Large Amplitude Libration and Structural Phase Transition

对<19><14><127>几种烷基铵盐和富勒烯化合物进行了^1H、^2H、^ F、^ N和^1NMR和扩展X射线吸收精细结构（EXAFS）的测量，以阐明大振幅振动，特别是振动，及其与结构相变的关系。测定了自旋-晶格弛豫时间、自旋-自旋弛豫时间、NMR谱线宽度二阶矩和Debey-Waller因子随温度的变化关系。获得了以下结果。（1）在20-300 K温度范围内，用碘K边EXAFS研究了CH_3NH_3I在I^-离子周围的局域结构，用单晶X射线衍射确定了室温相的晶体结构。由EXAFS得到的Debye-Waller因子在166 K附近出现反常行为。(2)Sn用EXAFS方法研究了（CH_3NH_3）_2SnBr_6在149 K附近的相变温度，得到了（CH_3NH_3）_2SnBr_6和（Br）_2SnBr_6的K边EXAFS谱 ...更多信息 这是温度变化的反常现象。（3）在10-293 K温度范围内，用Pb L-edge和Sn K-edge EXAFS研究了CH_3NH_3PbX_3（X=Cl，Br，I）和CH_3NH_3SnX_3（X=Br，I）中Pb（II）和Sn（II）的局域结构<III>，分别测定了CH_3NH_3PbCl_3、CH_3NH_3PbBr_3、CH_3NH_3PbI_3、CH_3NH_3SnBr_3和CH_3NH_3SnI_3在三、四、三、五和两相中的M-X距离（M=Pb，Sn ; X=Cl，Br，I）、配位数和Debye-Walker因子。(4)Rb在<60>6-300 K范围内对Rb_3C_2超导体进行了K边EXAFS研究，发现距离（r_<Rb-C>）和Debye-waller因子反映了T_c附近的反常行为。(5)在高于480 K的离子塑性相中测量了高氯酸三甲基铵的^1H NMR和电导率。在该相中，阳离子和阴离子都进行了自扩散。计算了阳离子扩散的活化能。(6)研究<19><14><127>了（CH_3）_3NHBF_4和（CH_3CH_2）_3NHBF_4的~ 1H、~ 1F、~ 1 N和~ 1 I NMR、粉末和单晶X射线衍射、差热分析（DTA）和差示扫描量热（DSC）以及电导率。（CH_3）_3NC_2H_5I、（CH_3）_3NC_2H_5BF_4和（CH_3CH_2）_3NHBF_4分别得到三个、五个和三个固相。确定了阳离子和阴离子的动力学行为及其与相变的关系。少

Measurements of ^1H,^2H,^<19>F,^<14>N and ^<127>I NMR and Extended X-ray Absorption Fine Structure (EXAFS) were carried out in several alkylammonium salts and fulleren compounds, in order to clarify the large amplitude vibration, especially librations, and its relation to the structural phase transitions. The temperature dependence of spin-lattice and spin-spin relaxation times and of second moments of NMR linewidth and Debey-Waller factor were determined. The following results were obtained.(1)The local structure of CH_3NH_3I around the I^- ion was studied by iodine K-edge EXAFS in the temperature range of 20-300 K.The crystal structure in the room temperature phase was determined by single crystal X-ray diffraction. The Debye-Waller factor derived from EXAFS shows an anomalous behavior around the order-disorder transition temperature of 166 K.(2)Sn and Br K-edge EXAFS studies were made in (CH_3NH_3)_2SnBr_6 around the phase transition temperature of 149 K.The Debye-walker factor show … More s an anomalous behavior around the temperature.(3)Local structures around Pb (II) and Sn (II) in CH_3NH_3PbX_3 (X=Cl, Br, I) and CH_3NH_3SnX_3 (X=Br、I) were studied by Pb L_<III>-edge and Sn K-edge EXAFS in the temperature range of 10-293 K.The M-X distances (M=Pb, Sn ; X=Cl, Br, I), the coordination numbers, and the Debye-Walker factors were determined in three, four, three, five, and two solid phases of CH_3NH_3PbCl_3, CH_3NH_3PbBr_3, CH_3NH_3PbI_3, CH_3NH_3SnBr_3, and CH_3NH_3SnI_3, respectively.(4)Rb K-edge EXAFS studies on Rb_3C_<60> superconductor were made in the range 6-300 K.The distance (r_<Rb-C>) and Debye-waller factors were found to show the anomalous behavior near T_c.(5)^1H NMR and electrical conductivity of trimethylammonium perchlorate were measured in the ionic plastic phase obtainable above 480 K.In this phase, both cation and anion were revealed to perform self-diffusion. The activation energy of the cationic diffusion was evaluated.(6)^1H,^<19>F,^<14>N and ^<127>I NMR,powder and single crystal X-ray diffraction, differential thermal analysis (DTA) and differential scanning calorimetry (DSC), and electrical conductivity were studied for (CH_3)_3NC_2H_5X (X=I,BF_4) and (CH_3CH_2)_3NHBF_4. Three, five and three solid phases were obtained for (CH_3)_3NC_2H_5I,(CH_3)_3NC_2H_5BF_4 and (CH_3CH_2)_3NHBF_4, respectively. The dynamical behavior of the cation and anion, and its relation to the phase transition were determined. Less