scholarly journals Microwave Dielectric Properties of CCTO/PVA Composites

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
M. P. F. Graça ◽  
K. D. A. Sabóia ◽  
F. Amaral ◽  
L. C. Costa
Keyword(s):  
Complex Permittivity ◽  
Effective Medium Theory ◽  
Ceramic Powder ◽  
Microwave Dielectric Properties ◽  
Weight Fraction ◽  
Dielectric Behavior ◽  
X Ray Diffraction ◽  
Medium Theory ◽  
Classical Models ◽  
High Dielectric

The CaCu3Ti4O12 (CCTO) ceramic powder was inserted in the polyvinyl alcohol (PVA) polymeric matrix, with an increasing weight fraction of the filler, to form a flexible and high dielectric constant composite at the GHz region. The structural characterization of the samples was performed using X-ray diffraction and scanning electron microscopy (SEM). The complex permittivity was calculated by the small perturbation theory using two resonant cavities (2.7 GHz and 5.0 GHz). Several classical models (Maxwell Garnett, Lichtenecker, effective medium theory (EMT), and Yamada) were used to fit the real part of the complex permittivity of the composite as a function of the weight fraction of CCTO powder inserted in the PVA matrix. The best predictions for the dielectric behavior of these samples were obtained with the EMT and Yamada models.

scholarly journals Structural, optical and microwave dielectric properties of Ba(Ti1−xSnx)4O9, 0 ≤ x ≤ 0.7 ceramics

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Asad Ali ◽  
Sarir Uddin ◽  
Madan Lal ◽  
Abid Zaman ◽  
Zafar Iqbal ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Orthorhombic Symmetry ◽  
X Ray Diffraction ◽  
Low Dielectric ◽  
Microwave Dielectric ◽  
Ceramic Samples ◽  
Red Color ◽  
High Dielectric ◽  
Quality Factor Q

AbstractSn-doped BaTi4O9 (BT4) dielectric ceramics were prepared by a mixed oxide route. Preliminary X-ray diffraction (XRD) structural study shows that the ceramic samples have orthorhombic symmetry with space group (Pnmm). Scanning electron microscopy (SEM) shows that the grain size of the samples decreases with an increase in Sn4+ content. The presence of the metal oxide efficient group was revealed by Fourier transform infrared (FTIR) spectroscopy. The photoluminescence spectra of the ceramic samples reported red color ~ 603, 604, 606.5 and 605 nm with excitation energy ~ 2.06, 2.05, 2.04 and 2.05 eV for Sn4+ content with x = 0.0, 0.3, 0.5, and 0.7, respectively. The microwave dielectric properties of these ceramic samples were investigated by an impedance analyzer. The excellent microwave dielectric properties i.e. high dielectric constant (εr = 57.29), high-quality factor (Qf = 11,852), or low-dielectric loss (3.007) has been observed.

Microwave dielectric properties of MO–La2O3–TiO2 (M = Ca, Sr, Ba) ceramics

2002 ◽  
Vol 17 (12) ◽  
pp. 3084-3089 ◽  
Author(s):  
Isuhak Naseemabeevi Jawahar ◽  
Narayana Iyer Santha ◽  
Mailadil Thomas Sebastian ◽  
Pezholil Mohanan
Keyword(s):  
Dielectric Properties ◽  
Single Phase ◽  
Microwave Dielectric Properties ◽  
Quality Factors ◽  
X Ray Diffraction ◽  
Microwave Dielectric ◽  
Narrow Bandwidth ◽  
Polycrystalline Ceramics ◽  
State Ceramic ◽  
High Dielectric

Single-phase polycrystalline ceramics in the MO–La2O3–TiO2 (M = Ca, Sr, Ba) system, such as cation-deficient hexagonal perovskites CaLa4Ti4O15, SrLa4Ti4O15, BaLa4Ti4O15, and Ca2La4Ti5O18 and the orthorhombic phases CaLa4Ti5O17 and CaLa8Ti9O31, were prepared through the solid-state ceramic route. The phases and structure of the ceramics were analyzed through x-ray diffraction and scanning electron microscopy. The microwave dielectric properties of the ceramics were studied using a network analyzer. The investigated ceramics show high εr in the range 42 to 54, high quality factors with Q ×f in the range 16,222 to 50,215 GHz, and low Tf in the range –25 to +6 ppm / °C. These high dielectric constant materials with high Q × f up to 50,215 GHz are suitable for applications where narrow bandwidth and extremely low insertion loss is necessary, especially at frequencies around 1.9 GHz.

Electrical Properties of (1–x)(0.8PMN-0.2PNN)-xPT Ceramics near the Morphotropic Phase Boundary

2007 ◽  
Vol 336-338 ◽  
pp. 18-20
Author(s):  
Guo Yuan Zhou ◽  
Jin Song Pan ◽  
Xiao Wen Zhang
Keyword(s):  
Phase Boundary ◽  
Morphotropic Phase Boundary ◽  
Piezoelectric Properties ◽  
Dielectric Behavior ◽  
Dielectric Constants ◽  
Ferroelectric Ceramics ◽  
X Ray Diffraction ◽  
Precursor Method ◽  
High Dielectric ◽  
Columbite Precursor

Ferroelectric ceramics of (1x)(0.8PMN0.2PNN)xPT (x = 0.280.43) were synthesized by the columbite precursor method. Their phase structures as well as the dielectric, ferroelectric and piezoelectric properties were investigated. X-ray diffraction (XRD) results demonstrate that the morphotropic phase boundary (MPB) of this system lies in the composition range of x = 0.31–0.37. Examination of the dielectric behavior indicates that the ceramics exhibit high dielectric constants near the MPB compositions. In addition, the piezoelectric properties of the ceramics were found quite well around the MPB. The interrelated mechanism was also discussed.

