Dielectric Properties of Hot-Pressed of SiCN/A3S2 Nanocomposites

2007 ◽  
Vol 334-335 ◽  
pp. 697-700 ◽  
Author(s):  
Fa Luo ◽  
Dong Mei Zhu ◽  
San Tuan Zhao ◽  
Wan Cheng Zhou
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Sintering Temperature ◽  
Dissipation Factor ◽  
Saed Pattern ◽  
Pressing Method ◽  
The Real ◽  
X Band ◽  
Higher Temperature ◽  
High Dielectric

A series of nanocomposites, SiCN/A3S2 ceramics, were prepared by hot-pressing method. The nanometer SiCN powder is characterized of high dielectric dissipation. The dielectric properties of the SiCN/A3S2 nanocomposites were investigated. XRD and SEM were conducted to study the phases and microstructure of the nanocomposites. Compared with the pure A3S2 ceramic, the grain size in the nanocomposites is reduced due to the addition of nanometer SiCN powder. The relative densities of the nanocomposites are also lower than that of the pure A3S2 ceramic. Both the real and imaginary parts of the complex permittivity of nanocomposites in X band increase as the content of SCN powder in the samples rises obviously. When the contents of SiCN powder in samples are same, the real and imaginary parts of the samples vary with the sintering temperature. The tanδ of the nanocomposites reduces from 1.9 to 1.4 when sintering temperature increases from 1450OC to 1650 OC. SAED pattern reveals that structure of the SiCN in SiCN/ A3S2 sintered at higher temperatures tend to crystallize. The real, imaginary parts and dissipation factor of the nanocomposites sintered at higher temperature is lower than those sintered at 1450 °C.

The Effects of Sintering Temperature on the Dielectric Properties of Sr(FeNb)0.5O3 Doped with Ba(Zr0.25Ti0.75)O3

2016 ◽  
Vol 675-676 ◽  
pp. 651-654
Author(s):  
Lalita Tawee ◽  
Kachaporn Sanjoom ◽  
Thanatep Phatungthane ◽  
Tawee Tunkasiri ◽  
Gobwute Rujijanagul ◽  
...  
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Solid State ◽  
Wide Temperature Range ◽  
Solid State Reaction ◽  
Sintering Temperature ◽  
Dielectric Constants ◽  
Solid State Reaction Technique ◽  
Cubic Symmetry ◽  
High Dielectric

In this work, ceramics of Sr(Fe0.5Nb0.5O3) doped with Ba(Zr0.25Ti0.75)O3 (10 mol%), were synthesized by a solid-state reaction technique. The powders were calcined at 1300 °C for 12 hr and then sintered at 1400-1500 °C for 4 hr. Effects of sintering temperature on the properties of the ceramic were studied. Phase formation, microstructure, and dielectric properties were investigated. The ceramics exhibited a perovskite structure with cubic symmetry. Grain size of the ceramics increased with increasing the sintering temperature. The ceramics exhibited a dielectric relaxation like behavior with high dielectric constants over a wide temperature range

scholarly journals Snow dielectric properties: from DC to microwave X-band

1994 ◽  
Vol 19 ◽  
pp. 92-96 ◽  
Author(s):  
TH. Achammer ◽  
A. Denoth
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Frequency Range ◽  
Snow Density ◽  
Cold Room ◽  
X Band ◽  
Grain Size And Shape

Broadband measurements of dielectric properties of natural snow samples near or at 0°C are reported. Measurement quantities are: dielectric permittivity, loss factor and complex propagation factor for electromagnetic waves. X-band measurements were made in a cold room in the laboratory; measurements at low and intermediate frequencies were carried out both in the field (Stubai Alps, 3300 m; Hafelekar near Innsbruck, 2100 m) and in the cold room. Results show that in the different frequency ranges the relative effect on snow dielectric properties of the parameters: density, grain-size and shape, liquid water content, shape and distribution of liquid inclusions and content of impurities, varies significantly. In the low-frequency range the influence of grain-size and shape and snow density dominates; in the medium-frequency range liquid water content and density are the dominant parameters. In the microwave X-band the influence of the amount, shape and distribution of liquid inclusions and snow density is more important than that of the remaining parameters.

scholarly journals Effect of Sintering Temperature on the Microstructure, Electrical and Magnetotransport Properties of La0.67Sr0.33MnO3 Compound

