGM loading were 2.5, 1.0, and 10 wt %, respectively. This composition achieved an HGM/geopolymer composite material with low thermal conductivity (k ∼ 0.05 W/mK), high adhesion strength (∼5.0 MPa), and high stability under immersion in water and vibration environments (particularly exposed to water). The results showed that HGM/geopolymer composites could be used as a thermal insulation material in energy-intense industries.

Review on properties of some thermal insulating materials providing more comfort in the building

The energy demand for buildings is rapidly increasing due to climate change and meeting sustainability due to environmental pollution are major challenges in the 21st century. The role of thermal insulation materials in the building envelope is significant. However, conventional building envelopes record a high amount of energy consumption to meet the demand for heating and cooling. There have been many researchers conducted on eco-friendly thermal insulation materials for building nevertheless very few attempts have been made a report on life cycle cost criteria but no attempt has been made concise the benefits of several thermal insulation materials to curtail heat ingress and more exclusively on thermal properties, CO2 emission, embodied energy, and safety of thermal insulating materials. In this context, this paper reviews the prior development and current findings of various thermal insulation materials to curtail heat ingress and contribution to sustainability. Thermal insulation materials include Cork, Fibreglass, Mineral wool, Cellulose, Polyurethane, Polystyrene, Rice husk, crumb rubber, sheep wool, date palm, Perlite, Phase change materials, Aerogels, Vacuum Insulation materials and Nano materials incorporated insulation materials are discussed. Among composition of organics materials, cork, fibreglass, cellulose with additives, polystyrene are potential thermal insulation materials by reducing thermal conductivity up to 30 which could curtail the heat ingress whereas inorganic compositions Vacuum insulation panels (VIP), aerogels and Nano silica (up to 3%) are the most promising insulating materials consisting of inorganic composition with low thermal conductivity. Finally, the paper also describes the limitation that fiberglass aerogel had achieved poor strength and VIPs are high cost. Finally, this comprehensive review may help researchers to acquire knowledge on all available thermal insulation materials and selection of suitable current thermal insulating materials based on the framework proposed in the paper.

Empirical Implementation of the Steinmetz Equation to Compute Eddy Current Loss in Soft Magnetic Composite Components

Finite element analysis of magnetic materials allows accurate prediction of losses and is crucial in the design of electromagnetic devices and products. Soft magnetic composites are an alternative to silicon steel laminations, yet the electromagnetic material properties are less well documented and include uncertainties which can lead to inaccurate iron and Joule loss computations. The microstructure of soft magnetic composites, which is based on ferromagnetic particles coated by inorganic resistive insulation, makes the process of iron loss prediction unique. Composite core materials require further attention by design engineers in terms of the effect of component size and pressing processes on core loss predictions, which for laminations uses the well-known Steinmetz law. This study accesses the existing soft magnetic composite core loss modelling trends using experimentally measured results. The challenges of estimating and using Steinmetz core loss coefficients via curve fitting approaches are discussed. The study indicates that soft magnetic composite components need to be treated differently to laminated iron cores. Modelling the composite materials in finite element software requires experimentally informed loss models to be able to accurately compute power losses under varying magnetic flux density and electrical frequency. An approach is suggested which can predict iron losses to within 7%, but is only validated for component cross sectional areas of 144 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> or less.

Polymer dielectric films exhibiting superior high-temperature capacitive performance by utilizing an inorganic insulation interlayer.

With the rapid development of next-generation electrical power equipment and microelectronics, there is an urgent demand for dielectric capacitor films which can work efficiently under extreme conditions. However, sharply increased electrical conduction and drastically degrading electric breakdown strength are inevitable at elevated temperatures. Herein, a facile but effective method is proposed to improve high temperature capacitive performance. We report that utilizing an inorganic insulation interlayer can significantly increase the discharge energy density with a high efficiency above 90% at 150 °C, i.e., a discharged energy density of 4.13 J cm-3 and an efficiency of >90% measured at 150 °C, which is superior to the state-of-the-art dielectric polymers. Combining the experimental results and computational simulations reveals that the remarkable improvement in energy storage performance at high temperature is attributed to the blocking effects that reduce the leakage current and maintain the breakdown strength. The proposed facile method provides great inspiration for developing polymer dielectric films with high capacitive performance under extreme environments.

