Opal Photonic Crystals Modified by Fe-Based Inclusions

Fe-based particles were produced in pores of photonic crystals consisting of amorphous silica nanospheres via infiltration with a ferrocene solution in diethyl ether, followed by pyrolysis. Magnetooptic characterization of the modified material indicated the presence of isotropic, ferromagnetically ordered regions. It is shown that magnetooptic measurements provide a tool for assessing the qualitative composition of opal photonic crystals containing Fe-based inclusions.     

Photonic Bandgaps in Disordered Inverse‐Opal Photonic Crystals

Three‐dimensional photonic crystals with full bandgaps at optical wavelengths can be fabricated with inverse‐opal techniques. We have shown that the bandgap is extremely sensitive to the presence of geometric disorder in the crystals (see Figure). The bandgap closes completely with a disorder strength as small as under two percent of the lattice constant. This fragility persists even at very high refractive index contrasts and is attributed to the creation of a bandgap at high frequency bands (8–9 bands) in inverse‐opal crystals. This should impose severe demand on the quality of lattice uniformity.     

NaGd(WO4)2:Yb3+/Tm3+反蛋白石光子晶体的制备与上转换发光调制研究

三维光子晶体具有长程有序的结构特点, 在可见和近红外光谱范围内有着广泛的应用。光子晶体的一个重要性质是其对嵌入其中的发光中心自发辐射具有调制作用。本研究利用自组装和模板辅助法制备高质量的三维NaGd(WO₄)₂:Yb³⁺/Tm³⁺反蛋白石光子晶体, 探究了光子带隙对Tm³⁺离子上转换荧光发射与发光动力学的调制作用。通过对比分析发现, 由于反蛋白石光子晶体独特的周期性大孔结构和光子带隙效应, 处于光子带隙内的Tm³⁺离子¹G₄-³H₆的发光强度被抑制约45%, 自发辐射速率(SDR)被抑制约30%, 同时上转换局域热效应得到有效的调制。本实验结果对探索新型高效稀土掺杂上转换发光材料和提高上转换发光效率有指导意义。     

Inverse Opal Scaffolds and Their Biomedical Applications

Three‐dimensional porous scaffolds play a pivotal role in tissue engineering and regenerative medicine by functioning as biomimetic substrates to manipulate cellular behaviors. While many techniques have been developed to fabricate porous scaffolds, most of them rely on stochastic processes that typically result in scaffolds with pores uncontrolled in terms of size, structure, and interconnectivity, greatly limiting their use in tissue regeneration. Inverse opal scaffolds, in contrast, possess uniform pores inheriting from the template comprised of a closely packed lattice of monodispersed microspheres. The key parameters of such scaffolds, including architecture, pore structure, porosity, and interconnectivity, can all be made uniform across the same sample and among different samples. In conjunction with a tight control over pore sizes, inverse opal scaffolds have found widespread use in biomedical applications. In this review, we provide a detailed discussion on this new class of advanced materials. After a brief introduction to their history and fabrication, we highlight the unique advantages of inverse opal scaffolds over their non‐uniform counterparts. We then showcase their broad applications in tissue engineering and regenerative medicine, followed by a summary and perspective on future directions.     

反蛋白石结构光子晶体及其应用的研究

反蛋白石结构光子晶体因具有完全光子带隙、制备材料广泛、特殊的周期结构、大的比表面积和连通的孔洞结构,近年来在自发辐射的调制、提高光催化反应速率和染料敏化太阳能电池反应速率等领域成为研究热点之一,并且在光、电、催化、传感、显示、检测等领域有着巨大的应用价值。介绍了反蛋白石结构光子晶体的基本概念及制备方法,阐述了反蛋白石结构在材料自发辐射的调制、能量传递的调制、促进物理化学反应、外界环境响应材料等方面的作用及其应用。     

Superconductivity of Bi Confined in an Opal Host

Superconductivity is observed in a composite of rhombohedral crystalline bismuth nanoparticles imbedded in an insulating porous opal host via electrical transport and AC magnetic susceptibility. The onset of superconductivity in this system occurs in two steps, with upper transition temperature T _c,U =4.1 K and lower transition temperature of T _c,L =0.7 K, which we attribute to the granular nature of the composite. The transition at T _c,U is observed to split into two transitions with the application of a magnetic field, and these have upper critical fields extrapolated to T=0 K of H _c2,1(0)=0.7 T and H _c2,2(0)=1.0 T, corresponding to coherence lengths of ξ ₁(0)=21 nm and ξ ₂(0)=18 nm, respectively. We suggest that because of the lack of bulk-like states in the Bi nanoparticles due to confinement effects, superconductivity originates from surface states arising from Rashba spin-orbit scattering at the interface.     

热处理对蛋白土粉体性能的影响

对嫩江流域产出蛋白土采用焙烧热处理工艺,研究了热处理温度、时间对该流域产出蛋白土比表面积和孔体积的影响。结果表明:当温度为550℃,热处理时间为2 h,蛋白土的比表面积提高到103.2 m2/g,孔体积达到0.16 mL/g;分析了样品的失重(TG)、差热分析(DTA)曲线,采用SEM对处理前后样品的形貌进行表征。     

一种MGPM/Opal固-固相变储能材料的相变及结晶行为

采用含有相变单元的单体缩聚法合成了侧链含有聚乙二醇单甲醚（MPEG）的新型固-固相变储能复合材料（相变共聚物缩写名称为（MGPM）/蛋白石（opal））,通过广角X射线衍射（WAXD）、差热扫描量热仪（DSC）和热台偏光显微镜（POM）、热重（TG）等测试手段对其结晶结构、结晶行为、结晶形态和热稳定性进行了研究,结果表...     

Photonic Crystals

Abstract

In this paper, we review the early motivation for photonic crystal research which was derived from the need for a photonic bandgap in quantum optics. This led to a series of experimental and theoretical searches for the elusive photonic bandgap structures: those three-dimensionally periodic dielectric structures which are to photon waves, as semiconductor crystals are to electron waves. We shall describe how the photonic semiconductor can be ‘doped’, producing tiny electromagnetic cavities. Finally, we shall summarize some of the anticipated implications of photonic band structure for quantum electronics and the prospects for the creation of photonic crystals in the optical domain.