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Using first principles calculations, we have confirmed the electronic and optical properties of 2D kagomes graphene doped with IVA elements (Si, Ge, Sn, Pb). The results show that Si-doped system has higher structural stability. The doping system increases the band gap of single-layer kagomes graphene, with Sn doping system being the most pronounced, and therefore can be considered as an attractive material for optoelectronic devices. The difference charge density and bonding population verify that the covalence of doping atoms and C atoms decreases, and that the degree of covalence diminution increases with increasing atomic number. The undoped kagomes graphene exhibits a strong light absorption capacity in the ultraviolet region, and the absorption peaks value decreases after doping, indicating that the element doping has a great weakening effect on the light absorption capacity, which has a certain potential significance for this material to be used as the antireflection film and wave permeable material of solar cells. In addition, the Pb and Sn-doped models possess the highest and lowest static dielectric constants, respectively. The peak value of electron energy loss is lower in the range of ultraviolet and visible wavelengths. These characteristics demonstrate that kagomes graphene offers substantial potential in the areas of optoelectronic and microelectronic devices. [ABSTRACT FROM AUTHOR]

The lack of systematic research on the phase structure, defect structure, and polarization mechanism hinders the full comprehension of the colossal permittivity (CP) behavior for SrTiO 3 -based ceramics. For this purpose, Ta-doped SrTiO 3 -based ceramics were synthesized in an N 2 atmosphere with a traditional method. When the appropriate amount of Ta was doped, colossal permittivity (ԑ r ∼ 62505), low dielectric loss (tanδ ∼ 0.07), as well as excellent temperature stability (−70 °C–180 °C, ΔC/C 25°C ≤ ±15%) were obtained in the Sr 0.996 Ta 0.004 TiO 3 ceramic. The relationship between Ta doping, polarization mechanism, and dielectric performance was systematically researched according to experimental analysis and theoretical calculations. The first-principle calculations indicate that the Ta5+ ion prefers to replace the Sr-site. The defect dipoles and oxygen vacancies formed by heterogeneous-ion doping play an active role in regulating the dielectric performance of ceramics. In addition, the interface barrier layer capacitance (IBLC) effect associated with semi-conductive grains and insulating grain boundaries is the primary origin of colossal permittivity for Sr 1-x Ta x TiO 3 ceramics. The polarization mechanism and defect structure proposed in the study can be extended to the research of SrTiO 3 CP ceramics. The results have a good development prospect in colossal permittivity (CP) materials. [ABSTRACT FROM AUTHOR]

Background: To assess the prevalence, risk factors, clinical characteristics of Acute fatty liver of pregnancy (AFLP) patients, and outcomes of AFLP patients treated with plasma exchange (PE). Methods: We retrospectively reviewed the AFLP patients admitted to the First Affiliated Hospital of Xi'an Jiaotong University and Xijing Hospital of Air Force Medical University from January 2012 to May 2022. Final prediction model for death among AFLP by means of stepwise backward elimination with p value < 0.05. Patients treated with and without PE were compared by propensity-matched cohort study. Results: Two hundred ninety eight patients with the diagnosis of AFLP, and finally 290 patients were enrolled in the cohort study, 50 of whom (17.2%) were dead. Compared with AFLP patients alive, the dead of patients were more likely to be combined encephalopathy (p < 0.01), postpartum hemorrhage (p < 0.01), and found significantly higher frequency of fetal distress (p = 0.04), fetal death (p < 0.01). we developed a predicted probability value and with an area under the receiver operating characteristics (ROC) curve of 0.94 (95%CI 0.87 to 1.00), indicating AFLP patients' death. The patients treated with PE had a significantly lower 60-day mortality rate (OR 0.42, 95% CI 0.29 to 2.64, p = 0.04), and significantly shorter duration of hospital-free days at day 28 (p = 0.01). Conclusions: In conclusion, our study indicated that liver function were risk factors for maternal mortality, and PE was a protective factor for maternal 60-day mortality and hospital-free days at day 28 in AFLP patients. [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]

Artificial intelligence (AI) has become the core driving force for innovation and development of manufacturing enterprises. This paper selects Haier COSMOPLAT as a case study to systematically discuss the evolution process and internal mechanism of AI-enabled manufacturing enterprise innovation. First, in the start-up stage, the industrial internet platform empowers manufacturing innovation along the path of resource patchwork to platform empowerment to dependency-oriented symbiosis, promoting the cocreation of economic value between manufacturing enterprises and platforms. Next, in the growth stage, the industrial internet platform empowers manufacturing enterprise innovation along the path of resource orchestration to field empowerment to nested symbiosis, boosting the cocreation of network value between manufacturing enterprises and platforms. Finally, in the maturity stage, the industrial internet platform empowers manufacturing enterprises to innovate along the path of resource coordination to ecological empowerment to equality symbiosis, advancing the cocreation of ecological value between manufacturing enterprises and platforms. This study not only enriches AI-enabled manufacturing innovation research area but also provides beneficial management enlightenment to accelerate the intelligent transformation and upgrading of the manufacturing industry. [ABSTRACT FROM AUTHOR]

Introduction: Cervical cancer is a severe malignant tumor that endangers the health of women worldwide. Eukaryotic initiation factor-5A2 (EIF5A2) expression has been reported to be increased in cervical cancer and correlates with prognosis. An attempt was made in this paper to explore the impact and potential mechanisms of EIF5A2 in the cell biology of cervical cancer. Methods: We first knocked down EIF5A2 in cervical cancer cells. Then, we examined the proliferation, migration, invasion, and apoptosis of these cells by cell counting kit 8, wound healing, Transwell, and terminal deoxynucleotidyl transferase dUTP nick-end labeling assays. Cells were processed with different concentrations of cisplatin to observe their sensitivity to cisplatin. Next, the relationship between EIF5A2 and anterior gradient 2 (AGR2) was verified by co-immunoprecipitation. Following AGR2 overexpression, the biological processes of these cells were examined. Results: EIF5A2 knockdown inhibited cell proliferation, migration, and invasion, and it promoted apoptosis and enhanced the sensitivity to cisplatin in cervical cancer cells. Additionally, AGR2 expression was positively correlated with EIF5A2, and its overexpression alleviated the reduction in proliferation, migration, and invasion of cervical cancer cells induced by EIF5A2 knockdown. Overexpression of AGR2 also reduced apoptosis and their sensitivity to cisplatin in EIF5A2-knockdwon cervical cancer cells. Conclusion: EIF5A2 knockdown inhibited the biological process of cervical cancer cells through modulation of AGR2. The in-depth investigation of the molecular mechanism of EIF5A2 in cervical cancer cells provides new strategies for the prevention and treatment of clinical malignancies. [ABSTRACT FROM AUTHOR]

In many microwave dielectric ceramics systems, like MgTiO3–CaTiO3, MgTiO3–SrTiO3, and tri-layer MgTiO3/TiO2/MgTiO3, the resonant frequency shows a non-linear variation over a wide temperature range (−40 – 105 °C), indicating that the negative τf (−40 – 25 °C) value deviates from zero when the positive τf (25–105 °C) value is tuned to zero. To suppress the non-linear variation of resonant frequency in the range of −40 – 105 °C, a well-established and efficacious method has been proposed by introducing Li2Ti0.85(Mg1/3Nb2/3)0.15O3 ceramic to the MgTiO3 system. Furthermore, a tri-layer architecture ceramic was designed to improve the dielectric properties. Compared with randomly distributed samples, the Q × f value can be increased by up to 51%. Moreover, the electric field distribution was simulated by the finite element method with the aid of the eigenmode solver of high frequency structure simulator (HFSS) to clarify the dielectric mechanism and predict the microwave dielectric characteristics of the tri-layer structure ceramics. Finally, tri-layer Li2Ti0.85(Mg1/3Nb2/3)0.15O3/MgTiO3/Li2Ti0.85(Mg1/3Nb2/3)0.15O3 ceramic with wide temperature stability and high Q × f value was obtained [εr = 18.4, Q × f = 85 000 GHz, τf+ = −3.8 ppm/°C (25–105 °C), τf− = 4.0 ppm/°C (−40 – 25 °C)], which refines the theory of non-linear variation of resonant frequency and holds promise for application in the 5G communication system. [ABSTRACT FROM AUTHOR]

