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Internal strain is considered to be related to the dielectric loss of tungsten bronze structural ceramics, while its effects often cannot be effectively distinguished from non‐intrinsic factors. To quantitatively determine the influential mechanism of dielectric loss by internal strain, B‐site controllable co‐substituted (Al3+, Ga3+, and Sc3+) Ba4Nd9.33Ti18O54 ceramics with single phase were designed and synthesized, and the ratio is designed with the equivalent radius of substituted ions is equal to Ti4+. Through calibrating the global instability index, the relatively straightforward relationship between internal strain and Q×f value is established. As a result, a loss gradient (Q×f value from 8468 to 14311 GHz) and an almost stable real part of permittivity (εr ∼ 68 with near‐zero τf) can be obtained. Not only does it provide direct evidence for the effectiveness of internal strain control on dielectric loss, but also decouples three key parameters of microwave dielectric ceramics, which may be of great significance in future device physics, especially for all‐ceramic non‐Hermitian devices. [ABSTRACT FROM AUTHOR]

Tri‐layer ZnZrNb1.99(Sn0.5W0.5)0.01O8–TiO2–ZnZrNb1.99(Sn0.5W0.5)0.01O8 and random distribution ZnZrNb1.99(Sn0.5W0.5)0.01O8@TiO2 ceramics with different mass fractions of TiO2 were initially synthesized. The effects of the laminated cofiring and the random distribution processes on the crystal structure and microwave dielectric properties of the composite ceramics were investigated. The advantages of the unique tri‐layer architecture were fully demonstrated. It not only allows the effects of the chemical reactions between ZnZrNb1.99(Sn0.5W0.5)0.01O8 and TiO2 can be effectively limited to a narrow region (∼20 μm in width) within the ZnZrNb1.99(Sn0.5W0.5)0.01O8/TiO2 interfaces, and acts as the "glues" to bond each layer well. The layers are well connected and the possibility of deterioration of Q× f values during the modification process can be greatly reduced. When compared with ZnZrNb1.99(Sn0.5W0.5)0.01O8@TiO2 ceramics with random distribution type, the tri‐layer design can produce a roughly 60% improvement in Q× f value with no noticeable loss in dielectric constant while maintaining temperature stability. After sintering at 1340°C for 6 h, ZnZrNb1.99(Sn0.5W0.5)0.01O8–TiO2–ZnZrNb1.99(Sn0.5W0.5)0.01O8 tri‐layer ceramics exhibited excellent dielectric properties (εr = 30.29, Q× f = 56,880 GHz, and τf = −5.73 ppm/°C) with 0.05 wt% TiO2, and the cooperative optimization of microwave dielectric properties was achieved. The current research provides a strategy for synthesizing microwave dielectric devices with high dielectric properties for applications in 5G network communications. [ABSTRACT FROM AUTHOR]

Tri‐layered structural Zn0.997Cu0.003ZrNb2O8–TiO2+ZnO/TiO2+CuO/TiO2–Zn0.997Cu0.003ZrNb2O8 ceramics with different mass fractions of TiO2+ZnO/TiO2+CuO/TiO2 were successfully prepared. The advantages of the multilayered design were completely demonstrated, and the microwave dielectric characteristics were modified by the components of each dielectric layer. In comparison to the random distribution‐type, Zn0.997Cu0.003ZrNb2O8@TiO2+ZnO, this tri‐layered construction could increase the Q ×$ \times {\rm{\;}}$f value by approximately 100%. Meanwhile, based on the electronic compensation mechanisms, the Q ×$ \times {\rm{\;}}$f value of the tri‐layered structural ceramics with TiO2‐doped interlayer can be increased by nearly 20% compared with that of the pure TiO2 interlayer. The Zn0.997Cu0.003ZrNb2O8–TiO2+ZnO–Zn0.997Cu0.003ZrNb2O8 tri‐layered ceramic exhibited excellent dielectric characteristics (εr${\varepsilon _r}$ = 33.75, Q × f = 59 000 GHz, and τf${\tau _f}$ = +2.27 ppm/°C) with 0.05 wt% TiO2+ZnO sintered at 1240°C for 6 h, and the integrated optimization of microwave dielectric characteristics was achieved. This article provides a strategy for the synthesis of high‐performance microwave dielectric components for application in 5G/6G wireless communication technologies. [ABSTRACT FROM AUTHOR]

