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91.
This work presents a comprehensive study about the influence of Ba-substitution on the structural and ferroelectric properties of Pb1?x Ba x Zr0.40Ti0.60O3 (PBZT) ceramic system. Pb1?x Ba x Zr0.40Ti0.60O3 ceramic samples were then prepared by solid state reaction method and characterized as a function of composition and temperature by X-ray diffraction (XRD) and impedance spectroscopy techniques. The dielectric measurements show that the substitution of Pb2+ for Ba2+ ions leads to a diffuse behavior of the dielectric permittivity curves for all samples and that only the x?=?0.50 sample presents a typical relaxor behavior. In good agreement with dielectric measurements, the structural phase transition study showed a phase transition from a tetragonal structure with P4mm space group to a cubic structure with Pm-3m space group for all samples, except for the x?=?0.50 sample were a cubic structure was observed in the complete temperature interval measured. 相似文献
92.
Sreenu Kurra Perala Venkataswamy Gundeboina Ravi Chandhiri Sudhakar Reddy Boggu Jaganmohan Reddy Muga Vithal 《无机化学与普通化学杂志》2019,645(5):529-536
Perovskite type oxides, sodium bismuth titanate (Na0.5Bi0.5TiO3), and Ag+, Cu2+, and Sn2+ doped Na0.5Bi0.5TiO3 were prepared by pechini and ion exchange methods, respectively. Photocatalytic activities of these catalysts were tested by decomposition of methylene blue (MB) under visible light irradiation. Results showed that the photocatalytic activity of metal ion doped Na0.5Bi0.5TiO3 was higher than undoped Na0.5Bi0.5TiO3. Relatively high photocatalytic performance of Ag+‐doped Na0.5Bi0.5TiO3 is mainly ascribed to the efficient separation of electron‐hole (e–, h+) pairs, lower bandgap energy and the creation of active hydroxyl radicals ( ? OH). Further, the Ag+‐doped Na0.5Bi0.5TiO3 catalyst showed good reusability up to four cycles. A possible mechanism for the enhanced photocatalytic performance was proposed. The synthesized photocatalysts were characterized by XRD, SEM, EDS, XPS, FT‐IR, and UV/Vis DRS techniques. 相似文献
93.
Nanoparticle zinc-titanium oxide materials were prepared by the aerogel approach. Their structure, surface state and reactivity were investigated. Zinc titanate powders formed at higher zinc loadings possessed a higher surface area and smaller particle size. X-ray photoelectron spectroscopy (XPS) revealed a stronger electronic interaction between Zn and Ti atoms in the mixed oxide structure and showed the formation of oxygen vacancy due to zinc doping into titania or zinc titanate matrices. The 8-45 nm aerogel particles were evaluated as catalysts for methanol oxidation in an ambient flow reactor. Carbon dioxide was favorably produced on the oxides with anion defects. Titanium based oxides exhibited a high selectivity to dimethyl ether, so that a strong Lewis acidic character suggested for the catalysts was associated primarily with the Ti4+ center. Both methanol conversion and dimethyl ether formation rates increased with increasing the zinc content added to the oxide support. Results demonstrate that cubic zinc titanate phases produce new Lewis acid sites having also a higher reactivity and that the nature of the catalytic surface transforms from Lewis acidic to basic characters due to the presence of reactive oxygen vacancies. 相似文献
94.
《中国化学快报》2020,31(9):2254-2258
In the work, we successfully explore a two-step hydrothermal method for scalable synthesis of the hybrid sodium titanate (NaTi8O13/NaTiO2) nanoribbons well in-situ formed on the multi-layered MXene Ti3C2 (designed as NTO/Ti3C2). Benefiting from the inherent structural and componential superiorities, the resulted NTO/Ti3C2 composite exhibits long-duration cycling stability and superior rate behaviors when evaluated as a hybrid anode for advanced SIBs, which delivers a reversible and stable capacity of ∼82 mAh/g even after 1900 cycles at 2000 mA/g for SIBs. 相似文献
95.