Y-Doping Effects on the Dielectric Behavior of RF-Sputtered BST Thin Films

2004 ◽  
Vol 833 ◽  
Author(s):  
Ruey-Ven Wang ◽  
Paul C. McIntyre ◽  
John D. Baniecki ◽  
Kenji Nomura ◽  
Takeshi Shioga ◽  
...  
Keyword(s):  
Thin Films ◽  
Inductively Coupled Plasma ◽  
Strain Analysis ◽  
Deposition Process ◽  
Dielectric Behavior ◽  
X Ray Diffraction ◽  
Bst Thin Films ◽  
Inductively Coupled ◽  
Doping Effects ◽  
High Dielectric

AbstractHigh dielectric constant, perovskite-structure materials, such as barium strontium titanate (BST), have been widely investigated for use in GHz LSI decoupling capacitor applications. In addition to modifying deposition process parameters, such as increasing deposition temperature, doping may be a viable way to increase permittivity and tunability in BST thin films without increasing the thermal budget. In this research, the effects of Y dopants on the dielectric behavior of RF-sputtered BST thin films have been systematically investigated. The BST thin films were deposited using ceramic targets with different compositions of yttrium oxide dopant. With Y-doping concentration of ∼ 1.3 at.%, the permittivity at around zero electrical fields can be increased by more than 70% compared to nominally undoped BST thin films produced under the same deposition conditions. Based on x-ray diffraction strain analysis and inductively-coupled plasma composition measurements, the correlations among the dopant composition, BST film elastic strain and dielectric behavior have been systematically studied.

Consistent modeling of the electrical and elastic properties of sedimentary rocks

Geophysics ◽  
1991 ◽  
Vol 56 (8) ◽  
pp. 1236-1243 ◽  
Author(s):  
Ping Sheng
Keyword(s):  
Effective Medium Theory ◽  
Sedimentary Rocks ◽  
Fluid Phase ◽  
Compressional Wave ◽  
Effective Medium ◽  
Dielectric Behavior ◽  
Unified Framework ◽  
Medium Theory ◽  
Archie’S Law ◽  
Component Material

An effective medium theory is formulated which reproduces many of the observed electrical and elastic characteristics of sedimentary rocks within a unified framework. The effective medium consists of fluid, solid, and cement components, with the component material properties related to those of the composite through a differential effective medium (DEM) scheme. The resulting microstructure of the composite both conducts electricity through the fluid phase and supports shear. Besides deriving Archie’s law, the theory gives an excellent account of the shear‐wave and compressional‐wave velocity correlations, and predicts corrections to the Wyllie equation that are consistent with observed deviations. The three‐component DEM also accommodates clay conductivity and finite‐frequency dielectric behavior.

scholarly journals Effective Medium Theory for Multi-Component Materials Based on Iterative Method

Photonics ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 113
Author(s):  
Ravshanjon Nazarov ◽  
Tianmiao Zhang ◽  
Mikhail Khodzitsky
Keyword(s):  
Composite Materials ◽  
Dielectric Properties ◽  
Iterative Method ◽  
Complex Permittivity ◽  
Biomedical Applications ◽  
Effective Medium Theory ◽  
Effective Medium ◽  
Medium Theory ◽  
Terahertz Band ◽  
Relative Errors

For biomedical applications in the terahertz band, composites such as macromolecule compounds, biotissues and phantoms are studied. A description of dielectric properties of composite materials using mathematical models has its own fundamental and technological importance. In this work, we present an iterative effective medium theory for multi-component materials. The model has good performance in describing composite materials with more than two components. The theory is evaluated by comparing with the complex permittivity of three different composite materials. A comparison with other commonly used models is given in the form of relative errors.

scholarly journals Thermal conductivity of silicone elastomer with a porous alumina continuum

e-Polymers ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 845-853
Author(s):  
Qichao Song ◽  
Bo Wang ◽  
Zhiyu Han ◽  
Zhidong Han
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Effective Medium Theory ◽  
Porous Alumina ◽  
Theoretical Models ◽  
Silicone Elastomer ◽  
Interfacial Thermal Resistance ◽  
X Ray Diffraction ◽  
Medium Theory ◽  
Gel Casting

Abstract In this paper, porous alumina continuum (PAC) was prepared with alumina powders (APs) by the gel-casting method and was applied to obtain silicone elastomer (SR) composites (PAC/SR) by the impregnating process. The structure was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influences of PAC on thermal conductivity and dielectric permittivity of PAC/SR composites were studied in comparison with AP/SR composites. When the alumina content was 14 vol%, the thermal conductivity of the PAC/SR composites reached 0.84 W·(m·K)−1, which was 3.1 times higher than that of the AP/SR composites. The thermal conductivity of PAC/SR and AP/SR was simulated by theoretical models, and the interfacial thermal resistance was calculated by effective medium theory, which indicated the advantages of PAC in enhancing the thermal conductivity of SR-based composites and the reduced interfacial thermal resistance between PAC and SR.

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