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This article introduces the design theory of ceramic waveguide filter and proposes a new type of negative coupling structure with a conical through-hole, which has fine-adjustment of negative coupling without significantly increasing the insertion loss of the filter. Based on this, the article proposes an eight-cavity ceramic waveguide filter design for 5G base stations. It also presents a detailed discussion on the influence of the cross-coupling slot lengths L2 and L4 on the transmission zeros positions during the filter optimization process and the relevant change rules. For the proposed optimized filter, the observed performance indicators include the center frequency of 3.5 GHz, working bandwidth of 200 MHz, an insertion loss of ≤ 2.0 dB, return loss of ≥ 19 dB, and out-of-band near-end suppression and out-of-band far-end suppression of ≥ 39 dB and ≥ 63 dB, respectively. The test performance results obtained for the sample, with structural parameters as per the simulation model, were in good agreement with the simulation results.

Effects of two-step hot-pressing on microstructure, thermal conductivity and flexural strength of silicon carbide (SiC) ceramics were investigated. A novel combination of aluminium nitride (AlN), La2O3and LaF3was employed as sinter additives in this study. SiC ceramics prepared through both one-step (OS samples) and two-step (TS samples) hot-pressing method exhibited high relative densities. Compared with OS samples, the TS samples yielded finer microstructures with both higher thermal conductivities and flexural strengths. Impedance spectroscopy analysis was employed to reinforce the investigation on thermal conductivity variations in different samples. According to the analysis results, TS samples exhibited higher fitting grain and grain boundary resistances, which stood for a lower concentration of vacancies, indicating that two-step hot-pressing is more beneficial to the elimination of defects and improvement of thermal conductivity in SiC ceramics. On the other hand, TS samples were strengthened by a combined effect of finer microstructure and formation of SiC-AlN solid solution, thereby obtained higher flexural strengths. Hence, the present study suggests that two-step hot-pressing is more favorable to the improvement of both thermal conductivity and flexural strength of SiC ceramics with AlN-La2O3-LaF3additive combinations.

In pursuit of high thermal conductivity of SiC ceramics, this article reports the effects of AlN and sintering atmospheres on the thermal properties and microstructure evolution of SiC ceramics. Dense SiC ceramics with different contents of AlN additive were fabricated through hot-press sintering at 1950°C in Ar/N2atmosphere under a pressure of 40 MPa for 3 h. The results showed that the thermal conductivity of samples without AlN addition was 53.5 W.m−1.K−1when sintered in Ar and 50.3 W.m−1.K−1when sintered in N2. The SiC ceramics with 4 wt% AlN sintered in Ar showed abnormally large grains and exhibited the highest thermal conductivity of 121.7 W.m−1.K−1among all the samples. The sample with 2 wt% AlN sintered in N2exhibited a thermal conductivity of 108.6 W.m−1.K−1; the thermal conductivity deceased with the increasing AlN content afterwards. Such a decreasing trend of thermal conductivity was attributed to the ascending 2Hsscontent and smaller grains of ceramics. There existed an optimal content of AlN and a proper sintering atmosphere for perfecting the microstructure and the thermal conductivity of SiC ceramics.

