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.

scholarly journals Sintering behaviour and microwave dielectric properties of MgO-2B2O3-xwt%BaCu(B2O5)-ywt%H3BO3 ceramics

2021 ◽  
Author(s):  
Haiquan Wang ◽  
Shixuan Li ◽  
Kangguo Wang ◽  
Xiuli Chen ◽  
Huanfu Zhou
Keyword(s):  
Dielectric Properties ◽  
Bulk Density ◽  
Single Phase ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
X Ray Diffraction ◽  
Microwave Dielectrics ◽  
X Ray ◽  
Microwave Dielectric ◽  
Sintering Behaviour

AbstractThis study investigates the bulk density, sintering behaviour, and microwave dielectric properties of the MgO-2B2O3 series ceramics synthesised by solid-state reaction. According to the X-ray diffraction and microstructural analyses, the as-prepared MgO-2B2O3 ceramics possess a single-phase structure with a rod-like morphology. The effects of different quantities of H3BO3 and BaCu(B2O5) (BCB) on the bulk density, sintering behaviour, and microwave dielectric properties of the MgO-2B2O3 ceramics were investigated. Accordingly, the optimal sintering temperature was obtained by adding 30 wt% H3BO3 and 8 wt% BCB. We also reduced the sintering temperature to 825 °C. Furthermore, the addition of 40 wt% H3BO3 and 4 wt% BCB increased the quality factor, permittivity, and temperature coefficient of resonance frequency of MgO-2B2O3 to 44,306 GHz (at 15 GHz), 5.1, and −32 ppm/°C, respectively. These properties make MgO-2B2O3 a viable low-temperature co-fired ceramic with broad applications in microwave dielectrics.

scholarly journals Effects of (Mg1/3Sb2/3)4+ Substitution on the Structure and Microwave Dielectric Properties of Ce2Zr3x(Mg1/3Sb2/3)3-3x(MoO4)9 Ceramics

2020 ◽  
Author(s):  
Zhou Xu ◽  
Sun Jiajia ◽  
Zhang Ningkang ◽  
Sun Huazhang ◽  
Tao Wenhong ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Single Phase ◽  
Microwave Dielectric Properties ◽  
Far Infrared ◽  
Structural Refinement ◽  
X Ray Diffraction ◽  
Solid State Method ◽  
Microwave Dielectric ◽  
Refinement Method ◽  
Traditional Solid State Method

Abstract Ce2[Zr1-x(Mg1/3Sb2/3)x]3(MoO4)9 (0.02≤x≤0.10) ceramics were prepared well through the traditional solid-state method. A single phase, belonging to the space group of R-3c, was detected by using X-ray diffraction at sintering temperatures ranging from 700 to 850 °C. The crystallization micro-structural of specimens was examined by applying Scanning electron microscopy. The structural refinement of these samples was investigated in detail by performing the Rietveld refinement method. The intrinsic properties were calculated and explored via far-infrared reflectivity spectroscopy. The correlations between the chemical bonds parameters and microwave dielectric properties were calculated and analyzed by P-V-L theory. Ce2[Zr0.94(Mg1/3Sb2/3)0.06]3(MoO4)9 ceramics with excellent dielectric properties: εr = 10.37, Q×f = 71748 GHz and τf = −13.6 ppm/°C sintered at 725 °C for 6 hours.

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 Ba4LaTi0.3Sn0.7Nb3O15 ceramic

2014 ◽  
Vol 28 (15) ◽  
pp. 1450092 ◽  
Author(s):  
Abdul Manan ◽  
Imtiaz Hussain
Keyword(s):  
Dielectric Properties ◽  
Single Phase ◽  
Least Squares Method ◽  
Microwave Dielectric Properties ◽  
Network Analyzer ◽  
X Ray Diffraction ◽  
Microstructural Investigation ◽  
Microwave Frequencies ◽  
Microwave Dielectric ◽  
Lcr Meter

