反射衰减诊断激光光束的应用分析

介绍了普通光学元件反射诊断激光光束的应用,提出了利用平面平晶的平面反射进行光能衰减,详细论述了采用该方法进行光能衰减的可行性,分析了平面平晶反射衰减中反射光S偏振态和P偏振态能量的差异,对激光束诊断的影响和解决方法,结合半导体绿激光器的光束诊断进行了应用分析。实验证明,该方法结构简单、调整方便、误差小,利用普通平面平晶反射衰减即可满足激光强度的匹配要求,实现了待测激光束无失真取样,达到很好的测试效果。     

Epsilon-near-zero or mu-near-zero materials composed of dielectric photonic crystals

We theoretically demonstrate that at certain frequencies two-dimensional dielectric photonic crystals （PCs） may be regarded as either epsilon-near-zero or mu-near-zero materials. We show that the transmission through a slab of such materials upon normal incidence is normally non-unity and decays with slab thickness. However, when the incident angle increases slightly, the transmittance experiences a dramatic increase due to the Brewster effect. The combination of the tunneling and resonance effects makes such materials good candidates for almost perfect bending waveguides and cloaking in waveguides. The zero index also enables applications of focusing and directive emission. At last, the distinction between the single-zero and double-zero media is discussed. In all of the above results, the numerical simulations perfectly match with theoretical predictions from the effective medium analysis.     

Liquid crystal oligo(cyclosiloxanes)

The synthesis and properties of individual liquid crystal oligo(cyclosiloxanes),, wherex=4–8 andR is a 4-methoxyphenyl-4-alkyloxybenzoate type of mesogenic group, is described. Preliminary results concerning the effect of ring size on the mesophase formation are included. X-ray diffraction studies have shown that the cyclosiloxanes form a smectic A₁ phase.     

Critical Review of Fluorinated Electrolytes for High-Performance Lithium Metal Batteries

Lithium metal batteries (LMBs), due to their ultra-high energy density, are attracting tremendous attentions. However, their commercial application is severely impeded by poor safety and unsatisfactory cycling stability, which are induced by lithium dendrites, side reactions, and inferior anodic stability. Electrolytes, as the indispensable and necessary components in lithium metal batteries, play a crucial role in regulating the electrochemical performance of LMBs. Recently, the fluorinated electrolytes are widely investigated in high-performance LMBs. Thus, the design strategies of fluorinated electrolytes are thoroughly summarized, including fluorinated salts, fluorinated solvents, and fluorinated additives in LMBs, and insights of the fluorinated components in suppressing lithium dendrites, improving anodic stability and cycling stability. Finally, an outlook with several design strategies and challenges will be proposed for novel fluorinated electrolytes.     

对微波布拉格衍射实验中产生衍射极大值晶面的讨论

通过理论推导出三厘米微波布拉格衍射实验中的模拟晶体只能产生一、二级衍射,而且只有十个晶面可以产生衍射极大值,并且采用微波分光仪可以进行测量。本文还对这些晶面的特点进行了分析讨论,得出只要通过三个有代表性的晶面（晶面族）作为该实验的研究对象,就能够全面研究微波布拉格衍射实验,以便于从事这方面教学与研究的有关专业人士参考。     

实型和虚型结构因子的代数公式

应用晶体正空间和倒易空间等效点的矩阵表示讨论结构因子类型，在得到倒易空间点的一般型结构因子类型和系统消光型结构因子类型的代数公式之后，得到并证明了倒易空间点的实型和虚型结构因子的代数公式．即满足提出的实型结构因子类型或虚型结构因子类型的代数公式的任意一倒易空间点h，其结构因子Fh分别为实型和虚型．     

双BGO晶体能谱测井

Ｃ／Ｏ测井可以利用ＢＧＯ晶体探测效率高的特点，在其探测器部分放置两个探测器，称为双探测Ｃ／Ｏ测井仪，长短源距两个探头所测谱数据进行补偿，有效地去除了井眼条件的影响，提高了测量精度和油水差值，更加有产地分油水层，并有望能在低孔隙度的地层中使用Ｃ／Ｏ测井仪器。     

SYSNTHESIS AND CHARACTERIZATION OF A NEW COMPOUND K_6Ti_2Nb_(14)O_(42)IN K_2O-TiO_2-Nb_2O_5SYSTEM

A new compound K_6Ti_2Nb_(14)O_(42)was found inthe ternary system K_2O-TiO_2-Nb_2O_5.The compound was char-acterized and investigated by electron,probe,X-ray powderdiffraction and differential thermal analysis.The transpar-ent crystal of light yellow color in form of hexagon-thinplate can be grown by flux method.Further,its crystal struc-ture was determined by four-circle diffratometer K_6Ti_2Nb_(14)O_(42)crystallizes in he(?)(?)(?)onal system with unitcell parameters a=9.1106(5)×10~(-10)m·c=12.0136(9)×10~(-10)m,Z=l andspace.group P6_3/mcm(193).     

添加晶种对硅酸盐水泥生料易烧性影响的研究

采用实验室制备不同种类单矿物，纯熟料及白水泥熟料为晶种，利用ＤＴＡ，ＸＲＤ及测定游离石灰等方法，研究了其对硅酸盐水泥生料易烧性的影响。结果表明；铁相的作用在四种单矿物中最为明显，其它三种主要矿物也均有不同程度地促进煅烧过程的熟料矿物形成的作用。