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991.
Yuhang Zhang Baojiu Chen Xizhen Zhang Xiangping Li Jinsu Zhang Sai Xu Xin Wang Yanqiu Zhang Li Wang Desheng Li Hai Lin 《Journal of the American Ceramic Society》2021,104(1):350-360
Lighting sources with full-color visible output are widely preferred in practical applications. In addition, modern lighting sources also tend to be intelligentized, and the intelligentization asks for smart luminescence materials. In this work, we attempt to develop novel full-color emitting material with temperature sensing and thermochromatic ability. To this end, the Cu2+ is successfully reduced to Cu+ which is incorporated into the germanate glasses. The glasses are prepared via a melt-quenching technique using graphite powders as reducing reagent. The supper-broadening of the excitation and the emission spectra of Cu+ in the germanate glasses are observed. Full-color emission is realized by introducing Tm3+ as co-dopant to provide the blue component in the spectra. The energy transfer behavior between Cu+ and Tm3+ is investigated, and it is found that these two luminescence centers are independently existent without energy transfer between them. The chromatic properties of the Cu+/Tm3+ co-doped glasses are tuned by Tm3+ concentration and excitation wavelength. The temperature sensing based on the fluorescence intensity ratio technique is demonstrated, and a constant sensitivity for the temperature detection is obtained. Moreover the thermochromatic property is also investigated, and it is found that the studied Cu+/Tm3+-doped glasses exhibit excellent thermochromatic performance. 相似文献
992.
Kang Du Yan-Bo Guo Fei Wang Jun Fan Xiao-Chuan Wang Wen-Zhong Lu Wen Lei 《Journal of the American Ceramic Society》2021,104(2):974-984
Ca1+2xSnSi2x+yO3+6x+2y (0.1 ≤ x ≤ 0.9; 0.1 ≤ y ≤ 0.9) microwave dielectric ceramics were prepared through traditional solid-state reaction sintered at 1450°C–1500°C for 5 hours. The Ca3SnSi2O9 second phase replaced the SnO2 second phase of the Ca1+2xSnSi2xO3+6x (x = 0, y = 0) ceramics by controlling the ratio of Ca:Sn:Si. The cracks of CaSnO3 (x = 0, y = 0) ceramic were inhibited, the microwave dielectric properties were optimized by introducing the Ca3SnSi2O9 second phase, and the CaSnO3-Ca3SnSi2O9 mixture system existed at (0.1 ≤ x ≤ 0.9, y = 0). The CaSnSiO5 phase with positive τf value was related to the Si-rich in CaSnSiyO3+2y (x = 0; 0.1 ≤ y ≤ 0.9), and the coexistence of three and four phases was obtained at CaSnSiyO3+2y (0.1 ≤ y ≤ 0.9) ceramics. The CaSnSiO5 phase appeared at CaSnSiyO3+2y (0.3 ≤ y ≤ 0.9) ceramics. The CaSnSiyO3+2y (y = 0.8) ceramic with 49.2 wt% CaSnSiO5 phase exhibited excellent microwave dielectric properties: εr = 11.06, Q × f = 57,500 GHz (at 11.5 GHz), and τf = +8.1 ppm/°C. 相似文献
993.
Stéphane J. C. Weusten Luc C. E. M. Murrer Matheus T. de Groot John van der Schaaf 《American Institute of Chemical Engineers》2021,67(6):e17263
This article investigates the effect of inlet shape, entrance length, and turbulence promoters on mass transfer by using 3D-printed electrolyzers. Our results show that the inlet design can promote turbulence and lead to an earlier transition to turbulent flow. The Reynolds number at which the transition occurs can be predicted by the ratio of the cross-sectional area of the inlet to the cross-sectional area of the electrolyzer channel. A longer entrance length results in more laminar behavior and a later transition to turbulent flow. With an entrance length of 550 mm, the inlet design did no longer affect the mass transfer performance significantly. The addition of gyroid type turbulence promoters resulted in a factor of 2 to 4 increase in mass transfer depending on inlet design, entrance length, and the type of promoter. From one configuration to another, there was a minimal variation in pressure drop (<1600 Pa). 相似文献
994.