Boosted dielectric performance of organic–inorganic nanocomposites based on BaTiO3 via 2D TiO2 templates

Organic–inorganic hybrid dielectrics composed of nanoscale ceramic fillers in polymer matrices have attracted considerable attention because they can overcome the inherent limitations such as the low dielectric constant, high dielectric loss, and low film density associated with mechanically flexible pristine polymer materials. Barium titanate (BaTiO3), a representative perovskite-based material with a high permittivity, is suitable for applications as nanofillers in nanocomposite dielectrics. X-ray diffraction combined with Raman analysis suggest that a two-step hydrothermal synthesis, which uses synthesized TiO2 nanosheets as a template, is an effective method for the synthesis of pure BaTiO3 nanoparticles compared with other methods. Ultrasonic treatment is employed to disperse BaTiO3 nanoparticles with different concentrations in polyvinyl alcohol (PVA) polymer, and the dielectric performance of the nanocomposite films has been examined. In this study, 20 wt% BaTiO3–PVA nanocomposite dielectric showed superior capacitance and dielectric constant performance, i.e. five times higher than that of the pristine PVA.

A facile method to prepare high-performance thermal insulation and flame retardant materials from amine-linked porous organic polymers

Developing porous functional materials with good thermal insulation and flame retardant properties is of great importance in modern eco-friendly buildings. Herein, we report the one-step synthesis of imine chain monolithic porous phosphorus-containing organic porous polymers (PPOPs) using Schiff base polycondensation reaction and as an example of efficient thermal insulation and flame retardant. Experimental results show that the PPOPs have low thermal conductivity (0.055 W·m−1·K−1) and excellent flame retardant properties. Measurements by microcalorimetry (MCC) showed a peak heat release rate (pHRR) value was 23.9 W·g−1, which is nearly an order of magnitude lower than that of most currently reported flame retardant materials. Using PPOPs in the epoxy resin (EP) matrix, the prepared EP composites exhibited excellent flame retardant properties. Cone calorimeter (CC) tests showed that the peak heat release rate (pHRR) and peak smoke release rate (pSPR) during combustion of PPOPs/EP composites were reduced by 42.0% and 36.4%, respectively, compared with pure EP. Tensile tests showed that the addition of PPOPs improved the mechanical properties of the composites to some extent. In addition, PPOPs can be designed into different shapes for practical applications compared with those fragile inorganic insulation materials and powders that were usually non-processable. Taking these advantages into account, PPOPs have great potential for modern building applications as monolithic foams or coatings with both excellent flame retardancy and thermal insulation properties.

Study on Permanent Thermal Insulation Formwork of Mass Concrete Prepared by Different Types of Nano-modified Lightweight Aggregate

Aiming at the problems of low strength, flammability, easy falling off, and aging of traditional organic thermal insulation materials, inorganic thermal insulation materials of different types of nano-modified lightweight aggregates were prepared in this paper. The feasibility of preparing permanent thermal insulation formwork of mass concrete with nano-modified lightweight aggregate was studied through experiments and calculation analysis of mechanical, durability, and thermal properties. The results show that the water absorption of shale ceramsite modified by nano-permeable hydrophobic agent is reduced to 1.21%, and the water absorption rate of inorganic precast hollow aggregate produced by nano-silica powder is lower, which is 0.79%. Inorganic precast hollow aggregate concrete, modified shale ceramsite concrete, and organic foamed aggregate concrete have the characteristics of high strength, fire resistance, aging resistance and low thermal conductivity. Inorganic precast hollow aggregate concrete and modified shale ceramsite concrete have excellent impermeability and frost resistance. Organic foamed aggregate concrete has the lowest thermal conductivity and good thermal insulation effect and its durability can be improved by surface protection technology. According to the principle of equivalent surface heat release coefficient, it is feasible to use lightweight aggregate precast formwork as permanent insulation formwork of mass concrete with thickness between 50 and 100 cm. The permanent thermal insulation formwork of nano-modified lightweight aggregate concrete can also be used as the formwork for concrete construction to realize the temperature control measures of tracking thermal insulation and slow cooling of mass concrete, reduce the risk of cracking, and improve the construction efficiency.

Hysteretic load behavior of pre‐casted reinforced concrete shear wall systems with high thermal resistance capability

ABSTRACTIt is essential to determine the thermal conductivity and earthquake performances by developing earthquake‐resistant building systems that have high thermal insulation properties that will be economical for people considering the need for energy deficit and low‐cost earthquake‐resistant residences in the world. This study aims to evaluate the seismic performance of pre‐casted reinforced concrete shear wall systems with double layer high thermal resistance capability and compare to standard monolithic reinforced concrete shear wall systems with non‐high thermal resistance capability. The coating material used for thermal insulation was developed as an inorganic, economical, easily applicable, high‐fire resistance capable and not to cause the problems observed in the currently used products. In the research, new generation methods were used to reduce the unit weight of cement binder inorganic insulation material to low levels and provide high thermal resistance features. The seismic performance tests of the new double insulation layer, pre‐casted reinforced concrete shear wall system were realized. The seismic performance of conventional reinforced concrete shear walls was compared with the developed system by testing lateral reversed cyclic loading that simulates the earthquake.

