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This research employed a conventional solid-state technique to synthesize a novel AgMoVO6 ceramic material and conducted an analysis of its microwave dielectric properties. The analysis revealed that the sample synthesized at 520 °C possessed a monoclinic structure and belonged to the C2/m (12) space group, indicating a pure AgMoVO6 phase. The dielectric constant of the ceramic was primarily influenced by its density, porosity, and ionic polarizability. Moreover, an increase in the packing fraction and lattice energy significantly enhanced the Q × f values of the ceramic. The correlation between the bond valence of the specimen and its τf value was found to be strong. Furthermore, the study demonstrated that the dielectric characteristics of the specimens were highly dependent on their unit-cell volume, which critically affected their microwave dielectric properties. Notably, the phase-pure AgMoVO6 ceramic exhibited exceptional dielectric properties at microwave frequencies, with an εr of ~ 12.4, Q × f of ~ 21,300 GHz, and τf of ~ –46.9 ppm/°C. Additionally, the ceramic material has been successfully employed in the design of a dual-band filter, showcasing its potential for utilization in 5G systems. [ABSTRACT FROM AUTHOR]

Cubic-structured Li 2 ZnTi 5 O 12 ceramics were prepared by a conventional solid-state reaction method, and their characterization and microstructure were investigated, with the microwave dielectric properties of these ceramics being studied for the first time. The relationships between the sintering temperature and the microwave dielectric properties in Li 2 ZnTi 5 O 12 ceramics were also studied. The variation trend of the dielectric constant was in accordance with that of the apparent density. The Q × f and τ f were correlated with the density (an extrinsic factor), FWHM (an intrinsic factor) and bond valence in these compositions, respectively. The new microwave dielectric material Li 2 ZnTi 5 O 12 ceramics sintered at 1260 °C for 4 h have a dielectric constant ( ε r ) of ∼38.4, a Q × f of ∼54,300 GHz ( f = 5.898 GHz), and a τ f ∼ 82.9 ppm/°C, and thus they are a suitable candidate for use in microwave applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] Low-loss dielectrics (Mg1− x Zn x )4Ta2O9 (x =0.02–0.08) have been extensively investigated. [•] Formation of solid solution was confirmed by the XRD analysis and measured lattice parameters. [•] The ionic polarizabilities of the solid solutions were also obtained for the specimens. [•] The Q × f value can be promoted up to a value of 385,000GHz at x =0.05. [ABSTRACT FROM AUTHOR]

A compact bandpass filter is designed using stepped impedance ring resonators with zero-degree feed structure.This compact bandpass filters using FR4 and high-permittivity ceramic substrates (with respective dielectric constants of 4.5 and 13.46) are investigated. Using high Q, high permittivity dielectric ceramic materials as substrates, the filters demonstrate high selectivity, compact size, and can be applied in several microwave communication systems. An electromagnetic simulator is used to design the ring resonators, and to calculate the coupling coefficient of the basic coupling strictures. A precise planar bandpass filter with ceramic substrates has been fabricated using the screen printing technique. The responses of bandpass filters using FR4 (εr = 4.5, tan δ = 0.015) and Mg4Nb2O9 with 0.75 wt% Fe2O3 (εr = 13.46, tan δ = 0.00004) ceramic substrates are designed at a center frequency of 2.4 GHz with bandwidth of about 9%. The compact size, low-loss, and performance of the filter are demonstrated in this article. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:660-663, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27346 [ABSTRACT FROM AUTHOR]

Abstract: The microwave dielectric properties of the (1− x)Li2TiO3–xZnO (x =0.1–0.5) ceramic system prepared by mixed oxide route have been investigated. The rock-salt structured (1− x)Li2TiO3–xZnO were characterized by using X-ray diffraction spectra, scanning electron microcopy (SEM). The dielectric properties are strongly dependent on the compositions, the densifications and the microstructures of the specimens. The decrease of Q × f value at high-level ZnO addition (x >0.3) was owing to the intensity of the (002) superstructure reflection decreased and became disordered rock-salt structure. For practical applications, a new microwave dielectric material 0.7Li2TiO3–0.3ZnO is suggested and it possesses a good combination of dielectric properties with an of ∼22.95, a Q × f of ∼99,800GHz (measured at 8.91GHz), and a of ∼0ppm/°C. A low-loss dielectric resonant antenna using aperture-coupled cylindrical dielectric resonant was designed and fabricated using the proposed dielectric to study its performance. [Copyright &y& Elsevier]

