scholarly journals A Study of the Effect of Sintering Conditions of Mg0.95Ni0.05Ti3 on Its Physical and Dielectric Properties

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5988
Author(s):  
Chun-Hsu Shen ◽  
Chung-Long Pan ◽  
Shih-Hung Lin
Keyword(s):  
Dielectric Properties ◽  
Temperature Coefficient ◽  
Unit Cell ◽  
Holding Time ◽  
Q Factor ◽  
Cell Constant ◽  
Two Phase ◽  
Solid State Route ◽  
Sintering Conditions ◽  
Unit Cell Constant

Mg0.95Ni0.05TiO3 ceramics were prepared by traditional solid-state route using sintering temperatures between 1300 and 1425 °C and holding time of 2–8 h. The sintered samples were characterized for their phase composition, micro-crystalline structure, unit–cell constant, and dielectric properties. A two-phase combination region was identified over the entire compositional range. The effect of sintering conditions was analyzed for various properties. Both permittivity (εr) and Q factor (Qf) were sensitive to sintering temperatures and holding times, and the optimum performance was found at 1350 °C withholding time of 4 h. The temperature coefficient of resonant frequency (τf) in a range from −45.2 to −52 (ppm/°C) and unit–cell constant were not sensitive to both the sintering temperature and holding time. An optimized Q factor of 192,000 (GHz) related with a permittivity (εr) of 17.35 and a temperature coefficient (τf) of −47 (ppm/°C) was realized for the specimen sintered at 1350 °C withholding time of 4 h. For applications of 5G communication device (filter, antennas, etc.), Mg0.95Ni0.05TiO3 is considered to be a suitable candidate for substrate materials.

Effect of Sintering Behaviors on Microwave Dielectric Properties of (Ca0.3Sr0.1)Sm0.4TiO3 Ceramics

2014 ◽  
Vol 602-603 ◽  
pp. 738-741
Author(s):  
Cheng Hsing Hsu ◽  
Shang Hung Tsai ◽  
Wen Shiush Chen ◽  
Chun Hung Lai ◽  
Jenn Sen Lin
Keyword(s):  
Dielectric Properties ◽  
Solid State ◽  
Microwave Dielectric Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solid State Route ◽  
Microwave Dielectric ◽  
Sintering Conditions ◽  
Diffraction Patterns ◽  
Conventional Solid State Route

The microstructure and dielectric properties of the (Ca0.3Sr0.1)Sm0.4TiO3 ceramics with various sintering conditions have been investigated. The compounds were prepared by the conventional solid-state route with various sintering temperatures from 1340 to 1400°C and sintering duration from 3 h. The resultant microwave dielectric properties were analyzed based upon the densification, the X-ray diffraction patterns and the microstructures of the ceramics. The correlation between the microstructures, the microwave dielectric properties and sintering behaviors was also examined. The εr value of 96.7 and Q×f value of 11,600 GHz were obtained for (Ca0.3Sr0.1)Sm0.4TiO3 ceramics sintering at 1370°C for 3 h. The (Ca0.3Sr0.1)Sm0.4TiO3 ceramics had suitable dielectric properties can find applications in microwave devices such as resonator, filter and antenna.

scholarly journals Tunable Microwave Dielectric Properties of Ca0.6La0.8/3TiO3 and Ca0.8Sm0.4/3TiO3-Modified (Mg0.6Zn0.4)0.95Ni0.05TiO3 Ceramics with a Near-Zero Temperature Coefficient

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 4715
Author(s):  
Chung-Long Pan ◽  
Chun-Hsu Shen ◽  
Shih-Hung Lin ◽  
Qi-Zi Lin
Keyword(s):  
Dielectric Properties ◽  
Temperature Coefficient ◽  
Dielectric Material ◽  
Microwave Dielectric Properties ◽  
Material System ◽  
Zero Temperature ◽  
Two Phase ◽  
Solid State Method ◽  
Microwave Dielectric ◽  
Communication Devices

The microstructures and microwave dielectric properties of (Mg0.6Zn0.4)0.95Ni0.05TiO3 with Ca0.6La0.8/3TiO3 and Ca0.8Sm0.4/3TiO3 additions prepared by the solid-state method has been investigated. The crystallization and microstructures of these two mixed dielectrics were checked by XRD, EDX, BEI, and SEM to demonstrate two phase systems. Furthermore, the tunable dielectric properties can be achieved by adjusting the amounts of Ca0.6La0.8/3TiO3 and Ca0.8Sm0.4/3TiO3 additions, respectively. After optimization of processed parameters, a new dielectric material system 0.88(Mg0.6Zn0.4)0.95Ni0.05TiO3-0.12Ca0.6La0.8/3TiO3 possesses a permittivity (εr) of 24.7, a Qf value of 106,000 (GHz), and a τf value of 3.8 (ppm/°C), with sintering temperature at 1225 °C for 4 h. This dielectric system with a near-zero temperature coefficient and appropriate microwave properties revealed a high potential for high-quality substrates adopted in wireless communication devices.

scholarly journals Nonlinear multiscale simulation of instabilities due to growth of an elastic film on a microstructured substrate

2020 ◽  
Vol 90 (11) ◽  
pp. 2397-2412
Author(s):  
Iman Valizadeh ◽  
Oliver Weeger
Keyword(s):  
Deformation Gradient ◽  
Multiscale Simulation ◽  
Numerical Results ◽  
Unit Cell ◽  
Homogeneous Material ◽  
Two Phase ◽  
Biological Phenomena ◽  
Elastic Film ◽  
Living Tissues ◽  
Analytical Approaches