2014 ◽  
Vol 895 ◽  
pp. 319-322
Author(s):  
Lim Kean Pah ◽  
Abdul Halim Shaari ◽  
Chen Soo Kien ◽  
Chin Hui Wei ◽  
Albert Gan ◽  
...  
Keyword(s):  
Grain Size ◽  
Single Phase ◽  
Sintering Temperature ◽  
Measurement Range ◽  
Hexagonal Structure ◽  
Precipitation Method ◽  
Metal Insulator ◽  
Higher Temperature ◽  
Co Precipitation ◽  
Grain Surface

In this work, we report the effect of sintering temperature (900°C, 1000°C, 1100°C and 1200°C) on the electrical and magnetotransport properties of polycrystalline La0.67Sr0.33MnO3 (LSMO). Single phase of LSMO hexagonal structure (R-3c) accompanied with minor phases was successfully synthesized by co-precipitation method. With increasing sintering temperature, grain growth was promoted and grain connectivity was improved. It was found that an enhancement of resistivity on smaller grain size was due to larger grain surface over volume (grain boundaries effect). The shifting of the metal-insulator transition (TMI) to higher temperature was also responsible for observed changes in physical properties. TMI of 900°C, 1000°C and 1100°C were 232 K, 278 K and 298 K respectively however 1200°C was out of measurement range (higher than 300 K). In summary, CP900 with smaller grain size distribution (~200 nm) displayed the highest resistivity and MR% of -19.2% (at 80 K, 10 kG).

Effect of Sintering Temperature on Structure and Dielectric Properties of Lead Free K0.5Na0.5NbO3 Prepared via Hot Isostatic Pressing

2017 ◽  
Vol 888 ◽  
pp. 42-46 ◽  
Author(s):  
Fatin Khairah Bahanurdin ◽  
Julie Juliewatty Mohamed ◽  
Zainal Arifin Ahmad
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Hot Isostatic Pressing ◽  
Solid State Reaction Method ◽  
Lead Free ◽  
Tangent Loss ◽  
Isostatic Pressing ◽  
Tan Δ

In this research, alkaline niobate known as K0.5Na0.5NbO3 (KNN) lead-free piezoelectric ceramic was synthesis by solid state reaction method which pressing at different sintering temperatures (1000 °C and 1080 °C) prepared via hot isostatic pressing (HIP)). The effect of sintering temperature on structure and dielectric properties was studied. The optimum sintering temperature (at 1080 °C for 30 minutes) using hot isostatic pressing (HIP) was successfully increase the density, enlarge the particle grain size in the range of 0.3 µm – 2.5 µm and improves the dielectric properties of K0.5Na0.5NbO3 ceramics. The larger grain size and higher density ceramics body will contribute the good dielectric properties. At room temperature, the excellent relative permittivity and tangent loss recorded at 1 MHz (ɛr = 5517.35 and tan δ = 0.954), respectively for KNN1080HIP sample. The KNN1080HIP sample is also exhibits highest relative density which is 4.485 g/cm3. The ɛr depends upon density and in this work, the density increase as the sintering temperature increase, which resulting the corresponding ɛr value also increases.

HIGH DIELECTRIC PROPERTIES OF LOW-TEMPERATURE SINTERED (Ca0.5Cu0.5)TiO3 CERAMICS

2011 ◽  
Vol 01 (02) ◽  
pp. 203-207 ◽  
Author(s):  
JIAN-CONG YUAN ◽  
YUAN-HUA LIN ◽  
BO CHENG ◽  
CE-WEN NAN
Keyword(s):  
Dielectric Properties ◽  
Sintering Temperature ◽  
Sol Gel ◽  
Impedance Spectrum ◽  
Dielectric Constants ◽  
Sintering Process ◽  
Remarkable Effect ◽  
High Dielectric Permittivity ◽  
Wide Range ◽  
High Dielectric

High dielectric-permittivity ( Ca0.5Cu0.5)TiO3 -based ceramics have been prepared by a sol-gel method combined with a solid state sintering process. The results indicate that the additives of H3BO3 have a remarkable effect on the sintering temperature, microstructure and dielectric properties. High density ( Ca0.5Cu0.5)TiO3 bulk ceramics can be obtained after sintering at 900°C. The as-sintered ceramics show high dielectric constants (~1000), and low losses (~0.05). The dielectric properties are nearly independent of frequency and temperature in a wide range. The activation energy is calculated as about 0.50 eV by impedance spectrum method.

