Search

This study investigates NaY9Si6O26 ceramics prepared through the solid‐phase method, focusing on their microwave dielectric properties and crystallographic characteristics. X‐ray diffraction analysis reveals a hexagonal crystal structure for NaY9Si6O26 ceramics within the P63/m (176) space group. Rietveld refinement analysis precisely determines the lattice constants as a = b = 9.3423 Å, c = 6.7524 Å, and a unit cell volume of V = 510.3877 Å3. Additionally, Raman spectroscopy unveils a noteworthy correlation between the quality factor and the full width at half maximum of the A1g(O) mode at 878 cm−1. The structural attributes, including lattice fringes and diffraction patterns of hexagonal NaY9Si6O26 ceramics, are elucidated through transmission electron microscopy. Of significance are the microwave dielectric properties of NaY9Si6O26 ceramics sintered at 1465°C, revealing a relative permittivity (εr) of 10.42, an impressive Q × f product of 33 766 GHz (at f = 11.14 GHz), and a temperature coefficient of resonant frequency (τf) of −28.7 ppm/°C. This comprehensive investigation contributes to the understanding of both the structural and microwave dielectric characteristics of NaY9Si6O26 ceramics, with potential applications in advanced electronic devices. [ABSTRACT FROM AUTHOR]

In this work, a silicate ceramic, CaY2Al4SiO12 (CYASO), with a low dielectric constant and low loss was prepared using traditional solid-state methods. X-ray diffraction (XRD) refinement analysis shows that the CYASO material crystallized into a phase with an Ia-3d space group and an impurity peak. The orthogonal cubic structure of the CYASO ceramic was confirmed through transmission electron microscopy (TEM), and the structure exhibited an orderly layered arrangement. The internal microstructure was characterized using scanning electron microscopy (SEM), which showed that the sample's relative density reached 97.8%. We discuss the correlation between the full width at half maximum (FWHM) of the Raman matrix corresponding to the vibration mode of the symmetric bending mode of AlO4 at the Raman shift of 855 cm−1 and the Q × f value. Additionally, the analysis focused on the various factors that influence the dielectric constant, including density, secondary phase, and porosity changes. The ceramics exhibited remarkable microwave dielectric properties (εr = 8.7, Q × f = 34,700 GHz, τf = −35 ppm/°C) when calcined at 1425°C. CYASO ceramic shows great capacity as a microwave dielectric material. [ABSTRACT FROM AUTHOR]

This study delves into the microwave dielectric properties of Li2Y9(SiO4)6O2F ceramics, synthesized using the conventional solid-state method. By employing x-ray diffraction analysis and meticulous data refinement across various temperatures, we unequivocally confirm the hexagonal crystal structure of Li2Y9(SiO4)6O2F ceramics. The refined lattice parameters, observed at a sintering temperature of 1275°C, exhibit a = b = 9.33318 Å, c = 6.71725 Å, with a corresponding unit cell volume of V = 506.73529 Å3. In-depth scrutiny of the microstructure of the ceramics' grains using scanning electron microscopy (SEM) reveals an optimal relative density of 96.2%. Subsequently, the study explores the impact of porosity, packing fraction, relative density, and Si-O bond valence (VSi-O) on the microwave dielectric properties of Li2Y9(SiO4)6O2F ceramics. Notably, the Li2Y9(SiO4)6O2F ceramic sintered at 1275°C demonstrates superior performance metrics, boasting an εr value of 14.28, a Q × f product of 16,760 GHz (at f = 9.4 GHz), and a temperature coefficient of frequency (τf) at 3.14 ppm/°C. This comprehensive investigation contributes valuable insights into optimizing the microwave dielectric characteristics of Li2Y9(SiO4)6O2F ceramics for potential applications in advanced electronic devices. [ABSTRACT FROM AUTHOR]

The structural characteristics and microwave dielectric properties of SrBi2TeO7 ceramics intended for low-temperature co-fired ceramic (LTCC) applications were investigated. Comprehensive analyses were conducted using x-ray diffraction, structural refinement, transmission electron microscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy. The findings demonstrated that SrBi2TeO7 ceramics possess a pure cubic structure. Scanning electron microscopy characterizes the grain microstructure, revealing a relative density of 95.5% for SrBi2TeO7 ceramic. Optimal microwave dielectric properties were achieved for SrBi2TeO7 ceramics calcined at 765°C, displaying a relative permittivity (εr) of 24.96, a Q × f value of 25,898 GHz (f = 6.6 GHz), and a temperature coefficient of resonant frequency (τf) of –80.7 ppm/°C. The combination of low sintering temperature and minimal dielectric loss renders these ceramics advantageous for utilization in LTCC materials. [ABSTRACT FROM AUTHOR]