In the broad application of tunable devices, the temperature stability of the dielectric tunable performance of ceramics should be considered. In this work, (1- x)Ba(Zr 0.36 Ti 0.64)O 3 – x (Ba 0.82 Ca 0.18)TiO 3 (BZ 0.36 T– x BC 0.18 T) ceramics, where x = 0.3–0.7, were prepared by the solid-state high-temperature method. The combined effects of Ca2+ and Zr4+ ions on the microstructure of BZ 0.36 T– x BC 0.18 T ceramics were observed. The crystal structure was analyzed through X-ray diffraction, showing a pure perovskite ABO 3 -type structure, indicating the formation of a BCZT solid solution. High dielectric tunability (n r > 85% at < 10 kV/cm) under a low DC bias field is achieved in BZ 0.36 T–0.5BC 0.18 T and BZ 0.36 T–0.6BC 0.18 T, especially the maximum value of n r ∼87.51% at 7.68 kV/cm obtained for BZ 0.36 T–0.6BC 0.18 T. High tunability under a low DC bias field may be related to not only the extrinsic contribution (dipole reorientation, domain-wall motion) but also the intrinsic contribution (lattice phonon or anharmonic interactions of B-site ions). The maximum FOM value of ∼847 is achieved in BZ 0.36 T–0.5BC 0.18 T, which is related to the high n r ∼74.57% and lower tan δ ∼8.8 × 10−4 at 400 V, demonstrating its excellent performance for tunable device applications. Furthermore, the FOM – T curve of BZ 0.36 T–0.3BC 0.18 T ceramics in the range of 126–269 is flatter than other compositions in the temperature range of −20°C-100 °C, showing an improved dielectric tunable performance with better temperature stability. The improved temperature stability of BZ 0.36 T–0.3BC 0.18 T may contribute to the enhancement of the diffuse phase transition (DPT) degree, which results in a flattened phase transition region. These results suggest that BZ 0.36 T–0.3BC 0.18 T is competitive candidate for temperature-stable tunable device applications, and the compositional tailored DPT can be expected to be a feasible means to improve the temperature stability of dielectric tunable performance. [ABSTRACT FROM AUTHOR]

The low loss and small density of lithium-based microwave dielectric ceramics (MWDCs) make them promising for communication devices such as dielectric filters, antennas, and substrates. In this study, (1- x)[Li 2 Ti 0.98 Mg 0.02 O 2.96 F 0.04 −1 wt%Nb 2 O 5 ]- x Li 3 Mg 2 NbO 6 (LTMN 0.02 -LMN, 0 ≤ x ≤ 0.1) MWDCs fabricated via solid solution reaction were successfully synthesized to obtain a near-zero temperature coefficient of the resonant frequency (τ f). The X-ray diffraction pattern and Rietveld refinement results showed that a good solid solution was formed and that the phase composition of the LTMN 0.02 system gradually changed from monoclinic to cubic. Scanning electron microscopy images revealed that the microstructure of LTMN 0.02 improved as the LMN content increased. Ultimately, desirable dielectric properties were obtained by sintering at 1220 °C with x = 0.08: ε r ∼18.1, Q × f ∼105,661 GHz, and τ f ∼ + 1.3 ppm/°C. Furthermore, the highest Q × f value (∼131,157 GHz) was achieved in the x = 0.04 composition with relatively homogeneous grains. The high-performance LTMN 0.02 -LMN ceramics developed in this study provide a new alternative material for the dielectric components of communication systems. [ABSTRACT FROM AUTHOR]

Due to the scarcity of indium (In) in the earth and its potential harm to individuals, the development of In-free transparent conductive film is considered crucial. In this work, In-free SnO 2 :Sb/Au/SnO 2 :Sb (ATO/Au/ATO, SAS) tri-layer films with high transparency and conductivity were successfully prepared on polycarbonate (PC) substrates by RF and DC magnetron sputtering at room temperature. The influence of the Au layer thickness on microstructure, electrical and optical performances was systematically studied after fixing the ATO thickness to 50 nm. It was indicated by X-ray diffraction patterns that ATO is amorphous and Au is oriented along (111). The trend of increasing and then decreasing light transmission with Au layer thickness was observed in both experimental and simulation results. The improved figure of merit (FoM, 1.89 × 10−2 Ω−1) was achieved in SAS tri-layer film, the resistivity and average transmittance of which was lowered to 7.50 × 10−5 Ω cm and 81.4%, respectively, when Au layer thickness is 11 nm. Moreover, the mechanism of the variation of optical and electrical properties at different Au layer thickness was proposed. Particularly, the SAS tri-layer films also exhibit superior flexibility, durability and adhesion. These results demonstrate SAS tri-layer films are promising alternative to ITO in flexible electronics applications. [ABSTRACT FROM AUTHOR]

Strain and stress play an important role in functional materials, but they are often neglected in electroceramics. Here we report the stress effect on microwave dielectric loss in rutile-related (Ti 0.6 Zr 0.4) 0.8 (Zn 1/3 Nb 2/3) 0.2 O 2 solid solutions. The macroscopic, microscopic and nano-scale residual stresses have been systematically investigated, including their relationships. The average Raman spectra have demonstrated considerable macro-residual stresses, especially for the heavily cracked sample. The high-resolution Raman images reveal the inhomogeneity of residual stress distribution at the grain-level, which is reflected by the shifts of Raman-active modes. The high-resolution transmission electron microscope (HRTEM) images and geometric phase analysis (GPA) analysis show the aggregation of dislocations and resulting distortion of crystal. It can be found that the dielectric loss depends strongly on residual stresses, that samples with greater residual stress exhibit much higher dielectric loss because the residual stress increases the vibration anharmonicity of the lattice. [ABSTRACT FROM AUTHOR]

MgNb 2-x V x/2 O 6-1.25x (0.1≤x≤0.6) ceramics with orthorhombic columbite structures were prepared at low-temperature by a solid-phase process. The phase component, microscopic morphology, low-temperature sintering mechanism and microwave dielectric performance of MgNb 2-x V x/2 O 6-1.25x ceramics were comprehensively investigated. Low-temperature sintering densification of dielectric ceramics was achieved via the nonstoichiometric substitution of vanadium (V) at the Nb-site. In contrast to pure MgNb 2 O 6 ceramics, the sintering temperature of MgNb 2-x V x/2 O 6-1.25x (x = 0.2) ceramics was reduced by nearly 300 °C owing to the liquid-phase assisted sintering mechanism. The liquid phase arises from the autogenous low-melting-point phase. Meanwhile, MgNb 2-x V x/2 O 6-1.25x (x = 0.2) samples with nonstoichiometric substitution could achieve a more than 900% improvement in the Q × f value, compared with stoichiometrically MgNb 2-x V x O 6 (x = 0.1, 0.2) ceramics. Finally, MgNb 2-x V x/2 O 6-1.25x dielectric ceramics possess outstanding microwave dielectric properties: ε r = 20.5, Q × f = 91000, and τ f = -65 ppm/°C when sintered at 1030 °C for x = 0.2, which provides an alternative material for LTCC technology and an effective approach for low-temperature sintering of Nb-based microwave dielectric ceramics. [ABSTRACT FROM AUTHOR]

