JAC 2020 年第 9 卷第 5 期導讀

為便於讀者查找和閱讀近年來 Journal of Advanced Ceramics 上發表的論文，本公眾號將陸續推出近年來 JAC 各期論文導讀專題。這一導讀將提供每一期所有論文的題目、作者、檢索信息、摘要及全文下載二維碼 (掃描二維碼即可方便地下載論文全文)、全文下載地址。

Micro-nano structured functional coatings deposited by liquid plasma sprayingYuchun Huan, Kaidi Wu, ... Chao ZhangJ. Adv. Ceram., 2020, 9 (5): 517 - 534Abstract: Inspired by the micro-nano structure on the surface of biological materials or living organisms, micro-nano structure has been widely investigated in the field of functional coatings. Due to its large specific surface area, porosity, and dual-scale structure, it has recently attracted special attention. The typical fabrication processes of micro-nano structured coatings include sol-gel, hydrothermal synthesis, chemical vapor deposition, etc. This paper presents the main features of a recent deposition and synthesis technique, liquid plasma spraying (LPS). LPS is an important technical improvement of atmospheric plasma spraying. Compared with atmospheric plasma spraying, LPS is more suitable for preparing functional coatings with micro-nano structure. Micro-nano structured coatings are mainly classified into hierarchical-structure and binary-structure. The present study reviews the preparation technology, structural characteristics, functional properties, and potential applications of LPS coatings with a micro-nano structure. The micro-nano structured coatings obtained through tailoring the structure will present excellent performances.

https://link.springer.com/article/10.1007/s40145-020-0402-9Optimal performance of Cu1.8S1-xTex thermoelectric materials fabricated via high-pressure process at room temperatureRui Zhang, Jun Pei, ... Bo-Ping ZhangJ. Adv. Ceram., 2020, 9 (5): 535 - 543Abstract: Cu1.8S has been considered as a potential thermoelectric (TE) material for its stable electrical and thermal properties, environmental benignity, and low cost. Herein, the TE properties of nanostructured Cu1.8S1−xTex (0 <= x <= 0.2) bulks fabricated by a facile process combining mechanical alloying (MA) and room-temperature high-pressure sintering (RT-HPS) technique were optimized via eliminating the volatilization of S element and suppressing grain growth. Experimentally, a single phase of Cu1.8S was obtained at x = 0, and a second Cu1.96S phase formed in all Cu1.8S1−xTex samples when 0.05 <= x <= 0.125. With further increasing x to 0.15 <= x <= 0.2, the Cu2−zTe phase was detected and the samples consisted of Cu1.8S, Cu1.96S, and Cu2−zTe phases. Benefiting from a modified band structure and the coexisted phases of Cu1.96S and Cu2−zTe, the power factor is enhanced in all Cu1.8S1−xTex (0.05 <= x <= 0.2) alloys. Combining with a drastic decrease in the thermal conductivity due to the strengthened phonon scatterings from multiscale defects introduced by Te doping and nano-grain boundaries, a maximum figure of merit (ZT) of 0.352 is reached at 623 K for Cu1.8S0.875Te0.125, which is 171% higher than that of Cu1.8S (0.130). The study demonstrates that doping Te is an effective strategy to improve the TE performance of Cu1.8S based materials and the proposed facile method combing MA and RT-HPS is a potential way to fabricate nanostructured bulks.

https://link.springer.com/article/10.1007/s40145-020-0385-6Creep deformation behavior during densification of ZrB2-SiBCN ceramics with ZrO2 additiveBo Feng, Zhenhang Wang, ... Yue ZhangJ. Adv. Ceram., 2020, 9 (5): 544 - 557Abstract: ZrB2-SiBCN ceramics with ZrO2 additive are hot-pressed under a constant applied pressure. The densification behavior of the composites is studied in a view of creep deformation by means of the Bernard-Granger and Guizard model. With determination of the stress exponent (n) and the apparent activation energy (Qd), the specific deformation mechanisms controlling densification are supposed. Within lower temperature ranges of 1300–1400 °C, the operative mechanism is considered to be grain boundary sliding accommodated by atom diffusion of the polymer-derived SiBCN (n = 1, Qd = 123±5 kJ/mol) and by viscous flow of the amorphous SiBCN (n = 2, Qd = 249±5 kJ/mol). At higher temperatures, the controlling mechanism transforms to lattice or intra-granular diffusion creep (n = 3–5) due to gradual consumption of the amorphous phase. It is suggested that diffusion of oxygen ions inside ZrO2 into the amorphous SiBCN decreases the viscosity, modifies the fluidity, and contributes to the grain boundary mobility.