This article describes the two-pole microstrip band-pass filters using miniaturized center-stubbed open stubs and tapped-line input/output ports. The two-poles bandpass filters by using FR4 and high-permittivity ceramic substrates (with respective dielectric constants of 4.5 and 31.55) are investigated. Microwave dielectric ceramics with high permittivity are commonly applied in several microwave communication components. The advantage of using high permittivity ceramic substrates is to reduce the sizes and increase the performance of microstrip bandpass filters. The responses of the filters using FR4 (εr = 4.5, tan δ = 0.015) and Nd(Zn1/2Ti1/2)O3 (εr = 31.55, tan δ= 0.00005) ceramic substrates are designed at a center frequency of 2 GHz. The compact size, low-loss, sharp response, and performance of the filter are presented in this article. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1683-1686, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26889 [ABSTRACT FROM AUTHOR]

Abstract: The (Mg0.95M0.05)Ta2O6 (M=Ni, Zn, Mn) ceramics are prepared through the solid-state ceramic route and their microwave dielectric properties are investigated as a function of ionic radius difference of M and Mg. The forming of (Mg0.95M0.05)Ta2O6 solid solutions were confirmed by the XRD analysis and the measured lattice parameters and the ceramics showed a nonlinear variation of dielectric properties with the sintering temperature. In addition, the sintering temperature has slight effect on dielectric constant and temperature coefficient of resonant frequency, but significant on Q×f value. In particularly, (Mg0.95Ni0.05)Ta2O6 shows a relatively high Q×f of 88,300 GHz along with a dielectric constant of 28.73 and a τ f of 44.9 ppm/°C, indicating the dielectric can be used for high-frequency applications. [Copyright &y& Elsevier]

Abstract: (Co1−x Zn x )TiO3 (x =0–0.1) ceramics with high relative density were prepared by the conventional solid-state reaction, followed by sintering at 1290–1380°C. X-ray diffraction patterns illustrated that a single rhombohedral crystal structure solid solution could be formed between the two end members with 0≤ x ≤0.1. The unit cell volume slightly increased with increasing Zn content (x). The microwave dielectric properties of (Co1−x Zn x )TiO3 ceramics showed a significant dependence on the Zn content, the density of the specimen, and to some extent on the morphology of the grains. Specimen using (Co0.95Zn0.05)TiO3 sintered at 1350°C for 3h could obtain the microwave dielectric properties as follows; an value of ∼20, a Q × f value of ∼107,000GHz (measured at f =9.27GHz), and a value of −60ppm/°C. [Copyright &y& Elsevier]

Using a conventional solid-state reaction, followed by sintering at 1080°C-1200°C Li2( Zn1− x A x) 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− x A x) 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 εr = 26.1, Q × f = 150 000 GHz, and τ f = −13.9 ppm/°C, and Li2(Zn0.92Co0.08)Ti3O8 ceramics show εr = 24.7, Q × f = 140 000 GHz, and τ f = −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. [ABSTRACT FROM AUTHOR]

Abstract: The microwave dielectric properties and microstructure of Mg1+δ TiO3+δ (−0.05≤ δ ≤0.05) ceramics prepared via the conventional solid-state route were investigated. A slight deviation from stoichiometry does not practically affect the relative permittivity and temperature coefficient of resonant frequency of the specimen. However, the Q × f value is very sensitive to the composition and it shows a non-linear variation corresponding to a relative amount of Mg. A very high Q × f can be achieved for specimen with single MgTiO3 phase, which can be obtained within the compositional range −0.02≤ δ ≤0.02. In addition, a low Q × f measured for specimens at δ <−0.02 can be attributed to the presence of second phase MgTi2O5. An extremely high Q × f of ∼357,600GHz (at 10GHz) together with an ɛ r of ∼18.3 and a τ f of ∼−50ppm/°C can be found for specimen using Mg1.02TiO3.02. [Copyright &y& Elsevier]

