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Chengliang Huang - One of the best experts on this subject based on the ideXlab platform.
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high q microwave dielectric Ceramics in the li2 zn1 xax ti3o8 a mg co x 0 02 0 1 System
Journal of the American Ceramic Society, 2011Co-Authors: Chengliang Huang, Chung Min ChangAbstract:Using a conventional solid-state reaction, followed by sintering at 1080°C–1200°C Li2(Zn1−xAx)Ti3O8 (A = Mg, Co and x = 0.02–0.1) Ceramic System with >96% density were prepared. The XRD patterns of the sintered samples revealed single-phase formation with a cubic crystal symmetry. The molecular volume shows good linear relationship with x value. The microwave dielectric properties of Li2(Zn1−xAx)Ti3O8 Ceramics exhibited a significant dependence on the x value and to some extent on the morphology of the specimens. The Li2(Zn0.94Mg0.06)Ti3O8 Ceramics possess er = 26.1, Q × f = 150 000 GHz, and τf = −13.9 ppm/°C, and Li2(Zn0.92Co0.08)Ti3O8 Ceramics show er = 24.7, Q × f = 140 000 GHz, and τf = −13.4 ppm/°C, respectively. It indicates a substantial increase in the Q × f in comparison with that of pure Li2ZnTi3O8. The microwave dielectric properties of these partially substituted Ceramics are reported for the first time.
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high q microwave dielectrics in the mg1 xznx al2o4 x 0 0 1 System
Journal of Alloys and Compounds, 2011Co-Authors: Chengliang Huang, Yu Hua Chien, Chen Yi Tai, Chiyuen HuangAbstract:Abstract The microwave dielectric properties and the microstructures of (Mg1−xZnx)Al2O4 (x = 0–0.1) Ceramic System prepared by the conventional solid-state route were investigated. The forming of spinel-structured (Mg1−xZnx)Al2O4 (x = 0–0.1) solid solutions was confirmed by the XRD patterns and the measured lattice parameters, which linearly varied from a = b = c = 8.0815 A for MgAl2O4 to a = b = c= 8.0828 A for (Mg0.9Zn0.1)Al2O4. By increasing x, the Q × f of (Mg1−xZnx)Al2O4 can be tremendously boosted from 82,000 GHz at x = 0 to a maximum of 156,000 GHz at x = 0.05. The Zn substitution was effective in reducing the dielectric loss without detrimental effects on the ɛr and τf values of the Ceramics.
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dielectric properties of low loss 1 x mg0 95zn0 05 tio3 xsrtio3 Ceramic System at microwave frequency
Journal of the American Ceramic Society, 2007Co-Authors: Chengliang Huang, Junjie Wang, Yupin ChangAbstract:The microstructures and the microwave dielectric properties of the (1-x)(Mg 0.95 Zn 0.05 )TiO 3 -xSrTiO 3 Ceramic System were investigated. (Mg 0.95 Zn 0.05 )TiO 3 possesses high dielectric constant (e r ∼17.05), high quality factor (Qx f value∼264000 at 9 GHz), and negative τ f value (-40.31 ppm/°C). In order to achieve a temperature-stable material, SrTiO 3 , having a large positive τ f value of 1700 ppm/°C, was added to (Mg 0.95 Zn 0.05 )TiO 3 . Two-phase System was confirmed by the X-ray diffraction patterns and the measured lattice parameters. Evaporation of Zn occurred at temperatures higher than 1300°C and caused an increase in the dielectric loss of the System. As the x value varies from 0 to 0.1, (1-x)(Mg 0.95 Zn 0.05 )TiO 3 -xSrTiO 3 Ceramic System has the dielectric properties as follows: 17.05
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liquid phase sintering of mgtio3 catio3 microwave dielectric Ceramics
Materials Chemistry and Physics, 2003Co-Authors: Chengliang Huang, Shen Jiunn ShiumAbstract:Abstract The effects of CuO additive on the microstructures, the phase formation and the microwave dielectric properties of MgTiO 3 –CaTiO 3 Ceramics were investigated. The sintering temperature of CuO-doped 0.95MgTiO 3 –0.05CaTiO 3 (95MCT) Ceramics can be lowered to 1275 °C due to the liquid phase effect. The microwave dielectric properties are found strongly correlate with the sintering temperature as well as the amount of CuO addition. At 1275 °C, 0.95MgTiO 3 –0.05CaTiO 3 Ceramics with 0.25 wt.% CuO addition possesses a dielectric constant e r of 20, a Q × f value of 51 000 (at 7 GHz) and a τ f value of −8.3 ppm °C −1 . By appropriately adjusting the x value in the (1− x )MgTiO 3 – x CaTiO 3 Ceramic System, zero τ f value can be obtained.
