Fine texture and superstructure of minerals by ultra-high resolution TEM

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Antigorite and cariopilite were studied with a JEOL model JEM-4000EX ultra-high resolution electron microscopy and a JEOL model JEM-2000FX analytical electron microscopy in the HVEM laboratory of Kyushu University. The JEM-4000EX used in this investigation has 0.17nm point-to-point resolution. The value is nearly equal to a Si-O or Mg-O bond length. The obtained results of antigorite by HRTEM observations as follows.(1) The optical fourie transform of the obtained HRTEM images shows the resolution of 0.20-0.15nm. The values is a similar to the resolution power of the HRTEM used in this study.(2) The through-focus series of images were not able to get because of the rapid electron beam damage.(3) The c-axis HRTEM images of the Sasaguri antigorite sample A1 are divided into two types. The first type shows continuos (200) and discontiunous (130) fringes of 0.25nm. The offsets in (130) fringeoccur along at 3.5nm seperation. The supercell periodicity corresponds to M=6.5. The second type shows (110) and (020) fringes of 0.46nm spacing and the similar offsets in (110) fringe at 3.5nm separation.(4) The above two type of images were interpreted by image simulation using multi-slice method.(5) A new superstructure, which has a C-centered space lattice was confirmed in the Sasaguri antigorite samples A1, The C-centered superstructure model that was predicted by Uehara and Shirozu (1985).(6) A new one-layr monoclinic superstructure with large beta angle of 95ﾟ was found in so-called "picrolite" sample S7 (Uehara and Shirozu, 1985).