Abstract: The microwave dielectric properties and microstructures of (Mg1−x Zn x )4Nb2O9 (x =0.02–0.08) solid solutions prepared by the conventional solid-state route have been investigated. Lattice parameters of the ceramics were also measured and linearly increased with the increase of x. The formation of solid solutions (Mg1−x Zn x )4Nb2O9 (x =0.02–0.08) was confirmed by the X-ray diffraction patterns, the EDS analysis and the measured lattice parameters. A substantial increase in the Q × f was achieved in the solid solution system whereas the dielectric constant and the temperature coefficient of resonant frequency retained similar compared to that of the pure Mg4Nb2O9. A fine combination of microwave dielectric properties (ɛ r ∼13, Q × f ∼247,000GHz, τ f ∼−67ppm/°C) can be achieved for specimen using (Mg0.95Zn0.05)4Nb2O9 ceramics sintered at 1340°C for 4h. [ABSTRACT FROM AUTHOR]

Abstract: The microwave dielectric properties and the microstructures of (1− x)Mg0.95Co0.05TiO3–xCa0.6La0.8/3TiO3 ceramic system, prepared by a mixed oxide route, have been investigated. The sintered 0.9Mg0.95Co0.05TiO3–0.1Ca0.6La0.8/3TiO3 ceramics with B2O3 addition were characterized using X-ray diffraction spectra and scanning electron microscopy (SEM). The microwave dielectric properties are found to strongly correlate with the sintering temperature as well as the amount of B2O3 addition. The Q × f value of 0.9Mg0.95Co0.05TiO3–0.1Ca0.6La0.8/3TiO3 ceramic increased with increasing temperature to 1225°C/4h and decreased thereafter. The decrease in Q × f value was coincident with the abnormal grain growth. A maximum Q × f value of 76,000GHz associated with an dielectric constant (ɛ r ) of 22.67 and a temperature coefficient (τ f ) of −12ppm/°C, was achieved for samples with 0.5wt.% B2O3 additions sintering at 1225°C/4h. By appropriately adjusting the x value in the (1− x)Mg0.95Co0.05TiO3–xCa0.6La0.8/3TiO3 ceramic system, zero τ f value can be obtained. A parallel-coupled line band-pass filter is designed and simulated using the proposed dielectric to study its performance. [Copyright &y& Elsevier]

Abstract: The microwave dielectric properties of the (1− x)(Mg0.95Mn0.05)TiO3–xCaTiO3 ceramic system prepared by mixed oxide route have been investigated. The microstructures of the ceramics were characterized by SEM. Ilmenite-structured (Mg0.95Mn0.05)TiO3 and perovskite-structured CaTiO3 were coexisted and the two-phase system was confirmed by the XRD and EDX analysis. The microwave dielectric properties are strongly related to the density and matrix of the specimen. Combination of (Mg0.95Mn0.05)TiO3 and CaTiO3 forms a two-phase system and leads to a near-zero τ f. With increasing x, the microwave Q × f decreased and ɛ r increased. A new microwave dielectric material, 0.93(Mg0.95Mn0.05)TiO3–0.07CaTiO3 possesses excellent microwave dielectric properties with a dielectric constant (ɛ r) of ∼22.67, a Q × f of ∼90,700GHz (where f =9GHz, is the resonant frequency) and a τ f value of ∼0.8ppm/°C at 1270°C for 4h. It is proposed as a suitable material candidate for applications requiring low microwave dielectric loss. [Copyright &y& Elsevier]

Abstract: The microwave dielectric properties of the (1− x)(Mg0.95Co0.05)2TiO4–xCa0.8Sm0.4/3TiO3 ceramic system prepared by mixed oxide route have been investigated. The crystal structures and the microstructures of the ceramics were characterized by means of X-ray and SEM, respectively. The microwave dielectric properties are strongly related to the density and the matrix of the specimen. Combining (Mg0.95Co0.05)2TiO4 (spinel structure) and Ca0.8Sm0.4/3TiO3 (perovskite structure) forms a two-phase system and leads to a near-zero τ f . With increasing x, the Q × f of the specimen decreased, whereas its ɛ r increased due to a compositional variation. A new microwave dielectric 0.8(Mg0.95Co0.05)2TiO4–0.2Ca0.8Sm0.4/3TiO3, possessing excellent microwave dielectric properties with a dielectric constant (ɛ r ) of 20.84, a Q × f of 112,600GHz (where f =9.1GHz, is the resonant frequency) and a τ f value ∼0.8ppmK−1 at 1573K/4h, is proposed as a candidate material for GPS patch antennas and 3G passive components. [Copyright &y& Elsevier]

