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High Q·f value and temperature-stable MgF 2 -doped MgTi 1-x (Mn 1/3 Sb 2/3) x O 3 ceramics have been successfully prepared by the solid-state reaction method. Microwave dielectric properties and sintering performance of MgF 2 -doped MgTi 1-x (Mn 1/3 Sb 2/3) x O 3 ceramics were systematically investigated by the classic theory and the P-V-L theory. The results show that MgF 2 doping and complex cation (Mn 1/3 Sb 2/3)4+ substitution not only further reduces the sintering temperature of MgTiO 3 ceramics from 1400 °C to 1250 °C, but also effectively improves the quality factor from 110210 GHz to 228713 GHz and adjust the τf value from −53.55 ppm/°C to −20.42 ppm/°C. The ionicity, the bond valence and octahedral distortion confirmed that Ti/(Mn 1/3 Sb 2/3)-O bonds exert a greater influence on microwave dielectric properties than Mg-O bonds in MgTiO 3 ceramics, which provides a guide to further improve the microwave dielectric performances. The optimal microwave dielectric properties: ε r = 18.8 ± 0.28, Q·f = 228713 ± 2500 GHz (at 6.08 GHz), τ f = (−20.42 ± 1.1) ppm/°C were achieved for 3 wt% MgF 2 doped MgTi 0.99 (Mn 1/3 Sb 2/3) 0.01 O 3 ceramics sintered at 1250 °C. [ABSTRACT FROM AUTHOR]

High-Q and temperature-stable 0.63SrTiO3–0.37LaAlO3 (63ST–37LA) ceramic with different mole ratio of Na2SiO3·9H2O/MgO (Si/Mg) was produced by the solid-phase method. The effect of Si/Mg mole ratio (the value of Si/Mg mole ratio referred to R) on the phase transformation, sintering, and dielectric characteristics of 63ST–37LA ceramic was researched. X-ray diffraction and Rietveld refinement proved that a cubic perovskite structure of SrTiO3-based solid solution with a Pm-3m space group was formed. Scanning electron microscopy proved that appropriate amount of Na2SiO3·9H2O/MgO could promote the grain growth and generate a compact and uniform microstructure, so high relative density and quality factor (Q·f) value were achieved. When R was 0.53 and the addition of MgO was 2 mol%, the sintering temperature decreased by 200 °C and Q·f value increased by 44%, and outstanding dielectric characteristics with εr of 45.97 ± 0.35, Q·f value of 69,928 ± 1850 GHz, τf value of 1.7 ± 0.8 ppm/°C were achieved for 63ST-37LA ceramic at 1350 °C. [ABSTRACT FROM AUTHOR]

(1−x)(Ca0.88Sr0.12)TiO3–x(Bi0.5Na0.5)TiO3 (CST–BNT, x = 0, 0.025, 0.05, 0.075, 0.10) high dielectric constant ceramics were prepared by the solid state reaction method, and the effects of (Bi0.5Na0.5)TiO3 (BNT) on the sintered properties, phase composition, microstructures, and dielectric properties of (Ca0.88Sr0.12)TiO3 (CST) ceramics were investigated as a function of the x-value and sintering temperature. The results showed that: BNT had no obvious influence on phase composition of CST ceramics, and the single phase solid solutions were obtained throughout the studied compositional range. Adding a moderate amount of BNT not only effectively lowered the sintering temperature from 1400 to 1275 °C, but also improved the sintered properties and the dielectric properties, especially that the τf decreased from + 942 to + 639 ppm/°C, which was decreased by about 32%. For x = 0.05, the 0.95(Ca0.88Sr0.12)TiO3–0.05(Bi0.5Na0.5)TiO3 ceramics sintered at 1275 °C for 3 h exhibit an excellent combination of microwave dielectric properties: εr = 185.5, Q × f = 8116 GHz and τf = + 639 ppm/°C, and which could be used as a promising candidate to equalize the materials with negative temperature coefficient of resonant frequency. [ABSTRACT FROM AUTHOR]

0.6ZrO-0.4(ZnNb)O-TiO(ZN40) microwave dielectric ceramics were prepared by conventional solid-state reaction method, and the effects of LiCO, CuO, MnCO additives doping on their microstructures, phase composition, and dielectric properties were investigated. The results shown that suitable additives didn't change the crystal phase of ZN40 ceramics, and the main crystalline phase of all the samples was orthorhombic α-PbO type ZrTiO; a moderate amount of LiCO, CuO, MnCO could not only effectively lower the sintering temperature due to form liquid-phase, or promote ion diffusion by Ti-site ionic substitution of unequal values, but also improve the quality factor ( Q × f). The optimal integrated microwave dielectric properties( ε = 42.59, Q × f = 52,500 GHz and τ = +7.8 ppm/°C) were achieved for ZN40 ceramics containing 1 wt% MnCO sintered at 1220 °C for 3 h, and which make this material a prospective candidate for use in satellite communication and mobile communication base station. [ABSTRACT FROM AUTHOR]

Abstract: 0.87(Mg0.7Zn0.3)TiO3–0.13(Ca0.61La0.26)TiO3 (referred to as 87MZCLT) ceramics were prepared by microwave sintering and conventional sintering. The experimental results demonstrated that the sintering cycle of 87MZCLT ceramics was greatly shortened and the impurity phase (Mg0.7Zn0.3)Ti2O5 was eliminated by microwave sintering. Moreover, the 87MZCLT ceramics prepared by microwave sintering show more uniform, fine-grained microstructure as well as much less Zn evaporation. As a result, the quality factor was increased by 40% compared with conventional sintering. All samples were sintered at 1275°C for 20min with heating and cooling rate of 15°C/min and gave excellent microwave dielectric properties: ɛ r =26.21, Q × f =120,000GHz, τ f =−3ppm/°C. [Copyright &y& Elsevier]

Based on the mean-value theorem of multivariable vectors function F ( x ), two new iterative schemes with third-order and fifth-order convergence are constructed respectively by using Gauss quadrature formula for solving systems of nonlinear equations. Their error equations and asymptotic numerical convergence constants are obtained. The two suggested methods are compared with the related methods for solving systems of nonlinear equations and boundary-value problems of nonlinear ODEs in the numerical examples to demonstrate the efficiency and practicality. [ABSTRACT FROM AUTHOR]