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P.K. Patro A.R. Kulkarni S.M. Gupta C.S. Harendranath 《Physica B: Condensed Matter》2007,400(1-2):237-242
Ferroelectric strontium barium niobate (SBN) powder was synthesized by solid-state route. The green compacts were sintered in the temperature range 1250–1350 °C in a microwave furnace. The microstructural study, using SEM, revealed the grain size in the range 2–20 μm without microcracks, depending on the sintering temperature. This is in contrast to that obtained conventionally for sintered SBN powder synthesized by solid-state route, which resulted in duplex microstructure with microcracks [N.S. VanDamme, A.E. Sutherland, L. Jones, K. Bridger, S.R. Winzer, J. Am. Ceram. Soc. 74 (1991) 1785; P.K. Patro, A.R. Kulkarni, C.S. Harendranath, Ceram. Int. 30 (2004) 1405; P.K. Patro, Trans. Ind. Inst. Metals 59 (2006) 229]. Impedance analyzer and ferroelectric hysteresis loop tracer were used for the dielectric, ferroelectric, I–V and electric fatigue measurements. Microwave sintering also resulted in a dielectric maxima εmax 2590 at 1 kHz (compared to 1103 for conventional sintering [P.K. Patro, A.R. Kulkarni, C.S. Harendranath, Ceram. Int. 30 (2004) 1405]) for the sintering temperature of 1350 °C. Similar improvement in microwave-sintered SBN was observed depending on their sintering condition. The origin of this difference is attributed to microstructural differences arising from difference in heating method. In this paper the observed dielectric and ferroelectric behavior have been correlated with different sintering conditions and consequent microstructure due to microwave sintering. 相似文献
95.
研究了基于周期极化反转铌酸锂光波导级联二阶非线性效应实现非归零码到归零码高速全光码型转换的新方案,使用的是马赫-曾德尔干涉仪结构.转换原理是非归零码信号光在级联倍频和差频过程中受到的放大作用引起马赫-曾德尔干涉仪的不平衡,进而通过干涉相消产生归零码信号光输出.首先从耦合波方程出发,数值模拟了非归零码到归零码码型转换过程.然后分析了波导长度、光功率、相对时延对消光比的影响并对码型转换进行了优化设计.最后分析了转换带宽,模拟计算表明信号光在90nm的3dB带宽内可调谐,进而可以实现多信道的同时转换. 相似文献
96.
A mode-selective directional coupler based on titanium in-diffused channel waveguides in lithium niobate is investigated.
This coupler may be utilized as a key part of an add-drop multiplexer for dense wavelength division multiplexing in optical
network nodes. The proposed coupler is based on evanescent coupling of the fundamental mode of a single-mode channel to the
first higher mode of a parallel bi-modal waveguide. Our experimental results show that a compact directional coupler with
coupling efficiencies larger than 90%, large bandwidth around 1550 nm, and with negligible polarization dependence can be
realized using electro-optic lithium niobate substrates.
Presented at 9-th International Workshop on Nonlinear Optics Applications, NOA 2007, May 17–20, 2007, Świnoujście, Poland 相似文献
97.
M. B. Klein 《International Journal of Infrared and Millimeter Waves》1982,3(5):587-595
We describe electro-optic modulators at 95 GHz using LiNbO3 in an H-guide configuration. We have observed 70% amplitude modulation at l KHz in a bridge configuration, corresponding to an induced phase shift of ±29°. The prospects for improved device performance will be discussed.Supported in part by Subcontract #67-471915 with California Institute of Technology under Prime Contract N00014-79-C-0839 with Office of Naval Research. 相似文献
98.
Zoran Samardzžija Slavko Bernik Ryna B. Marinenko Barbara Malič Miran Čeh 《Mikrochimica acta》2004,145(1-4):203-208
Single crystals of KNbO3 and NaNbO3 were selected from the limited number of suitable alkali compounds that are available and evaluated as possible reference materials for the electron-probe microanalysis (EPMA) of alkaline niobates with a composition described by the general formula K1–XNaXNbO3. The EPMA study verified that KNbO3 and NaNbO3 single crystals are stable under the electron beam and compositionally homogeneous. A quantitative microanalysis confirmed the composition of pure KNbO3, while the NaNbO3 crystal contained 0.3 mass fraction % of Ca. A significant improvement in the accuracy of the quantitative EPMA of polycrystalline potassium–sodium niobates was achieved using these single crystals as standards. The crystals can also be useful as reference materials for the analysis of sodium and potassium in other materials. 相似文献
99.
A. P. Pivovarova O. P. Shustrova O. V. Mel'nikova 《Journal of Applied Spectroscopy》2002,69(4):642-645
By means of vibrational spectroscopy and crystal optic analysis, the symmetry of crystals with the structure of fersmite in the Li0.5Ln0.5Nb2O6 series, where Ln = Nd—Lu and Y, has been refined. 相似文献
100.