Objective. To explore the effects of Xiaoyutang combined with intraperitoneal heat perfusion chemotherapy on immune function, circulating Mir, and prognosis and survival of postoperative patients with colorectal cancer. Methods. A total of 96 patients with colorectal cancer who were treated in our hospital from May 2018 to August 2019 and followed up to August 2021 were selected as the study subjects. The patients were randomly divided into a control group and study group by a 1 : 1 random number table method, 48 cases in each group. Patients in the control group were given intraperitoneal thermal perfusion chemotherapy after surgery, and patients in the research group were treated with Xiaoyutang on this basis. The treatment cycle was 21 days, and all patients were treated for 3 consecutive cycles. The therapeutic efficacy, immune function (CD3+, CD4+, and CD4+/CD8+), circulating mir (mir-29a, mir-145, and mir-92a), prognosis, and survival of the two groups were compared. Results. After 3 cycles of treatment, ORR and DCR in the study group were higher than those in the control group (60.42% vs. 37.50%) and 85.42% vs. 66.67%, respectively, with statistical significance (P < 0.05). There were statistically significant differences in CD3+, CD4+, CD4+/CD8+, mir-29a, mir-145, and mir-92a time points and intergroup and intergroup interactions between the two groups (P < 0.05); the levels of CD3+, CD4+, and CD4+/CD8+ in the study group were higher than those in the control group after 1, 2, and 3 cycles of treatment (P < 0.05); the expressions of mir-29a, mir-145, and mir-92a were significantly lower than those in the control group (P < 0.05). By the end of follow-up, 3 cases were lost to follow-up in the study group and 5 cases in the control group. The recurrence rate and mortality of the study group were lower than those of the control group at 1- and 2-year follow-up (P > 0.05), and the mean survival time of patients in the study group was higher than that in the control group; the differences were statistically significant ( χ 2 = 5.151 , P = 0.023). Conclusion. Xiaoyutang combined with peritoneal heat perfusion chemotherapy has a good postoperative effect on patients with colorectal cancer, which can effectively improve the immune function and circulating Mir of patients with colorectal cancer, reduce tumor recurrence, and improve the prognosis of patients. [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]

Based on the relationship of dipole formation and charge compensation, we prepared BaTiO 3 -based (x %MnO 2 -0.05%Nb 2 O 5 –BaTiO 3 , x %Mn–Nb-BT) ceramics using a solid-phase reaction in air and a reducing atmosphere. The influences of MnO 2 doping and sintering atmospheres on crystal structure, charge compensation and dielectric properties were comprehensively studied. The ion substitution mechanism, solid solubility, and crystallinity of x %Mn–Nb-BT ceramics in different atmospheres were resolved by X-ray diffraction (XRD) and electron paramagnetic resonance (EPR) spectroscopy. X-ray photoelectron spectroscopy (XPS) showed that the percentages of oxygen vacancy and Ti3+ in this system were both affected by MnO 2 doping and the atmosphere due to the reducibility of Mn4+ and the reducing atmosphere. Thus, the influence of doped MnO 2 and the atmosphere on dipole formation and charge compensation was deeply discussed. These results provide further insight into the important role of MnO 2 in improving the anti-reduction performance of BT-based ceramics. [ABSTRACT FROM AUTHOR]

In next-generation mobile and wireless communication systems, low sintering temperature and excellent dielectric properties are synergistic objectives in the application of dielectric resonators/filters. In this work, Li 2 Ti 0·98 Mg 0·02 O 2·96 F 0.04 –1 wt% Nb 2 O 5 (LTMN) ceramics were fabricated, and their sintering temperature was successfully lowered from 1120 °C to 750 °C by adjusting the mass ratio of B 2 O 3 –CuO (BC) additive. The optimum dielectric properties (ԑ r ~ 24.44, Q × f ~ 60,574 GHz and τ f ~ 22.8 ppm/°C) were obtained in BC-modified LTMN ceramics sintered at 790 °C. Even if their sintering temperature was lowered to 750 °C, the lowest temperature among the Li 2 TiO 3 -based dielectric ceramics currently used for LTCC technology, excellent dielectric properties (ԑ r ~ 23.77, Q × f ~ 51,636 GHz) were still maintained. Additionally, no extra impurity phase was detected in BC-modified LTMN ceramics co-fired with Ag at 790 °C, indicating that BC-modified LTMN ceramics have a bright prospect in high-performance LTCC devices for 5G applications. [ABSTRACT FROM AUTHOR]

As a common flux agent, B 2 O 3 –CuO was introduced into Li 2 TiO 3 system to reduce the sintering temperature for the requirements of LTCC applications. The optimal mass ratio of CuO to B 2 O 3 was innovatively explored. When the mass ratio of CuO to B 2 O 3 increased to 1.2:1.0, excellent microwave dielectric properties were obtained in LTMF&LTZN 0.892 +CB 1.2 ceramic of ε r = 13.23, Q × f = 62,749 GHz, τ f = -2.48 ppm/°C and the sintering temperature was reduced from 1300 to 930 °C. In a wide temperature range, the sample still maintain high temperature stability of |τ f | < 5 ppm/°C (-40–120 °C). Based on the LTMF&LTZN 0.892 +CB 1.2 substrate, a millimeter wave microstrip antenna resonated at 30.12 GHz was designed with a considerably high radiation efficiency of 93.94% and a signal gain of 4.87 dB. Comprehensive microwave dielectric properties make LTMF&LTZN 0.892 +CB 1.2 become a candidate material for LTCC applications. [ABSTRACT FROM AUTHOR]

Dielectric tunable properties in ferroelectric ceramics have been optimized by a variety of approaches, e.g., isovalent/aliovalent substitution, system composite et al., while the study of non-stoichiometric regulation on the performance of BCZT ceramics was rarely concerned. Herein, a series of novel non-stoichiometric (Ba 0·91 Ca 0.09) x (Zr 0·18 Ti 0.82)O 3 (BCZT x) ceramic specimens were successfully prepared via solid-state reaction. The microstructures of BCZT x ceramics are simultaneously investigated through XRD and SEM. The diffuse phase transition (DPT) behaviour of BCZT x ceramics are studied by the Lorentz-type empirical formula. The significant enhancement of DPT behaviour is observed at x = 1.03, which probably due to the coaction of the generation of partial Schottky defects and prominent reduction of grain size. Furthermore, a high tunability (k) 87.80%, low dielectric loss (tan δ) 0.141%, and a remarkably enhanced FOM of 623 are achieved in x = 0.99 at a low DC bias electric fields (BEFs) of 7.28 kV/cm and room temperature (RT), which is superior to that of the stoichiometric BCZT ceramics and other available reported BT-based ceramics systems in term of the dielectric tunable properties. Meanwhile, it shows that the temperature dependent CQF value of x = 0.99 remained advantageous around the RT. These findings suggested that non-stoichiometric BCZT x ceramics with x = 0.99 are significantly competitive in the applications of dielectric tunable devices at RT. The non-stoichiometric regulation is an effective approach in improving the dielectric tunability properties of BCZT ceramics. [ABSTRACT FROM AUTHOR]