Abstract: Dielectric properties of x(Mg0.7Zn0.3)0.95Co0.05TiO3-(1−x)(La0.5Na0.5)TiO3 ceramic were investigated at microwave frequencies. A nearly 0ppm/°C temperature coefficient of resonant frequency was realized at x =0.9. A two-phase system was confirmed by XRD analysis. A dielectric material applicable to microwave devices with a Q × f of 20,000–87,000GHz and a dielectric constant of 21.27–26.2 was obtained at 1100°C after 4h of sintering. The microwave dielectric material 0.9(Mg0.7Zn0.3)0.95Co0.05TiO3-0.1(La0.5Na0.5)TiO3 sintered at 1150°C for 4h has a dielectric constant of 24.56, a Q × f of 68,000GHz, and a τ f value of 0ppm/°C. It is proposed as a candidate dielectric for GPS patch antennas. [Copyright &y& Elsevier]

Abstract: The microstructure and the microwave dielectric properties of (1− x)Mg2TiO4–x(Ca0.8Sr0.2)TiO3 ceramic system prepared by the mixed oxide route have been investigated. The phases of Mg2TiO4 and (Ca0.8Sr0.2)TiO3 were co-existed as a two-phase system, which was confirmed by the XRD patterns and the EDX analysis. The microwave dielectric properties of the specimens are strongly related to the sintering temperature and the density. Sintering temperature of pure Mg2TiO4 can be lowered by adding (Ca0.8Sr0.2)TiO3. Combination of Mg2TiO4 (spinel-structured) and (Ca0.8Sr0.2)TiO3 (perovskite-structured) also leads to a zero τ f . Consequently, a high Q × f of 90,500GHz (measured at 9.5GHz) associated with a ɛ r of 18.3 and a τ f of 0ppm/°C can be achieved by using 0.91Mg2TiO4–0.09(Ca0.8Sr0.2)TiO3 ceramics at 1300°C for 4h. It is proposed as a very promising dielectric for microwave applications requiring low dielectric loss. [Copyright &y& Elsevier]

Abstract: The microstructures and the microwave dielectric properties of the (1− x)(Mg0.95Co0.05)TiO3–x(Na0.5La0.5)TiO3 ceramic system were investigated. Two-phase system was confirmed by the XRD patterns and the EDX analysis. A co-existed second phase (Mg0.95Co0.05)Ti2O5 was also detected. The microwave dielectric properties are strongly related to the density and the matrix of the specimen. A new microwave dielectric material 0.88(Mg0.95Co0.05)TiO3–0.12(Na0.5La0.5)TiO3, possessing an excellent combination of dielectric properties: ∼22.36, Q × f ∼110,000GHz (at 9GHz), ∼2.9ppm/°C), is proposed as a candidate dielectric for GPS patch antennas. [Copyright &y& Elsevier]

Abstract: The microstructure and microwave dielectric properties of the (1− x)(Mg0.95Co0.05)2TiO4–xSrTiO3 (x =0.05–0.1) ceramic system have been investigated in this paper. The X-ray diffraction (XRD) results indicate that all samples exhibit a two-phase system, which has a spinel-structured primary phase (Mg0.95Co0.05)2TiO4 associated with a perovskite-structured SrTiO3 minor phase. In addition to these two phases, a (Mg0.95Co0.05)TiO3 second phase is also detected throughout the entire compositional range. The microwave dielectric properties are strongly related to the density and the surface morphology of the specimens. However, the presence of second phase would not deteriorate the dielectric properties of the specimen, since the second phase properties are very similar to the primary phase. The τ f value is strongly correlated to the compositions and can be controlled through the compositional ratio. A new microwave dielectric material 0.93(Mg0.95Co0.05)2TiO4–0.07SrTiO3, possessing an excellent combination of microwave dielectric properties with an ɛ r of 18.44, a Q × f of 102,200GHz (at 9.5GHz) and a τ f of 1.1ppm/°C, is proposed as a very promising candidate material for today''s 3G applications. [Copyright &y& Elsevier]

Abstract: The crystal structures, phase compositions and the microwave dielectric properties of the (1−x)Ca(Mg1/3Nb2/3)O3–x(Ca0.8Sr0.2)TiO3 perovskite-based composites prepared by the conventional solid state route have been investigated. The formation of solid solution is confirmed by the XRD patterns. A rapid grain growth is observed at temperatures higher than 1470°C, which would lead to a decrease in the density and Q × f of the ceramics. The temperature coefficient of resonant frequency increases with increasing (Ca0.8Sr0.2)TiO3 content and tunes through near zero at x =0.3. Specimen using 0.7Ca(Mg1/3Nb2/3)O3–0.3(Ca0.8Sr0.2)TiO3 possesses an excellent combination of microwave dielectric properties: ɛ r ∼43.75, Q × f ∼45,200GHz (where f =6.3GHz is the resonant frequency) and τ f ∼−4.2ppm/°C. It is proposed as a suitable candidate material for small-sized GPS patch antennas. [Copyright &y& Elsevier]

