Growth mechanisms of surface crystallized diopside

The two glasses A and B of similar composition are melted and annealed at 870 °C for up to 20 h to initiate the surface crystallization of diopside. Phase and orientation analyses are performed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). Both glasses show two discernible layers of crystal growth into the bulk: while multiple phases occur in glass A only diopside is detected in the adapted glass B. The most part of crystal growth in layer 1 is subject to an orientation change of 90°. In the adapted glass B, the predominant c-axes orientations of layer 1 and 2 are orthogonal to each other. Sample deformation and specific crack patterns near the surface are described and explained by occurring tensions.