Experimental determination of the growth rate anisotropy of garnets

The orientational dependence of the growth rate of a typical bubble garnet system is measured in the whole solid angle range of 4π for the case of low undercooling. There are found deep singular minima at <110> and <211> and shallow nonsingular minima at <321> and <100>. The maximum rate is attained near <111>. Conclusions are drawn to the equilibrium form of garnets and the results are discussed in terms of thermal roughening of the garnet F-faces. The sequence of the faces in the order of decreasing roughening temperature is 110, 211, 321, 100. The displacement velocity of misorientation steps on 211 faces is found to be 0.18 μm/s for 18 K undercooling. (author)