排序方式: 共有8条查询结果,搜索用时 15 毫秒
1
1.
1 INTRODUCTIONThecondensationofaldehydeswithaminesisavaluablesyntheticmethodleadingtopolyazapolycyclics,includingcagedcompounds.Animportantapplicationofthisreactionisthesynthesisofhexabenzylhexaazaisowurtzitane(HBIW)anditsderivativeswithsubstitutedbenz… 相似文献
2.
3.
4.
5.
Lead-free piezoelectric ceramics 0.92(Bi0.5Na0.5)TiO3-0.08BaTiO3 + xmol% Co3+ (BNBT-Co, x = 0-8) are prepared by the solid state reaction method. Effects of the amount of Co^3+ on the electrical properties and phase transition are studied. The results indicate that the addition of Co^3+ enhances the mechanical quality factor Q^3+ significantly, whereas the dissipation factor tanδ has a minimum value at x = 3.5. Meanwhile, addition of Co^3+ leads to small decreases of piezoelectric constant d33, and planar electromechanical coupling kp. The present 0.92(Bio.aNao.5) TiO3-0.08BaTiO3+3.5 moi% Co^3+ ceramics exhibit good performance with mechanical quality factor Qm = 910, piezoelectric constant d33 = 106pC/N, planar electromechanical coupling kp =10% and dissipation factor tanδ = 1.1% at 1 kHz. Saturated polarization hysteresis loops have been obtained for BNBT-Co ceramics. Two dielectric peaks at depolarization temperature Td and Tm appear in the curves of ε33^T vs temperature for the pure BNBT ceramics. However, the first dielectric peak Td disappears after the addition of Co^3+, which means that the transition from ferroelectric to antiferroelectric phase has been eliminated. 相似文献
6.
7.
3-叠氮甲基-3-硝酸酯甲基环氧丁烷的聚合反应研究 总被引:1,自引:0,他引:1
改进了单体3-叠氮甲基-3-硝酸酯甲基环氧丁烷的合成路线,以三氟化硼·乙醚为催化剂,1,4-丁二醇为引发剂,研究了该含能单体的开环聚合反应,得到了分子量可预计、分散度较小的聚合物.采用FTIR、1HNMR和GPC对聚合物结构进行了表征. 相似文献
8.
A polycyclic caged compound with high strain——hexanitrohexaazaisowurtzitane (HNIW)——has been synthesized via a three-step reaction: condensation, hydrogenolysis debenzylation and nitrolysis, starting with benzylmine and glyoxal. HNIW is the most powerful high energy density compound (HEDC) ever tested. β-HNIW possesses a caged structure consisting of two five-membered rings and one six-membered ring with a nitro group attached to each of the six bridging nitrogens. The nitro group lies basically within a plane. The lengths of C--C bonds of β-HNIW range from 0.156 nm to 0.159 nm, 0.002--0.005 nm longer than the sp~3 C-C bond. The β-HNIW's crystal belongs to orthorhombic system and space group Pca2_1 with parameters: a=0.9670 (2), b=1.1616 (2), c=1.3032 (3) nm; V=1.4638(5) nm~3, Z=4; D_c=1.989 g/cm~3 and D_m=1.982 g/cm~3. 相似文献
1