Control of superexchange interactions with DC electric fields

We discuss DC electric-field controls of superexchange interactions. We first present generic results about antiferromagnetic and ferromagnetic superexchange interactions valid in a broad class of Mott insulators, where we also estimate typical field strength to observe DC electric-field effects: $\sim 1~\mathrm{MV/cm}$ for inorganic Mott insulators such as transition-metal oxides and $\sim 0.1~\mathrm{MV/cm}$ for organic ones. Next, we apply these results to geometrically frustrated quantum spin systems. Our theory widely applies to (quasi-)two-dimensional and thin-film systems and one-dimensional quantum spin systems on various lattices such as square, honeycomb, triangular, and kagome ones. In this paper, we give our attention to those on the square lattice and on the chain. For the square lattice, we show that DC electric fields can control a ratio of the nearest-neighbor and next-nearest-neighbor exchange interactions. In some realistic cases, DC electric fields make the two next-nearest-neighbor interactions nonequivalent and eventually turns the square-lattice quantum spin system into a deformed triangular-lattice one. For the chain, DC electric fields can induce singlet-dimer and Haldane-dimer orders. We show that the DC electric-field-induced spin gap $\propto |\boldsymbol E|^{2/3}$ in the Heisenberg antiferromagnetic chain will reach $\sim 10~\%$ of the dominant superexchange interaction in the case of a spin-chain compound $\mathrm{KCuMoO_4(OH)}$ when the DC electric field of $\sim 1~\mathrm{MV/cm}$ is applied.

Ultra-flexible high-k transparent integratable fully-carbon-based capacitor arrays for sharp-switching transistors

Investigating dielectric layer is one of the keys in realizing flexible transistors, which propose higher requirements and more challenges on electrical performance, mechanical flexibility, and integrability of the dielectric. The previously reported researches mainly focused on inorganic rigid dielectrics or organic intrinsically-flexible dielectrics could not meet the requirements effectively and efficiently. In this work, we propose a sandwich-like carbon nanotubes/graphene oxide/carbon nanotubes design, which is applicable to both passive and active devices. Adopting this design, we realize integratable fully-carbon-based ultra-flexible and transparent capacitor arrays (FC-UFT-CAs) for both metal-insulator-metal (MIM) and metal-insulator-semiconductor (MIS) types. The MIM FC-UFT-CA exhibits competitive dielectric performance with high permittivity of 8.5 and high capacitance density of 250 nF cm−2. Significantly, the capacitance shows almost no degradation even after the bending radius is reduced to as small as 250 μm. And it keeps showing excellent electrical and mechanical properties after 10,000 bending cycles under a radius of 1 mm. Based on the MIS FC-UFT-CA, fully-carbon-based transistors are realized, which show sharp-switching characteristic with an ultra-small subthreshold swing of 88 mV dec−1. Overall, the proposed design and the fully-carbon-based devices provide a novel solution and show a great potential for further advancing flexible electronics.

Toward miniaturizing microelectronics using covalent organic framework dielectric

Toward miniaturizing microelectronics using covalent organic framework dielectric

An inorganic thermal insulation material with good performance prepared from obsidian

Both obsidian and perlite belong to acid volcanic rock and have a similar structure and chemical composition, but the insulation material prepared from expanded obsidian cannot reach the performance level of that prepared from expanded perlite. To date, obsidian cannot be used in large quantities, although its resource is abundant. In order to comprehensively utilise this resource, in the present work the authors developed a new type of lightweight thermal insulation material by using obsidian as a main raw material which is energy-efficient and environmentally friendly. The effects of raw materials such as obsidian, sodium silicate, hydrogen peroxide and cetyltrimethylammonium bromide on physical properties including thermal conductivity, porosity, density and compressive strength were studied in detail. The optimised thermal insulation material exhibits low thermal conductivity (0.051–0.86 W m−1 K−1), low density (0.1–0.24 g/cm3) and adjustable compressive strength (0.09–1.52 MPa). Compared to other inorganic insulation materials, this new thermal insulation material is very light and has a better thermal insulation performance. Therefore, this work proposes a new energy-efficient way to prepare a promising noncombustible thermal insulation material, and also provides a way to use obsidian resources in large quantities.