Fang Guan Yiquan Wu Iva Milisavljevic Xin Cheng Shifeng Huang 《Journal of the American Ceramic Society》2021,104(10):5148-5156
Spinel-structured NiMn2O4 ceramics, with different valence Ni sources, were originally prepared using Ni2O3 and NiO as raw materials, and the effects of different valence Ni sources on their electrical properties were first investigated. XRD patterns show that both Ni2O3-based and NiO-based NiMn2O4 ceramics are single cubic spinel structures. SEM/EDS images indicate that the NiMn2O4 ceramics exhibited high density at the experiment-determined sintering temperatures. XPS results and Raman drifts prove that the Ni valence-induced changes in Mn ions at B sites played a significant role in the electrical properties and thermal stability of NiMn2O4 ceramics. Compared with NiO-based NiMn2O4, the resistivity at 25°C (ρ25°C) of Ni2O3-based NiMn2O4 increased dramatically from 3109 to 106958 Ω cm, the thermal constant (B25/50) increased from 3264 to 4473 K, and the resistance shifts after annealing for 1000 h at 150°C decreased from 0.80% to 0.74%. The investigation of the relationship between the material properties and valence of Ni sources has provided a new and effective way for designing the spinel-structured negative temperature coefficient (NTC) materials by modulating the valence of ions at A sites in the raw materials. 相似文献
995.
Xiaoxia Lin Jianlin Wang Zhengping Fu Qiuping Huang Yalin Lu 《Journal of the American Ceramic Society》2021,104(9):4679-4686
GaFeO3-type iron oxide is a promising room-temperature multiferroic material due to its large magnetization and polarization. To expand the scope of its application, it is crucial to control the magnetic properties. Based on introducing the ferromagnetic (FM) Fe3O4 in the antiferromagnetic (AFM) GaFeO3 to build the FM-AFM interface by changing the Ga/Fe ratio, Ga0.69Fe1.31O3 (GFO) was successfully grown by the floating zone method. The resulting sample was characterized by X-ray diffraction (XRD), and its magnetic properties were measured using a superconducting quantum interference device (SQUID). The temperature-dependent AC susceptibility measurement shows that the spin glass-like behavior of GFO at temperatures close to 50 K is a manifestation of the geometrical frustration arising from cation site disorder. In addition, the magnetic property measurement shows that the magnetic transition temperature Tc is at 650 K, which is introduced by Fe3O4 and suppresses the ferromagnetic transition around 320 K of GFO. Interestingly, the observed exchange bias effect, which does not exist in the bulk GaFeO3-type family, is attributed to the formation of an FM/AFM interface due to the existence of FM Fe3O4 in the GFO. This study provides a new perspective on the properties of the GaFeO3-type family for potential applications in spintronic devices. 相似文献
996.
Gopal P. Khanal Ichiro Fujii Shintaro Ueno Satoshi Wada 《Journal of the American Ceramic Society》2021,104(9):4649-4658
The <110>-oriented BaTiO3 ceramics were fabricated using BaCO3 matrix and H1.08Ti1.73O4.nH2O (HTO) template particles, and the mechanism of BaTiO3 phase formation was investigated. The dielectric, ferroelectric, and piezoelectric properties were also investigated. The transformation of the HTO phase into the TiO2 bronze or TiO2 (B) phase was observed at 600°C, where the BaTiO3 nucleation was accompanied by the formation of a Ba2TiO4 phase. The TiO2 phase reacted with the Ba2TiO4 phase at 800°C to give a BaTiO3 phase, whereas its reaction with the BaTiO3 resulted in the formation of BaTi2O5 phase that got decomposed into BaTiO3 and Ba6Ti17O40 phase at sintering temperature ≥1300°C. Sintering with samples’ embedding in BaTiO3 powders prevented the formation of the Ba6Ti17O40 secondary phase. The crystallographic orientation along the <110> direction (F110) was developed by the epitaxial grain growth mechanism. In addition to the contribution of the grain-size increment for enhancing the F110, the preservation of the platelike structure was also found to have a significant impact. The ceramics prepared by the embedded sintering (grain size ≈12.4 µm and F110 = 83%) exhibited the room-temperature dielectric constant of 1708 and piezoelectric strain constant of 445 pm/V, which are higher than those of the BaTiO3 ceramics with randomly oriented grains. 相似文献
997.