The ZnZrNb2O8 + x wt% LiF, MgF2, CuO (0.00 ≤ x ≤ 0.10), and Zn1−xCuxZrNb2O8 (0.000 ≤ x ≤ 0.050) ceramics were synthesized through solid‐state reaction. Compared with pure ZnZrNb2O8 ceramic, the quality factor and microstructure densification of the specimens with the addition of trace additives were significantly improved. When CuO was utilized as a sintering additive, εr${\varepsilon _r}$ is mostly impacted by relative density, whereas Q×$ \times \;$f value is primarily influenced by grain size. When CuO was employed as a dopant, εr${\varepsilon _r}$ is strongly connected to the dielectric polarizability and lattice vibration, Q×$ \times \;$f value is driven mostly by chemical bond covalency, and τf${\tau _f}$ value is primarily dictated by variations in Nb–O bond energy and bond valence. Notably, the ceramics demonstrated excellent characteristics (εr${\varepsilon _r}$ = 27.404, Q×$ \times \;$f = 74 213 GHz, τf${\tau _f}$ = −52.779 ppm/°C, ZnZrNb2O8 + 0.06 wt% CuO; εr${\varepsilon _r}\;$= 27.448, Q×$\; \times $ f = 72 520 GHz, τf${\tau _f}\;$= −53.143 ppm/°C,Zn0.997Cu0.003ZrNb2O8), and these make them promising for use in fifth generation communications. [ABSTRACT FROM AUTHOR]

Recently, the progress of miniaturization and integration for dielectric communication devices is being motivated by the rapidly‐developed communication technology. Microwave dielectric ceramics, the foundation of dielectric communication devices, have been receiving great attention. In this study, 0.91MgTiO3‐0.09(Ca0.8Na0.1Ce0.1)TiO3 ceramic (0.91MT‐0.09CNCT) was synthesized by the traditional solid‐phase process to tune the temperature coefficient of resonant frequency (τf) to zero. Compared with 0.95MgTiO3–0.05CaTiO3 ceramic, a Q×f value increased by 15 % was achieved in 0.91MT‐0.09CNCT ceramic, meanwhile, the sintering temperature of which was significantly lowered by 225 °C. In general, the τf value is related to the (Ca0.8Na0.1Ce0.1)TiO3 content and sintering temperature. At the same time, the 0.91MT‐0.09CNCT ceramic sintered at 1175 °C has competitive dielectric properties: ϵr=20.4, Q×f=66,000 GHz, τf=0.2 ppm/°C, which suggests it a promising candidate for dielectric communication devices with low cost and green synthesis. [ABSTRACT FROM AUTHOR]

As a donor and acceptor separately, Nb5+ and Al3+ are used to substitute Ti4+ in the ixiolite ZnTiNb2O8 system for the first time. The dielectric responses in the terahertz range of this system are initially studied based on the data from terahertz time‐domain transmitted spectroscopy. Combined with ligand field theory, the formation of a secondary phase of ZnAl2O4 is reasonably explicated. Then, the origins of the lower dielectric loss and the terahertz wave absorption coefficient are determined to be the high chemical bond covalency and effective phase control. For the composition of ZnTi0.85(Al0.5Nb0.5)0.15Nb2O8 sintered at 1180°C, a low dielectric loss (<5 × 10−3 @ 0.5 THz) and absorption coefficient (<10/cm @ 0.5 THz) are obtained, which make this kind of material propitious for developing terahertz dielectric devices. [ABSTRACT FROM AUTHOR]