Abstract: The effect of Nd0.5Na0.5TiO3 addition on the microwave dielectric properties of Mg0.95Ni0.05TiO3 ceramics was investigated. The Nd0.5Na0.5TiO3 content plays a significant role in improving the dielectric properties. Microwave dielectric measurements show an increase in the dielectric constant (εr ) and temperature coefficient of the resonant frequency (τf ) and a decrease in the quality factor (Q × f value) with increasing Nd0.5Na0.5TiO3 content. By properly adjusting the Nd0.5Na0.5TiO3 content, a zero τf value can also be obtained, which make Mg0.95Ni0.05TiO3 a promising material in wireless systems. At 1300°C, the 0.81Mg0.95Ni0.05TiO3–0.19Nd0.5Na0.5TiO3 ceramics possess excellent microwave dielectric properties: a dielectric constant (εr ) of 25.61, a Q × f value of 69,100GHz, and a τf value of −6ppm/°C. [Copyright &y& Elsevier]

Abstract: The microstructures and microwave dielectric properties of the (1− x)(Mg0.95Ni0.05)TiO3–xCa0.8Sm0.4/3TiO3 ceramics system were investigated in the range of 0.1≦ x ≦0.9. The quality factor (Q × f value) and the temperature coefficient (τ f ) of the specimens were decreased with increasing Ca0.8Sm0.4/3TiO3 content. The microstructures of (1− x)(Mg0.95Ni0.05)TiO3–xCa0.8Sm0.4/3TiO3 ceramics were characterized using X-ray diffraction patterns and a scanning electron microscope (SEM). The areas of the various compositions in the ceramics were observed using energy dispersive spectroscopy (EDS), showing that Ca0.8Sm0.4/3TiO3 coexists with (Mg0.95Ni0.05)TiO3 in minor crystal grain. The existence of the Ca0.8Sm0.4/3TiO3 phase can inhibit the abnormal grain growth of the (Mg0.95Ni0.05)TiO3 phase. A relative permittivity (ɛ r) of 22.9, a Q × f value of 92,000GHz, and temperature coefficient of resonant frequency (τ f ) of −5.4ppm/°C were obtained for 0.9(Mg0.95Ni0.05)TiO3–0.1Ca0.8Sm0.4/3TiO3 ceramics sintered at 1275°C for 4h. [Copyright &y& Elsevier]

Abstract: The effect of Ca0.61Nd0.26TiO3 addition on the microwave dielectric properties of (Mg0.95Ni0.05)TiO3 ceramics was investigated. The Ca0.61Nd0.26TiO3 content plays a significant role in improving the dielectric properties. Microwave dielectric measurements show an increase in the dielectric constant (ɛ r) and temperature coefficient of the resonant frequency (τ f) and a decrease in the quality factor (Q × f value) with increasing Ca0.61Nd0.26TiO3 content. By properly adjusting the Ca0.61Nd0.26TiO3 content, a zero temperature coefficient of resonate frequency (τ f) can also be obtained, which make (Mg0.95Ni0.05)TiO3 a promising material in wireless systems. At 1350°C, the 0.85(Mg0.95Ni0.05)TiO3–0.15Ca0.61Nd0.26TiO3 ceramics possess excellent microwave dielectric properties: a dielectric constant (ɛ r) of 24.05, a Q × f value of 67,000GHz, and a τ f value of −9.3ppm/°C. [Copyright &y& Elsevier]