Abstract The objective of this contribution is the numerical investigation of growth-induced instabilities of an elastic film on a microstructured soft substrate. A nonlinear multiscale simulation framework is developed based on the FE2 method, and numerical results are compared against simplified analytical approaches, which are also derived. Living tissues like brain, skin, and airways are often bilayered structures, consisting of a growing film on a substrate. Their modeling is of particular interest in understanding biological phenomena such as brain development and dysfunction. While in similar studies the substrate is assumed as a homogeneous material, this contribution considers the heterogeneity of the substrate and studies the effect of microstructure on the instabilities of a growing film. The computational approach is based on the mechanical modeling of finite deformation growth using a multiplicative decomposition of the deformation gradient into elastic and growth parts. Within the nonlinear, concurrent multiscale finite element framework, on the macroscale a nonlinear eigenvalue analysis is utilized to capture the occurrence of instabilities and corresponding folding patterns. The microstructure of the substrate is considered within the large deformation regime, and various unit cell topologies and parameters are studied to investigate the influence of the microstructure of the substrate on the macroscopic instabilities. Furthermore, an analytical approach is developed based on Airy’s stress function and Hashin–Shtrikman bounds. The wavelengths and critical growth factors from the analytical solution are compared with numerical results. In addition, the folding patterns are examined for two-phase microstructures and the influence of the parameters of the unit cell on the folding pattern is studied.

Coefficients of thermal expansion of unidirectional fiber-reinforced composites using unit-cell model

2018 ◽  
Vol 53 (11) ◽  
pp. 1425-1436
Author(s):  
PC Upadhyay ◽  
JP Dwivedi ◽  
VP Singh
Keyword(s):  
Thermal Expansion ◽  
Cell Model ◽  
Unit Cell ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Unit Cell Model ◽  
Fiber Reinforced ◽  
Two Phase ◽  
Thermal Expansion Coefficients ◽  
Three Phase

Coefficients of thermal expansion of some uniaxially fiber-reinforced composites have been evaluated using three-phase unit-cell model. Results have been compared with the values predicted by two other models based on composite cylinders assembly (CCA), and also with some earlier reported experimental values. An extension of the two-phase unit-cell model has also been presented for the evaluation of thermal expansion coefficients of three-phase composites. The formulation has been used to evaluate the overall coefficients of thermal expansion of AS-graphite/epoxy system with a low modulus coating on the fibers. The results have been compared with the results obtained from the Sutcu's recursive concentric cylinders model for composites containing coated fibers. From the comparison of results of the unit-cell models (both, two-phase and three-phase) with the results obtained from some other models available in the literature, it is concluded that the overall thermal properties of fiber-reinforced composites evaluated by the unit-cell model can be used as effectively as by any other model.

Microwave Dielectric Properties of Ca[(Li1/3Nb2/3)0.92Zr0.08]O3−δ Ceramics with Glass Addition

2014 ◽  
Vol 556-562 ◽  
pp. 318-321
Author(s):  
Gang Xiong
Keyword(s):  
Dielectric Properties ◽  
Temperature Coefficient ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Glass Content ◽  
Glass Addition ◽  
Microwave Dielectric ◽  
Resonator Frequency

The effects of ZnO-B2O3-Na2O(ZBN) glass on the sinterability and microwave dielectric properties of Ca [(Li1/3Nb2/3)0.92Zr0.08]O3−δ −0.05TiO2 ceramics were investigated . ZBN glass doping can effectively reduce sintering temperatue by 100~150oC. The temperature coefficient of resonator frequency τf increased with an increase of ZBN glass content and sintering temperatue. When ZBN glass of 1.8wt% were added, the optimum microwave dielectric properties: εr=32.8, Qf =13420GHz and τf= − 4.3×10−6/oC were obtained at the sintering temperature of 1000oC.

scholarly journals Microstructure and Properties of SCE-Al2O3/PES-MBAE Composite

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Yufei Chen ◽  
Qiwang Dai ◽  
Xiwang Zhang ◽  
Tao Feng
Keyword(s):  
Dielectric Properties ◽  
Bisphenol A ◽  
Heat Resistance ◽  
Bending Strength ◽  
Sol Gel ◽  
Harmful Effect ◽  
Decomposition Temperature ◽  
Two Phase ◽  
Allyl Compound

SCE-Al2O3was the nano-Al2O3modified by supercritical ethanol and the surface of SCE-Al2O3was coated with active group. 4,4′-diaminodiphenylmethane bismaleimide (MBMI) was used as matrix; 3,3′-diallyl bisphenol A (BBA) and bisphenol-A diallyl ether (BBE) were used as reactive diluent, polyethersulfone (PES) as toughening agent, and SCE-Al2O3as modifier; SCE-Al2O3/PES-MBAE nanocomposite was prepared through in situ sol-gel method. The mechanism of composite toughened by PES was observed and analyzed. FTIR indicated that the reaction between MBMI and allyl compound occurred and SCE-Al2O3had doped into the polymer matrix. SEM showed that PES particle was inlaid in matrix and presented as a two-phase structure in matrix. The heat resistance, dielectric properties, and mechanical properties of SCE-Al2O3/PES-MBAE nanocomposites were evaluated. The results showed that with the incorporation of PES, although the toughness of the material improved, the heat resistance and dielectric properties of material declined, meanwhile. The adulteration of SCE-Al2O3could remedy the harmful effect caused by PES, while the content of SCE-Al2O3was reasonable. The decomposition temperature, dielectric constant, and dielectric loss of composite were 441.23°C, 3.63 (100 Hz), and 1.52 × 10−3(100 Hz); the bending strength and impact strength were 129.22 MPa and 13.19 kJ/mm2, respectively, when the content of SCE-Al2O3was 3 wt% and PES was 5 wt%.

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