Fractal nature of crack patterns in RbH2PO4 crystalsat high temperatures

I have investigated the surface of RbH2PO4 crystals by means of optical thermo-microscopy. It has been observed by thermo-microscopy that, upon heating above Tp≈115–130 °C, the cracks appeared at the surface and the crack pattern grew up, depending on the sample thickness. I observed the fractal nature for surface crack patterns of crystals caused by thermal decomposition. I used a box-counting method to get the fractal dimension of the surface cracks. The fractal dimension was 1.7 in the case of sample thickness=0.2 mm of RbH2PO4 crystals. This is similar to the fractal dimension in two-dimensional (2-D) DLA growth.