https://link.springer.com/article/10.1007/s40145-020-0393-6Structure, morphology, and microwave dielectric properties of SmAlO3 synthesized by stearic acid routeJiamao Li, Chuimin Zhang, ... Chuangang FanJ. Adv. Ceram., 2020, 9 (5): 558 - 566Abstract: A rapid and facile approach was developed for the synthesis of ultrafine SmAlO3 powders through the combustion of stearic acid precursors. The obtained products were characterized by typical techniques including X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to analyze the phase composition and microstructure. The dielectric characteristics of SmAlO3 microwave ceramics, using the as-obtained products as original materials, were also studied. Compared with the conventional solid-state reaction method, the synthesis temperature was dramatically reduced to 750 °C. The large-size sheet structure was composed of a number of micro/nano-scale crystallites, which were mostly irregular in shape due to the mutual growth and overlapping shapes of adjacent grains. The SmAlO3 ceramics with high density and uniform microstructure were obtained after sintering at 1500 °C for 4 h due to the favorable sintering activity of the as-synthesized powders. In addition, desired dielectric properties at microwave frequencies (dielectric constant εr = 20.22, quality factor Q·f = 74110 GHz, and a temperature coefficient of resonant frequency τf = −74.6 ppm/°C) were achieved.

https://link.springer.com/article/10.1007/s40145-020-0394-5Residual stress variation in SiCf/SiC composite during heat treatment and its effects on mechanical behaviorXiaowu Chen, Guofeng Cheng, ... Shaoming DongJ. Adv. Ceram., 2020, 9 (5): 567 - 575Abstract: Residual stress originated from thermal expansion mismatch determines the mechanical properties of ceramic matrix composites (CMCs). Here, continuous SiC fiber reinforced SiC matrix (SiCf/SiC) composites were fabricated by nano-infiltration and transient eutectic-phase (NITE) method, and the residual stress of the composites was investigated using high-temperature Raman spectrometer. With temperature increasing from room temperature to 1400°C, the residual stresses of the matrix and the fiber decrease from 1.29 to 0.62 GPa and from 0.84 to 0.55 GPa in compression respectively, while that of the interphase decreases from 0.16 to 0.10 GPa in tension. The variation of residual stress shows little effect on the tensile strength of the composites, while causes a slight decrease in the tensile strain. The suppression of fiber/matrix debonding and fiber pulling-out caused by the residual stress reduction in the interphase is responsible for the decreasing tensile strain. This work can open up new alternatives for residual stress analysis in CMCs.

https://link.springer.com/article/10.1007/s40145-020-0395-4Zn2+ substituted superparamagnetic MgFe2O4 spinel-ferrites: Investigations on structural and spin-interactionsLakshita Phor, Surjeet Chahal, Vinod KumarJ. Adv. Ceram., 2020, 9 (5): 576 - 587Abstract: Nano-magnetic ferrites with composition Mg1−xZnxFe2O4 (x = 0.3, 0.4, 0.5, 0.6, and 0.7) have been prepared by coprecipitation method. X-ray diffraction (XRD) studies showed that the lattice parameter was found to increase from 8.402 to 8.424 Å with Zn2+ ion content from 0.3 to 0.7. Fourier transform infrared (FTIR) spectra revealed two prominent peaks corresponding to tetrahedral and octahedral at around 560 and 430 cm−1 respectively that confirmed the spinel phase of the samples. Transmission electron microscopy (TEM) images showed that the particle size was noted to increase from 18 to 24 nm with an increase in Zn content from x = 0.3 to 0.7. The magnetic properties were studied by vibrating sample magnetometer (VSM) and electron paramagnetic resonance (EPR) which ascertained the superparamagnetic behavior of the samples and contribution of superexchange interactions. The maximum magnetization was found to vary from 23.80 to 32.78 emu/g that increased till x = 0.5 and decreased thereafter. Further, X-ray photoelectron spectroscopy (XPS) was employed to investigate the chemical composition and substantiate their oxidation states.

