Melting of San Carlos Olivine in the Presence of Carbon at 6-12 GPa

a. Bright field TEM micrograph of the quenched melt. Individual crystals (less than 100 nm in size) are visible. The black circle shows the approximate size and position of the Selected Area (SA) aperture used to tentatively identify the crystal marked by an arrow.

b. TEM Selected Area diffraction pattern obtained from the crystal showed in the previous micrograph by the arrow. Despite the presence of a few weak extra spots, probably due to other diffracting grains, this pattern corresponds to the Fe3C [11, 3, 1] zone-axis pattern.

c. TEM Selected Area diffraction pattern obtained from a thicker area, containing many crystals, of the same triple junction. This pattern shows the superposition of single-crystal diffraction patterns, locally forming partial powder-diffraction (Debye) rings. The position and contrast of most of the visible diffraction spots and rings can be interpreted as Fe3C reflections (e.g. 121, 031 the strongest, 230, etc.).

Fig.3. TEM investigation of a triple junction in the sample obtained at 6 GPa and 1400 .