The intrinsic point defect influence data for β –Si3N4 by far are incomplete and experimental clarification is not easy. In this contribution, the effects of vacancy ( V 2c , V 6h and V Si ) and interstitial ( I N and I Si ) defects on the electronic properties of H-passivated β –Si3N4 (0001) surface are explored based on density functional theory (DFT) calculation. The results show that it is easier to form N 6h vacancy defects in the surface layer under Si-rich conditions. The existence of N vacancies makes the bottom of conduction bands shift downwards, and the top of valance band is away from Fermi level. The presence of V Si makes the system have the characteristics of p-type semiconductor, and the closer to the inner layer, the narrower the range of additional energy bands and the greater the degree of localization of electrons. The closer the Si atom vacancy is to the surface, the smaller the photon energy corresponding to the maximum absorption coefficient is. Compared with the N vacancy system, the Si vacancy system has higher reflection ability in the low energy region. For the interstitial defect systems, I N is easy to form on the surface layer, and I Si is easy to produce in the inner layer. The I N system has a new additional energy level at the Fermi level, and as the I N is closer to the inner layer, the energy range of the additional energy level is also narrower. In the I Si system, the new additional energy levels appear at the Fermi level and the intermediate band. The results have positive significance for the design of this advanced structural and functional integrated ceramics. The absorption coefficient and reflection coefficient of I Si - 3 system are much higher than those of other systems when the energy is greater than 2.5 eV. [ABSTRACT FROM AUTHOR]

With the development of 5G technology, it would inevitably lead to the problem of energy consumption owing to the massive construction of 5G base stations and the increase in the number of antenna channels. Dielectric filters as the core component in the base station, the energy consumption was closely related to its insertion loss, which could be achieved by reducing the dielectric loss (tanδ = 1/Q) of microwave dielectric ceramics. In this work, in order to further enhance the Q × f value, the slowly cooling step process was innovatively introduced to the Ba(Mg 1/3 Ta 0.675)O 3 ceramic. The optimal microwave dielectric properties were obtained in Ba(Mg 1/3 Ta 0.675)O 3 ceramic with the step temperature of 1500 °C: ε r = 24.767, Q × f = 298,051 GHz, τ f = −0.66 ppm/°C. Based on ultra-high Q Ba(Mg 1/3 Ta 0.675)O 3 ceramic, the hairpin dielectric filter with high integration and low insertion loss was designed and simulated. Compared with traditional RT/duroid5870 dielectric substrate, the circuit area was reduced by more than 6 times and the passband insertion loss (|S 21 | < 1 dB) was decreased by more than 50%. The current work could provide a solution for the low-power applications of microwave dielectric devices in 5G base stations. [ABSTRACT FROM AUTHOR]

Heterovalent ion doping has been playing a remarkably significant role in the microwave dielectric performances of columbite A2+Nb 2 O 6 (A2+ = Zn, Ca, or transition metal). Here, the Q × f value of MgNb 2 O 6 ceramics can be effectively enhanced from 32,893 GHz to 117,659 GHz by doping with 1 mol% (TiW)5+. Based on the high Q value of Mg(Nb 0.98 Ti 0.01 W 0.01) 2 O 6 , TiO 2 was selected to further adjust the τ f value of the matrix material prepared by the conventional solid-state reaction method. The results show that the Mg(Nb 0.98 Ti 0.01 W 0.01) 2 O 6 ceramics undergo three phase zones with increasing TiO 2 content: columbite (MgNb 2 O 6) solid solution, a mixture of columbite and rutile (Ti 0.5 Mg 0.167 Nb 0.333 O 2), and Ti 0.5 Mg 0.167 Nb 0.333 O 2 solid solution. This variation in phase formation has an essential effect on the microwave dielectric behavior of Mg(Nb 0.98 Ti 0.01 W 0.01) 2 O 6 @xTiO 2 (0.03 ≤ x ≤ 0.25) ceramics. It is important to note that at x = 0.17, the specimen has excellent microwave dielectric performances, with ε r = 34.79, Q × f = 24,103 GHz, and the τ f of the specimen may be adjust to zero. It is anticipated that these materials will be utilised in contemporary microwave and telecommunication equipment. [ABSTRACT FROM AUTHOR]

High performance colossal permittivity ceramic materials are indispensable for the development of electronic devices. In this work, Mg and Nb co-doping BaTiO 3 ceramics were prepared by solid-state reaction under reducing atmosphere. The polarization mechanism, dielectric properties and insulation mechanism were investigated. The defect dipoles ( [ M g T i ″ − V O • • ] × and [ M g T i ″ − 2 N b T i • ] ×) could be formed inside co-doping BaTiO 3 ceramics with various content of MgO, which is the source of colossal permittivity. Appropriate MgO content doping is favorable to enhance short-range hopping, thus improve grain resistance, grain boundary resistance and grain boundary activation energy. The 1.0 at% MgO modified BaTiO 3 -0.01Nb 2 O 5 ceramics possess excellent performance at room temperature with colossal dielectric constant (ԑ r = 4.5 × 104), low dielectric loss (tanδ<0.018), and high insulation resistivity (ρ v = 6.52 × 1011 Ω cm). Meanwhile, good temperature stability is obtained in 1.0 at% MgO modified BaTiO 3 -0.01Nb 2 O 5 ceramics, which satisfies the Electronic Industries Association (EIA) X8R (−55–150 °C, △ε r /ε 25 ≤ ±15%) specification. This study suggests that the defect-dipoles related polarization mechanism can be used to design the colossal permittivity BaTiO 3 -based ceramics. [ABSTRACT FROM AUTHOR]

Relaxor ferroelectrics are attracting an increasing interest in the application of pulse power systems due to their excellent energy storage performance. In this paper, the (1-x)(Ba 0 · 85 Ca 0.15)(Zr 0 · 1 Ti 0.9)O 3 -xBi(Mg 0 · 5 Ti 0.5)O 3 ((1-x)BCZT-xBMT, x ≤ 0.2) relaxor ceramics are prepared by the solid state method. The influence of BMT on the microstructure, dielectric and energy storage properties of the prepared ceramics is investigated. The XRD results show that the peak intensity of impurities (Bi 2 O 3 , TiO 2 and Ba 2 Bi 4 Ti 5 O 18) is gradually stronger than that of BCZT phase with x increasing. Meanwhile, the grain size of (1-x)BCZT-xBMT ceramics gradually increases on account of the appearance of impurities Bi 2 O 3. Influenced by the impurities and BMT, the dielectric constant of prepared ceramics gradually decreases with x increasing. A large W rec value of 0.65 J/cm3 with an ultrahigh η value of 97.89% is achieved at x = 0.15 due to the high breakdown strength and slim P-E hysteresis loop. Meanwhile, the η is insensitive to the electric field. The ultrahigh η leads to lesser energy loss during the charge and discharge process. It makes the 0.85BCZT-0.15BMT ceramic more attractive in the application of pulse power systems. [ABSTRACT FROM AUTHOR]

Microwave dielectric ceramics are expected to yield unusually brilliant results in 5G (5th generation mobile networks) dielectric filter applications. In this paper, high-performance microwave dielectric ceramics with composite perovskite structure were synthesized by non-stoichiometric introduction of Mg2+ in Ba(Mg 1/3 Ta 2/3)O 3 (BMT). Typically, all samples synthesized exhibit predominant resonance frequency stability (resonance frequency shift below 1MHz) from -55°C to 85°C. Ultimately, the best microwave dielectric properties of ε r ~24.662, Q × f ~248,414GHz, τ f ~0.55ppm/°C were obtained by Ba(Mg 0.327 Ta 2/3)O 3 ceramics sintered at 1640°C for 12h and annealed at 1500°C for 12h, and its Q × f value was about 12% higher than that of pure BMT. A cross-coupling hairpin microstrip line dielectric filter was designed and fabricated using the dielectric substrate made of Ba(Mg 0.327 Ta 2/3)O 3 ceramics. The filter resonated at about 3.5GHz (one of 5G licensed bands) with a bandwidth ~560 MHz at −0.56dB insertion loss (S 21). The introduction of Ba(Mg 0.327 Ta 2/3)O 3 dielectric substrate not only improves the performance of the filter, but also greatly reduces its size (14 × 8 × 0.5mm), which suggest that the Ba(Mg 0.327 Ta 2/3)O 3 ceramics may have great application prospects in 5G dielectric filters. [ABSTRACT FROM AUTHOR]

