钒磷酸盐(NH3CH2CH2NH2)[VOPO4]的水热合成和结构表征

标题化合物是在反应物摩尔比为V2O5H3PO4H2NCH2CH2NH2H2O=0.5543.6265时,175℃水热反应5 d合成的.其结构特点是钒八面体[VO5N]共用角顶的氧形成"之"字型链,链间由[PO4]共角项连接成层;乙二胺分子的一个N直接与V配位,并伸向层间.相邻层间存在强氢键.晶体学数据单斜晶系,P21/c(No.14),a=0.92108(2)nm,b=0.72851(1)nm,c=0.98204(2)nm,β=101.269(7)°,V=0.6462(4)nm3,Z=4,Dc=2.303g·cm-3,R1=0.0417,wR2=0.0999.     

μ3-O-{[μ-(n-Bu)2Sn(μ-FcCO2)(n-Bu)2Sn]FcCO2}二聚物的晶体结构和分子结构

标题配合物Mr=933.84,属单斜晶系,空间群P2₁/n,晶胞参数a=15.244(4)Å,b=20.895(7)Å,c=12.375(4)Å,β=97.39(3)°,Z=4,V=3909(2)ų,Dc=1.5879·cm^-3,F(000)=1872,最终偏差因子R=0.0684.该配合物分子呈中心对称,是具有Sn₂O₂中心内环的二聚体,Sn₂     

μ3-O-{[μ-(n-Bu)2Sn(μ-FcCO2)(n-Bu)2Sn]FcCO2}二聚物的晶体结构和分子结构

标题配合物Ｍｒ＝９３３．８４,属单斜晶系,空间群Ｐ２_１／ｎ,晶胞参数ａ＝１５．２４４（４）Ａ,ｂ＝２０．８９５（７）Ａ,ｃ＝１２． ３７５（４）Ａ,β＝９７．３９（３）°,Ｚ＝４,Ｖ＝３９０９（２）Ａ~３,Ｄｃ＝１．５８７９·ｃｍ~（－３）,Ｆ（０００）＝１８７２,最终偏差因子Ｒ＝０．０６８４。该配合物分子呈中心对称,是具有Ｓｎ_２Ｏ_２中心内环的二聚体,Ｓｎ_２Ｏ_２中的每个桥氧原子又各连接一个外环锡而形成了四核分子。分子中四个羧酸酯基有桥联双齿（μ－ＣＯＯ）和单齿两种不同的配位模式;在内环锡和外环锡的配位单元中,锡均形成具有五配位的畸变三角双锥配位构型,同时另有一氧原子与中心锡原子之间有弱相互作用。它与类似物［ＦｃＣＯ_２Ｓｎ（ｎ－ＢＵ）_２］Ｏ｝_２·４Ｃ_６Ｈ_６的晶体结构完全不同,却又存在着内在的联系。     

包覆氧化锆对氮化硅力学性能的影响

以氮化硅粉体为原料,添加30wt;的ZrO2和8wt;的稀土氧化物Y2O3为烧结助剂.将Y2O3添加到稀的硝酸中形成硝酸钇透明溶液,并加入ZrO2形成硝酸钇包覆ZrO2的悬浮液,研究在硝酸钇包覆ZrO2的情况下对氮化硅力学性能的影响.实验结果表明在1700℃、30 MPa的热压环境下,在包覆ZrO2的作用下氮化硅陶瓷的致密度从74;提升到97;,断裂韧性从4.3 MPa·m1/2提升到6.0 MPa·m1/2.     

新型固态照明用发光材料Ca3SiO4Br2:Eu2+的合成、结构与发光性能

制备了一种Eu2+掺杂的新型Ca3SiO4Br2蓝色发光材料,详细研究了其晶体结构组成.采用助熔剂法生长出Ca3SiO4Br2片状单晶,解析并证实该晶体为Ca3SiO4Br2,其结构基元中存在交替排列的Ca2SiO4和CaBr2层.荧光光谱测试表明:Ca3 SiO4Br2:Eu2+材料可被近紫外光( 300～ 430 ...     

Pitch Angle Distribution Evolution of Energetic Electrons by Whistler-Mode Chorus

We develop a two-dimensional momentum and pitch angle code to solve the typical Fokker-Planck equation which governs wave-particle interaction in space plasmas. We carry out detailed calculations of momentum and pitch angle diffusion coefficients, and temporal evolution of pitch angle distribution for a band of chorus frequency distributed over a standard Gaussian spectrum particularly in the heart of the Earth＇s radiation belt L = 4.5, where peaks of the electron phase space density are observed. We find that the Whistler-mode chorus can produce significant acceleration of electrons at large pitch angles, and can enhance the phase space density for energies of 0.5 - 1 MeV by a factor of 10 or above after about 24h. This result can account for observation of significant enhancement in flux of energetic electrons during the recovery phase of a geomagnetic storm.