Abstract: In order to solve the problems of acceptor/donor individual doping in Li2TiO3 system and clarify the superiority mechanism of co‐doping for improving the Q value, Mg + Nb co‐doped Li2TiO3 have been designed and sintered at a medium temperature of 1260°C. The effects of each Mg/Nb ion on structure, morphology, grain‐boundary resistance and microwave dielectric properties are investigated. The substitution of (Mg1/3Nb2/3)4+ inhibits not only the diffusion of Li+ and reduction in Ti4+, but also the formation of microcracks in ceramics, which promotes the enhancement of Q value. The experiments reveal that Q × f value of Li2TiO3 ceramics co‐doped with magnesium and niobium is 113 774 GHz (at 8.573 GHz), which is increased by 113% compared with the pure Li2TiO3 ceramics. And the co‐doped ceramics have an appropriate dielectric constant of 19.01 and a near‐zero resonance frequency temperature coefficient of 13.38 ppm/°C. These results offer a scientific basis for co‐doping in Li2TiO3 system, and the outstanding performance of (Mg + Nb) co‐doped ceramics provides a solid foundation for widespread applications of microwave substrates, resonators, filters and patch antennas in modern wireless communication equipments. [ABSTRACT FROM AUTHOR]

This paper studies the development of hybrid thin‐film transistors in recent years based on patents and articles from companies in the display field. Including the comparison of the design concept of the hybrid thin‐film transistor by Apple and LG, and the improvement of the possible problems raised by the company. Finally, the application prospects and development trends of hybrid thin‐film transistors are analyzed. [ABSTRACT FROM AUTHOR]

Abstract: Al/Nb co‐doped SrTiO3 microwave ceramics with the composition of SrTi1–x(Al0.5Nb0.5)xO3 (x = 0.03, 0.05, 0.1, and 0.15) have been synthesized via a standard solid‐state reaction method. The substitution of (Al0.5Nb0.5)4+ in B‐site inhibits the reduction in Ti4+ ions and the growth of grain size, then the transport of mobile charge carriers is limited, and thus the Q value is improved. For the SrTi0.9(Al0.5Nb0.5)0.1O3 ceramics, in addition to their high dielectric constant (εr ~185), they exhibit correspondingly a high Qf value (~ 9077 GHz) at 2.9 GHz, making the microwave ceramics suitable for myriad device miniaturization and high‐performance wireless communication. [ABSTRACT FROM AUTHOR]

Tungsten-doped SnO2 (WTO) thin films with a given thickness of about 300 nm have been prepared by magnetron sputtering with a substrate temperature in the range 400°C-700°C. The effects of substrate temperature on the structural, optical, and electrical properties and of WTO thin films have been investigated. A texture transition from (1 1 0) to (2 1 1) crystallographic orientations has experimentally been found by X-ray diffraction measurements as substrate temperature is raised. It was found that all thin films showed smooth surface with no cracks and high transparency (>85%) with the optical band gap ranging from 4.22 to 4.32 eV. The mobility varied from 12.89 to 22.48 cm2·(V·s)−1 without reducing the achieved high carrier concentration of about 1.6 × 1020 cm−3. Such an increase in mobility is shown to be clearly associated with the development of (2 0 0) but concurrent degradation of (1 1 0) in WTO thin films. [ABSTRACT FROM AUTHOR]

The BMN/BST multilayer and BMN-BST composite thin films have been fabricated by pulsed laser deposition on Au/TiOx/SiO2/Si substrate. The multilayer thin films comprising one, two, and four periodic compositional Bi1.5MgNb1.5O7/Ba0.6Sr0.4TiO3 (BMN/BST) layers (PCBLs) have been elaborated with the final same thickness. The four PCBLs show the largest dielectric constant of ~168 and tunability of 40.6% at a maximum applied bias field of 0.67 MV/cm and the lowest loss tangent of ~0.006, whereas the figure of merit (FOM) is 72. The BMN-BST composite thin films exhibit medium dielectric constant of ~238, low loss tangent of ~0.0053, and superior tunable dielectric properties at room temperature. Calculations of tunability and FOM display a maximum value of 49.3% at 670 kV/cm and ~88, respectively. [ABSTRACT FROM AUTHOR]

