scholarly journals Insights Into the Microstructure and Dielectric Properties of Cold Sintered NaCa2Mg2V3O12 Based Composites

2021 ◽  
Vol 8 ◽  
Author(s):  
Rakhi Madhuri ◽  
Santha Narayana Iyer ◽  
Subodh Ganesanpotti
Keyword(s):  
Dielectric Properties ◽  
Secondary Phase ◽  
Ceramic Composites ◽  
Sintering Process ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Dielectric ◽  
Dielectric Ceramics ◽  
Quality Factor Q

Cold sintering process (CSP) was successfully employed to fabricate (1 − x) NaCa2Mg2V3O12-xNaCl [abbreviated as (1 − x) NCMVO-xNaCl] microwave dielectric ceramics. (1 − x)NCMVO-xNaCl ceramics prepared at 200°C and at a pressure of 450 MPa had a high relative density of 80–94%. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), and Raman spectroscopy showed that both NCMVO and NaCl phases co-exist in all composite ceramics without forming any secondary phase. Further, dependence of microstructure and dielectric properties on cold sintering temperature and duration were investigated in detail and their optimized values to obtain maximum density of ceramic composites were 200°C and 50 min, respectively. (1 − x)NCMVO-xNaCl (x = 0.4–0.7) composites have relative permittivity (εr) in the range of 6.9–7.4, and a reasonably high microwave quality factor (Q × f) of 5,000 to 13,830 GHz.

Li2ZnTi3O8 Microwave Dielectric Ceramics Prepared by the Reaction-Sintering Process

2015 ◽  
Vol 655 ◽  
pp. 164-167 ◽  
Author(s):  
Xu Sheng Hu ◽  
Guo Guang Yao ◽  
Xiu Lao Tian
Keyword(s):  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Reaction Sintering ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Dielectric ◽  
Pure Phase ◽  
Dielectric Ceramics ◽  
Sintering Method

Li2ZnTi3O8ceramics were prepared by reaction-sintering process (calcination free). The crystal phase and microstructure were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). A pure phase of Li2ZnTi3O8ceramics sintered at 1075 °C-1150 °C with cubic spinel structure was confirmed by XRD. The microwave dielectric properties (εr,Qxf) of Li2ZnTi3O8ceramics were strongly dependent on the densification and grain size. The τfof Li2ZnTi3O8ceramics was almost independent with the sintering temperatures. In particular, Li2ZnTi3O8ceramics by reaction-sintering method sintered at 1125 °C for 5 h exhibited good combination microwave dielectric properties of εr=21.7, Q×f=70 500 GHz (at 7.5 GHz) and τf=-13 ppm/°C.

scholarly journals Phase, microstructure and microwave dielectric properties of Mg0:95Ni0:05Ti0:98Zr0:02O3 ceramics

2015 ◽  
Vol 33 (1) ◽  
pp. 95-99 ◽  
Author(s):  
Abdul Manan ◽  
Dil Nawaz Khan ◽  
Atta Ullah ◽  
Arbab Safeer Ahmad
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
Secondary Phase ◽  
Network Analyzer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Dielectric ◽  
Scanning Electron

AbstractMg0:95Ni0:05Ti0:98Zr0:02O3 ceramics was prepared via conventional solid-state mixed-oxide route. The phase, microstructure and microwave dielectric properties of the sintered samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and a vector network analyzer. The microstructure comprised of circular and elongated plate-like grains. The semi quantitative analysis (EDS) of the circular and elongated grains revealed the existence of Mg0:95Ni0:05T2O5 as a secondary phase along with the parent Mg0:95Ni0:05Ti0:98Zr0:02O3 phase, which was consistent with the XRD findings. In the present study, εr ~17.1, Qufo~195855 ± 2550 GHz and τf ~ -46 ppm/K was achieved for the synthesized Mg0:95Ni0:05Ti0:98Zr0:02O3 ceramics sintered at 1325 °C for 4 h.

Sintering Temperature Influence on Microwave Dielectric Properties of TiO2-ZrO2 Ceramics

2010 ◽  
Vol 660-661 ◽  
pp. 646-651
Author(s):  
José Vitor C. Souza ◽  
Pedro José Castro ◽  
Maria do Carmo de Andrade Nono ◽  
Sergio Luiz Mineiro
Keyword(s):  
Dielectric Properties ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Dielectric Constants ◽  
Dielectric Resonators ◽  
Temperature Influence ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Dielectric ◽  
Dielectric Ceramics

Dielectric ceramics have been widely investigated and used for microwave applications such as resonators and filters. The present study deals with the influence of sintering temperature on microwave dielectric properties of TiO2 ceramics with 10, 20, and 30 wt% ZrO2. Three compositions have been developed through mixing procedures and then tested for each sintering temperature: 1500 and 1400 °C. X-ray diffraction and scanning electron microscopy are carried out aiming to explain the ceramic behavior of each sample. The dielectric constants of different ceramics for both temperatures varied from 85.4 to 62.6, while their quality factor due to dielectric losses varied from 3110 to 1630. The Q decrease is attributed to the non uniform grain growth and to the obtained crystalline phases. The best microwave parameters were obtained for the ceramics sintered at 1400 °C, which can be applied in microwave circuits as dielectric resonators.

