Crystals
·
2020
·Vol. 10
·期 8
·698
·
IF 2.404
Mengdi Fan,Guangda Wu,Fapeng Yu,Lili Li,Yanlu Li,Xiufeng Cheng,Xian Zhao
The bismuth layer-structured ferroelectrics (BLSFs) materials have potential for high-temperature piezoelectric applications. Among these piezoelectric materials, the CaBi4Ti4O15(CBT) piezoelectric ceramic with a high decomposition temperature of about 1250 °C attracts a lot of attention. Achieving a CBT single crystal is a significant way to improve its piezoelectric properties. For this purpose, the flux system for growing CBT crystal was explored in this study. The optimum flux composition ratio was found to be PbO:B2O3:CBT = 3:3:1 in mol%, where the PbO–B2O3mixtures were used as a flux system. Millimeter size flake-shaped CBT crystals were obtained using the spontaneous growth process for the first time. The relationship between the crystal structure and flake growth habit was analyzed. In addition, the bandgap was evaluated by the combination of transmittance spectrum and first-principle calculations. Besides, the piezoelectric property was predicted from the perspective of polyhedral distortion, which indicated the potential of CBT crystal for piezoelectric applications.Keywords:CaBi4Ti4O15;single crystal growth;flux method;dipole moments
研究领域:
材料科学
·
晶体学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Cleaner Production
·
2024
·
IF 9.7
Zhangsong Jiang,Guichun He,Yan Shi,Yilong Duan,Yue Lin,Yinmei Jiang
Although solid waste is a good raw material for preparing foam ceramics , the mechanisms of the discrepancies in different solid wastes affecting the properties of foam ceramics remain unelucidated. In this study, the properties of tin tailings-based foam ceramics with different proportions of waste glass (WG) or scheelite tailings (ST) were measured. Significant discrepancies in the influence effects were observed, with higher closed porosity for added WG and higher apparent porosity for added ST. To interpret this phenomenon, the effects of the main fluxing agents of the ST and WG were investigated, and the results indicated that their influence effects were controlled by the type and content of the fluxing agent. Furthermore, the structure and crystalline phase of foam ceramics demonstrated that their compressive strength was jointly driven by their microstructure and crystal phases, but other properties depended only on the microstructure. The pore size and type were significantly affected by the change in liquid phase characteristics and aluminosilicate , with the addition of WG dramatically decreasing the number of pore windows and the addition of ST increasing the content of anorthite. Further sintering process analysis results revealed that the chemical reactions in materials change with chemical compositions, which resulted in significant differences in the crystalline compositions of the foam ceramics for WG and ST additions, and the presence of WG obviously reduced the formation temperature of the liquid phase. Overall, our research provides a theoretical basis for better utilizing different solid wastes to prepare foam ceramics.
研究领域:
材料科学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF WUHAN UNIVERSITY OF TECHNOLOGY-MATERIALS SCIENCE EDITION
·
2018
·Vol. 33
·期 2
·381-388
·
IF 0.524
Shi Minxian,Chen Xia,Fan Shanshan,Shen Shirley,Liu Tianxiang,Huang Zhixiong
Fluxing agents of zinc borate, antimony oxide, galss frit A and glass frit B, with different melting or softening point temperatures, were added into MgO-Al 2 O 3 -SiO 2 /boron phenol formaldehyde resin (MAS/BPF) composites to lower the formation temperature of eutectic liquid phase and promote the ceramification of ceramifiable composites. The effects of fluxing agents on the thermogravimetric properties, phase evolution, and microstructure evolution of MAS / BPF composites were characterized by TG-DSC, XRD and SEM analyses. The results reveal that the addition of a fluxing agent highly reduces the decomposition rate of MAS / BPF composites. Fluxing agents lower the formation temperatures of liquid phases of ceramifiable MAS / BPF composites obviously, and then promote the ceramification and densification process. The final residues of composites are ceramic surrounded by large amount of glass phases.