In recent years, electronic learning (e-learning) has become an increasingly important method in education. Under the environment of Internet of Things, it has been predicted that e-learning systems will grow at an even greater pace. Therefore, it is crucial to find a simple and effective evaluation method to assess user trust in e-learning systems. In this paper, we present an evaluation model based on user trust cloud and user capability for trusted e-learning. A user trust cloud model is proposed to assess a user's subjective trust, and a capability matrix method is introduced to assess a user's objective trust. The proposed model has been implemented for trust management in e-learning systems. Experimental results show that the proposed trust evaluation model is useful and applicable to the user trust assessment in complex e-learning systems. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

NdNbO4 ceramics with substituted Nd3+ were prepared by conventional mixed oxide route. The solid solubility limits of Sr, Ca, Mn, and Co in NdNbO4 were discussed. The generated second phases had a direct affect on the quality factors of NdNbO4 ceramic. The effects of ionic substitution on the microstructures and microwave dielectric properties based on structural characteristics of NdNbO4 ceramics were investigated systematically. The specimens presented single NdNbO4 phase that were used to explain the microwave dielectric properties of NdNbO4 based on the structural characteristics. From microscopy and phase analysis, it was determined the microwave dielectric properties were strongly dependent on structural characteristics. The dielectric constants were related to the relative density and ion polarizabilities, the temperature coefficients of the resonant frequency τƒ were effected by the octahedral structures, and the quality factors Q × ƒ was dependent on, and increased monotonically with, packing fraction. [ABSTRACT FROM AUTHOR]

Ce-doped BaTiO3-based ceramics were prepared and studied to satisfy ultra-broad temperature stability (from −55°C to 300°C, capacitance variation rate based on C20°C is within ±15%). The sample with 0.6 mol% CeO2 succeeds to achieve this performance with a remarkably high ceiling temperature of 300°C. Meanwhile, the sample has good dielectric and electrical properties at room temperature (εr = 1667, tanδ = 1.478%, ρV = 5.9 × 1012 Ω·cm). Ce ion can substitute for Ti ion as Ce4+ or Ba ion as Ce3+. The substitution decreases the spontaneous polarization of BaTiO3, and then weakens the ferroelectricity of BaTiO3. As a result, the temperature stability of samples is improved obviously. Besides, CeO2 addition promotes the formation of exaggerated grains, which are consisting of Ba6 Ti17 O40. [ABSTRACT FROM AUTHOR]

A new low-loss, low-temperature sinterable microwave dielectric material ZnTiNbTaO8 was investigated for the first time. Single phase ZnTiNbTaO8 was obtained by the conventional solid-state route and sintered at 1120°C -1200°C for 6 h. Theoretical density, packing fraction, bond valence, and oxygen octahedron distortion were calculated. The excellent microwave dielectric properties of ε = 36.3, Qf = 67 000 GHz, τf = −57.66 × 10−6/°C were obtained from the new ZnTiNbTaO8 materials sintered at 1140°C for 6 h. [ABSTRACT FROM AUTHOR]

A new low-loss, low-temperature sinterable microwave dielectric material ZnTiNbTaO8 was investigated for the first time. Single phase ZnTiNbTaO8 was obtained by the conventional solid-state route and sintered at 1120°C -1200°C for 6 h. Theoretical density, packing fraction, bond valence, and oxygen octahedron distortion were calculated. The excellent microwave dielectric properties of ε = 36.3, Qf = 67 000 GHz, τf = −57.66 × 10−6/°C were obtained from the new ZnTiNbTaO8 materials sintered at 1140°C for 6 h. [ABSTRACT FROM AUTHOR]

Electric field-induced magnetization characteristics are demonstrated in (100− x) NaNbO3 - x NiFe2 O4( x = 15, 25, 35, 45), synthesized by the solid-state sintering method. The composites show well-defined ferroelectric behaviors and magnetic characteristics. The CME effect characteristics with driving frequency in a range 10 k -15 kHz were investigated at room temperature. The CME couplings increase initially with increasing the driving frequencies and then decrease with the further increase in the frequency. Large CME coefficients are obtained at electromechanical resonance frequency of 12.8 kHz. These lead-free multiferroic composites exhibiting electrostatically induced ME resonance provide great opportunities for electric field-tunable microwave devices. [ABSTRACT FROM AUTHOR]