Rare earth with radius ranges from 0.868 Å to 1.36 Å are introduced in BaTiO 3 (BT) -based ceramics by solid-state reaction method, representing different charge compensation modes. Based on X-ray diffraction (XRD) and electron paramagnetic resonance (EPR) measurement, the behavior and solid solubility of La3+, Ho3+, Y3+, and Yb3+ in BT-based ceramics are systematically analyzed, then the charge compensation mechanism in this system is ascertained. Meanwhile, the function of dielectric properties with temperature at different concentrations is measured, which can be reasonably clarified by the Curie–Weiss and modified Curie–Weiss laws. Through the excellent dielectric performance, it is proved that rare earth ions play a role in improving the performance of BT-based ceramics, and the defect complexes formed therein are conductive to insulation resistivity in reducing atmosphere. Among all samples, the Yb3+ doped BT-based ceramic possesses a relatively good comprehensive performance with high dielectric contant (ε > 2600), low dielectric loss (tanδ = 1.83%) and high insulation resistivity (4.38 × 1011 Ω·cm). Consequently, the defect compensation mechanism provides an effective regulatory method for BT-based ceramics, establishing a theoretical basis for multi-layer ceramic capacitor (MLCC). [ABSTRACT FROM AUTHOR]

Background. Diabetes distress is a negative emotion related to diabetes management, which can compromise self-care and management of diabetes. However, few studies on diabetes distress have focused on young adults with type 2 diabetes in China. Methods. A cross-sectional survey was conducted. Using a convenient sampling method, 98 young adults with type 2 diabetes who were admitted to our hospital from June 2017 to July 2018 were selected as research subjects. They were investigated using a basic demographic questionnaire, Diabetes Distress Scale, Summary of Diabetes Self-Care Activities Measure, and Audit of Disease Knowledge. Pearson's correlation analysis and regression analysis were used to analyze the influencing factors of diabetic distress. Results. Among participants, 90.82% suffered from diabetes distress with an average score of 3.01 ± 0.58. Regimen-related, emotional burden-related, and interpersonal-related distress were the most frequently reported as severe. The results of the single-factor analysis showed that gender (P = 0.019), age (P = 0.003), occupation (P = 0.022), smoking (P < 0.001), and diabetes complications (P = 0.001) were the main factors affecting diabetes distress. The correlation analysis showed that diabetes distress was negatively correlated with the level of diabetic self-management (P < 0.001 , r = − 0.377) but not with the level of diabetes knowledge (P = 0.052 , r = − 0.197). The results of a multiple regression analysis showed that self-management level (P = 0.001 , 95% CI: -0.039-0.011), age (P = 0.002 , 95% CI: -0.463-0.104), smoking (P = 0.018 , 95% CI: -0.504-0.048), and complications (P = 0.009 , 95% CI: -0.517-0.076) accounted for 35.42% of the total variation in diabetes distress. Conclusion. Young adults with type 2 diabetes reported severe diabetes distress. Age, smoking, and diabetes complications were the main factors influencing diabetes distress in young adults with type 2 diabetes. Results of the present study are fundamental in selecting targeted measures for alleviating diabetes distress and thus improving the quality of life in these patients. [ABSTRACT FROM AUTHOR]

The donor-acceptor co-doping grain-fine BaTiO 3 -0.5wt%Na 0.5 Ba 0.5 TiO 3 (BT-0.5wt%NBT) ceramics are obtained by conventional solid-state reaction method and sintered in different atmospheres. The dielectric properties are sensitively influenced by the sintering atmosphere, which the colossal permittivity can be activated and increased by enhanced atmospheric reducibility with the increase of H 2 content. However, the excessive H 2 content can make a significant deterioration in dielectric loss and insulation resistivity. The impedance spectra, XPS and EPR measurements indicate that sintering atmosphere can effectively regulate the concentration and distribution of charge carriers (delocalized electrons, oxygen vacancies and defects), which induce the interfacial polarization and hopping polarization. When sintered in 0.1% H 2 /N 2 , the sample possesses a relatively good comprehensive performance with colossal permittivity (ε γ >4×104), ultra-low dielectric loss (tanδ=0.0218) and high insulation resistivity (ρ v >1011Ω·cm), which related to the moderate values of resistance and conduction activation energy for the grain boundaries. [ABSTRACT FROM AUTHOR]

NiO thin films with different annealing temperature and films thickness were fabricated by magnetron sputtering on the Pt/TiO x /SiO 2 /Si substrates. The XRD results show the crystallinity of films can be improved with the annealing temperature and films thickness increased. While the preferential orientation is affected by annealing temperature and films thickness. The SEM results show that the average size of the needle like grains shape increases gradually from 42.4 nm to 72.5 nm and the grains of films are seen to be more uniform, with a smoother and finer morphology with film thickness increasing. XPS measurements show that two valence states of Ni2+ and Ni3+ exist in NiO films with the Ni2+/ Ni3+ ratio 1.01. However, the Ni3+ refers to the structure that contains Ni2+ ions with holes and not to Ni 2 O 3 phase as observed from the XRD results and the O1s XPS spectra, making the grains conductive due to plenty of holes. It results the grains have a key contribution to dielectric behavior. The frequency domain spectroscopy shows the films thickness and annealing temperature have a significance influence on the dielectric constant and dielectric loss tangent. And the preferential orientation of NiO films play a non-negligible impact on the dielectric performance due to the polarized NiO (111) plane. • The NiO thin films with different annealing temperature and films thickness were fabricated by magnetron sputtering on the Pt/TiO x /SiO 2 /Si substrates. • The effect of films thickness on the surface morphology, preferential orientation and dielectric property were discussed. • The preferential orientation of NiO films play a non-negligible impact on the dielectric performance due to the polarized NiO (111) plane. • The NiO films undergo a texture transition from (220) to (111) crystallographic orientation with the annealing temperature rising. [ABSTRACT FROM AUTHOR]

The (La 1/2 Ta 1/2) x Ti 1-x O 2 and (Er 1/2 Ta 1/2) x Ti 1-x O 2 ceramics with x = 0.01 and 0.03 were synthesized by a conventional solid-state reaction. The analysis of EDS mapping, ac conductivity spectra, impedance analysis, XPS, and DC bias indicate that electrons-pinned defect-dipole (EPPD) polarization plays the main role in both the (La 1/2 Ta 1/2) 0.01 Ti 0.99 O 2 and (Er 1/2 Ta 1/2) 0.01 Ti 0.99 O 2 ceramics, while the interfacial polarization and hopping polarization are respectively highlighted by the (La 1/2 Ta 1/2) 0.03 Ti 0.97 O 2 and (Er 1/2 Ta 1/2) 0.03 Ti 0.97 O 2 ceramics. Besides, the dielectric responses reveals that the interfacial polarization and hopping polarization are much slower than EPDD polarization and lead to poor frequency-, temperature-stability and higher dielectric loss (tanδ). Then the conclusion can be drawn that the outstanding dielectric properties can be achieved only the EPDD polarization takes the absolute dominant position, and excellent properties are obtained in (Er 1/2 Ta 1/2) 0.01 Ti 0.99 O 2 ceramic with ultra-low loss of tanδ≈0.0095 (@1 kHz) and excellent frequency, temperature and DC bias stability. • In this work, the effects of different polarizations on the CP TiO 2 systems are revealed and concretely discussed. • The dielectric properties of LTTO and ETTO ceramics with x=0.01 and 0.03 are systematically studied. • The 1% ETTO and 1% LTTO ceramics with ultralow dielectric loss (1%ETTO: tanδ≈0.0095; 1%LTTO: tanδ≈0.0155 at 1kHz). [ABSTRACT FROM AUTHOR]

