Composition (a) and morphology (b-e) evolution of the hydrothermal products. The products were obtained at 105°C for different times, with the molar ratio of FeCl3/H3BO3/NaOH = 2:3:4. Time (h) = 1.0 (a1, b); 3.0 (a2, c); 6.0 (a3, d, e). The asterisk represents α-Fe2O3 (JCPDS No. 33–0664); nabla represents β-FeOOH (JCPDS No. 34–1266); the bullet represents maghemite (γ-Fe2O3, JCPDS No. 25–1402). Inset: high-resolution SEM image of the corresponding sample (c1).
Zhu et al. Nanoscale Research Letters 2013 8:2 doi:10.1186/1556-276X-8-2