https://link.springer.com/article/10.1007/s40145-020-0396-3Effect of Sb-site nonstoichiometry on the structure and microwave dielectric properties of Li3Mg2Sb1-xO6 ceramicsCuijin Pei, Jingjing Tan, ... Huaiwu ZhangJ. Adv. Ceram., 2020, 9 (5): 588 - 594Abstract: The non-stoichiometric Li3Mg2Sb1−xO6 (0.05 <= x <= 0.125) compounds have been prepared via the mixed oxide method. The influences of Sb nonstoichiometry on the sintering behavior, microstructure, phase composition along with microwave dielectric performances for Li3Mg2Sb1−xO6 ceramics were studied. Combined with X-ray diffraction (XRD) and Raman spectra, it was confirmed that phase composition could not be affected by the Sb nonstoichiometry and almost pure phase Li3Mg2SbO6 was formed in all compositions. Appropriate Sb-deficiency in Li3Mg2SbO6 not only lowered its sintering temperature but also remarkably improved its Q×f value. In particular, non-stoichiometric Li3Mg2Sb0.9O6 ceramics sintered at 1250°C/5 h owned seldom low dielectric constant εr = 10.8, near-zero resonant frequency temperature coefficient τf = −8.0 ppm/°C, and high quality factor Q×f = 86,300 GHz (at 10.4 GHz). This study provides an alternative approach to ameliorate its dielectric performances for Li3Mg2SbO6-based compounds through defect-engineering.

https://link.springer.com/article/10.1007/s40145-020-0397-2High-entropy (Nd0.2Sm0.2Eu0.2Y0.2Yb0.2)4Al2O9 with good high temperature stability, low thermal conductivity, and anisotropic thermal expansivityZifan Zhao, Huimin Xiang,  ... Yanchun ZhouJ. Adv. Ceram., 2020, 9 (5): 595 - 605Abstract: The critical requirements for the environmental barrier coating (EBC) materials of silicon-based ceramic matrix composites (CMCs) include good tolerance to harsh environments, thermal expansion matches with the interlayer mullite, good high-temperature phase stability, and low thermal conductivity. Cuspidine-structured rare-earth aluminates RE4Al2O9 have been considered as candidates of EBCs for their superior mechanical and thermal properties, but the phase transition at high temperatures is a notable drawback of these materials. To suppress the phase transition and improve the phase stability, a novel cuspidine-structured rare-earth aluminate solid solution (Nd0.2Sm0.2Eu0.2Y0.2Yb0.2)4Al2O9 was designed and successfully synthesized inspired by entropy stabilization effect of high-entropy ceramics (HECs). The as-synthesized HE (Nd0.2Sm0.2Eu0.2Y0.2Yb0.2)4Al2O9 exhibits a close thermal expansion coefficient (6.96×10E-6 K-1 at 300–1473 K) to that of mullite, good phase stability from 300 to 1473 K, and low thermal conductivity (1.50 W·m–1·K–1 at room temperature). In addition, strong anisotropic thermal expansion has been observed compared to Y4Al2O9 and Yb4Al2O9. The mechanism for low thermal conductivity is attributed to the lattice distortion and mass difference of the constituent atoms, and the anisotropic thermal expansion is due to the anisotropic chemical bonding enhanced by the large size rare-earth cations.

https://link.springer.com/article/10.1007/s40145-020-0399-0Development of calcium stabilized nitrogen rich α-sialon ceramics along the Si3N4:1/2Ca3N2:3AlN line using spark plasma sinteringB. A. Ahmed, T. Laoui, A. S. HakeemJ. Adv. Ceram., 2020, 9 (5): 606 - 616Abstract: Calcium stabilized nitrogen rich sialon ceramics having a general formula of CaxSi12-2xAl2xN16 with x value (x is the solubility of cation Ca in α-sialon structure) in the range of 0.2–2.2 for compositions lying along the Si3N4:1/2Ca3N2:3AlN line were synthesized using nano/submicron size starting powder precursors and spark plasma sintering (SPS) technique. The development of calcium stabilized nitrogen rich sialon ceramics at a significantly low sintering temperature of 1500°C (typically reported a temperature of 1700°C or greater) remains to be the highlight of the present study. The SPS processed sialons were characterized for their microstructure, phase and compositional analysis, and physical and mechanical properties. Furthermore, a correlation was developed between the lattice parameters and the content (x) of the alkaline metal cation in the α-sialon phase. Well-densified single-phase nitrogen rich α-sialon ceramics were achieved in the range of 0.53(3) <= x <= 1.27(3). A nitrogen rich α-sialon sample possessing a maximum hardness of 22.4 GPa and fracture toughness of 6.1 MPa·m1/2 was developed.