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improved high q value of catio3 ca mg1 3nb2 3 o3 solid solution with near zero temperature coefficient of resonant frequency
Materials Research Bulletin, 2001Co-Authors: Chengliang Huang, Hui Liang Chen, Chen Cher WuAbstract:Abstract The crystal structures and the microwave dielectric properties of (1−x)CaTiO 3 –xCa(Mg 1/3 Nb 2/3 )O 3 perovskite Ceramic System have been investigated. (1−x)CaTiO 3 –xCa(Mg 1/3 Nb 2/3 )O 3 solid solution exhibited orthorhombic crystal structures for all compositions. With x = 0.66, a new microwave dielectric Ceramic material 0.34CaTiO 3 –0.66Ca(Mg 1/3 Nb 2/3 )O 3 applicable to microwave devices is suggested and possesses the dielectric properties of a dielectric constant e r ∼ 48, a Q×f values ∼ 32,500 (at 6.7 GHz) and a τ f value ∼−2 ppm/°C at 1450°C for 3 h. Further improvement of the Q×f value can be achieved by extending the sintering time to 6 h. It reveals a higher Q×f value of 34,000 (at 6.7 GHz) without degrading other microwave dielectric properties of 0.34CaTiO 3 –0.66Ca(Mg 1/3 Nb 2/3 )O 3 Ceramics.
Steven J Milne - One of the best experts on this subject based on the ideXlab platform.
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low variation in relative permittivity over the temperature range 25 450 c for Ceramics in the System 1 x ba0 8ca0 2tio3 x bi zn0 5ti0 5 o3
Journal of The European Ceramic Society, 2014Co-Authors: Steven J MilneAbstract:Abstract The dielectric and ferroelectric properties of the Ceramic System, (1 − x )Ba 0.8 Ca 0.2 TiO 3 – x Bi(Zn 0.5 Ti 0.5 )O 3 , were investigated for compositions 0 ≤ x ≤ 0.4. X-ray powder diffraction patterns indicated tetragonal symmetry at x ≤ 0.05, switching to pseudocubic at x ≥ 0.1, with a single-phase solid solution limit at 0.2 x x = 0 and 0.05 samples were ferroelectric; a change to relaxor behaviour occurred at x ≥ 0.1, with broad frequency dependent peaks in plots of relative permittivity versus temperature. A significant reduction in the temperature dependence of relative permittivity occurred at x = 0.3, with ɛ r = 1030 ± 15% over the temperature range ∼25–425 °C, and loss tangent, tan δ ≤ 0.01 from 110 °C to 420 °C. The dc resistivity values for x = 0.3 were ∼10 9 Ω m at 300 °C and ∼10 6 Ω m at 450 °C.
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low variation in relative permittivity over the temperature range 25 450 c for Ceramics in the System 1 x ba0 8ca0 2tio3 x bi zn0 5ti0 5 o3
Journal of The European Ceramic Society, 2014Co-Authors: Aurang Zeb, Steven J MilneAbstract:Abstract The dielectric and ferroelectric properties of the Ceramic System, (1 − x)Ba0.8Ca0.2TiO3–xBi(Zn0.5Ti0.5)O3, were investigated for compositions 0 ≤ x ≤ 0.4. X-ray powder diffraction patterns indicated tetragonal symmetry at x ≤ 0.05, switching to pseudocubic at x ≥ 0.1, with a single-phase solid solution limit at 0.2
Liang Fang - One of the best experts on this subject based on the ideXlab platform.
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k0 5na0 5 nbo3 bi zn0 5zr0 5 o3 perovskite Ceramics high relative permittivity low dielectric loss and good thermal stability
Ceramics International, 2015Co-Authors: Xiuli Chen, Guisheng Huang, Jie Chen, Liang FangAbstract:Abstract A novel lead-free perovskite Ceramic System with the composition of (1− x )(K 0.5 Na 0.5 )NbO 3 – x Bi(Zn 0.5 Zr 0.5 )O 3 [(1− x )KNN– x BZZ, x =0–0.02] was developed. The effects of BZZ addition on the phase transition, microstructure and dielectric performances of KNN Ceramic were Systematically investigated. The BZZ addition can significantly enhance the relative permittivity and thermal stability of permittivity of Ceramics below the Curie temperature. When x =0.015, the Ceramic possessed the optimized dielectric performance with small Δ e / e 115 °C value (≤±15%) and relatively high permittivity (~1500) over the temperature range from 115 to 343 °C. Moreover, the dielectric loss was dramatically reduced below 4.5% from room temperature to ~544 °C, which suggests that this Ceramic is a candidate for high-temperature capacitor application.
