The Mechanism of Structure Phase Transition of Hydrogen Bonding Materials by High Pressure X-Ray Diffraction

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(a) High Pressure X-Ray Diffraction and Crystal Structure of K_3D (SO_4)_2A diamond-anvil pressure cell for x-ray diffraction of single crystals was made on an experimental basis. The precise X-ray structure analysis of K_3D (SO_4)_2 single crystal under high pressure were tried. We collected integrated intensities from the 30% of reciprocal lattice spqce at room temperature under the condition of high pressure. The following results were made clear. (1) A drastic change of the crystal structure in K_3D (SO_4)_2 crystal was not observed at pressures below about 3GPa. (2) The length of hydrogen bond was contracted as function of pressure. But, these results and the distribution of electron density of D-atom had large error. Now, we plan the structure analysis of K_3D (SO_4)_2 single crystal at high pressure with high energy X-ray in SOR (SPring-8).(b) Even and Odd Effect and Crystal Structure in C_nH_<2n+1>NH_3H_2PO_4 Crystals.In order to clarify the even and odd effect in n-alkyl ammon … More ium dihydrogen phosphate C_nH_<2n+1>NH_3H_2PO_4 (abbreviated as CnADP) crystals, we carried out the x-ray crystal structure analysis in CnADP (n=2-6) single crystals at room temperature. Yhe following results were made clear. (1) CnADP (n=2-6) crystals belong a monoclinic system with space group of P2_1/n (Z=8). (2) The crystal structure of CnADP (n=2-6) crystals are characterized by an arrangement of anti-parallel planar organic chains along b-axis interdistributed with inorganic units. (3) The overlap of n-alkyl group increase with increasing carbon atoms. It was considered that the length between the end carbon atom in the n-alkyl group and the nitrogen atom in the another n-alkyl ammonium group was kept constant. (4) In the case of CnADP (n=2,4 and 6) crystals, which was the even number of the carbon atom in n-alkyl group, the zigzag structure of the n-alkyl group was overlapped in parallel and fill the space with each other. On the other hand, in the case of CnADP (n=3 and 5) crystals, which was the odd number of the carbon atom in n-alkyl group, the zigzag structure of the n-alkyl group was overlapped just like clash. It was concluded that this difference was the origin of the even and odd effect. Less