This study presents the dielectric properties of Ba2Zr2Si3O12 ceramics, synthesized using the solid state method. The cubic crystal structure of Ba2Zr2Si3O12 ceramics was conclusively verified through the analysis of XRD patterns and subsequent structural refinement. Refined lattice parameters of a = b = c = 10.23178 Å were found, with a corresponding unit cell volume of V = 1071.159026 Å3. The grain microstructure of the ceramics was characterized using SEM, which showed density of 97.6% for the Ba2Zr2Si3O12 ceramic. The Si-O bond valences (VSi-O) were found to be closely related to the τf of the Ba2Zr2Si3O12 ceramics. The microwave dielectric properties of the Ba2Zr2Si3O12 ceramics sintered at 1490°C were ascertained to be εr = 15.08, Q × f = 14885 GHz (f = 9.9 GHz), and τf = −78.6 ppm/°C. [ABSTRACT FROM AUTHOR]

In this work, the efficacy of sintering aid BaO–ZnO–Li2O–B2O3–SiO2 (BZLBS) on the sintering process at lower temperatures was verified for the Ca0.244Li0.3Nd0.404Ti0.96Al0.02Nb0.02O3 (CLNTAN) ceramics. Crystalline phases and dielectric properties of samples were systematically investigated as well. The results exhibited that the BZLBS apparently reduced the sintering temperature of CLNTAN by forming the liquid phase. Additionally, doping BALBS sintering aid not only reduced the sintering temperature, but also declined the dielectric constant (εr) and the quality factor (Q × f) for CLNTAN ceramic. Eventually, the microwave dielectric properties are as follows: εr = 104.7, Q × f = 2560 GHz and τf = − 2.1 ppm/°C (sintered at 950 °C). The results demonstrated that the CLNTAN ceramic doped with 4 wt% BZLBS is a potential LTCC ceramic application. [ABSTRACT FROM AUTHOR]

This study introduced a novel low-loss tungstate ceramic, La 7 Nb 3 W 4 O 30 (LNWO), synthesized using the solid-state techniques. The structural analysis of the La 7 Nb 3 W 4 O 30 ceramic material, utilizing X-ray diffraction (XRD) patterns and followed by detailed structural refinement, validated its rhombohedral structure. Transmission electron microscopy (TEM) was utilized to confirm the ordered layer arrangement characteristic of the rhombohedral structure. The internal structure was characterized by scanning electron microscopy (SEM), with the sample's relative density reaching 97.5 %. The correlation between the full width at half maximum (FWHM) of the Raman matrix at 901 cm−1 corresponding to the symmetric bending mode vibrations of WO 5 and the Q × f value was discussed. Furthermore, the main factors affecting the dielectric constant, including density, bond valence, secondary phases, and variations in porosity, were analyzed. Encouragingly, the ceramic showed significant microwave dielectric properties when it was sintered at 1425 °C (ε r = 23.68, Q × f = 26,687 GHz (f = 7.2 GHz), τ f = −35.2 ppm/°C). [ABSTRACT FROM AUTHOR]

A novel Li 4 AlSbO 6 (LASO) microwave dielectric ceramic with a monoclinic structure and space group C12/c1 was successfully prepared using traditional solid-state methods. When the sintering temperature was 1200 °C, it had excellent microwave dielectric properties, with ε r = 8.2, Q × f = 22,098 GHz, and τ f = −15.53 ppm/°C. Raman spectroscopy analysis showed that the FWHM of the strong peak at 691 cm−1 reflected the variation trend of Q × f value and was opposite to the variation trend of Q × f value. Additionally, the augmentation in the Q × f value can be attributed to a higher relative density. As per the bond valence analysis, ε r is closely connected to the rattling and compressing effects of A-site cations, and the higher ε theo than ε r in Li 4 AlSbO 6 can be attributed to the strong compression effect induced by Li+. Additionally, τ f may be influenced by both the Sb–O bond and relative density. [ABSTRACT FROM AUTHOR]