Giant permittivity ceramic is one of the most significant classes of material to realize the miniaturization and integration of a high-performance capacitor. In this paper, to realize good giant dielectric properties, the (Nd 0.5 Ta 0.5) x Ti 1-x O 2 ceramics (NTTO x = 0.005, 0.01, 0.03, 0.05) were synthesized by a standard conventional solid-state reaction. Comparing with the previous co-doped TiO 2 ceramics giant permittivity material system, NTTO ceramics perform extremely colossal permittivity and ultralow dielectric loss (1%NTTO: ε = 82052, tanδ = 0.008 at 1 kHz; 5%NTTO: ε = 170131, tanδ = 0.090 at 1 kHz). The broad distinction of the dielectric behavior between the (Nd 0.5 Ta 0.5) x Ti 1-x O 2 ceramics can be explained by the impedance analysis and the calculated polarization activation energies. The main electron-pinned defect-dipole (denoted as EPDD) polarization corresponds to the ultralow loss, embodying in the maximum value of E gb (the activation energy of the grain boundary), E a2 (the EPDD polarization activation energies) and the minimum value of E a1 (the total polarization activation energies). Though the interfacial polarization can cause the permittivity increase, it can also give rise to poor frequency stability and higher loss. [ABSTRACT FROM AUTHOR]

Microwave ceramic with ultra-high Q value is one of the most significant classes of material to realize the miniaturization and integration of microwave devices. In this paper, to improve the microwave dielectric properties of ceramics, MgTiO 3 - x wt.% MgF 2 (x = 0, 3, 4, 5, and 6) microwave ceramics with high-quality factor were synthesized by solid-state reaction method. The effects of MgF 2 addition on the phase composition, sintering behavior, and microwave dielectric properties of MgTiO 3 were investigated. In comparison to pure MgTiO 3 , our study demonstrates that the Q × f values can be dramatically enhanced with the doping of MgF 2. After being sintered at 1300 °C for 4 h, the MgTiO 3 -3 wt.% MgF 2 showed the best microwave dielectric properties of ε r ∼18.09, Q × f ∼262,900 GHz (at 8.98 GHz) and τ f ∼ −41.5 ppm/°C. The outstanding performance of MgF 2 doped MgTiO 3 ceramics provides a solid foundation for widespread applications of microwave dielectric substrates, resonators, filters and patch antennas in modern wireless communication equipment. • Mg 2 TiO 4 phase of ceramics were analyzed based on RP phase. • The leakage current was analyzed based on the grain boundary barrier effect. • The bulk density at different sintering temperatures were analyzed. • The optimum densification sintering process was determined. [ABSTRACT FROM AUTHOR]

To evaluate the health-related quality of life (HRQOL) in locally advanced cervical cancer (LACC) patients treated with neoadjuvant concurrent chemoradiation (CCRT) or radiation (RT) alone followed by radical surgery (RS). In a single-center retrospective study from a prospective database, 275 FIGO Stage IB2-IIIB patients who underwent CCRT/RT + RS were included. HRQOL was prospectively assessed by EORTC QLQ-C30 and EORTC QLQ-CX24 prior to any treatment (baseline) and 6 months after surgery, respectively. A statistically significant and clinically relevant improvement in physical functioning (P < 0.001) and role functioning (P = 0.002, P = 0.031) was observed in patients receiving either CCRT+RS or RT + RS at follow-up. In addition, quality of life (QoL), physical functioning, and social functioning were better in the RT + RS group than the CCRT+RS group after treatment (P = 0.028, P = 0.010, P = 0.014). Symptom scores of fatigue decreased in both groups over time (P < 0.001, P = 0.004) while insomnia decreased only in the RT + RS group (P = 0.042). Worsened menopausal symptoms were documented in both groups at follow-up (P = 0.001, P = 0.047), while lymphedema was deteriorated only in patients receiving CCRT + RS (P < 0.001). Sexuality scores did not differ between groups or over time with the exception of sexual worry, which was deteriorated in patients receiving RT + RS (P = 0.042). QLQ-C30 functioning and tumor-related symptoms scores improved while lymphedema and menopausal symptoms worsened 6 months after neoadjuvant CCRT or RT alone followed by RS in LACC patients. Patients treated with RT + RS had a generally better HRQOL compared with those receiving CCRT+RS, though further validation with prospective randomized clinical trials is warranted. • Physical/role functioning improved 6 months after concurrent chemoradiation (CCRT)/radiation (RT) + radical surgery (RS). • Tumor-related symptoms of fatigue and insomnia decreased 6 months after treatment. • Treatment-related symptoms of lymphedema and menopausal symptoms increased after treatment. • Sexuality was not impaired significantly except for a worsened sexual worry in the RT + RS group. • Generally RT + RS seems superior to CCRT+RS with greater improvement in functioning and less toxicity. [ABSTRACT FROM AUTHOR]

To determine the mechanism of microwave response in AZrNb 2 O 8 (A: Mn, Zn, Mg, Co, et al.) wolframites, CuZrNb 2 O 8 ceramic with low sintering temperature (920 °C) is successfully fabricated by solid-state reaction method. Meanwhile, its structural stability is synthetically evaluated, the vibration modes are also calibrated. Except for the extrinsic factor like sintering temperature, the condition of Jahn-Teller ion Cu2+ as intrinsic part is characterized for the first time in relation to the microwave dielectric properties of the system. In virtue of Raman and EPR spectra, it is predicted that the electronic structure of transition metal ions, as the less concerned factor, may be influential on the dielectric properties of ceramics at microwave range, especially in the structure with mixed ion occupancy. In addition, the CuZrNb 2 O 8 ceramic is well matched with the silver electrode, which makes it a prospective candidate for temperature compensation material of LTCC (low-temperature co-fired ceramic) passive integration technology. [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]

In order to tailor the microwave dielectric performances of Mg(Nb 0.98 Ti 0.01 W 0.01) 2 O 6 –TiO 2 composite ceramics, Mg(Nb 0.98 Ti 0.01 W 0.01) 2 O 6 –Mg doped TiO 2 –Mg(Nb 0.98 Ti 0.01 W 0.01) 2 O 6 and Mg(Nb 0.98 Ti 0.01 W 0.01) 2 O 6 –TiO 2 –Mg(Nb 0.98 Ti 0.01 W 0.01) 2 O 6 tri-layer architectural ceramics with different volume fractions and different TiO 2 doping were designed and prepared. This work systematically investigates the crystal structure and microwave dielectric performances of composite ceramics. Raman spectroscopy confirmed the formation of a solid solution at the interface. Raman spectroscopy were used to analyze the ion diffusion behavior at the interface. Based on the law of mixing for composites, the Q × f value of the tri-layer structural ceramics with Mg doped TiO 2 interlayer can be increased by nearly 33 % compared with that of the pure TiO 2 interlayer. The Mg(Nb 0.98 Ti 0.01 W 0.01) 2 O 6 –Mg doped TiO 2 –Mg(Nb 0.98 Ti 0.01 W 0.01) 2 O 6 tri-layer ceramics exhibit remarkably outstanding dielectric performances: ε r = 27.5, Q × f = 72,148 GHz, and τ f = +6.37 ppm/°C with 0.03 wt% Mg doped TiO 2 sintered at 1340 °C for 6 h to achieve a comprehensive optimization of microwave dielectric performances. [ABSTRACT FROM AUTHOR]

