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21 results on '"Hong, Xuekun"'

18. Microwave dielectric properties of Ba5+nTinNb4O15+3n ceramics

Author

L. Chen, Chunli Diao, Hong Xuekun, Liang Fang, H. X. Liu, and Hui Zhang

Subjects
Permittivity, Diffraction, Materials science, Scanning electron microscope, Analytical chemistry, Mineralogy, Dielectric, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Phase (matter), visual_art, Microscopy, visual_art.visual_art_medium, Ceramic, Electrical and Electronic Engineering, Microwave
Abstract

New dielectric ceramics Ba5 + nTi n Nb4O15 + 3n (n = 1,2,3) with cation-deficient hexagonal perovskite-related structure were prepared by the conventional solid-state reaction route. The phase and structure of the ceramics were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The microwave dielectric properties of the ceramics were studied using a network analyzer. These ceramics show dielectric constant (e r ) of in the range of 45.1–48.6, τ f in the range +59 to +175 ppm°C− 1, and high quality factors with Q×f values up to 22882. The values of e r and τ f of the ceramics gradually increase as the number of n increases.

Published
2005
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19. Preparation, characterization and dielectric properties of Sr5LnTi3Ta7O30(Ln=La, Nd) ceramics

Author

Liang Fang, F. C. Meng, Jie Yang, Hong Xuekun, and Hongquan Zhang

Subjects
Permittivity, Materials science, Solid-state reaction route, Analytical chemistry, Mineralogy, Dielectric, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Tetragonal crystal system, visual_art, visual_art.visual_art_medium, Dielectric loss, Ceramic, Electrical and Electronic Engineering, Temperature coefficient, High-κ dielectric
Abstract

Sr5LnTi3Ta7O30 (Ln=La, Nd) ceramics were prepared by the conventional high temperature solid state reaction route. The sintered samples were characterized by X-ray diffraction and scanning electron microscopy methods. SLTT and SNTT belong to paraelectric phases of filled tetragonal TB structure at room temperature. SLTT and SNTT ceramics show high dielectric constant of 131 and 116 together with low dielectric loss 0.008 and 0.0036 at 1 MHz, respectively. In comparison with Ba-based ceramics with TB structure, the temperature coefficients of the dielectric constant (τe) are significantly reduced.

Published
2004
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21. Modulation of Ferroelectric and Optical Properties of La/Co-Doped KNbO 3 Ceramics.

Author

Zhang, Xue, Qi, Ruijuan, Dong, Shangwei, Yang, Shuai, Jing, Chengbin, Sun, Lin, Chen, Ye, Hong, Xuekun, Yang, Pingxiong, Yue, Fangyu, and Chu, Junhao

Subjects
OPTICAL modulation, OPTICAL properties, CERAMICS, FERROELECTRIC ceramics, FERROELECTRICITY, PHASE transitions
Abstract

The phase transition, microscopic morphology and optical and ferroelectric properties are studied in a series of La- and Co-doped KNbO3-based ceramics. The results show that the doping induces the transformation from the orthorhombic to the cubic phase of KNbO3, significantly reduces the optical bandgap and simultaneously evidently improves the leakage, with a slight weakening of ferroelectric polarization. Further analysis reveals that (i) the Co doping is responsible for the obvious reduction of the bandgap, whereas it is reversed for the La doping; (ii) the slight deterioration of ferroelectricity is due to the doping-induced remarkable extrinsic defect levels and intrinsic oxygen vacancies; and (iii) the La doping can optimize the defect levels and inhibit the leakage. This investigation should both provide novel insight for exploring the bandgap engineering and ferroelectric properties of KNbO3, and suggest its potential applications, e.g., photovoltaic and multifunctional materials. [ABSTRACT FROM AUTHOR]

Published
2021
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