Development of a new multi-anvil apparatus for in situ X-ray diffraction, "SPEED-Mk.II"

Difficulty of V measurement by in situ X-ray diffraction using MA

  • Limited number of grains
    • Due to the limited diffraction V
    • Particularly, the number of grains largely decreases at high T due to grain growth
      • Diffraction peaks disappear at high T
  • Limited pressure range
    • Only 30 GPa can be generated by a usual multi-anvil apparatus with tungsten carbite anvils
      • Not enough to investigate pressure dependence of α of Pv
    • Practical use of sintered-diamond anvils is necessary in order to generate higher pressure than 30 GPa
      • However, it is difficult!

A new HP apparatus for in situ X-ray diffraction

  • Development of a new Kawai-type high pressure apparatus, SPEED-Mk.II
    • Installed at the bending magnet white X-ray beam line, BL04B1 at SPring-8 in 2001.
    • Constructed by the group grant for the HP geoscience community of Japan, represented by Prof. Eiji Ohtani


Basic design of SPEED-Mk.II

  • Followed the basic design of SPEED-1500
    • Installed at the bending magnet white X-ray beam line, BL04B1 at SPring-8
    • Kawai-type multi-anvil apparatus with a DIA-type guide block system
      • Maximum Load: 15 MN
    • Energy dispersive X-ray diffraction system with a horizontal goniometer
    • CCD camera for radiography
  • Two major improvements from SPEED-1500

Improvement 1.

  • Oscillation system
    • The whole press can rotate in the 20°range
      • Press weight: 20 tons.
      • Shift of the sample by oscillation is suppressed to less than 50μm
    • Renders it possible to take high-quality diffraction patterns against grain growth

Left: 0-degree, Right: 20-degrees


Example: MgO

  • Without oscillation, all peaks but (311) and (422) disappeared
  • With oscillation, all peaks but (331) appeared
    • Intensity ratios are largely deviated from the crystal structure
    • 20°oscillation is useful but not perfect
  • Sufficiently high-quality diffractions determine volumes


Improvement of precision in pressure determination


Improvement 2.

  • Adjustable guide block system
  • In the DIA-type guide block system, compressions in the horizontal and vertical directions are not equivalent
    • Break brittle sintered diamond anvils
    • cause blow out
  • The top and bottom first-stage anvils are placed on the supporting columns that are separated from the guide block
    • The strength of the supporting columns can be adjusted by try-and-error

Guide block adjustment


Progress in pressure generation

  • Max pressure was 45 GPa before introducing SPEED-Mk.II
  • The pressure record has been renewed by 10 GPa every 2 years
  • In Feb. 2008, the max. P has exceeded 90 GPa.