Preliminary tri-layer architecture ZnNb 1.8 V 0.1 O 5.75 -TiO 2 +CuO–ZnNb 1.8 V 0.1 O 5.75 ceramics with high-temperature stability and low dielectric loss have been prepared. In the past, the stacked co-firing process could only be used at normal sintering temperatures. In this paper, the effect of the transition layer in ZnNb 1.8 V 0.1 O 5.75 -TiO 2 +CuO–ZnNb 1.8 V 0.1 O 5.75 ceramics with tri-layer architecture sintered at low temperatures (950 °C) on the crystalline structure, microscopic structure, and integrated microwave dielectric performance of specimens has been investigated in depth for the first time. This low-temperature stacked-layer co-firing technique can effectively enable the chemical reaction between ZnNb 1.8 V 0.1 O 5.75 and TiO 2 +CuO to take place in a rather narrow region (about 20 μm), i.e., the interface of the heterogeneous layers. In this interface, diffusion of Zn, Nb, V, Ti, and Cu can be observed. This heterogeneous interface can act as an in-situ "glue" that holds the layers together well. The effect of TiO 2 +CuO content on the microwave dielectric performances of laminated architectural specimens under low-temperature sintering was systematically investigated. Among the existing layer architectures, the stack of ZnNb 1.8 V 0.1 O 5.75 -TiO 2 +CuO–ZnNb 1.8 V 0.1 O 5.75 with 0.03 wt% TiO 2 +CuO exhibits the most excellent microwave dielectric performances. τ f can be efficiently tuned close to zero (−7.14 ppm/°C), and remarkably, a low dielectric loss (14,587 GHz) and a high value of ε r (24.00) are also achieved. This low-temperature sintered tri-layered architecture is designed to help open new avenues for the development of high-performance microwave dielectrics based on existing material systems, providing effective strategies and methods for 5G applications and multilayer packaging technologies. [ABSTRACT FROM AUTHOR]

The effect of TiW substitution on the microwave dielectric performances of MgNb 2 O 6 ceramics prepared via solid-state reaction has been investigated using Raman scattering spectroscopy, microscopic morphology analysis, and complex chemical bond theory. The dielectric permittivity is mainly affected by porosity, molecular polarizability and crystal vibrations. The Q × f value is mainly determined by the bond covalency of the Nb–O bond and the FWHM value of the Raman spectrum. In addition, τ f value is mainly affected by the bond valence of the Nb–O bond. This research demonstrates that a moderate amount of (TiW)5+ not only reduces the sintering temperature (from 1460 °C to 1340 °C) and lowers the dielectric loss, but also improves the temperature stability. The composition (x = 0.01) exhibits excellent properties: ε r = 20.67, Q × f = 117,660 GHz, and τ f = −45.73 ppm/°C, providing a promising candidate for 5 G electronic devices. [ABSTRACT FROM AUTHOR]

Abstract Low firing NP0-type Bi 2 (Mg 2/3 Nb 4/3)O 7 / 0.9Bi 2 (Mg 2/3 Nb 4/3)O 7 − 0.1SrCO 3 / 0.7Bi 2 (Mg 2/3 Nb 4/3)O 7 − 0.3SrCO 3 tri-layer composite ceramics are fabricated using solid state sintered technology at low sintering temperature of 950 °C. Compared to the single-layer ceramics, the tri-layers reveal prominently enhanced dielectric performance. The enhanced-mechanism of dielectric properties is elucidated in multilayer structure due to the influence of interface. A low dielectric loss tangent of 0.0018 and near-zero τ ε value of − 29 ppm/°C can be obtained, while dielectric constant is increased to ~200. The results indicate that the tri-layer composite ceramics are excellent candidates for low firing negative-positive-zero-type multilayer ceramic capacitors. [ABSTRACT FROM AUTHOR]

Abstract LiZn 1-x M x NbO 4 (M = Co, Ni) (x = 0–0.06) systems were fabricated by a facile solid-state reaction method. Structure and property relationships of spinel structured LiZn 1-x M x NbO 4 were investigated systematically. Appropriate amount of Co2+ and Ni2+ greatly improved the dielectric loss of LiZnNbO 4 ceramics. While, the dielectric loss deteriorated seriously when the doping content exceeded x = 0.02. The origin of dielectric loss in LiZn 1-x M x NbO 4 ceramics was investigated systematically. Moreover, the theoretical dielectric constant and linear expansion coefficient were calculated on the bases of the crystallographic parameters from XRD refinement. The temperature coefficient of resonant frequency calculated by the P-V theory agreed well with the test values. Due to the small doping content, the change in chemical bonds was negligible. Density became the major factor determining the variation of dielectric constant in LiZnNbO 4 ceramics. At last, excellent microwave dielectric properties were obtained: Ts = 1010 °C, ε r = 15.25, Q f = 107,000 GHz, τ f = −63.3 ppm/°C for LiZn 0.98 Co 0.02 NbO 4 and Ts = 995 °C, ε r = 14.85, Q f = 104,000 GHz, τ f = −61.7 ppm/°C for LiZn 0.98 Ni 0.02 NbO 4. Highlights • Structure and property of spinel structured LiZn 1-x M x NbO 4 are investigated. • The origin of dielectric loss in LiZn 1-x M x NbO 4 ceramics is clarified. • Dielectric constant and linear expansion coefficient are obtained by the P-V theory. • Excellent microwave performance make it a promising candidate for LTCC applications. [ABSTRACT FROM AUTHOR]

Abstract Low voltage driven capacitors, based on nickel oxide (NiO), were fabricated on the Pt/TiO x /SiO 2 /Si substrates by radio frequency magnetron sputtering. The effects of post-annealing conditions on preferential orientation, microstructure and tunable performance of NiO thin films were investigated. The NiO capacitors prepared at low annealing temperature possess large capacitance and the increasing trend is observed with the increase of bias voltage. For well-crystallized NiO thin films, the dielectric nonlinearity is observed after annealed at higher temperatures. The mechanisms leading to these dielectric responses are illuminated in detail. Finally, NiO thin film capacitors annealed at 300 °C present the highest tunability (68.1% @100 kHz) under a small applied field of 82 kV/cm. The dielectric performance reveals that NiO capacitors may be a potential candidate for tunable applications. Highlights • The crystal structure and dielectric properties of NiO thin films were studied. • The reasons of high dielectric behavior at low annealing temperature were proposed. • The mechanisms of tunability for well-crystallized NiO thin films were proposed. • NiO capacitors annealed at 300 °C present tunability of 68.1% at 82 kV/cm. [ABSTRACT FROM AUTHOR]

Abstract As an admirable candidate of thermostable LTCC materials, Bi 2 (Zn 1-x Ni x) 2/3 Nb 4/3 O 7 (0.0 ≤ x ≤ 0.5) ceramics with improved dielectric properties have been prepared via conventional mixed oxide route. Microstructure analysis manifests that the phase transition occurs from monoclinic zirconolite phase (β-BZN) to cubic phase (α-BZN) for Ni doped specimens. The crystal field theory supported the analysis of the initial phase transition processes. From the structure transformation and electrical properties test result, the Ni2+ substituted Zn2+ shows an effective method to restrain the grain growth and improve dielectric constant when sintered at 925 °C. The temperature coefficient of dielectric constant is controlled by phase composition and is found to be −6.4 ppm/°C at the two-phase coexistence region of the doping content x = 0.35. The dielectric properties of ε = 101.2, tanδ = 9.5 × 10−4 are obtained in this component. The features of the Bi 2 (Zn 1-x Ni x) 2/3 Nb 4/3 O 7 ceramics make them promising for use in high-frequency applications. Highlights • In Bi 2 Zn 2/3 Nb 4/3 O 7 system, the phase transition caused by Ni2+ was initially discussed through crystal field theory. • The correlation between phase transition and dielectric performance was established. • A good combination of dielectric properties ε = 101.2, tanδ = 9.5 × 10−4, τ ε = 6.4 ppm/°C was obtained at x = 0.35. [ABSTRACT FROM AUTHOR]