This study delves into the synthesis and characterization of rare earth germanate La 4 GeO 8 ceramics, employing the solid-phase reaction method, with a focus on their microwave dielectric properties and crystallographic characteristics. The research employs X-ray diffraction (XRD) and transmission electron microscopy (TEM) to ascertain the orthorhombic crystal structure within the Pnma space group. Rietveld refinement analysis precisely determines the lattice constants (a = 18.3006 Å, b = 7.6697 Å, c = 5.8513 Å) and unit cell volume (V = 821.28429 Å3). Raman spectroscopy provides insights into the correlation between the quality factor (Q × f) and the Full Width at Half Maximum (FWHM) of the A g (O) mode at 733 cm⁻1. A notable highlight of the study is the exceptional microwave dielectric performance of La 4 GeO 8 ceramic sintered at 1540 °C, characterized by a relative dielectric constant (ε r) of 13.24, a Q × f product of 47,826 GHz at 10.16 GHz, and a temperature coefficient of frequency (τ f) of −82.3 ppm/°C. This comprehensive investigation offers valuable insights into the structural and microwave dielectric properties of AB-type rare earth germanate La 4 GeO 8 ceramics, underscoring their potential in advanced dielectric material applications. [ABSTRACT FROM AUTHOR]

• ① A novel Nd 2 CaSnO 6 microwave dielectric ceramic was first discovered: ε r = 20.65, Q × f = 27,523 GHz, and τ f = –36.0 ppm/°C. • ② We analyzed the relationship between Raman spectroscopy and microwave dielectric properties. • ③ TEM analysis confirmed the double perovskite structure of Nd 2 CaSnO 6 ceramics. • ④ SEM images revealed the microstructure of the ceramic grains, with the maximum relative density reaching 97.5 %. This study elucidates the synthesis of a new class of Nd 2 CaSnO 6 microwave dielectric ceramics employing the conventional solid-phase method. X-ray diffraction (XRD) patterns and Rietveld refinement analysis revealed that the Nd 2 CaSnO 6 material crystallized into a single phase with an P21/n (14) space group. The double perovskite structure Nd 2 CaSnO 6 ceramics was confirmed through transmission electron microscopy (TEM), the structure exhibits a layered arrangement that is orderly. The internal microstructure was characterized using SEM, which showed that the sample's relative density reached 97.5 %. We discuss the correlation between FWHM and Q × f value of the Raman matrix at the Raman shift of 650.1 cm–1. Additionally, the main factors affecting the dielectric constant were analyzed, including density, secondary phase and porosity changes, etc. The ceramics exhibited remarkable microwave dielectric properties (ε r = 20.65, Q × f = 27523 GHz, and τ f = –36.0 ppm/ °C) when sintered at 1390 °C, indicating their potential as a microwave dielectric material. [Display omitted] [ABSTRACT FROM AUTHOR]

Ceramics of Y 2 GaSbO 7 (YGSO) were prepared by the solid-state reaction method. The ceramics were confirmed by XRD and TEM to exhibit the Fd-3 m (227) space group and a cubic pyrochlore structure within the temperature range of 1420–1500 °C. XPS verified that the valence states of Y, Ga, and Sb in the ceramics were + 3, + 3, and + 5, respectively. Additionally, the relationship between the FWHM of the notable peak at 775 cm−1 and the Q × f value was elucidated through Raman spectroscopic analysis. The analysis of the P-V-L theory revealed that the Sb-O bond is crucial in determining ε r , while the values of τ f and Q × f are affected by the Y-O bond. At 1460 °C, YGSO ceramics obtained the maximum relative density (97.5%) and the best microwave dielectric properties (ε r = 14.78, Q × f = 50,153 GHz, and τ f = –22.3 ppm/°C). • For the first time, a Y 2 GaSbO 7 microwave dielectric ceramic with a pyrochlore structure was discovered. • The Raman spectra of the ceramics were analyzed, and the valence state was studied using XPS. • TEM analysis confirmed the cubic structure of Y 2 GaSbO 7 ceramics. • SEM images revealed the microstructure of the ceramic grains, with the maximum relative density reaching 97.5%. • The relationship between α , f i , E b , U b , and the dielectric properties of Y 2 GaSbO 7 ceramics was examined using P-V-L theory. [ABSTRACT FROM AUTHOR]