Ba 4 LaTi 0.3 Sn 0.7 O 15 ceramic was prepared through conventional solid state mix oxide route followed by characterization using X-ray diffraction (XRD) and scanning electron microscope (SEM) for phase and microstructural investigation. The dielectric properties at low and microwave frequencies were measured using LCR meter and vector network analyzer. XRD results revealed single phase ceramics and the microstructure was comprised of compact grains with size ranging from 4–12 μm. The lattice parameters refined by the least squares method were a = b = 5.7680(2) Å, c = 11.7491(6) Å, V = 337.81 Å3 and Z = 1. Optimum properties i.e., εr~44.6, Qufo~15, 500 GHz and τf~2.05 ppm /° C were achieved for Ba 4 LaTi 0.3 Sn 0.7 Nb 3 O 15 ceramic sintered at 1475°C for 4 h.

scholarly journals Effects of (Mg1/3Sb2/3)4+ substitution on the structure and microwave dielectric properties of Ce2Zr3(Mg1/3Sb2/3)3-3(MoO4)9 ceramics

2021 ◽  
Author(s):  
Zhou Xu ◽  
Liu Lintao ◽  
Sun Jiajia ◽  
Zhang Ningkang ◽  
Sun Huazhang ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Single Phase ◽  
Microwave Dielectric Properties ◽  
Far Infrared ◽  
Structural Refinement ◽  
X Ray Diffraction ◽  
Solid State Method ◽  
Microwave Dielectric ◽  
Refinement Method ◽  
Traditional Solid State Method

Abstract Ce 2 [Zr 1-x (Mg 1/3 Sb 2/3 ) x ] 3 (MoO 4 ) 9 (0.02≤x≤0.10) ceramics were prepared well through the traditional solid-state method. A single phase, belonging to the space group of R-3c, was detected by using X-ray diffraction at sintering temperatures ranging from 700 to 850 °C. The crystallization micro-structural of specimens was examined by applying Scanning electron microscopy. The structural refinement of these samples was investigated in detail by performing the Rietveld refinement method. The intrinsic properties were calculated and explored via far-infrared reflectivity spectroscopy. The correlations between the chemical bonds parameters and microwave dielectric properties were calculated and analyzed by P-V-L theory. Ce 2 [Zr 0.94 (Mg 1/3 Sb 2/3 ) 0.06 ] 3 (MoO 4 ) 9 ceramics with excellent dielectric properties: ε r = 10.37, Q×f = 71748 GHz and τ f = −13.6 ppm/°C sintered at 725 °C for 6 hours.

scholarly journals Processing and microwave dielectric properties of Sr5Ta4TiO17 ceramics

2018 ◽  
Vol 35 (4) ◽  
pp. 767-772
Author(s):  
Abdul Manan ◽  
Arbab Safeer Ahmad ◽  
Atta Ullah ◽  
Abid A Shah
Keyword(s):  
Dielectric Properties ◽  
Single Phase ◽  
Least Squares Method ◽  
Microwave Dielectric Properties ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Microwave Dielectric ◽  
Average Size ◽  
Single Phase Formation

Abstract Sr5Ta4TiO17 ceramics was processed via solid state mixed oxide sintering route. X-ray diffraction revealed single phase formation of Sr5Ta4TiO17 ceramics that crystallized into an orthorhombic crystal structure with a space group Pnnm with lattice parameters of a = 5.681 Å, b = 32.542 Å and c = 3.968 Å, refined by the least squares method. The unit cell density (ρth) was 6.71 g/cm3. The microstructure consisted of plate-like grains and the average size was increased from 2 μm to 5 μm with an increase in sintering temperature from 1450 °C to 1575 °C. Optimum microwave dielectric properties, i.e. єr ~ 66,Qufo ~ 8500 GHz and τf ~ 180 ppm/°C, were achieved for Sr5TaTiO17 ceramics sintered at 1550 °C for 4 h.

scholarly journals Effects of (Mg1/3Sb2/3)4+ substitution on the structure and microwave dielectric properties of Ce2Zr3(MoO4)9 ceramics

2021 ◽  
Author(s):  
Xu Zhou ◽  
Lintao Liu ◽  
Jiajia Sun ◽  
Ningkang Zhang ◽  
Huazhang Sun ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Single Phase ◽  
Structure Refinement ◽  
Microwave Dielectric Properties ◽  
Far Infrared ◽  
X Ray Diffraction ◽  
Solid State Method ◽  
Microwave Dielectric ◽  
Refinement Method ◽  
Traditional Solid State Method