The Zhaotong National Shale Gas Demonstration Area along the southern margin of the Sichuan Basin is located in the complex marine tectonic area of South China, where shale deformation and reformation are intense and the factors controlling sweet spots are complex, so the preservation conditions have an important impact on the enrichment of shale gas. In order to support the selection and evaluation of shale gas sweet spots in this area and improve the success rate of drilling, this paper carried out a geological survey on field outcrops. Then, based on drilling, mud logging and physical property test data, the structural deformation pattern and the regional deformation characteristics of this demonstration area were analyzed, and the development characteristics of formation joints and fractures, the sealing capacity of shale surrounding rock and the distribution characteristics of gas reservoirs were studied. Finally, the preservation conditions of shale gas in the Wufeng Formation of Upper Ordovician and the Longmaxi Formation of Lower Silurian were discussed. And the following research results were obtained. First, in the Zhaotong National Shale Gas Demonstration Area, three structural deformation patterns are developed from south to north, including trough type, equal amplitude type and baffle type, which are distributed in three major deformation zones, respectively, i.e., the shear deformation zone of Central Guizhou Uplift, the compression–torsion deformation zone of northern Yunnan–Guizhou Depression and the compression deformation zone of Southern Sichuan Depression. Second, three types of joints and fractures whose relationships with the direction of strata are high angle, middle–low angle and bedding intersection are developed in the Wufeng–Longmaxi formations and its overlying strata, and their occurrence characteristics are basically consistent with those of the three major deformation zones. Third, the shale of Wufeng–Longmaxi formations is thick in the north and thin in the south and possesses the preservation conditions of source–reservoir integration and self-sealing hydrocarbon accumulation. And combined with the sealing ability of the overburden strata and the roof and floor, its preservation conditions are overall better. Fourth, from the perspective of shale gas component, this area can be divided into three belts, i.e., methane, methane + nitrogen mixture and nitrogen from north to south. And the preservation conditions of shale gas are generally better in the north and worse in the south. In conclusion, the shale in the central–northern part of Zhaotong National Shale Gas Demonstration Area (compression deformation area and its southern margin) is the most favorable area because of its large shale thickness, weak reformation and deformation, bedding development of joints and fractures, good sealing performance and excellent preservation conditions. The compression–torsion deformation zone of northern Yunnan–Guizhou Depression in the central part is moderate in preservation conditions, and it is the relatively favorable area. The shear deformation zone of Central Guizhou Uplift in the southern part has poor preservation conditions, and it is a prospective area.

This review covers the evolution of flexible mechanical sensors from an “electronic” language to an “ionic” language, which provides key reference information for the development of next‐generation bio‐intelligent sensing devices. Unlike sensors that rely solely on electron modulation, the core feature of the ionic flexible mechanical sensor (IFMS) is the ability of mechanical deformation to induce ion transport and compensation, thus demonstrating their conceptual similarity to biomechanical strain systems. Here, the basic design principles of flexible mechanical sensors modulated by ion transport are highlighted. This review provides a detailed description of the mechanotransduction mechanisms of IFMS devices based on ion transport modulation. First, although with similar mechanisms to conventional flexible mechanical sensors via piezoresistive, piezoelectric, and triboelectric transduction mechanisms, the core driver for IFMS devices is ions (not electrons). In addition, the transduction models and principles of action of novel transduction mechanisms that have been explored in the last decade are described in detail, which include interfacial iontronic sensing and potentiometric and electrokinetic energy conversion. According to the characteristics of the device, the relevant structural engineering is further highlighted. A comprehensive review of important IFMS application approaches (human–machine interfaces, life and health applications) is presented. Importantly, future challenges and possible solutions for IFMS devices are presented based on the existing research. This review covers the development of flexible mechanical sensors from an “electronic” language to an “ionic” language. First, a detailed description of the mechanotransduction mechanisms of ionic flexible mechanical sensors (IFMSs) is provided. Further, the relevant structural engineering is highlighted. A comprehensive review of important IFMS applications is provided. Finally, future challenges and possible solutions for IFMS devices are presented.

Ba1-xZn1/3Nb2/3O3($0\leq x\leq 0.02$) ceramics were prepared by the solid-state reaction. The effects of Ba deficiency on the long-range order (LRO) of B-site ions, grain growth, and microwave dielectric properties of Ba1-xZn1/3Nb2/3O3ceramics were investigated. Results show that Ba deficiency can effectively improve the sinterability of the ceramics and reduce the densification temperature by about 100 °C. The X-ray diffraction (XRD) and Raman spectra reveal that Ba-deficient samples exhibit a higher degree of LRO, and that the samples with $x = 0.01$ exhibit the highest degree of LRO. Furthermore, the degree of LRO increases with the decrease in sintering temperature in the range of 1400--1550 °C. Good microwave dielectric properties of $\varepsilon_{\text{r}} = 39.8$, $Q \times f = 66532$ GHz, and $\tau_{\text{f}} = +23.9$ ppm/°C are obtained for the Ba-deficient samples with $x = 0.01$ when sintered at 1450 °C for 4 h. After a second sintering process at 1400 °C/10 h during cooling, the $Q \times f$ values of Ba1-xZn1/3Nb2/3O3ceramics are improved. An optimized $Q \times f$ value of 72650 GHz is obtained for the Ba0.99Zn1/3Nb2/3O3($x = 0.01$) ceramics after two-step sintering.