Abstract: The effects of additive sintering aids on the microstructures and microwave dielectric properties of 0.8(Mg0.95Zn0.05)TiO3–0.2Ca0.61Nd0.26TiO3 ceramics were investigated. V2O5 was selected as a liquid phase sintering aid to lower the sintering temperature of 0.8(Mg0.95Zn0.05)TiO3–0.2Ca0.61Nd0.26TiO3 ceramics. With added V2O5, the densification temperature of 0.8(Mg0.95Zn0.05)TiO3–0.2Ca0.61Nd0.26TiO3 can be effectively reduced from 1350°C to 1175–1275°C. Low-level doping of V2O5 (0.5–4wt%) significantly improves the density and dielectric properties of 0.8(Mg0.95Zn0.05)TiO3–0.2Ca0.61Nd0.26TiO3 ceramics. The quality factor Q × f was strongly dependent upon the amount of additives. Q × f values of 46,100 and 14,700GHz could be obtained at 1175–1275°C with 0.5 and 4wt% V2O5 added, respectively. Over all ranges of addition, the relative dielectric constants differed significantly and ranged from 20.6 to 26.5. The temperature coefficient varied from −14.9 to 8.91ppm/°C. [Copyright &y& Elsevier]

Abstract: Crystal structure and the microwave dielectric properties of xMgTiO3–(1−x)MgTa2O6 sintered specimens with x =0.3, 0.5, 0.7 are investigated. The X-ray diffraction patterns revealed the sintered specimens are mixed phases of MgTiO3, MgTa2O6 and MgTi2O5. The microwave dielectric properties are strongly correlated with the sintering temperature and the composition. With x =0.7, a new microwave dielectric ceramic material 0.7MgTiO3–0.3MgTa2O6 at 1460°C for 3h is suggested for microwave device and it possesses excellent dielectric properties; a dielectric constant ɛ r ∼23, a Q × f value ∼81,000GHz and a τ f value ∼−2ppm/°C. The correlation between microwave dielectric properties and the microstructures is also discussed. [Copyright &y& Elsevier]

Abstract: Low-loss Mg1.8Ti1.1O4 ceramics were prepared by the conventional solid-state route and their microwave dielectric properties were investigated for the first time. The forming of tetragonal-structured Mg1.8Ti1.1O4 main phase associated with a second phase MgTiO3 were confirmed by the X-ray diffraction patterns. However, the presence of the second phase would cause no significant variance in the dielectric properties of the specimen because the second phase properties are very similar to that of the main phase. A fine combination of microwave dielectric properties (ɛ r ∼15.74, Q × f ∼141,000GHz at 10.57GHz, τ f ∼−52.4ppm/°C) was achieved for Mg1.8Ti1.1O4 ceramics sintered at 1450°C for 4h. [Copyright &y& Elsevier]

Abstract: The effects of sintering aids additives on the microstructures and microwave dielectric properties of (1− x)CaTiO3–xNd(Mg1/2Ti1/2)O3 ceramics were investigated. The effects of V2O5 additions on the microwave dielectric properties and the microstructures of (1− x)CaTiO3–xNd(Mg1/2Ti1/2)O3 ceramics have been investigated. Doping with 0.5wt% V2O5 can effectively promote the densification and the microwave dielectric properties of (1− x)CaTiO3–xNd(Mg1/2Ti1/2)O3. It is found that CaTiO3–Nd(Mg1/2Ti1/2)O3 ceramics can be sintered at 1325°C due to the liquid phase effect of a V2O5 additions. The dielectric constant decreases from 140 to 28 as x varies from 0.1 to 1.0. The microwave dielectric properties indicate the possibility of a phase transformation for x between 0.3 and 0.5. A low-pass filter is designed and simulated using the proposed dielectric to study its performance. [Copyright &y& Elsevier]

Abstract: Composite ceramics in the solid solution of Zr x (Zn1/3Nb2/3)1−x TiO4 (x =0.1–0.4) have been prepared by the mixed oxide route. Formation of solid solution was confirmed by the X-ray diffraction patterns. The microwave dielectric properties, such as dielectric constant (ɛ r ), Q × f value and temperature coefficient of resonant frequency (τ f ) have been investigated as a function of composition and sintering temperature. With x increasing from 0.1 to 0.4, the dielectric constant decreases from 70.9 to 43.2, and the τ f decreases from 105 to 55ppm/°C. The Q × f value, however, increases with increasing x value to a maximum 26,600GHz (at 6GHz) at x =0.3, and then decreases thereafter. For low-loss microwave applications, a new microwave dielectric material Zr0.3(Zn1/3Nb2/3)0.7TiO4, possessing a fine combination of microwave dielectric properties with a high ɛ r of 51, a high Q × f of 26,600GHz (at 6GHz) and a τ f of 70ppm/°C, is suggested. [Copyright &y& Elsevier]

