Fig. 2
Crystalline and amorphous silica from higher SMS concentration SB microemulsions. Representative TEM of the silica phases synthesized from SB (Span® 80 and Brij® 30) microemulsions after 2 days using 5 μl g-1 of a 10 wt.% (a, b and d) and a 14 wt.% (c, e) aqueous SMS (sodium metasilicate) solution. a HREM image of ≈50 nm cristobalite particles. b Higher magnification image of the lower particle shown in a. The inset shows the FFT, which indexes on the 〈110〉 zone axis of cristobalite. c Representative amorphous silica material, which formed the majority silica phase for the 14 wt.% aqueous SMS microemulsion. The inset shows the particle’s electron diffraction pattern and absence of sharp diffraction spots. d HREM image of a cluster of ≈2–10 nm particles, with some showing lattice fringes. e HREM image of a 5 nm particle. The inset shows the FFT, which indexes on the 〈212〉 zone axis of α-quartz. Scale bars are 50 nm in a and c, 5 nm in b, d and e and 2 nm-1 in the insets to b, c and e
