多棒串接固体激光器谐振腔的研究

运用矩阵光学的方法对多棒串接固体激光器的谐振腔参数及其在平平腔时的热稳条件进行了研究，并计算了六棒串接平平腔固体激光器的稳定区.结果证明：多棒串接固体激光器的稳定区和非稳区相互间隔，在平平腔总腔长、激光棒数量n和棒间距L一定的条件下，当采用对称结构时(L₁=L₂)，则谐振腔的每段稳定区均达到最大；且只要 平平腔满足L₁=L₂=L/2以及热焦距f在大于某个下限值f_m时，稳定性条件01< 关键词： 多棒串接固体激光器 稳定区 热稳条件     

Facile Synthesis of Processable Semi-aromatic Polyamide Containing Thioether Units

A series of processable semi-aromatic polyamides containing thioether units have been developed. They were synthesized through the reaction of 4,4’-bis(4-chloroformylphenylthio)benzene (BPB-DC) and aliphatic diamine by the method of interfacial polycondensation. These polyamides had excellent thermal properties with glass transition temperatures (T_g) of 124–137.9°C, melting temperatures (T_m) of 306.4–324.1°C and initial degradation temperatures (T_d) of 409.5–437°C. They had wider processing windows than traditional semi-aromatic polyamides and can be processed by the melting method. They had better tensile strengths of 61.2–73.7 MPa, low-temperature mechanical properties, low water absorption of 0.17%–0.23%, low dielectric constants of 3.47–3.66 at 100 kHz and better melt flowability properties of 37.3 to 164.4 Pa. s, 48.2 to 281.7 Pa. s and 58.3 to 486.7 Pa. s at different shear rates, respectively. Additionally, these polyamides showed good corrosion resistance, they did not dissolve in solvents such as NMP, DMSO, hydrochloric acid (6 mol/L), H₃PO₄ and solution of NaOH (1 mol/L) etc.     

Synthesis and Crystal Structure of a Novel Ca(Ⅱ) Coordination Polymer Containing Dipyridine Dicarboxylic Ligand

The novel alkaline metal complex Ca(BPDCH)2(1, BPDCH2 = 2,2'-bipyridine-5,5'-dicarboxylic acid) has been synthesized by the hydrothermal reaction of Ca(NO3)2·4H2O with 2,2'-bipyridine-5,5'-dicarboxylic acid. The molecular and crystal structures of complex 1 have firstly been characterized by FTIR, elemental analysis, and X-ray single-crystal diffraction. The 3D MOF structure of complex 1 was interpreted by the versatile binding modes-the intermolecular hydrogen bonds and π-π stacking interactions of 2,2'-bipyridine-5,5'-dicarboxylic acid ligand. The analysis results show complex 1 belongs to a coordination polymer with 3D MOF structure. The results of thermogravimetric analysis and solubility demonstrate complex 1 is a thermostable compound and does not dissolve in water and traditional organic solvents.     

用碳化硅合成的金刚石微晶的抗氧化性

用碳化硅加Ni70Mn25Co5合金体系在高温高压下合成出具有完好晶形的金刚石微晶.通过粒度分析和热重量分析对这种晶体的热稳定性进行了评价.作为比较,对工业上用石墨合成的六种不同粒度的金刚石微粉和微晶也作了热重量分析.结果表明,用石墨合成的四种普通金刚石微粉的氧化温度随粒度的减小而明显降低,当粒度为80～100μm到1～2.5μm时,其起始氧化温度为770℃到627℃;两种未经破碎的金刚石微晶的抗氧化性能明显较高,其粒度为20～70μm,起始氧化温度为806℃和819℃.与它们相比,用碳化硅合成出的金刚石晶体的粒度分布在10～50μm范围,而起始氧化温度为838℃,完全氧化温度为1101℃,比用石墨合成的未经破碎的金刚石微晶具有更高的抗氧化性能.本文定性地讨论了用碳化硅合成的金刚石具有高耐热性的原因,认为完好的表面和硅杂质的存在可能对这种晶体热稳定性起了重要作用.