Effect of H3BO3 Additive and Forming Pressure on Microwave Dielectric Properties of 0.95MgTiO3-0.05CaTiO3

2014 ◽  
Vol 941-944 ◽  
pp. 521-524
Author(s):  
Jin Bao Huang ◽  
Yi Xiang Cai ◽  
Zhao Xian Xiong ◽  
Hao Xue
Keyword(s):  
Dielectric Properties ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Solid State Reaction Method ◽  
Sintering Process ◽  
Microwave Dielectric ◽  
Method Effect ◽  
Best Value ◽  
Dielectric Ceramics ◽  
Quality Factor Q

0.95MgTiO3-0.05CaTiO3 (95MCT) microwave dielectric ceramics was prepared solid-state reaction method. Effect of H3BO3 additive and forming pressure on sintering process, microstructure and microwave dielectric properties of 95MCT were investigated. The result showed that the additive of H3BO3 can lower the sintering temperature of 95MCT, and improve the densification of 95MCT. MgTi2O5 was found as mesosphere, which can be effectively suppressed through the additive of H3BO3. Excellent microwave dielectric properties of ceramics was obtained when the H3BO3 additive was 0.50wt%. The best value of dielectric constant (εr), quality factor (Q×f) and temperature coefficient of resonant frequency (τf ) of 21.54, 67,286GHz and-4.1ppm/oC was obtained for the ceramics with sintering 1220oC for 2h.

Sinterability and Microwave Dielectric Properties of Li2CO3-V2O5 Added Mg4Nb2O9-CaTiO3 Composite Ceramics

2010 ◽  
Vol 663-665 ◽  
pp. 1196-1199
Author(s):  
Cui Jin Pei ◽  
Guo Guang Yao ◽  
Hong Ma ◽  
Xiu Lao Tian
Keyword(s):  
Dielectric Properties ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Dielectric ◽  
Microscopy Techniques ◽  
Co Doped ◽  
Scanning Electron

The effects of Li2CO3-V2O5 (LV) co-doped on the sinterability, phase compositions and microwave dielectric properties of Mg4Nb2O9-CaTiO3 composite ceramics have been investigated. The phase compositions and microstructure were analyzed using X-ray diffraction, energy dispersive X-ray analysis and scanning electron microscopy techniques. The densification sintering temperature is lowed from 1275oC to 1200oC with an amount LV addition. For the specimen with 1.5 wt% LV addition sintered at 1200oC for 5 h exhibited dielectric properties: εr=23, Q·f=24 000 GHz (at 7.7GHz ), τf =1.0 ppm/oC. These properties were correlated with the formation of non-stoichiometric compound Mg4(Nb1-xTix)2O9-δ.

Structural Evolution and Microwave Dielectric Properties of Ba(Co1/3(Nb1-xW5x/6)2/3)O3 Ceramics

2018 ◽  
Vol 281 ◽  
pp. 585-590
Author(s):  
Zhe Fei Wang ◽  
Chen Yao Zhai ◽  
Xu Hong Wang
Keyword(s):  
Dielectric Properties ◽  
Sintering Temperature ◽  
Structural Evolution ◽  
Microwave Dielectric Properties ◽  
Solid State Reaction Method ◽  
Second Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Dielectric ◽  
Dielectric Ceramics

Ba(Co1/3(Nb1-xW5x/6)2/3)O3 (0<x≤0.05) (BCWN) microwave dielectric ceramics have been prepared by solid-state reaction method. The microstructure and microwave dielectric properties of BCWN ceramics were investigated systematically in this paper. The results show that the sintering temperature decreases with the substitution of W6+. The Ba(Co1/3(Nb1-xW5x/6)2/3)O3 solid solution is formed with the small substitution of W6+ (x≤0.01). With the increase of x, the impurity phase BaWO4 occurrs and the grains become less homogeneous. Combined with the analysis of X-Ray Diffraction, the cation ordering degree on B-site increases in the sample of x=0.01, which leads to the decrease of the dielectric loss. However, the second phase BaWO4 inhibits the formation of the ordered structure with the reduction of sinterability. Due to the formation of BaWO4, the values of εr and τf of all samples decrease subsequently. The optimized microwave dielectric properties of Ba(Co1/3(Nb1-xW5x/6)2/3)O3 ceramics were obtained in the samples of x=0.01: εr=33.8, Q×f =110761 GHz, τf = -17 ppm/°C.