研究领域:
材料科学
·
无机化学
✓ 已验证
产品关联
DOI
高影响因子
Nature Communications
·
2024
·Vol. 15
·期 1
·1-9
·
IF 14.7
Lei Jingdan,Zhao Kunpeng,Liao Jincheng,Yang Shiqi,Zhang Ziming,Wei Tian-Ran,Qiu Pengfei,Zhu Min,Chen Lidong,Shi Xun
Grain boundary plays a vital role in thermoelectric transports, leading to distinct properties between single crystals and polycrystals. Manipulating the grain boundary to realize good thermoelectric properties in polycrystals similar as those of single crystals is a long-standing task, but it is quite challenging. Herein, we develop a liquid-phase sintering strategy to successfully introduce Mg 2 Cu nano-sintering-aid into the grain boundaries of Mg 3 (Bi, Sb) 2 -based materials. The nano-aid helps to enlarge the average grain size to 23.7 μm and effectively scatter phonons, leading to excellent electrical transports similar as those of single crystals and ultralow lattice thermal conductivity as well as exceptional thermoelectric figure of merit (1.5 at 500 K) and conversion efficiency (7.4% under temperature difference of 207 K). This work provides a simple but effective strategy for the fabrication of high-performance polycrystals for large-scale applications.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Hongcheng Yang,Qingyu Wen,Enzhu Li
Lithium borosilicate (LBS) and lithium fluoride (LiF) are verified to be effective sintering aids for CaAl 2 B 2 O 7 microwave dielectric ceramic to reduce the sintering temperature and lower the activation energies . Benefiting from the liquid phase sintering , low-firing, low permittivity and low-loss CaAl 2 B 2 O 7 microwave dielectric composite has been successfully obtained. Typically, CaAl 2 B 2 O 7 assembled with 1 wt % LBS composite possesses desirable properties of ε r = 5.91, Q × f = 39,443 GHz, τ f = −23.51 ppm/°C (@16.53 GHz). For composite ceramics with 0.5 wt % LiF, the optimal microwave dielectric properties are ε r = 6.08, Q × f = 37,295 GHz, τ f = −22.39 ppm/°C (@15.78 GHz). The two kinds of composite are densified at 875 °C, with co-existed CaB 2 O 4 and liquid phase. The mechanism underlying the low temperature sintering is revealed by well-matched wettability and lower activation energy of composite ceramics with additions.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
OPTICAL MATERIALS
·
2021
·
IF 3.08
Xiao Min,Mengzhu Hu,Yaoyao Yang,Bingfa Liu,Yuheng Wu,Yuansheng Wu,Lixin Yu
The effect of fluxes on CaSi 2 O 2 N 2 :Eu 2+ phosphors obtained via conventional solid-state reaction at atmospheric pressure is systematically investigated. The photoluminescence excitation and emission spectra of CaSi 2 O 2 N 2 :Eu 2+ phosphors containing fluxes are investigated and discussed in detail. A strong emission band is observed peaked at 548 nm originating from transitions between 4f 6 5d 1 emitting state and 4f 7 ground state of Eu 2+ under near ultraviolet light (398 nm) excitation. The results show that the best synthesis temperature of the sample is 1450 °C with the absence of combustion aid to obtain single phase of CaSi 2 O 2 N 2 :Eu 2+ . After adding BaF 2 , NH 4 Cl and Na 2 CO 3, single phase samples of CaSi 2 O 2 N 2 :Eu 2+ with well-defined morphology can be successfully prepared at a temperature as low as 1400 °C. It is interesting that in the samples prepared under the assistance of BaF 2 fluxes, the luminous intensity of Eu 2+ is much higher than in the absence of fluxes.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Shuai Yan,Sen Wang,Gaobin Liu,Qi Yuan,Kuoming Song,He Zhao,Xin Li,Rongzheng Shen
Herein, MgO–12 % TiO 2 (w) ceramics with different contents of Bi 2 O 3 –CuO sintering aid were prepared using a solid-state method. The effects of the sintering aid content on the sintering temperature and the dielectric and mechanical properties of the ceramics were studied. The material was characterized using scanning electron microscopy and X-ray diffraction and Precision LCR tester and universal testing machine and Archimedes drainage method. When the Bi 2 O 3 –CuO content was less than 9 wt%, the ceramic sample has higher dielectric properties. When the Bi 2 O 3 –CuO content was greater than 9 wt%, the dielectric properties will deteriorate. This is because Bi 2 O 3 participates in the chemical reaction between MgO and TiO 2 , forming a high dielectric loss Bi 4 Ti 3 O 7 phase. At high temperatures, Cu 2+ can easily change valence to Cu + , promoting oxygen vacancies and increasing dielectric loss in ceramic samples. The introduction of Bi 2 O 3 –CuO produces new MgTiO 3 , Mg 2 TiO 4 , and Bi 4 Ti 3 O 12 phases in the sample structure, resulting in a structure in which the MgO grains in the sample are surrounded by the new phases that appear around them. This structure fills the pores, increases density, enhances mechanical properties. The dielectric properties of the ceramics were the when the sintering temperature was 1050 °C, and the Bi 2 O 3 –CuO content was 3 wt%. The dielectric constant and dielectric loss were 11.19 and 1.17 × 10 −4 , respectively. The bending strength of the ceramic sample increased from 138.72 MPa to 179.64 MPa when the Bi 2 O 3 –CuO content was increased from 3 wt% to 15 wt%. The Bi 2 O 3 –CuO sintering aid enables MgO to be better applied in ceramic substrates.
