Open Access Research Article Issue
Colossal permittivity and ultralow dielectric loss in Nb-doped SrTiO3 ceramics
Journal of Advanced Ceramics 2023, 12 (12): 2247-2256
Published: 04 January 2024
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Defect engineering has been applied to prepare materials with modifiable dielectric properties. SrTiNbxO3 (x = 0, 0.003, 0.006, 0.009, 0.012) ceramics were synthesized using the traditional solid-state reaction method and sintered in a reducing atmosphere. All samples show excellent dielectric properties with giant permittivity (> 3.5×104) and low dielectric loss (< 0.01). SrTiNb0.003O3 ceramic exhibits a colossal permittivity of 4.6×104 and an ultralow dielectric loss of 0.005 (1 kHz, room temperature) as well as great temperature stability in the range of (−60)–160℃. The mechanism of the presented colossal permittivity (CP) properties is investigated by conducting X-ray photoelectron spectroscopy (XPS) and analyzing activation energies. The results indicate that the introduction of Nb5+ and the reducing sintering atmosphere together generated the formation of Ti3+ and VO··. These defects further form TiTiVO··TiTi defect dipoles, contributing to the coexisting giant permittivity and low dielectric loss in Nb-doped SrTiO3 (STN) ceramics.

Open Access Research paper Issue
Novel fast ionic conductor ceramic composite separator for high-performance safe Li-ion power batteries
Journal of Materiomics 2022, 8 (6): 1184-1190
Published: 03 June 2022
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The ceramic composite separators coated with silica or alumina particles have been used in power batteries due to their better electrolyte wettability and better thermal stability compared with bare polymer separators. However, these oxide ceramics are Li+ ion insulators, which increase internal resistance and hinder the improvement of rate capability of batteries. Herein, we report a strategy to further improving the performance of lithium-ion batteries (LIBs) by using fast ionic conductor ceramic composite separator as an alternative to traditional ceramic coated separators. Lithium lanthanum titanate (LLTO), a fast ionic conductor with excellent room temperature bulk conductivity, are coated on the common polyethylene (PE) separators. Our results demonstrate that such a novel LLTO-coated separator possess excellent electrolyte wettability and thermal stability; and the assembled NCM523/graphite lithium-ion pouch cells with LLTO-coated separator show better rate capability and cyclic performance with 88.7% capacity retention after 1000 cycles at room temperature compared with the pouch cells with Al2O3-coated separators. The fast ionic conductor ceramic composite separators will be a potential competitor to the next-generation novel separators for high-performance Li-ion power batteries.

Open Access Rapid Communication Issue
Pyrochlore-based high-entropy ceramics for capacitive energy storage
Journal of Advanced Ceramics 2022, 11 (7): 1179-1185
Published: 25 May 2022
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High-performance dielectrics are widely used in high-power systems, electric vehicles, and aerospace, as key materials for capacitor devices. Such application scenarios under these extreme conditions require ultra-high stability and reliability of the dielectrics. Herein, a novel pyrochlore component with high-entropy design of Bi1.5Zn0.75Mg0.25Nb0.75Ta0.75O7 (BZMNT) bulk endows an excellent energy storage performance of Wrec 2.72 J/cm3 together with an ultra-high energy efficiency of 91% at a significant enhanced electric field Eb of 650 kV/cm. Meanwhile, the temperature coefficient (TCC) of BZMNT (~ -220 ppm/℃) is also found to be greatly improved compared with that of the pure Bi1.5ZnNb1.5O7 (BZN) (~ -300 ppm/℃), demonstrating its potential application in temperature-reliable conditions. The high-entropy design results in lattice distortion that contributes to the polarization, while the retardation effect results in a reduction of grain size to submicron scale which enhances the Eb. The high-entropy design provides a new strategy for improving the high energy storage performance of ceramic materials.

Open Access Rapid Communication Issue
Electrical and thermal transport behaviours of high-entropy perovskite thermoelectric oxides
Journal of Advanced Ceramics 2021, 10 (2): 377-384
Published: 29 January 2021
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Oxide-based ceramics could be promising thermoelectric materials because of their thermal and chemical stability at high temperature. However, their mediocre electrical conductivity or high thermal conductivity is still a challenge for the use in commercial devices. Here, we report significantly suppressed thermal conductivity in SrTiO3-based thermoelectric ceramics via high-entropy strategy for the first time, and optimized electrical conductivity by defect engineering. In high-entropy (Ca0.2Sr0.2Ba0.2Pb0.2La0.2)TiO3 bulks, the minimum thermal conductivity can be 1.17 W/(m·K) at 923 K, which should be ascribed to the large lattice distortion and the huge mass fluctuation effect. The power factor can reach about 295 μW/(m·K2) by inducing oxygen vacancies. Finally, the ZT value of 0.2 can be realized at 873 K in this bulk sample. This approach proposed a new concept of high entropy into thermoelectric oxides, which could be generalized for designing high-performance thermoelectric oxides with low thermal conductivity.

Open Access Rapid Communication Issue
Mechanical and biocompatible properties of polymer-infiltrated- ceramic-network materials for dental restoration
Journal of Advanced Ceramics 2020, 9 (1): 123-128
Published: 05 February 2020
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Dental restorative materials with high mechanical properties and biocompatible performances are promising. In this work, polymer-infiltrated-ceramic-network materials (PICNs) were fabricated via infiltrating polymerizable monomers into porous ceramic networks and incorporated with hydroxyapatite nano-powders. Our results revealed that the flexural strength can be enhanced up to 157.32 MPa, and elastic modulus and Vickers hardness can be achieved up to 19.4 and 1.31 GPa, respectively, which are comparable with the commercial computer-aided design and computer-aided manufacturing (CAD/CAM) blocks. Additionally, the adhesion and spreading of rat bone marrow mesenchymal stem cells (rBMSCs) on the surface of such materials can be improved by adding hydroxyapatite, which results in good biocompatibility. Such PICNs are potential applicants for their application in the dental restoration.

Open Access Review Issue
Low-dimensional nanostructured photocatalysts
Journal of Advanced Ceramics 2015, 4 (3): 159-182
Published: 08 September 2015
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Low-dimensional nanostructures are a promising class of ideal high-performance candidates for energy storage and conversion owing to their unique structural, optical, and chemical properties. Low-dimensional nanostructured photocatalysts have attracted ever-growing research attention. In this review, we mainly emphasize on summarizing the 0-, 1-, and 2-dimensional nanostructured photocatalysts systematically, including their photocatalytic performance, synthesis methods, and theoretical analysis. From the viewpoint of dimension, we try to figure out the way to design more high-efficiency photocatalysts towards numerous applications in the field of solar energy conversion, hoping to promote efficient control and rational development of photocatalysts.

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