Effect of Li2CO3-V2O5 on the Sintering and Microwave Dielectric Properties of 0.6Mg4Nb2O9-0.4SrTiO3 Composite Ceramics

2010 ◽  
Vol 663-665 ◽  
pp. 608-611
Author(s):  
Cui Jin Pei ◽  
Guo Guang Yao ◽  
Xiu Lao Tian ◽  
Hong Ma
Keyword(s):  
Dielectric Properties ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Solid State Reaction Method ◽  
Composite Ceramics ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray ◽  
Microwave Dielectric ◽  
Co Doped

The effects of Li2CO3-V2O5 (LV) co-doped on the sinterability, phase compositions and microwave dielectric properties of 0.6Mg4Nb2O9-0.4SrTiO3 composite ceramics have been investigated. All specimens were prepared by solid-state reaction method and sintered at 1050-1200oC for 5h. With an amount LV addition, the densification sintering temperature is significantly lowed from 1300oC to 1175oC. The non-stoichiometric compounds Sr(NbTi)O3+δ and Mg4(Nb1-xTix)2O9-δ were confirmed by X-ray diffraction and energy dispersive X-ray analysis. For the specimen with 1.5 wt% LV addition sintered at 1175oC for 5 h exhibited dielectric properties: εr=20.1, Q•f=10 240 GHz, τf =0.15 ppm/oC.

Influences of Pressure Conditions on Synthesis of Mg(Zr0.05Ti0.95)O3 Dielectric Ceramics

2012 ◽  
Vol 430-432 ◽  
pp. 692-695
Author(s):  
Ching Fang Tseng ◽  
Cheng Hsing Hsu ◽  
Ci Jie Huang ◽  
Chun Hung Lai
Keyword(s):  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solid State Route ◽  
Microwave Dielectric ◽  
Dielectric Ceramics ◽  
Microscopy Techniques ◽  
Structure And Microstructure ◽  
Conventional Solid State Route

The microwave dielectric properties and microstructures of an Mg(Zr0.05Ti0.95)O3 ceramic system have been investigated. The compounds were prepared by the conventional solid-state route with various pressure conditions from 25 to 100 Kg/cm2 and sintered at 1420oC for 4 h. The structure and microstructure were analyzed using X-ray diffraction and scanning electron microscopy techniques. The Mg(Zr0.05Ti0.95)O3 had excellent dielectric properties: Q×f ~ 194,000 (GHz), εr ~ 17.9, and τf ~ -43 ppm/oC for the sample at 90 Kg/cm2.

Effect of Pressure Conditions on Characteristics of (Ca0.2Sr0.8)3Ti2O7 Dielectric Ceramics

2013 ◽  
Vol 278-280 ◽  
pp. 377-380
Author(s):  
Hsin Han Tung ◽  
Yu Chuan Chen ◽  
Wen Shiush Chen ◽  
Cheng Hsing Hsu ◽  
Jenn Sen Lin
Keyword(s):  
Dielectric Properties ◽  
Microwave Dielectric Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solid State Route ◽  
Microwave Dielectric ◽  
Dielectric Ceramics ◽  
Microscopy Techniques ◽  
Structure And Microstructure ◽  
Conventional Solid State Route

The microwave dielectric properties of (Ca0.2Sr0.8)3Ti2O7 ceramic system have been investigated with various pressure conditions. The compounds were prepared by the conventional solid-state route with various pressure conditions from 60 to 80 Kg/cm2 and sintered at 1450oC for 4 h. The structure and microstructure were analyzed using X-ray diffraction and scanning electron microscopy techniques. The (Ca0.2Sr0.8)3Ti2O7 had excellent dielectric properties: Q×f ~ 50,000 (GHz) and εr ~ 63.2 for the sample at 70 Kg/cm2.

Temperature-stable microwave dielectric ceramics in the Ca5A2Ti1-xZrxO12 (A = Nb, Ta) system

2004 ◽  
Vol 19 (10) ◽  
pp. 2922-2928 ◽  
Author(s):  
Pazhoor Varghese Bijumon ◽  
Mailadil Thomas Sebastian
Keyword(s):  
Dielectric Properties ◽  
Communication Systems ◽  
Satellite Communication ◽  
Microwave Dielectric Properties ◽  
X Ray Diffraction ◽  
Microwave Frequencies ◽  
X Ray ◽  
Microwave Dielectric ◽  
State Ceramic ◽  
Dielectric Ceramics

Ca5A2Ti1−xZrxO12 (A = Nb, Ta) ceramics were prepared through conventional solid-state ceramic route for 0 ⩽ x ⩽ 1. The crystal structures of the ceramics were studied by x-ray diffraction techniques, and dielectric properties were measured at microwave frequencies. In the Ca5Nb2Ti1−xZrxO12 system as x increases from 0 to 1, ϵr decreases from 48 to 25, Qu× f from 26,000 to 19,000 GHz, and τf from +40 to −21 ppm/°C. In Ca5Ta2Ti1−xZrxO12 ceramics, ϵr varies from 38 to 22, Quxf from 33,000 to 24,000 GHz, and τf from +10 to −26 ppm/°C as x is changed from 0 to 1. The variation of microwave dielectric properties with bond valence and electronegativity in the two systems were also investigated. Ca5Nb2Ti0.2Zr0.8O12 and Ca5Ta2Ti0.7Zr0.3O12 dielectric ceramics were found to have stable resonant frequency with temperature and are potential candidates for applications in personal and satellite communication systems in the S and C band (2–8 GHz).

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