研究领域:
材料科学
·
电子材料
✓ 已验证
产品关联
DOI
高影响因子
CRYSTENGCOMM
·
2024
·
IF 2.6
yufei Song,Xiaojie Guo,Wenxiang Mu,Xutang Tao,Zeliang Gao
β-Ga2O3 is an ultra-wide bandgap semiconductor with immense potential applications in high voltage, electronic devices, and deep-ultraviolet optoelectronic devices, etc. However, to date, the growth of bulk β-Ga2O3 crystals has predominantly utilized melt methods, which are heavily dependent on specific growth vessels. In this work, bulk crystal β-Ga2O3 with a size of 7 × 13 × 4 mm3 is grown using TeO2-Li2CO3 as flux by a top-seeded solution growth (TSSG) method for the first time. It is noteworthy that the saturation point of β-Ga2O3 in the flux has been reduced to 1023 K, significantly lower than its melting point of 2073 K. The resulting β-Ga2O3 crystal exhibits well-formed faces, predominantly the (010), (100), (01(-)1), and (11(-)1(-)) forms, which closely align with the ideal morphological predictions made by the Bravais-Friedel and Donnay-Harker methods.The full-width at half maximum (FWHM) of the rocking curves for the (010) oriented plane is determined to be 140.4″. This work provides a potential β-Ga2O3 crystal growth method with a little platinum loss at a low temperature.
研究领域:
材料科学
·
半导体物理
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2022
·Vol. 106
·期 3
·1912-1920
·
IF 4.186
Gang Wang,Zhipeng Chen,Hui Yan,Tao Xuan,Mengyan Wu,Xue Zhu,Tong Ding,Li Ding,Xingang Ren,Xianliang Wu,Huaiwu Zhang
Low-temperature co-fired ceramics technology (LTCC) exhibits enormous superiorities in packaging, integration, and interconnection. However, the complex compositions of low-melting point sintering aids may react with ceramic matrix, which increases the difficulties of phase control and tape casting. In this work, the Li 2 CO 3 –B 2 O 3 –Bi 2 O 3 –SiO 2 (LBBS) sintering aid was adopted to sinter ZnZrNb 2 O 8 ceramics with single phase at low temperatures. The LBBS glass could be used to fabricate pure-phase ZnZrNb 2 O 8 ceramics at a low sintering temperature, promote the grain growth, and increase the densification of ZnZrNb 2 O 8 ceramics. Furthermore, the unit cell volume, NbO 6 octahedral distortion, Raman shift, and FWHM changed along with LBBS addition, thereby affecting the microwave dielectric properties. Remarkably, ZnZrNb 2 O 8 ceramics doped with 0.75 wt.% LBBS at 950°C were chemically compatible with the silver electrode and exhibited excellent microwave dielectric characteristics: ε r = 27.1, Q × f = 54 500 GHz, and τ f = −48.7 ppm/°C, providing candidates for LTCC applications.