Zemin He Ping Yu Haiyang Wang Jianjing Gao Yang Zhao Haiquan Zhang Yuzhen Zhao Zongcheng Miao 《Journal of the American Ceramic Society》2021,104(9):4389-4397
Ferroelectric BaTiO3 was combined with Ag nanoparticles for piezocatalytic and photocatalytic viewpoints. Microstructural characterization (X-ray diffraction and electron microscopy images) revealed that the Ag was successfully bounded with BaTiO3. X-ray photoelectron spectrum also confirmed the presence of Ag. Further, its performance was examined for dye degradation under visible light (for photocatalysis) and ultrasonication (for piezocatalysis). In both the catalysis processes, there was a significant improvement in Ag-loaded BaTiO3 sample-based catalytic reactions. Catalytic performance was evaluated for multiple cycles and was found consistent. Scavenger tests were also performed to understand catalytic reactions. 相似文献
998.
Jin Xu Tingting Zang Ding Du Sandeep Kumar Moolchand Sharma Rahul Vaish 《Journal of the American Ceramic Society》2021,104(4):1661-1668
The BaTiO3 powder was prepared via a solid-state reaction route. It was studied for the degradation of bacterial cells, dye, and pharmaceuticals waste using ultrasonically driven piezocatalytic effect. The bacterial catalytic behavior of poled BaTiO3 was remarkably increased during ultrasonication (10% E coli survival in 60 minutes). The structural damages were illustrated using scanning electron micrographs of bacterial cells which demonstrated morphological manifestations under different conditions. Methylene blue (MB dye), ciprofloxacin and diclofenac were also cleaned using the piezocatalytic effect associated with the poled BaTiO3 powder. Around 92, 85, and 78% of degradations were observed within 150 minutes duration for methylene blue, ciprofloxacin, and diclofenac, respectively. 相似文献
999.
Pengyu Xu Hao Wang Lu Ren Bingtian Tu Weimin Wang Zhengyi Fu 《Journal of the American Ceramic Society》2021,104(12):6455-6466
Knowledge on the mechanical and thermophysical properties of ZnO·nAl2O3 is essential for practical applications. Based on the first-principles calculations and the bond valence method, the disordered spinel-type structure of ZnO·nAl2O3 (n = 1–4) was constructed to investigate the composition-dependent mechanical and thermophysical properties. The effects of cation substitution on the hardness, elastic modulus, thermal expansion, and thermal conductivity were revealed from the insights into the chemical bonds. At a higher n, the tetrahedral bond is stronger, manifested as its higher hardness and bulk modulus as well as smaller thermal expansion coefficient. Meanwhile, the octahedral bond is weaker, leading to the lower hardness and bulk modulus, along with the larger expansion coefficient. In consequence, the hardness and elastic moduli of ZnO·nAl2O3 are improved moderately while the expansion coefficient is decreased with the rise of n. Due to the different vibration characteristics of ZnIV and AlIV, the cation disorder in the 8a site provides the primary source of phonon scattering, resulting in the dramatic reduction of thermal conductivity as n increases. The understanding offers guidance on the application-oriented design of new oxide spinels. 相似文献
1000.
Shuai Huang Lixin Yu Kangliang Peng Youjun Zhao Jindi Wang Mengmeng Shang 《Journal of the American Ceramic Society》2021,104(11):5848-5858
To enhance the display quality of light-emitting diodes (LEDs), it is of great significance to exploit green/yellow-emitting phosphors with narrow emission band, high quantum yield, and excellent color purity to satisfy the application. Herein, orthophosphate-based green/yellow-emitting Na3Tb(PO4)2:Ce3+/Eu2+ (NTPO:Ce3+/Eu2+) phosphors have been successfully synthesized by a facile solid-state reaction method. The absorption band of NTPO samples was extended to the near-ultraviolet region and the absorption efficiency was significantly improved owing to a highly efficient energy transfer from Ce3+/Eu2+ ion to Tb3+ ion in NTPO host certified by time-resolved PL spectra. Upon 300 nm excitation, the NTPO:Ce3+ is characterized by ultra-narrow-band green emission of Tb3+ with an absolute quantum yield of 94.5%. Unexpectedly, NTPO:Eu2+ emits bright yellow light with a color purity of 73% as a result of the blending of green light emission from Tb3+ and red light emission from Eu3+. The thermal stability has been improved by controlling the stoichiometric ratio of Na+. The prototype white LED used yellow-emitting NTPO:Eu2+ phosphor has higher color-rendering index (Ra = 83.5), lower correlated color temperature (CCT = 5206 K), and closer CIE color coordinates (0.338, 0.3187) to the standard white point at (0.333, 0.333) than that used green-emitting NTPO:Ce3+ phosphor, indicating the addition of the yellow light component improved the Ra of the trichromatic (RGB) materials. 相似文献