Physical properties of titanates,semiconductors and nickelates derived from ionization energy theory
《Physics letters. A》2020,384(36):126917
Ionization energy theory is exploited to predict the changes to atomic polarizability for both anions and cations, the polarization in doped titanates and the energy gap in III–V and II–VI semiconductors. We then extend the above analysis to discuss the physics of metallic and superconducting phases in the recently discovered superconducting nickelates. In doing so, we are able to prove the existence of Ni2+ cations and oxygen vacancy in the metallic normal state of nickelates. We find that the normal state resistivity of the nickelates follows exactly as predicted by the ionization energy theory. Quantitative estimates are also given for the concentrations of Ni2+ and oxygen vacancy in superconducting nickelates. 相似文献
96.
97.
Synergistic effect of CdS decorated sodium titanate nanostructures showed enhanced H2 production abilities. The confinement effect and synergistic effect of decorated CdS inside the sodium titanate nanotubes are investigated. 相似文献
98.
采用溶胶-凝胶法制备了纳米钙钛矿型复合氧化物SrTiO3催化剂,并用X射线粉末衍射、透射电子显微镜、原位电子自旋共振和程序升温表面反应等技术对催化剂进行了表征,测定了催化剂对甲烷氧化偶联(OCM)反应的催化性能.结果表明,与相同组成的常规SrTiO3催化剂相比,纳米SrTiO3催化剂具有较好的低温(~650℃)催化性能.通过增大Sr/Ti比可进一步优化纳米SrTiO3的催化性能.纳米SrTiO3催化剂表面的吸附氧物种和F中心均具有活化及催化甲烷分子生成C2烃产物的活性,但吸附氧物种易使OCM反应中间体和产物深度氧化,而F中心具有低温活化甲烷分子及高选择性生成C2烃产物的特性.纳米氧化物粒子因表面原子配位不饱和(配位数低),其表面存在较多的F中心。 相似文献
99.
《印度化学会志》2023,100(2):100901
The novel calcium titanate-lithium lanthanum titanate doped with zinc oxide (0.10, 0.30, and 0.50 mol. %) ceramic samples were prepared by solid-state reaction route. The phase formation, microstructure, densification, and microwave dielectric properties were investigated. It was found that the doping with zinc oxide led to a decrease in sintering temperature by 25 oC as compared with pure calcium titanate lithium lanthanum titanate due to the liquid phase effect. Also, the calcium titanate lithium lanthanum titanate (10ZCTLLT&30ZCTLLT)) doped with lower zinc oxide (0.10 and 0.30 mol. %) led to higher densification parameter. This was followed by increasing the zinc oxide doping up to (0.50 mol. %) which resulted in a decrease in densification and microwave dielectric properties which may be attributed to increase in porosity and grain growth upon the evaporation of zinc and oxygen vacancy. This led to the increase in dielectric loss (≈10 × 10?4) value with 50ZCTLLT. Hence, the best result of microwave dielectric characteristics was obtained for 0.5CaTiO3–0.5(Li0.5La0.5)TiO3 with (0.10 and 0.30 mol. % ZnO) 10ZCTLLT and 30ZCTLLT ceramic samples sintered at 1175 oC/2h, with low dielectric constant (εr) = 4.4–10.5, very low dielectric loss = 1.07-2.23 × 10?4 and high quality factor (Q x ?) ≈59-55 × 104 at 8 GHz. Consequently, they can be used not only in wireless satellite communications technology but also can be used in the fifth-generation telecommunication 5G technology construction. 相似文献
100.
《Arabian Journal of Chemistry》2023,16(2):104473
The coupling of piezocatalysis and photocatalysis known as piezo-photocatalysis has attracted a lot of attention as one of the most effective advanced oxidation process (AOPs) for wastewater treatment, especially for the degradation of organic pollutants and disinfection of microbes. To advance this technology, there’s a need to develop lead free piezoelectric materials to drive both piezocatalytic and photocatalytic process to prevent secondary pollution due to lead toxicity. Hence, barium titanate (BaTiO3) has been widely used as lead free piezoelectric material for several applications including water splitting, bacterial disinfection, and wastewater treatment due to its exceptional optical and piezoelectric properties. This work presents a comprehensive review on the application of BaTiO3 as a promising lead-free piezo-photocatalyst for the catalytic degradation of organic pollutants and bacterial disinfection from aqueous solution. This review article details the optical and piezoelectric properties, modification strategies, and synthetic methods of BaTiO3. Furthermore, the application of BaTiO3 as a preferred piezo-photocatalyst for wastewater treatment and a future perspective is presented. 相似文献