AbstractCe2[Zr1−x(Mg1/3Sb2/3)x]3(MoO4)9 (0.02 ⩽ x ⩽ 0.10) ceramics were prepared by the traditional solid-state method. A single phase, belonging to the space group of $$R⩈erline 3 c$$ R 3 ¯ c , was detected by using X-ray diffraction at the sintering temperatures ranging from 700 to 850 °C. The microstructures of samples were examined by applying scanning electron microscopy (SEM). The crystal structure refinement of these samples was investigated in detail by performing the Rietveld refinement method. The intrinsic properties were calculated and explored via far-infrared reflectivity spectroscopy. The correlations between the chemical bond parameters and microwave dielectric properties were calculated and analyzed by Phillips-van Vechten-Levine (P-V-L) theory. Ce2[Zr0.94(Mg1/3Sb2/3)0.06]3(MoO4)9 ceramics with excellent dielectric properties were sintered at 725 °C for 6 h (εr = 10.37, Q×f = 71,748 GHz, and τf = −13.6 ppm/°C, εr is the dielectric constant, Q×f is the quality factor, and τf is the temperature coefficient of resonant frequency).

scholarly journals Microwave dielectric properties and vibrational spectroscopic analysis of MgTe2O5 ceramics

2008 ◽  
Vol 23 (6) ◽  
pp. 1551-1556 ◽  
Author(s):  
G. Subodh ◽  
R. Ratheesh ◽  
M.V. Jacob ◽  
M.T. Sebastian
Keyword(s):  
Dielectric Properties ◽  
Spectroscopic Analysis ◽  
Sintering Temperature ◽  
Microwave Dielectric Properties ◽  
Quality Factors ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solid State Route ◽  
Microwave Dielectric ◽  
Structure And Microstructure

MgTe2O5 ceramics were prepared by solid-state route. These materials were sintered in the temperature range of 640–720 °C. The structure and microstructure of the compound was investigated using x-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman spectroscopy, and scanning electron microscopy (SEM) techniques. The dielectric properties of the ceramics were studied in the frequency range 4–6 GHz. The MgTe2O5 ceramics have a dielectric constant (ϵr) of 10.5, quality factors (Qu × f) of 61000 at 5.3 GHz, and temperature coefficient of resonant frequency (τf) of −45 ppm/°C at the optimized sintering temperature of 700 °C. The microwave dielectric properties of these materials at cryogenic temperatures were also investigated.

scholarly journals Sintering Behavior and Microwave Dielectric Properties of MgO-2B 2 O 3 - Xwt %H 3 BO 3 - Ywt %BCB Ceramics

2021 ◽  
Author(s):  
Haiquan WANG ◽  
Shixuan LI ◽  
Kangguo WANG ◽  
Huanfu ZHOU ◽  
Xiuli Chen
Keyword(s):  
Dielectric Properties ◽  
Bulk Density ◽  
Single Phase ◽  
Sintering Temperature ◽  
Microstructural Analysis ◽  
Microwave Dielectric Properties ◽  
Solid State Reaction Method ◽  
Sintering Behavior ◽  
X Ray Diffraction ◽  
Microwave Dielectric

Abstract The bulk density, sintering behavior and microwave dielectric properties of MgO-2B2O3 series ceramics synthesized by solid-state reaction method were systematically studied in this paper. X-ray diffraction and microstructural analysis revealed that the as-prepared MgO-2B2O3 ceramics possessed a single-phase structure with rod-like morphology. Through the investigation of the effects of different dosages of H3BO3 and BCB on bulk density, sintering behavior and microwave dielectric properties of MgO-2B2O3 ceramics, the optimum sintering temperature was obtained at an addition of 30wt%H3BO3 and 8wt%BCB and the sintering temperature was reduced to 825 oC. The addition of 40wt %H3BO3 and 4 wt%BCB increased the quality factor Q×f, permittivity εr and temperature coefficient of resonance frequency τf of MgO-2B2O3 to 44,306 GHz, 5.1 and -32 ppm/oC, respectively, meeting the criteria of low-temperature co-fired ceramics.

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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