By using Tb407 and MoO3 as starting materials, ferroelectric Tb2（MoO4）3 crystal was grown by the Czochralski method. The as-grown crystal was pale green color, transparent and crack-free. X-ray powder diffraction （...By using Tb407 and MoO3 as starting materials, ferroelectric Tb2（MoO4）3 crystal was grown by the Czochralski method. The as-grown crystal was pale green color, transparent and crack-free. X-ray powder diffraction （XRPD）, transmission spectrum, dielectric constant and polarization-electric field （P-E） hysteresis loop measurements were performed to characterize the crystal. The XRPD confirmed the as-grown crystal to be Tb2（MoO4）3. The transmission spectrum of the crystal showed that its transmittance in the entire visible and most near-infrared region was more than 70% except for an absorption peak around 486 nm. Obvious dielectric anomaly could be observed at low frequencies with increasing temperature through the dielectric constant measurement and the Curie temperature of Tb2（MoO4）3 crystal was determined to be 162.3℃ The unsaturated P-E hysteresis loops indicated that it was difficult for the ferroelectric domains in Tb2（MoO4）3 crystal to array regularly with repeated switching of the electric field.展开更多
A set of 2D steady state finite element numerical simulations of electromagnetic fields and heating distribution for an oxide Czochralski crystal growth system was carried out for different input current shapes (sine,...A set of 2D steady state finite element numerical simulations of electromagnetic fields and heating distribution for an oxide Czochralski crystal growth system was carried out for different input current shapes (sine, square, triangle and sawtooth waveforms) of the induction coil. Comparison between the results presented here demonstrates the importance of input current shape on the electromagnetic field distribution, coil efficiency, and intensity and structure of generated power in the growth setup.展开更多
In the present research, mixed crystals KCl1–xBrx (x = 0.1, 0.3, 0.5, 0.7 & 0.9) were grown by Czochralski method. Then some analysis such as chemical etching, XRD, and absorbing spectrum were established on the ...In the present research, mixed crystals KCl1–xBrx (x = 0.1, 0.3, 0.5, 0.7 & 0.9) were grown by Czochralski method. Then some analysis such as chemical etching, XRD, and absorbing spectrum were established on the irradiated crystals by γ-ray. The results of this research show that configuration of defects in mixed crystals in contrast with pure crystals is different. Somehow that type and percentage of cumulative composition cause to changing in lattice parameter and lattice defect density in alkali halide crystals and finally change optical properties of crystal.展开更多
μ-Czochralski technique has been analyzed using two-dimensional crystallization simulator. It is observed that the temperature is relatively uniform in the entire Si region after the laser irradiation because the hea...μ-Czochralski technique has been analyzed using two-dimensional crystallization simulator. It is observed that the temperature is relatively uniform in the entire Si region after the laser irradiation because the heat conductivity of the Si region is much higher than that of the underneath SiO2. Grain growth advances from the grain filter to the channel region and continues until it collides with what advances from random nucleation in the channel region. When the initial temperature is high, the random nucleation rarely occurs even under the supercooling condition, and the grain size becomes large. Moreover, it is qualitatively reproduced that the grain size increases as the irradiated energy of the laser irradiation increases.展开更多
基金supported by the National Natural Science Foundation of China (50590401)
文摘By using Tb407 and MoO3 as starting materials, ferroelectric Tb2（MoO4）3 crystal was grown by the Czochralski method. The as-grown crystal was pale green color, transparent and crack-free. X-ray powder diffraction （XRPD）, transmission spectrum, dielectric constant and polarization-electric field （P-E） hysteresis loop measurements were performed to characterize the crystal. The XRPD confirmed the as-grown crystal to be Tb2（MoO4）3. The transmission spectrum of the crystal showed that its transmittance in the entire visible and most near-infrared region was more than 70% except for an absorption peak around 486 nm. Obvious dielectric anomaly could be observed at low frequencies with increasing temperature through the dielectric constant measurement and the Curie temperature of Tb2（MoO4）3 crystal was determined to be 162.3℃ The unsaturated P-E hysteresis loops indicated that it was difficult for the ferroelectric domains in Tb2（MoO4）3 crystal to array regularly with repeated switching of the electric field.
文摘A set of 2D steady state finite element numerical simulations of electromagnetic fields and heating distribution for an oxide Czochralski crystal growth system was carried out for different input current shapes (sine, square, triangle and sawtooth waveforms) of the induction coil. Comparison between the results presented here demonstrates the importance of input current shape on the electromagnetic field distribution, coil efficiency, and intensity and structure of generated power in the growth setup.
文摘In the present research, mixed crystals KCl1–xBrx (x = 0.1, 0.3, 0.5, 0.7 & 0.9) were grown by Czochralski method. Then some analysis such as chemical etching, XRD, and absorbing spectrum were established on the irradiated crystals by γ-ray. The results of this research show that configuration of defects in mixed crystals in contrast with pure crystals is different. Somehow that type and percentage of cumulative composition cause to changing in lattice parameter and lattice defect density in alkali halide crystals and finally change optical properties of crystal.
文摘μ-Czochralski technique has been analyzed using two-dimensional crystallization simulator. It is observed that the temperature is relatively uniform in the entire Si region after the laser irradiation because the heat conductivity of the Si region is much higher than that of the underneath SiO2. Grain growth advances from the grain filter to the channel region and continues until it collides with what advances from random nucleation in the channel region. When the initial temperature is high, the random nucleation rarely occurs even under the supercooling condition, and the grain size becomes large. Moreover, it is qualitatively reproduced that the grain size increases as the irradiated energy of the laser irradiation increases.