Abstract: The microwave dielectric properties and microstructures of (1− x)La(Mg0.5Ti0.5)O3–x(Ca0.8Sr0.2)TiO3 ceramics, prepared by a mixed oxide route, have been investigated. The forming of solid solutions was confirmed by the XRD patterns and the measured lattice parameters for all compositions. A near zero τ f was achieved for samples with x =0.5, although the dielectric properties varied with sintering temperature. The Q × f value of 0.5La(Mg0.5Ti0.5)O3–0.5(Ca0.8Sr0.2)TiO3 increased up to 1475°C, after which it decreased. The decrease in dielectric properties was coincident with the onset of rapid grain growth. The optimum combination of microwave dielectric properties was achieved at 1475°C for samples where x =0.5 with a dielectric constant ɛ r of 47.12, a Q × f value of 35,000GHz (measured at 6.2GHz) and a τ f value of −4.7ppm/°C. [ABSTRACT FROM AUTHOR]

Abstract: The microwave dielectric properties of conventional solid-state route prepared (1− x)(Mg0.95Co0.05)2TiO4–x(Ca0.8Sr0.2)TiO3 ceramic system have been investigated. A two-phase system was confirmed by the X-ray diffraction patterns. (Mg0.95Co0.05)TiO3 was also detected as a second phase in the system. The microwave dielectric properties are strongly related to the density and the morphology of the specimens. The presence of the second phase, however, would cause no significant variation in the dielectric properties of the specimen because it possesses similar properties compared to that of the main phase (Mg0.95Co0.05)2TiO4. Specimen using 0.92(Mg0.95Co0.05)2TiO4–0.08(Ca0.8Sr0.2)TiO3 leads to a good combination of microwave dielectric properties with an ɛ r of 19.22, a Q × f of 123,200GHz (at 9.2GHz) and a τ f value of 2.8ppm/°C. It is proposed as a candidate dielectric for applications in GPS patch antennas and 3G passive components. [Copyright &y& Elsevier]

Abstract: The influences of Fe2O3 additives on the sintering behavior and microwave dielectric properties of Mg4Nb2O9 ceramics were investigated. The prepared ceramics exhibits a mixture of phases Mg4Nb2O9 and Mg5Nb4O15. Lowering the sintering temperature (as low as 1240°C) and promoting the Q × f value of Mg4Nb2O9 ceramics could be effectively achieved by adding Fe2O3 (up to 1wt%). At 1270°C, 0.75wt% Fe2O3-doped Mg4Nb2O9 ceramics possess a dielectric constant (ɛ r ) of 13.46, a Q × f value of 280,000GHz, and a temperature coefficient of resonant frequency (τ f ) of −62ppm/°C. In contrast to that of pure Mg4Nb2O9 ceramics, incorporating additional Fe2O3 helps to render a dielectric material with a >40% dielectric loss reduction, a higher dielectric constant and retains a comparable τ f , which makes it a very promising candidate for applications requiring an extremely low microwave dielectric loss. [Copyright &y& Elsevier]

Tetragonal-structured Mg 2 YVO 6 ceramics were prepared by conventional solid-state method, and their physical and microwave dielectric properties were investigated for the first time. The forming of Mg 2 YVO 6 main phase was confirmed by XRD diffraction pattern. XPS and Raman spectrum were recorded to clarify the chemical states of elements and vibration and rotation modes of the specimen, respectively. In addition, the relationships between sintering temperature, packing fraction, and microwave dielectric properties in Mg 2 YVO 6 ceramics were also studied. The new microwave dielectric material Mg 2 YVO 6 ceramics sintered at 1290 °C for 4 h has a dielectric constant ( ε r ) of ∼10.88, a Q × f of ∼68,300 GHz ( f = 10.389 GHz), and a τ f ∼ −53.9 ppm/°C, demonstrating a candidate for microwave application. [ABSTRACT FROM AUTHOR]

Abstract: To understand the role of a residual MgO phase plays inside a ceramic body, a simple magnesium oxide ceramics was prepared to investigate its microwave dielectric properties. The ɛ r and τ f values of specimens using simple MgO only vary in a small range at the investigated temperatures (1400–1550°C) implying they are not sensitive to the sintering temperature. However, the Q × f is strongly related to the density of the ceramics and a high Q × f of ∼113,600GHz can be achieved by sintering the specimen at 1490°C for 4h. It indicates MgO may exist as a low-loss dielectric inside a dense ceramic body at microwave frequency. [Copyright &y& Elsevier]