The effects of WO3additive on the phase transformation, microstructure, varistor properties, and capacitance--voltage ($C$--$V$) characteristics of a Bi2O3-based ZnO varistor were investigated. A series of Bi2WyO3(1+y)($0\leq y\leq 2/7$) interstitial solid solutions were formed at the ZnO grain boundary when WO3content ($x$) was in the range of 0--0.3 mol %, while the plate-like Bi2WO6phases presented for further addition. The phase transformation between Bi2WyO3(1+y)($0\leq y\leq 2/7$) solid solutions and the Bi2WO6phase at the ZnO grain boundary affects the microstructure and electrical properties of the varistor ceramic. WO3, involved in the formation of interfacial states or deep bulk traps at grain boundaries in the range of $0\leq x\leq 0.3$, provides large potential barriers to enhance the nonlinearity of a varistor ceramic. However, for $x\geq 0.7$, the present of the low resistive Bi2WO6at the ZnO grain boundary results in a lowering of potential barriers and the deterioration of nonlinearity. The varistor ceramics for $x=0.3$ mol % exhibited the best performance: voltage gradient $E_{\text{1mA}}=54.2$ V/mm, nonlinear coefficient $\alpha=36$, and leakage current $I_{\text{L}}=0.8$ \mbox{$\mu$}A, but changed to ohmic behavior for $x=1.1$ mol %.

The influences of pre-firing process and sintering temperature on the microstructure and electrical properties of ZnO-Bi2O3-TiO2-Sb2O3-MnO2-CoO low-voltage varistor ceramics were studied. Especially, twin boundaries and exaggerated grain growth (EGG) were observed here, and the mechanism of EGG was discussed. It seems that the formation of twin boundaries has a correlation with Sb2O3content and sintering temperature, and that twin boundaries have a great influence in grain growth of ZnO.

The composite electroceramics Ba(Sn,Sb)O 3 +Bi 2 O 3 were designed and fabricated. With the increasing content of Bi 2 O 3 , the resistivity and the radius shrinkage of this composite disk rapidly increased. The structure of this composite was investigated by XRD, EPA and SEM. The conductivity of this ceramic has been measured as a function of temperature. The experimental results proved that this composite ceramic is one kind of thermistor with linear negative temperature coefficient in the temperature range 0-250°C. And the resistivity at room temperature can be adjusted by monitoring the content of Bi 2 O 3 . The typical temperature coefficient of resistor was around 2.3×10/°C.

In this paper, we provided a manufacturing method for low-sintering-temperature radio frequency (RF) devices by stereolithographic (SLA) printing. The effect of ceramic powder percentage on rheological properties, curing behavior, sintering properties, microstructure, and dielectric properties was discussed. With the proportion of ceramic powder ranging from 60wt.% to 75wt.%, the viscosity of slurries declined, the sintering shrinkage rate varied from 21.61% to 15.83%, the dielectric constant raised from 5.22 to 6.64, and the dielectric loss initially reached the optimum value of 0.0024 and then deteriorated to 0.0035. The maximum solid content of slurries was 75wt.%, and the printable viscosity should be below 7.33Pa·s. At the mass ratio of 65:35, the samples sintered at 850 °C showed good properties: a density of 3.0135g·cm−3, a dielectric constant of 5.56, a low dielectric loss of 2.4 × 10−3, and τf= −32.76 ppm/°C. The printed Luneburg lens showed a gain enhancement of over 5dB, by using a 10 dBi standard gain horn antenna as a feed source. Thus, this research established a foundation for the fabrication of ceramic RF devices with high-performance, complex structures, and low sintering temperature via SLA printing.

The conductivity of BaSnO 3 ceramics have been measured at elevated temperature as a function of oxygen partial pressure. The experimental data allows us to propose that the dominant defect in BaSnO 3 is an oxygen vacancy. The effects of doping with Sb 2 O 3 on the electrical properties of BaSnO 3 have been investigated. The dependence of the resistivity value of Ba(Sn,Sb)O 3 materials on the doping content has a pronounced minimum at the molar concentration of Sb 2 O 3 about 2%. At first the introduction of Sb 2 O 3 results in a significant decrease of the resistivity of BaSnO 3 , the successive increase of Sb 2 O 3 results in the appearance of the insulator phases. This leads to the increase of the resistivity value of Ba(Sn,Sb)O 3 materials. No variation of the crystal cell parameter is observed under the doping procedure. The resistance characteristics of Ba(Sn,Sb)O 3 materials as a function of temperature show that Ba(Sn,Sb)O 3 is a kind of electroceramics with low activation energy.