Fig. 6

Back-scattered electron images of representative run products. a 3.7 GPa at 750 °C, run SPT1; b 3.8 GPa at 800 °C, run EFSP1; c 3.8 GPa at 900 °C, run EFSP3; d 3.8 GPa at 900 °C, run EFSP4; e 4.0 GPa at 870 °C, run FB6; f 4.2 GPa at 900 °C, run SPT5; g, h 4.2 GPa at 900 °C, sandwich experiment SPT8, CO₂/H₂O = 2.7; i, j 4.2 GPa at 900 °C, sandwich experiment SPT10, CO₂/H₂O = 33.8; k 3.8 GPa at 1000 °C, run SPT3, bulk 593; l 3.8 GPa at 1000 °C, run SPT3-8, bulk 803