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thermally stable batio3 bi mg2 3nb1 3 o3 solid solution with high relative permittivity in a broad temperature usage range
Journal of the American Ceramic Society, 2015Co-Authors: Xiuli Chen, Jie Chen, Liang FangAbstract:A combined X-ray diffraction (XRD), Raman spectra, X-ray photoelectron spectroscopy, Scanning electron microscopy, and dielectric characterization of (1–x)BaTiO3−xBi(Mg2/3Nb1/3)O3 Ceramic System were investigated for compositions of 0 ≤ x ≤ 0.2. Single-phase perovskite-type XRD patterns were observed for all compositions. A Systematically structural change from tetragonal to pseudocubic symmetry occurred at 0.04 Tm significantly ameliorated at x = 0.1: near-stable temperature coefficient of higher relative permittivity (~6800 ± 15%) and the corresponding loss tanδ ≤ 0.09 over a more broader temperature range of 25°C–240°C (1 kHz), which indicates that this Ceramic is a promising dielectric material for elevated temperature dielectrics.
Xiuli Chen - One of the best experts on this subject based on the ideXlab platform.
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k0 5na0 5 nbo3 bi zn0 5zr0 5 o3 perovskite Ceramics high relative permittivity low dielectric loss and good thermal stability
Ceramics International, 2015Co-Authors: Xiuli Chen, Guisheng Huang, Jie Chen, Liang FangAbstract:Abstract A novel lead-free perovskite Ceramic System with the composition of (1− x )(K 0.5 Na 0.5 )NbO 3 – x Bi(Zn 0.5 Zr 0.5 )O 3 [(1− x )KNN– x BZZ, x =0–0.02] was developed. The effects of BZZ addition on the phase transition, microstructure and dielectric performances of KNN Ceramic were Systematically investigated. The BZZ addition can significantly enhance the relative permittivity and thermal stability of permittivity of Ceramics below the Curie temperature. When x =0.015, the Ceramic possessed the optimized dielectric performance with small Δ e / e 115 °C value (≤±15%) and relatively high permittivity (~1500) over the temperature range from 115 to 343 °C. Moreover, the dielectric loss was dramatically reduced below 4.5% from room temperature to ~544 °C, which suggests that this Ceramic is a candidate for high-temperature capacitor application.
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thermally stable batio3 bi mg2 3nb1 3 o3 solid solution with high relative permittivity in a broad temperature usage range
Journal of the American Ceramic Society, 2015Co-Authors: Xiuli Chen, Jie Chen, Liang FangAbstract:A combined X-ray diffraction (XRD), Raman spectra, X-ray photoelectron spectroscopy, Scanning electron microscopy, and dielectric characterization of (1–x)BaTiO3−xBi(Mg2/3Nb1/3)O3 Ceramic System were investigated for compositions of 0 ≤ x ≤ 0.2. Single-phase perovskite-type XRD patterns were observed for all compositions. A Systematically structural change from tetragonal to pseudocubic symmetry occurred at 0.04 Tm significantly ameliorated at x = 0.1: near-stable temperature coefficient of higher relative permittivity (~6800 ± 15%) and the corresponding loss tanδ ≤ 0.09 over a more broader temperature range of 25°C–240°C (1 kHz), which indicates that this Ceramic is a promising dielectric material for elevated temperature dielectrics.
O P Thakur - One of the best experts on this subject based on the ideXlab platform.
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effect of neodymium substitution on structural and ferroelectric properties of bnt Ceramics
Materials Research Bulletin, 2014Co-Authors: R K Dwivedi, O P ThakurAbstract:Abstract Polycrystalline specimens of (Bi 1− x Nd x ) 0.5 Na 0.5 TiO 3 (BNNT) Ceramic System with compositions x ≤ 0.04 were synthesized by semi-wet technique using ethylene glycol precursor. Structural and electrical properties were investigated in detail to observe the effect of neodymium (Nd) substitution in BNT System. XRD patterns for all the specimens showed single phase formation with rhombohedral structure. Field emission scanning electron micrographs (FE-SEM) revealed that the grain growth was inhibited significantly with Nd content. The temperature dependence behaviour of dielectric constant revealed that the depolarisation temperature ‘ T d ’ decreases whereas temperature of maximum dielectric constant ‘ T m ’ increases with Nd concentration. The piezoelectric charge coefficient (d 33 ) showed maxima at x = 0.02 and well defined ferroelectric behaviour was observed for all the samples.