Abstract: The microwave dielectric properties of the (1− x)Mg2(Ti0.95Sn0.05)O4–x(Ca0.8Sr0.2)TiO3 ceramic system prepared by mixed oxide route have been investigated. The crystal structures and the microstructures of the ceramics were characterized by means of X-ray and SEM. The microwave dielectric properties are strongly related to the density and matrix of the specimen. Combination of Mg2(Ti0.95Sn0.05)O4 (spinel-structured) and (Ca0.8Sr0.2)TiO3 (perovskite-structured) forms a two-phase system and leads to a near-zero τ f . With increasing x, the microwave Q × f decreased and ɛ r increased. A new microwave dielectric material 0.91Mg2(Ti0.95Sn0.05)O4–0.09(Ca0.8Sr0.2)TiO3, possessing excellent microwave dielectric properties with a dielectric constant (ɛ r ) of 18.32, a Q × f of 109,200GHz (where f =9.5GHz, is the resonant frequency) and a τ f value ∼−0.5ppm/°C at 1270°C for 4h, is proposed as a suitable candidate material for microwave applications requiring low dielectric loss. [Copyright &y& Elsevier]

Abstract: High-relative-permittivity and low-loss ceramics in the (1− x)Ca(Mg1/3Ta2/3)O3–xCa0.8Sm0.4/3TiO3 system have been prepared by the conventional solid state route and their microwave dielectric properties have been investigated. (1− x)Ca(Mg1/3Ta2/3)O3–xCa0.8Sm0.4/3TiO3 solid solution exhibited orthorhombic crystal structures for all compositions. A rapid grain growth is observed at temperatures higher than 1450°C, which would lead to a decrease in the density and the Q × f of the ceramics. A near-zero temperature coefficient of resonant frequency can be achieved for Ca(Mg1/3Ta2/3)O3 with the addition of Ca0.8Sm0.4/3TiO3. The temperature coefficient of resonant frequency increases with increasing Ca0.8Sm0.4/3TiO3 content and tunes through zero at x =0.45. Specimen using 0.55Ca(Mg1/3Ta2/3)O3–0.45Ca0.8Sm0.4/3TiO3 possesses an excellent combination of microwave dielectric properties: ɛ r ∼44.96, Q × f ∼41,700GHz (where f =6.6GHz, is the resonant frequency) and τ f value of 0ppm/°C. It is proposed as a suitable candidate material for today''s 3G passive components and small-sized GPS patch antennas. [Copyright &y& Elsevier]

Abstract: The dielectric properties and microstructures of 0.92(Mg0.95Co0.05)2TiO4–0.08(Ca0.8Sr0.2)TiO3 ceramics with B2O3 additions have been investigated. The sintered 0.92(Mg0.95Co0.05)2TiO4–0.08(Ca0.8Sr0.2)TiO3 ceramics were characterized by using X-ray diffraction spectra, scanning electron microscopy (SEM), backscattering electron image (BEI) and energy dispersive X-ray (EDX). The dielectric properties are strongly dependent on the densifications and the microstructures of the specimens. The decrease of Q × f value at high-level B2O3 addition was owing to the inhomogeneous grain growth and the high-dielectric-loss of the liquid phase. In comparison with that of pure 0.92(Mg0.95Co0.05)2TiO4–0.08(Ca0.8Sr0.2)TiO3 ceramics, specimen with 0.5wt% B2O3 addition possesses a substantial fine combination of dielectric properties (an ɛ r of 18.07, a Q × f of 95,000GHz at 9.5GHz and a τ f of −4.7ppm/°C) at a lower sintering temperature of 1200°C for 4h. Moreover, a band-pass filter is also designed and simulated on the proposed dielectric to study its performance. [ABSTRACT FROM AUTHOR]

Abstract: Rock-salt-structured Li2MgTiO4 ceramic was prepared by the conventional mixed oxide route and its microwave dielectric properties were investigated. The microstructures of the ceramics were characterized by SEM. The dielectric properties of the ceramics exhibited a significant dependence on the sintering condition and crystal structure. A new microwave dielectric material, Li2MgTiO4 sintered at 1360°C has a dielectric constant (ɛ r ) of ∼17.25, a Q × f of ∼97,300GHz (where f =9.86GHz, is the resonant frequency) and a τ f of ∼–27.2ppm/°C. The microwave dielectric properties of the ceramic are reported for the first time. [Copyright &y& Elsevier]