共查询到20条相似文献,搜索用时 62 毫秒
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开展"专题研究"实施研究性教学 总被引:2,自引:0,他引:2
研究性教学是指学生在学习过程中要参与研究活动,即学生用以获取知识、领悟科学的思想观念,类似科学家研究自然和社会的态度与方法进行的各种研究性学习活动,包括观察、测量、制作、实验、假设和交流等.不难看出,大学研究性教学实质上是将科学领域的某些研究环节引入大学教学,使学生通过类似科学家的研究过程学习科学概念和科学规律的本质,培养科学研究思想、方法和能力的一种现代的教学方法. 相似文献
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本文在简要阐述研究性学习的基础上,提出研究性物理实验的实施策略,并简要阐述已开展研究性物理实验教学的实践研究,最后提出若干思考和建议。 相似文献
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研究性学习是指学生在教师指导下,从学习生活和社会生活中选择和确定研究专题,主动获得知识、应用知识、解决问题的学习活动,它强调学生通过实践,增强探究性和创新意识,学习科学方法,发展综合运用知识的能力;形成一种积极地、开放地、生动 相似文献
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物理学是一门以实验为基础的自然科学,在物理教学过程中,利用物理学科“以实验为基础”这个基本特征,充分挖掘和开发物理实验在研究性学习中的功能,对于使学生养成主动积极的学习方式,从而形成终身学习的能力具有十分重要的意义。本文就物理实验作为研究性学习途径的有关问题进行初步探讨。 相似文献
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对掺有镉、硒、硫的玻璃在500—800℃退火2—24h,生长了不同尺寸的CdSxSe1x纳米晶体.用分光光度计和光致发光光谱(PL)分析了纳米晶体的性能.退火温度低于550℃,纳米晶体处于成核阶段,600—625℃处于正常扩散生长阶段,700—800℃处于竞争生长阶段;而650℃处于两种生长阶段之间.虽然650℃下生长的纳米晶体的尺寸分布比较窄,但纳米晶体的尺寸随退火时间的延长几乎不变,在该温度改变退火时间很难改变纳米晶体的平均尺寸.在所有样品中出现了深能级缺陷,在650℃退火时间小于4h或大于16h有利
关键词:
纳米晶体
生长机理
深能级缺陷 相似文献
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对笔者在物理实验教学过程中,所指导学生进行的一些具有创新性的研究性实验进行了探索、研究,归纳和总结,对学生进行研究性实验的情况进行了介绍,以供各位同仁师生参考。 相似文献
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A. I. Karasevskii V. V. Lubashenko 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,66(3):375-383
We demonstrate that the discrete character of the vibrational spectrum of a small crystal accounts for size dependence of
its thermodynamic properties and melting temperature. Using a self-consistent statistical method [Phys. Rev. B 66, 054302 (2002)] we derive the Gibbs free energy of free nanocrystalline plates and calculate the thermodynamic parameters
as functions of plate thickness for Cu. 相似文献
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K. K. Pukhov T. T. Basiev Chang-Kui Duan Yu. V. Orlovskii 《Optics and Spectroscopy》2013,114(6):868-872
Taking into account electron-phonon interaction effects, we have studied the radiative characteristics of doped nanoellipsoids in a dielectric medium with an arbitrary fraction of nanoparticles in a nanocomposite. The obtained analytical expressions for the radiative characteristics allow it to be concluded to what extent they are susceptible to changes in the phonon subsystem and electron-phonon interaction caused by the spatial confinement effect. 相似文献
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Petra Lommens Celso de Mello Donega Luc Piraux Stefan Mátéfi-Tempfli Zeger Hens 《Journal of luminescence》2006,118(2):245-250
We performed photoluminescence experiments on colloidal, Co2+-doped ZnO nanocrystals in order to study the electronic properties of Co2+ in a ZnO host. Room temperature measurements showed, next to the ZnO exciton and trap emission, an additional emission related to the Co2+ dopant. The spectral position and width of this emission does not depend on particle size or Co2+ concentration. At 8 K, a series of ZnO bulk phonon replicas appear on the Co2+-emission band. We conclude that Co2+ ions are strongly localized in the ZnO host, making the formation of a Co2+d-band unlikely. Magnetic measurements revealed a paramagnetic behaviour. 相似文献
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Optical properties of manganese-doped nanocrystals of ZnS 总被引:1,自引:0,他引:1
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对掺有镉、硒、硫的玻璃在650—800℃退火4?h,生长了不同尺寸的CdS0.13Se0.87纳米晶体,测量了纳米晶体的吸收光谱、光致发光(PL)谱和电调制光谱,确定了纳米晶体部分电子态的能量,讨论了CdSSe纳米晶体的光学性质与其尺寸之间的依赖关系.随着纳米晶体尺寸的增大,对应激子的吸收峰、PL峰及电吸收信号发生红移,表现出明显的量子尺寸效应.小尺寸纳米晶体的电吸收表现为量子受限的Stark效应,而大尺寸纳米晶体的电吸收线形与体材料的相似;随着纳米晶体尺寸的增大,电吸收信号增强.所有尺寸的纳米晶体都表现
关键词:
CdSSe纳米晶体
吸收光谱
光致发光谱
电光响应 相似文献
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Recently, a lattice-type-sensitive model, free of any adjustable parameter, for the size dependence of the cohesive energy of nanocrystals (nanodisks, -films, -wires and -particles) has been developed, taking into account the effects of the averaged structural and energetic properties of their surface and volume. These effects are related to the first- and second-nearest-neighbor atomic interactions. Now, considering the intimate relation between cohesive energy and other physical properties of materials, the recently obtained formula for the cohesive energy of nanocrystals has been applied to the cases of melting point (In, Bi, Si and Ag), evaporation temperature (Ag and Au), vacancy formation energy (Au), diffusion activation energy (Au), surface energy (Au, Al and Na), liquid–vapor interfacial energy (Al and Na), Curie temperature (Pb), Debye temperature (Au and Fe) and band gap energy (Si) of nanocrystals. In general, good agreement between the present model and the data has been obtained. Moreover, the surface-area-difference (SAD) model has been derived as a first-order approximation of the present model. 相似文献
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Electroluminescence properties of light emitting devices based on silicon nanocrystals 总被引:1,自引:0,他引:1
A. Irrera D. Pacifici M. Miritello G. Franzo F. Priolo F. Iacona D. Sanfilippo G. Di Stefano P. G. Fallica 《Physica E: Low-dimensional Systems and Nanostructures》2003,16(3-4):395
We have fabricated MOS devices where the dielectric layer consists of a substoichiometric SiOx (x<2) thin film, annealed at 1100°C for 1 h to induce the separation of the Si and SiO2 phases, with the formation of silicon nanocrystals (nc) embedded in the insulating matrix. We have studied the electroluminescence (EL) properties of such devices as a function of the current density and of the temperature. We have evaluated the excitation cross section of Si nc under electrical pumping at room temperature and at low temperature (12 K). Moreover, we have used the experimental EL intensities and decay times to evaluate the radiative rate as a function of the temperature. 相似文献