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Sine-Gordon Solitons and Breathers in Rod-like Magnetic Liquid crystals under External Magnetic Field

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Communications in Theoretical Physics 2018年第12期69卷 759-764页

作者：李妍鲁小波侯春风 Department of Physics Harbin Institute of Technology Department of Physics Science and Technology Heilongjiang University

To study the nonlinear phenomena in rod-like magnetic liquid crystals(RMLCs), this paper establishes the dynamic model of molecular motion when giving a twisting disturbance to the molecules under external magnetic field.We find the twist of the molecules under magnetic field can be propagated in the form of a traveling wave. The dynamic equation of the molecular twisting we derived satisfies the form of Sine-Gordon equation. We obtain two solutions of the Sine-Gordon equation by theoretical calculation: the kink and anti-kink solitons and breathers. The characteristics of those solitons and breathers are discussed.

关键词： rod-like magnetic liquid crystals Sine-Gordon equation kink and anti-kink solitons breathers

LOW MACH NUMBER LIMIT OF A COMPRESSIBLE NON-ISOTHERMAL NEMATIC LIQUID crystals MODEL

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Acta Mathematica Scientia 2019年第2期39卷 449-460页

作者：樊继山栗付才 Department of Applied Mathematics Nanjing Forestry University Department of Mathematics Nanjing University

In this paper, we study the low Mach number limit of a compressible nonisothermal model for nematic liquid crystals in a bounded domain. We establish the uniform estimates with respect to the Mach number, and thus pro... 详细信息

关键词： compressible non-isothermal liquid crystals bounded domain low Mach number limit

Preparation and spectral characteristics of anthracene/tetracene mixed crystals

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Science China Chemistry 2009年第2期52卷 181-187页

作者： LI HuiPing DUAN Lian ZHANG DeQiang DONG GuiFang WANG LiDuo QIU Yong Key Lab of Organic Optoelectronics&Molecular Engineering of Ministry of Education Department of ChemistryTsinghua Univer-sityBeijing 100084China

A series of tetracene-doped anthracene crystals with different doping concentrations(the highest mo-lar ratio 100:1) are grown from solution.Crystal structures and optical characteristics of the above mixed crystals are investigated at room temperature.By changing the doping concentrations,the fluorescence can be adjusted from blue-green to green and even to yellow-green.The emission spectra of anthracene/tetracene(An/Te) mixed crystals reveal the sensitized fluorescence of tetracene and the partial quenching of anthracene emission.The data of transient photoluminescence(PL) decays illus-trate that in An/Te mixed crystals,the decay of anthracene becomes faster,while the PL lifetime of tet-racene is longer than that of the tetracene single crystals.All above experimental results suggest that there is excitation energy transfer from anthracene to tetracene in the mixed crystals.

关键词： anthracene tetracene organic mixed crystals fluorescence spectrum energy transfer

Rapid Growth of Halide Perovskite Single crystals:From Methods to Optimization Control

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Chinese Journal of Chemistry 2019年第6期37卷 616-629页

作者： Yu-Ling Wang Shuai Chang Xiao-Mei Chen Yan-Dong Ren Li-Fu Shi Yong-Hao Liu Hai-Zheng Zhong School of Mechatronics Engineering Daqing Normal UniversityXibin Xi RoadRanghulu DistrictDaqingHeilongjiang 163712China Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems School of Materials Science&EngineeringBeijing Institute of TechnologyZhongguancun South StreetHaidian DistrictBeijing 100081China

Metal halide perovskites are emerging as new generation optoelectronic materials due to their high carrier mobility, long carrier diffusion length and large light absorption coefficient, which have broad applications in solar cell, light-emitting diode, laser, photodetector and transistors. Perovskite single crystal is an ideal platform for discerning the intrinsic properties of these materials. In some cases, perovskite single crystals are better candidates to gain high performance optoelectronics. However, the growth of perovskite single crystals is time and cost consuming, which has an obvious disadvantage for device exploration. Therefore, fast growth technique is highly desirable in not only promoting the use of perovskites in commercial applications but also facilitating deep physical investigation of the materials. In this review, we summarize thoroughly the development of fast growth of the halide perovskites single crystal. Specifically, we highlight the progress of rapid growth techniques with emphasis on the optimization control.

关键词： crystal growth semiconductors synthetic methods metal halide perovskite single crystals rapid growth

Machine Learning Application for Prediction of Sapphire crystals Defects

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电子科技学刊：英文版 2020年第1期18卷 1-9页

作者： Yulia Vladimirovna Klunnikova Maxim Vladimirovich Anikeev Alexey Vladimirovich Filimonov Ravi Kumar Institute of Nanotechnology Electronics and Engineering EquipmentSouthern Federal UniversityTaganrog 347928 Institute of Computer Technology and Information Security Southern Federal UniversityTaganrog347928 Department of Physical Electronics Peter the Great St.Petersburg Polytechnic UniversitySt.Petersburg 195251 the Department of Metallurgical and Materials Engineering Indian Institute of Technology MadrasChennai600036

We investigate the impact of different numbers of positive and negative examples on machine learning for sapphire crystals defects prediction. We obtain the models of crystal growth parameters influence on the sapphire crystal growth. For example, these models allow predicting the defects that occur due to local overcooling of crucible walls in the thermal node leading to the accelerated crystal growth. We also develop the prediction models for obtaining the crystal weight, blocks, cracks, bubbles formation, and total defect characteristics. The models were trained on all data sets and later tested for generalization on testing sets, which did not overlap the training set.During training and testing, we find the recall and precision of prediction, and analyze the correlation among the features. The results have shown that the precision of the neural network method for predicting defects formed by local overcooling of the crucible reached 0.94.

