Abstract:The ion valence state, phase composition, microstructure, and microwave dielectric properties of Sr(1−1.5x)CexTiO3 (x = 0.1–0.67, SCT) ceramics were systematically investigated. Sr(1−1.5x)CexTiO3 ceramics were produced with gradual structural evolution from a cubic to a tetragonal and turned to an orthorhombic structure in the range of 0.1 ≤ x ≤ 0.67. Above a critical Ce proportion (x = 0.4), microstructural changes and normal grain growth initially occurred. On the basis of chemical analysis results, the redu… Show more
“…Moreover, the presence of Ce 3+ may inhibit the reduction of Ti 4+ because of the favorable electron compensation. 24 As shown in Fig. 2d, we observed differences in binding energies of Ti-2p core level (Ti-2p3/2 and Ti-2p1/2 spin-orbit splitting) acquired for TiO2 and CeO2-TiO2 hybrid structures.…”
supporting
confidence: 51%
“…The relative high area ratio O2/O1, (0.38) in the CeO2-TiO2 O-1s spectrum in comparison to that of TiO2 (0.16) could point to an increase of oxygen vacancies. 24 Detailed deconvolution of O-1s core levels is shown in the supplementary information (Fig. S8) The photocatalytic activity of the prepared CeO2-TiO2 hybrid catalyst was first evaluated by degrading Methylene Blue (MB) under ultra-violet (UV) light irradiation (in comparison to bare TiO2) as shown in Fig.…”
“…Moreover, the presence of Ce 3+ may inhibit the reduction of Ti 4+ because of the favorable electron compensation. 24 As shown in Fig. 2d, we observed differences in binding energies of Ti-2p core level (Ti-2p3/2 and Ti-2p1/2 spin-orbit splitting) acquired for TiO2 and CeO2-TiO2 hybrid structures.…”
supporting
confidence: 51%
“…The relative high area ratio O2/O1, (0.38) in the CeO2-TiO2 O-1s spectrum in comparison to that of TiO2 (0.16) could point to an increase of oxygen vacancies. 24 Detailed deconvolution of O-1s core levels is shown in the supplementary information (Fig. S8) The photocatalytic activity of the prepared CeO2-TiO2 hybrid catalyst was first evaluated by degrading Methylene Blue (MB) under ultra-violet (UV) light irradiation (in comparison to bare TiO2) as shown in Fig.…”
“…As some ions tend to segregate at the grain boundaries, the growth of grain is restrained. 19 As a result, the grains tend to become small and uniform with the increment of doping content. As presented in Figure 2 (C) and (D), the average grain size decreases to~1.30 lm when x = 0.1 and becomes a little smaller at x = 0.15.…”
Al/Nb co-doped SrTiO 3 microwave ceramics with the composition of SrTi 1-x (Al 0.5 Nb 0.5 ) x O 3 (x = 0.03, 0.05, 0.1, and 0.15) have been synthesized via a standard solid-state reaction method. The substitution of (Al 0.5 Nb 0.5 ) 4+ in B-site inhibits the reduction in Ti 4+ ions and the growth of grain size, then the transport of mobile charge carriers is limited, and thus the Q value is improved. For the SrTi 0.9 (Al 0.5 Nb 0.5 ) 0.1 O 3 ceramics, in addition to their high dielectric constant (e r 185), they exhibit correspondingly a high Qf value (~9077 GHz) at 2.9 GHz, making the microwave ceramics suitable for myriad device miniaturization and high-performance wireless communication.
K E Y W O R D Sdielectric materials/properties, electroceramics, microwaves
“…(1-x)Mg(Ti 0.95 Sn 0.05 )O 3 -xBaTiO 3 compounds experienced a phase transition of tetragonal-structure BaTiO 3 , monoclinic-structure Ba 4 Ti 11 O 26 , and triclinic-structure Ba 2 Ti 9 O 20 [419]. Likewise, Sr (1-1.5x) Ce x TiO 3 (x = 0.1-0.67) ceramics changed from cubic, tetragonal, to orthorhombic, and the dielectric behaviors were dominated by oxygen vacancies and defect dipoles [420]. Tian et al [421,422] reported that (Co 0.5 W 0.5 ) 4+ and (Zn 0.5 W 0.5 ) 4+ occupying the Ti-site in BaTiO 3 would render the τ f value change from positive to negative.…”
The explosive process of 5G communication evokes the urgent demand of miniaturized and integrated dielectric ceramics filter. It is a pressing need to advance the development of dielectric ceramics utilization of emerging technology to design new materials and understand the polarization mechanism. This review provides the summary of the study of microwave dielectric ceramics (MWDCs) sintered higher than 1000 from 2010 up to now, °C with the purpose of taking a broad and historical view of these ceramics and illustrating research directions. To date, researchers endeavor to explain the structure-property relationship of ceramics with multitude of approaches and design a new formula or strategy to obtain excellent microwave dielectric properties. There are variety of factors that impact the permittivity, dielectric loss, and temperature stability of dielectric materials, covering intrinsic and extrinsic factors. Many of these factors are often intertwined, which can complicate new dielectric material discovery and the mechanism investigation. Because of the various ceramics systems, pseudo phase diagram was used to classify the dielectric materials based on the composition. In this review, the ceramics were firstly divided into ternary systems, and then brief description of the experimental probes and complementary theoretical methods that have been used to discern the intrinsic polarization mechanisms and the origin of intrinsic loss was mentioned. Finally, some perspectives on the future outlook for high-temperature MWDCs were offered based on the synthesis method, characterization techniques, and significant theory developments.
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