Sintering characteristics and microwave dielectric properties of 0.5(Ca0.7Nd0.2)TiO3–0.5(Li0.5Nd0.5)TiO3 ceramics with La2O3–B2O3–CaO–P2O5 additive

2021 ◽  
Author(s):  
Jiawen Shi ◽  
Xingyu Chen ◽  
Weijun Zhang ◽  
Haijun Mao ◽  
Fenglin Wang ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
High Dielectric Constant ◽  
Sintering Temperature ◽  
Glass Ceramics ◽  
Microwave Dielectric Properties ◽  
Low Loss ◽  
Sintering Aid ◽  
Microwave Dielectric ◽  
Sintering Characteristics ◽  
High Dielectric

In this paper, the effects of glass-ceramics sintering aid, La2O3–B2O3–CaO–P2O5 (LBCP), on the sinterability, microstructure, and microwave dielectric properties of 0.5(Ca[Formula: see text]Nd[Formula: see text]TiO3–0.5(Li[Formula: see text]Nd[Formula: see text]TiO3 (CNT–LNT) ceramic have been investigated. The results indicated that LBCP glass-ceramics has good wettability to CNT–LNT (contact angle at 980[Formula: see text]C is 31.9[Formula: see text]), and it can be used as an effective sintering aid to reduce the sintering temperature of CNT–LNT ceramic from 1300[Formula: see text]C to 980[Formula: see text]C. LBCP glass-ceramics did not change the main crystal phase (perovskite structure) of the sample, but a small amount of LaBO3 and LaPO4 phases was precipitated. Since the LaBO3 and LaPO4 phases are low-loss phases, it is believed that the crystal phases can improve the dielectric properties of the sample, especially the dielectric loss. The samples with 10 wt.% of glass additive sintered for 4 h at 980[Formula: see text]C exhibit the optimized properties: a high dielectric constant of 80.8 and a [Formula: see text] value of 2031 GHz. The high [Formula: see text] and [Formula: see text] value, coupled with a relatively low sintering temperature, suggest that the optimized compositions have the potential to be used in microwave low-temperature co-fired ceramics applications.

Effects of additives on the microstructure and dielectric properties of Ba2Ti9O20 microwave ceramic

2003 ◽  
Vol 18 (5) ◽  
pp. 1179-1187 ◽  
Author(s):  
Sea-Fue Wang ◽  
Yung-Fu Hsu ◽  
Tzuu-Hsing Ueng ◽  
Chung-Chuang Chiang ◽  
Jinn P. Chu ◽  
...  
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Quality Factor ◽  
Sintering Temperature ◽  
Decomposition Temperature ◽  
Nonstoichiometric Compound ◽  
Microwave Ceramic ◽  
Phase Pure ◽  
Excess Amount ◽  
Evolution Phase

Preparation of dense and phase-pure Ba2Ti9O20 is generally difficult to achieve using a solid-state reaction, due to the presence of several thermodynamically stable compounds in the vicinity of the desired composition. This work investigated the effects of various additives (TiO2, MnO, and ZrO2) on the densification, microstructural evolution, phase stability, and dielectric properties of Ba2Ti9O20. Ceramics with theoretical density of ≥95% were achieved in all cases after sintering at 1300 °C. A pure Ba2Ti9O20 phase was obtained by treating the material with TiO2 additions (≤5.6 wt.%) and sintering at temperatures ranging between 1200 and 1350 °C. Ba2Ti9O20 is a nonstoichiometric compound that can accommodate an excess amount of TiO2. As the temperature was increased, pure Ba2Ti9O20 partially decomposed and formed a mixture of BaTi4O9 and Ba2Ti9O20. The ceramic with excess TiO2 sintered at 1390 °C possessed a higher permittivity and a lower quality factor due to the larger grain size and lower density. For ceramic with the addition of ZrO2 (≤6 wt.%), pure Ba2Ti9O20 phase was obtained after sintering between 1200 and 1390 °C, and the quality factor was improved. The decomposition temperature of the Ba2Ti9O20 phase was greater than 1390 °C. For sintering temperatures ≥1350 °C, the extent of Ba2Ti9O20 phase decreased with MnO additions. As the MnO content reached 0.5 wt.%, only BaTi4O9 and TiO2 phases existed, suggesting a decrease in the decomposition temperature of Ba2Ti9O20 with the addition of MnO. The microwave properties of the ceramics degraded significantly at the sintering temperature of 1390 °C.