关键词： Defects machine learning sapphire crystals

Study on the vibration band gap and vibration attenuation property of phononic crystals

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Science China(Technological Sciences) 2008年第1期51卷 85-99页

作者： WEN JiHong WANG Gang YU DianLong ZHAO HongGang LIU YaoZong WEN XiSen College of Mechantronic Engineering and Automation National University of Defense TechnologyChangsha 410073China

Phononic crystals (PCs) are functional materials with periodic structures and elas- tic wave (vibration) band gaps, where propagation of vibrations with frequencies within band gaps is forbidden. PCs with finite periods can restrain the propagation of vibrations with frequencies in band gaps and thus has vibration attenuation property. Worldwide, many institutions and researchers are engaged in the re- search of PCs, however, studies on the vibration attenuation property of PCs are still limited. In this paper, we report our study of band gaps and vibration attenua- tion properties of 1) a simplified PC—periodic mass-spring structures, 2) longitu- dinal vibration of one-dimensional (1D-), 2D-, 3D-PCs, and 3) the flexural vibration of 1D- and 2D-PCs. These studies provide a foundation for the applications of PCs in vibration attenuation.

关键词： phononic crystals elastic band gaps vibration band gaps vibration attenuation

Investigation into the room temperature creep-deformation of potassium dihydrogen phosphate crystals using nanoindentation

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Advances in Manufacturing 2018年第4期6卷 376-383页

作者： Yong Zhang Ning Hou Liang-Chi Zhang School of Mechatronics Engineering The Harbin Institute of Technology Harbin 150001 People's Republic of China Ministry of Education Key Laboratory of Micro-systems and Micro-structures Manufacturing The Harbin Institute of Technology Harbin 150001 People's Republic of China Laboratory for Precision and Nano Processing Tech no logies. School of Mechanical and Manufacturing Engineering The University of New South Wales Sydney NSW 2052 Australia

It has been a tremendous challenge to manu facture damage-free and smooth surfaces of potassium dihydrogen phosphate (KDP) crystals to meet the require ments of high-energy laser systems. The intrinsic issue is whether a KDP crystal can be plastically deformed so that the material can be removed in a ductile mode during the machining of KDP. This study investigates the room tem perature creep-deformation of KDP crystals with the aid of nanoindentation. A stress analysis was carried out to identify the creep mechanism. The results showed that KDP crystals could be plastically deformed at the nanoscale. Dislocation motion is responsible for creep-deformation. Both creep rate and creep depth decrease with decrease in peak force and loading rate. Dislocation nucleation and propagation bring about pop-ins in the load displacement curves during nanoindentation.

关键词： Potassium dihydrogen phosphate (KDP) crystals Creep-deformation Stress Dislocation

Progress on the optoelectronic functional organic crystals

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Science China Chemistry 2007年第4期50卷 433-452页

作者： WANG Huan XIE ZengQi Ma YuGuang Shen JiaCong Key Laboratory for Supramolecular Structure and Materials of Ministry of Education Jilin UniversityChangchun 130012China

Organic crystals constructed by pi-conjugated molecules have been paid great attention to in the field of organic optoelectronic materials. The superiorities of these organic crystal materials, such as high thermal stability, highly ordered structure, and high carrier mobility over the amorphous thin film ma-terials, make them attractive candidates for optoelectronic devices. Single crystal with definite struc-ture provides a model to investigate the basic interactions between the molecules (supramolecular interaction), and the relationship between molecular stacking modes and optoelectronic performance (luminescence and carrier mobility). Through modulating molecular arrangement in organic crystal, the luminescence efficiency of organic crystal has exceeded 80% and carrier mobility has been up to the level of 10 cm2·V?1·s?1. Amplified stimulated emission phenomena have been observed in many crys-tals. In this paper, we will emphatically introduce the progress in optoelectronic functional organic crystals and some correlative principle.

关键词： organic crystals luminescence mobility laser field effect

A collection of 505 papers on false or unconfirmed ferroelectric properties in single crystals,ceramics and polymers

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Frontiers of physics 2019年第6期14卷 35-72页

作者： Zbigniew Tylczynski Faculty of Physics Adam Mickiewicz UniversityUniwersytetu Poznanskiego 2PoznanPoland

This collection presents 505 papers on ferroelectricity in single crystals,ceramics and polymers in which pointed or elliptical hysteresis loops would testify to their ferroelectric properties.In some papers,the autho... 详细信息

关键词： ferroelectricity hysteresis loop single crystals multiferroic polymers