研究领域:
材料科学
·
无机化学
✓ 已验证
产品关联
DOI
高影响因子
OPTICAL MATERIALS
·
2023
·
IF 3.9
Qingxiong Liu,Chuan Tang,Yiyang Wen,Tianyu Wang,Qian Wu,Chongjun He,Mingjun Xia
Nonlinear optical (NLO) crystal, simultaneously exhibits second-harmonic generation response and linear electric-optical (EO) susceptibility, is of great significance for optoelectronics due to its frequency extension technique and optical modulation effect. In this paper, the growth system of K 3 B 6 O 10 Br (KBB) crystal in the green-flux K 2 MoO 4 –KBF 4 was systematically investigated to get rid of the non-intrinsic absorption in the ultraviolet wavelength range, which is beneficial for high-power applications. Bulk KBB NLO crystals were successfully grown by the top-seeded solution growth method from different fluxes for comparison. Moreover, the electro-optical (EO) property of KBB crystal was explored, and the effective EO coefficient γ 22 along transverse modulation was determined to be 1.10 p.m./V.
研究领域:
材料科学
·
光学
·
电光
✓ 已验证
DOI
高影响因子
Journal of Materiomics
·
2019
·
IF 0
Pengyuan Fan,Yangyang Zhang,Shan-Tao Zhang,Bing Xie,Yiwei Zhu,Mohsin Ali Marwat,Weigang Ma,Kai Liu,Liang Shu,Haibo Zhang
Low-temperature sintered (Na 1/2 Bi 1/2 ) 0.935 Ba 0.065 Ti 0.975 (Fe 1/2 Nb 1/2 ) 0.025 O 3 (NBT-BT-0.025FN) lead-free incipient piezoceramics were investigated using high-purity Li 2 CO 3 as sintering aids. With the ≤0.5 wt% Li 2 CO 3 addition, the introduced Li + cations precede to enter the A-sites of the perovskite lattice to compensate for the A-site deficiencies. Once the addition exceeds 0.5 wt%, the excess Li + cations will occupy B-sites and give rise to the generation of oxygen vacancies, which accelerate the mass transport and thus lower the sintering temperature effectively from 1100 °C down to 925 °C. It was also found that a small amount of Li + addition has little effect on the phase structure and electromechanical properties of the system, but overweight seriously disturbs these characteristics because of the large lattice distortion. The sintered NBT-BT-0.025FN incipient piezoceramics with 1.25 wt% Li 2 CO 3 addition at 925 °C provides a large strain of 0.33% and a corresponding large signal piezoelectric coefficient d * 33 of 550 pm/V at 60 kV/cm, indicating this system is a very promising candidate for lead-free co-fired multilayer actuator application.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
JOURNAL OF RARE EARTHS
·
2023
·
IF 4.9
Zihao Wang,Sisi Liang,Chenyang Zhan,Kunyuan Xu,Jie Hu,Dejian Chen,Liping Song,Haomiao Zhu
Full-spectrum phosphor-converted white-light-emitting diodes (pc-WLED) are emerging as a mainstream technology in semiconductor lighting. Nevertheless, high-performance blue phosphor which can be excited efficiently by a 400 nm NUV diode chip is still lacking. Herein, we present a blue-emitting Na 3 KMg 7 (PO 4 ) 6 :Eu 2+ phosphor synthesized by the solid-reaction method. Particularly, we find that the using of Li 2 CO 3 as flux can significantly improve the crystal quality and thus the emission efficiency of the phosphor. Meanwhile, the excitation peak of the phosphor shifts from 365 to 400 nm, which is pivotal for efficient NUV (400 nm) diode chip excitation. The practical Eu 2+ concentration is also enhanced by using Li 2 CO 3 as flux, and the absorption efficiency is greatly increased. This phosphor exhibits superior PL thermal stability, namely retains 94% integrated photoluminescence intensity at 150 °C of that at 25 °C. As a result, the optimized phosphor shows an emission band peaked at 437 nm with a bandwidth of 40 nm and a high external photoluminescence quantum yield of 51.7%. Finally, a pc-WLED was fabricated by using NKMPO:Eu 2+ blue, Sr 2 SiO 4 :Eu 2+ green, CaAlSiN 3 :Eu 2+ red phosphors, and a 400 nm NUV diode chip. It shows a high color rendering index of R a = 96.4 and a correlated color temperature of 4358 K. These results prove that NKMPO:Eu 2+ is a promising blue phosphor for full-spectrum WLED based on NUV diode chips.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）