Preparation and Microwave Dielectric Properties of xBaZn2Ti4O11-(1-x)BaNd2Ti4O12 Ceramics

2017 ◽  
Vol 726 ◽  
pp. 210-214
Author(s):  
Xu Wang ◽  
Ren Li Fu ◽  
Yue Xu ◽  
Yang Yang ◽  
Jun De Cai ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Solid State Reaction Method ◽  
Phase System ◽  
Microwave Ceramics ◽  
Two Phase ◽  
Microwave Dielectric ◽  
X Band ◽  
High Dielectric

xBaZn2Ti4O11–(1-x)BaNd2Ti4O12 (x = 0.18–0.30) ceramics were prepared by solid-state reaction method and their microwave dielectric properties were investigated with the purpose of finding a microwave ceramics with high dielectric constant (εr), high quality factor (Q×f ) and zero temperature coefficient of resonant frequency (τf).The two phase system BaZn2Ti4O11–BaNd2Ti4O12 affected the unit cell volume and the microstructure, the microwave dielectric properties (εr, Q×f, τf). As increasing x from 0.18 to 0.30, the main phase composition was BaNd2Ti4O12. Therefore, the εr decreased from 64.9 to 60.3 and the Q×f values raised from 11,350GHz to 13,210GHz, and the τf values decreased from 7ppm/° to -5ppm/°.The 0.22BaZn2Ti4O11–0.78BaNd2Ti4O12 ceramics sintered at 1250°C for 4 h displayed the best dielectric constant εr,Q×f and τf, as 63.9, 12380 GHz and-0.1 ppm/° respectively.

Structural and dielectric properties of SrFexTi1-xO3 (x = 0.001, 0.005 and 0.01) ceramics

2013 ◽  
Vol 03 (01) ◽  
pp. 1350006
Author(s):  
Zhanwu Yu ◽  
Peng Shi ◽  
Wei Ren ◽  
Xiaoqing Wu ◽  
Xi Yao
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Leakage Current ◽  
Lattice Constant ◽  
Doping Concentration ◽  
Sintering Temperature ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction

Three different SrFe x Ti 1-x O 3(x = 0.001, x = 0.005, x = 0.01) ceramics were prepared by the conventional solid-state reaction. The crystalline structure, surface morphology and dielectric properties were studied by X-ray diffraction (XRD), scanning electron microscope (SEM) and Agilent 4294A impedance analyzer, respectively. It is shown that both the sintering temperature and doping concentration influence the lattice constant, grain size, dielectric constant and the dielectric loss. When the sintering temperature is higher than 1390°C, the lattice constant, grain size and dielectric constant all decrease with the increase of the doping concentration, except the dielectric loss tangent which shows the opposite trend. Leakage current tests show that the leakage current density falls down with the increase of Fe doping concentration in the given region.

AN INVESTIGATION ON THE DIELECTRIC PROPERTIES OF POLYANILINE-BASED NANOCOMPOSITE

2010 ◽  
Vol 24 (15) ◽  
pp. 1669-1674
Author(s):  
J. JIANG ◽  
L. H. AI
Keyword(s):  
Dielectric Properties ◽  
Imaginary Part ◽  
Complex Permittivity ◽  
Room Temperature ◽  
In Situ Polymerization ◽  
Dissipation Factor ◽  
Frequency Range ◽  
The Real ◽  
Tan Δ

Polyaniline/ LiNi 0.5 Gd 0.08 Fe 1.92 O 4 nanocomposite was synthesized by an in-situ polymerization of aniline in the presence of LiNi 0.5 Gd 0.08 Fe 1.92 O 4 particles. The dielectric properties of the as-prepared polyaniline-based nanocomposite were investigated using an Agilent E4991A RF Impedance/Material Analyzer at room temperature in the frequency range from 1 MHz to 1 GHz. The real (ε') and imaginary part (ε″) of complex permittivity, and dissipation factor ( tan δ) were found to be frequency-dependent, which decreased with increasing of frequency. It was shown that ε', ε″ and tan δ of the nanocomposite were lower than those of pristine polyaniline. In order to investigate the dielectric process in detail, the complex electric modulii derived from the complex permittivity were analyzed as a function of the frequency.

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