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synthesis and ferroelectric behavior of gd doped bnt Ceramics
Current Applied Physics, 2014Co-Authors: Vijayeta Pal, R K Dwivedi, O P ThakurAbstract:Abstract In the present work, polycrystalline (Bi 1− x Gd x ) 0.5 Na 0.5 TiO 3 (BGNT) Ceramics with low amount of rare earth ion Gd 3+ ( x = 0, 0.02, 0.03, 0.04) have been synthesized by a semi–wet technique. XRD patterns show single phase formation for all the samples with a rhombohedral structure at room temperature. FE-SEM images show decrease in grain size with Gd concentration. The temperature dependence of dielectric constant has revealed that the depolarization temperature ‘ T d ’ decreases with increasing x and the temperature ‘ T m ’ of maximum dielectric constant increases initially for x = 0.02 thereafter decreases. All the samples have shown saturated hysteresis ( P – E ) loop at room temperature. The BGNT Ceramic System for composition, x = 0.02 exhibits improved piezoelectric properties and strong ferroelectricity. With increasing temperature, polarization has been found to be reduced and deformed P – E loops are observed around ‘ T d ’.
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structure and electrical properties of li and ta substituted k0 5na0 5nbo3 lead free piezoelectric Ceramics prepared from nanopowders
Journal of Alloys and Compounds, 2010Co-Authors: Chandramani K Singh, Chongtham Jiten, Radhapiyari Laishram, O P Thakur, D K BhattacharyaAbstract:Abstract Nanopowders of the lead-free Ceramic System (K 0.5− x Li x Na 0.5 )(Nb 0.9 Ta 0.1 )O 3 (KNN) with x = 0, 0.015, 0.045, and 0.060 have been synthesized by conventional solid state reaction followed by high-energy ball milling. The average particle size of all the milled powders as determined from the TEM analysis was about 35 nm. These powders were sintered at 1050 °C for 4 h. Analysis of all the Ceramic samples using X-ray diffraction method showed single-phase perovskite structure with orthorhombic symmetry. The effects of the Li substitution on the structural, dielectric, and ferroelectric properties of the Ceramics were Systematically studied. Without any sintering aid such as ZnO, MnO 2 and CuO, densities ≥95% of the theoretical density of the KNN Ceramics has been achieved. The SEM analysis of fractured surfaces of the Ceramics indicates that the fractures occur mostly within the grains. An increase in Li substitution in the KNN Ceramics produced an increase in the Curie temperature ( T c ) and a decrease in the coercive field ( E c ). In the range of Li contents studied, the sample with x = 0.015 possessed the highest values in the density, orthorhombic–tetragonal transition temperature ( T ot ), dielectric constant ( ɛ ′), and remnant polarization (Pr).
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ferroelectric relaxor behaviour and impedance spectroscopy of bi2o3 doped barium zirconium titanate Ceramics
Journal of Physics D, 2009Co-Authors: O P Thakur, D K Bhattacharya, Sandeep Mahajan, K SreenivasAbstract:Bi2O3-doped barium zirconate titanate Ceramics, Ba1−xBix(Zr0.05Ti0.95)O3, have been prepared by the conventional solid-state reaction method. The ferroelectric relaxor behaviour and dielectric properties have been investigated in detail. By XRD analysis, it is suggested that up to x = 0.04, Bi3+ substitutes A-site ion, and thereafter with higher Bi3+ content, it enters the B-site sub lattice. Substitution of Bi3+ ions induces ferroelectric relaxor behaviour and the degree of relaxation behaviour increases with bismuth concentration. The remanent polarization and strain behaviour show a slight increase with the substitution level. The degree of hysteresis (strain versus electric field) also reduces from 21.4% to 4.6% with bismuth substitution. Impedance measurements were made on the prepared sample over a wide range of temperatures (300–723 K) and frequencies (40 Hz–1 MHz), which show the presence of both bulk and grain boundary effects in the material. The bulk and grain boundary conductivities determined from impedance study indicate the Arrhenius-type thermally activated process. Impedance spectroscopy is shown to be an efficient method capable of detecting the contributions of the resistances of grains and grain boundaries to the complex impedance of a Ceramic System, accurately estimating its electrical conductivity as well as its corresponding activation energies and drawing conclusions on its structural properties.