https://link.springer.com/article/10.1007/s40145-020-0400-yRole of in-situ formed free carbon on electromagnetic absorption properties of polymer-derived SiC ceramicsZhaoju Yu, Xuan Lv, ... Anhua LiuJ. Adv. Ceram., 2020, 9 (5): 617 - 628Abstract: In order to enhance dielectric properties of polymer-derived SiC ceramics, a novel single-source-precursor was synthesized by the reaction of an allylhydrido polycarbosilane (AHPCS) and divinyl benzene (DVB) to form carbon-rich SiC. As expected, the free carbon contents of resultant SiC ceramics annealed at 1600 °C are significantly enhanced from 6.62 wt% to 44.67 wt%. After annealing at 900–1600 °C, the obtained carbon-rich SiC ceramics undergo phase separation from amorphous to crystalline feature where superfine SiC nanocrystals and turbostratic carbon networks are dispersed in an amorphous SiC(O) matrix. The dielectric properties and electromagnetic (EM) absorption performance of as-synthesized carbon-rich SiC ceramics are significantly improved by increasing the structural order and content of free carbon. For the 1600 °C ceramics mixed with paraffin wax, the minimum reflection coefficient (RCmin) reaches –56.8 dB at 15.2 GHz with the thickness of 1.51 mm and a relatively broad effective bandwidth (the bandwidth of RC values lower than –10 dB) of 4.43 GHz, indicating the excellent EM absorption performance. The carbon-rich SiC ceramics have to be considered as harsh environmental EM absorbers with excellent chemical stability, high temperature, and oxidation and corrosion resistance.

https://link.springer.com/article/10.1007/s40145-020-0401-xA comprehensive study on Li4Si1-xTixO4 ceramics for advanced tritium breedersYichao Gong, Lin Liu, ... Tiecheng LuJ. Adv. Ceram., 2020, 9 (5): 629 - 640Abstract: Hetero-element doped lithium orthosilicates have been considered as advanced tritium breeders due to the superior performances. In this work, Li4Si1−xTixO4 ceramics were prepared by proprietary hydrothermal process and multistage reactive sintering. The reaction mechanism of Li4Si1−xTixO4 was put forward. XRD and SEM analyses indicate that insertion of Ti leads to lattice expansion, which promotes the grain growth and changes the fracture mode. The compressive tests show that the crush load increases almost four times by increasing x from 0 to 0.2. However, the thermal conductivity and ionic conductivity are the best when x = 0.05 and x = 0.1, respectively. Thermal cycling stability of Li4Si1−xTixO4 pebbles was further appraised through investigating the changes of microstructure and crush load. After undergoing thermal cycling, the Li4Si1−xTixO4 still show higher crush load compared with Li4SiO4, despite Ti segregation in some samples. The x = 0.05 sample exhibits excellent thermal cycling stability. In summary, proper amount of Ti doping can improve the crush load, thermal and ionic conductivity, and thermal cycling stability of Li4SiO4.

https://link.springer.com/article/10.1007/s40145-020-0419-0Effect of octahedron tilt on the structure and magnetic properties of bismuth ferriteYang Hong, Jun Li, ... Zhongxiang ZhouJ. Adv. Ceram., 2020, 9 (5): 641 - 646Abstract: Multiferroic BiFeO3-based ceramics were synthesized using the rapid liquid-phase sintering method. The rare-earth ion (Sm3+, Gd3+, Y3+) doping causes structural distortion without changing the intrinsic rhombohedral perovskite structure. Raman analysis shows that the effect of doping on E modes is greater than A1 modes, and the microstructure of FeO6 octahedron can be regulated by ion doping. A-site trivalent ion doped ceramics exhibit improved magnetism compared with pure BiFeO3 ceramic, which originated from the suppressed spiral spin structure of Fe ions. The tilt of FeO6 octahedron as a typical structure instability causes the anomalous change of the imaginary part of permittivity at high frequency, and doped ceramics exhibit natural resonance around 16–17 GHz.

https://link.springer.com/article/10.1007/s40145-020-0398-1
本刊成立了《先進陶瓷》聯誼會，歡迎關心、支持本刊的朋友踴躍參加。掃描以下二維碼即可了解聯誼會條例並填寫會員登記表。JAC編委會每年年底從聯誼會成員中招募新人，有意加盟編委會的年輕朋友請務必及時加入聯誼會。計劃向本刊投稿的朋友也請儘可能加入聯誼會。