A low sintering temperature microwave dielectric material ZnZrNb2 O8 was reported. It exhibits a monoclinic structure, belongs to the space group P2/ c ( C2 h4), and Z = 1. The dielectric constant increased with increasing relative density. The Qf value increased with increasing packing fraction. The τf increased with increasing dielectric constant. The typical values of ZnZrNb2 O8 were ε = 30, Qf = 61 000 GHz, τ f=−52 × 10−6 °C−1, sintered at 950°C. [ABSTRACT FROM AUTHOR]

A low sintering temperature microwave dielectric material ZnZrNb2 O8 was reported. It exhibits a monoclinic structure, belongs to the space group P2/ c ( C2 h4), and Z = 1. The dielectric constant increased with increasing relative density. The Qf value increased with increasing packing fraction. The τf increased with increasing dielectric constant. The typical values of ZnZrNb2 O8 were ε = 30, Qf = 61 000 GHz, τ f=−52 × 10−6 °C−1, sintered at 950°C. [ABSTRACT FROM AUTHOR]

An ultra-broad working temperature dielectric material, BaTiO3- Na0.5 Bi0.5 TiO3- Nb2 O5- MgO-Glass with Nd2 O3 addition, was investigated for the first time. Microstructure and dielectric properties of the well-sintered samples were studied. XRD results showed the formation of tetragonal perovskite and the presence of a second phase of NaBiTi6 O14. It is found that the addition of Nd2 O3 produces a decrease in tetragonality of perovskite structure which could be interpreted by the substitution of Nd3+ ions into Ti sites. Bulk densities and dielectric properties were measured as a function of Nd2 O3 concentration. The 0.4 mol% Nd2 O3-doped sample showed the optimal dielectric performance (εr = 1445, tan δ<2.0%, Δ C/ C ≤±12%) that satisfied EIA- X9 R specification. In particular, the ceiling working temperature was significantly enhanced from 200°C to 270°C by doping Nd2 O3. Since it possesses large dielectric constant, low dielectric loss, and stable temperature character, this material shows promising applications for the ultra-broad temperature range components, e.g., multilayer ceramic capacitors. [ABSTRACT FROM AUTHOR]

A new temperature stable, low-loss, low sintering temperature microwave dielectric material Mg0.5 Zn0.5 TiNb2 O8 was investigated for the first time. Single phase Mg0.5 Zn0.5 TiNb2 O8 was obtained, and it showed Columbite structure which was tri-ixiolite structure. The variation trend of dielectric constant was in accordance with variation trend of relative density. When the sintering temperature was lower than 1120°C, the Qf value increased with the increasing of relative density. When the sintering temperature was higher than 1120°C, the Qf value decreased with the increasing of the unit cell volume. With the decrease of bond strength, the τ f increased. The typical values of ε = 30.74, Qf = 66 900 GHz, τ f = −4.01 × 10−6/°C were obtained for Mg0.5 Zn0.5 TiNb2 O8 sintered at 1120°C for 6 h. [ABSTRACT FROM AUTHOR]

A new temperature stable, low-loss, low sintering temperature microwave dielectric material Mg0.5 Zn0.5 TiNb2 O8 was investigated for the first time. Single phase Mg0.5 Zn0.5 TiNb2 O8 was obtained, and it showed Columbite structure which was tri-ixiolite structure. The variation trend of dielectric constant was in accordance with variation trend of relative density. When the sintering temperature was lower than 1120°C, the Qf value increased with the increasing of relative density. When the sintering temperature was higher than 1120°C, the Qf value decreased with the increasing of the unit cell volume. With the decrease of bond strength, the τ f increased. The typical values of ε = 30.74, Qf = 66 900 GHz, τ f = −4.01 × 10−6/°C were obtained for Mg0.5 Zn0.5 TiNb2 O8 sintered at 1120°C for 6 h. [ABSTRACT FROM AUTHOR]