1:2 ordered Ba 3 Zn(Nb 2-x Mo x )O 9+x/2 (BZNM) ceramics with space group P 3 ¯ ml were prepared by solid-state method. The nature of chemical bonds in Ba 3 Zn(Nb 2-x Mo x )O 9+x/2 (BZNM) ceramics was investigated for the first time. Firstly, the bond energy was closely related to the lattice vibration. High bond energy would lead to weak non-harmonic interactions, which were the main factors of improving Q f . Secondly, polarization of the chemical bond was the principal contributor to the relative permittivity of microwave ceramics. Compared with the traditional method, the calculated result based on the P-V theory reduced the error from 81% to 4.4%. Through the discussion, it was confirmed that the analysis method based on chemical bond was highly feasible and scientific in the microwave ceramics. At last, the system of Ba 3 Zn(Nb 1.992 Mo 0.008 )O 9.004 sintered at 1435 °C for 6 h and annealed at 1300 °C for 10 h had excellent microwave dielectric properties: ε r  = 38.9, Q f  = 102,931 GHz, τ f  = 19.2 ppm/°C, which, to our best knowledge, provided a alternative for the application of millimeter-wave communications. [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]

Inequivalent La 3+ is firstly utilized to modify the microwave dielectric properties in SrTiO 3 ceramic system. For the general composition of Sr 1-x La 2x/3 TiO 3 (0 ≤ x ≤ 1), the effects of La 3+ introduction on the phase transition and structural changes are systematically investigated. The correlation between A-site ordering degree and dielectric loss in microwave range is established, and the temperature coefficient of resonant frequency is also dramatically improved. When x = 0.945, excellent dielectric properties of ε r ∼89.3, Qf ∼15243 GHz (@4.3 GHz) and τ f  ∼ 160 ppm/°C are obtained, making it potential to meet the application requirements of 5G technologies. [ABSTRACT FROM AUTHOR]

Low-loss (Zn 1- x Ni x )ZrNbTaO 8 (0.02 ≤  x  ≤ 0.10) ceramics possessing single wolframite structure are initiatively synthesized by solid-state route. Based on the results of Rietveld refinement, complex chemical bond theory is used to establish the correlation between structural characteristics and microwave performance in this ceramic system. A small amount of Ni 2+ ( x  = 0.06) in A-site with the fixed substitution of Ta 5+ in B-site can effectually raise the Q  ×  f value of ZnZrNb 2 O 8 ceramic, embodying a dense microstructure and high lattice energy. The dielectric constant and τ f are mainly affected by bond ionicity and the average octahedral distortion. The (Zn 0.94 Ni 0.06 )ZrNbTaO 8 ceramic sample sintered at 1150 °C for 3 h exhibits an outstanding combination of microwave dielectric properties: ε r = 27.88, Q × f  = 128,951 GHz, τ f = –39.9 ppm/°C. Thus, it is considered to be a candidate material for the communication device applications at high frequency. [ABSTRACT FROM AUTHOR]

The effects of TiO 2 doping on the phase transition and microwave dielectric performances of ZnNb 1.8 V 0.1 O 5.75 @xTiO 2 (0.05 ≤ x ≤ 0.60) ceramics prepared by conventional mixing methods were investigated. In this study, we report for the first time the phase transition of ZnNb 2 O 6 with columbite structure at low temperature (950 °C) where the τ f value is adjusted to near zero. With the increase of TiO 2 doping, the following phase transitions are experienced in the ceramics: columbite + monoclinic → columbite + monoclinic + ixiolite → monoclinic + ixiolite → monoclinic + ixiolite + rutile. The microscopic morphology of ceramics is greatly influenced by TiO 2 doping. The grain size of ceramics continues to grow as TiO 2 doping increases. The microwave dielectric performances of ceramics are intimately connected to the phase transition process, which occurs when the Q × f value constantly declines while the τ f value steadily increases and is adjusted to near zero at x = 0.50. After sintering at 950 °C for 6 h, the most optimal microwave dielectric performances were obtained for x = 0.50 with a dielectric constant of 41.18, a Q × f value of 6852 GHz, and a τ f value of +6.83 ppm/°C, providing a new option with great potential for microwave devices requiring medium dielectric ceramics. [ABSTRACT FROM AUTHOR]

The ZnNb 2-x V x/2 O 6-1.25x (0.1 ≤ x ≤ 0.6) dielectric ceramics were synthesized through conventional solid-state technique and sintered at 925 °C–975 °C for 6 h. The specimens with the substitution of V5+ for Nb5+ could be sintered at a lower temperature than pure ZnNb 2 O 6 ceramic, densifying the microstructure more densely and improving the quality factor. Density analysis proves that the dielectric constant is related to the relative density. In addition, the [NbO 6 ] octahedral distortion, the bond valence and the average bond energy of the Nb–O bond also change, leading to a nonlinear variation for the temperature coefficient of the resonance frequency from x = 0.1 to 0.6. The ZnNb 2-x V x/2 O 6-1.25x (x = 0.2) ceramics sintered at 950 °C exhibited the superior characteristic while taking into account the applications of low temperature co-fired ceramics technology. Not only did it possesses outstanding dielectric performances of ε r = 22.25, Q × f = 51,701 GHz, and τ f = −67.02 ppm/°C, but also has excellent chemical compatibility with the widely used Ag electrode. [ABSTRACT FROM AUTHOR]

The phase composition, crystal structure and microwave dielectric properties of (1-x) (3ZnO-Nb 2 O 5 )-xGeO 2 were investigated systematically. The phase composition and phase transformation of (1-x) (3ZnO-Nb 2 O 5 )-xGeO 2 ceramics were confirmed by XRD refinement, SEM micrographs and EDS analysis. All sintered samples were composed of Zn 3 Nb 2 O 8 and ZnNb 2 O 6 phases. Phase transition between Zn 3 Nb 2 O 8 and ZnNb 2 O 6 was closely related the introduction of GeO 2 . When the doping content was low (x = 0–0.007), the phase transformation from ZnNb 2 O 6 to Zn 3 Nb 2 O 8 occurred, which was discovered for the first time. To clarify the phase transition, the local charge density and band structures were calculated using the CASTEP program. With the substitution of Ge 4+ , part of the electrons transferred from the oxygen atom to the middle of 'niobium-oxygen' and 'zinc-oxygen'. According, the covalency of 'niobium-oxygen' and 'zinc-oxygen' was enhanced. The shrinkage of ZnO 6 octahedron resulted in a decrease in the coordination number of zinc atoms. At last, the relationships between phase transition, crystal structure and the microwave performance were established. The system of 2.73ZnO-0.91Nb 2 O 5 -0.09GeO 2 sintered at 1150 °C for 6 h had excellent microwave dielectric properties: ε r  = 21.3, Q f  = 99,140 GHz, τ f  = −54 ppm/°C, which, to our best knowledge, the best performance with relative lower sintering temperature. [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]

In this work, in order to reduce the sintering temperature of BaTiO 3 -based ceramic and synchronously maintain excellent dielectric properties, submicron and nanosized ZnO-B 2 O 3 -Bi 2 O 3 (ZBB) additives were co-doped to produce BaTiO3-based ceramics at medium temperature (1150 °C). The concerted mechanism on the dielectric properties of different proportion of submicron and nanosized ZBB additive in BaTiO 3 -based X8R ceramics was investigated systematically. Complex impedance spectra and the calculated activation energy of the grain boundary results showed excess nanosized additive diffuse into the lattice of BaTiO 3 , which result in poor dielectric properties and low density. Resulting BaTiO 3 -based ceramics co-doped submicron additive and nanosized additive in a proportion of 2 to 1 exhibited sufficient relative density and ideal X8R performance with high dielectric constant (ε r = 3460 at 1 kHz and room temperature) low dielectric loss tan δ < 1.1%, which exhibits wide application prospect in electro-magnetic interference filter. [ABSTRACT FROM AUTHOR]