A. Mcewan et al., THE GROWTH AND PERFECTION OF ORGANIC NONLINEAR-OPTICAL CRYSTALS - N-METHYL UREA (NMU) FROM METHANOL SOLUTION .2. MORPHOLOGICAL INSTABILITY, Journal of crystal growth, 167(3-4), 1996, pp. 701-708
Studies of the anisotropy of the kinetics of growth of N-methyl urea (
NMU) crystals have shown that the dominant influence on the growth pro
cess is volume diffusion rather than solvent-surface interactions. The
consequence of this is that even at low supersaturations the crystals
become morphologically unstable with the ready inclusion of solvent a
nd consequent deterioration of crystal quality. This paper reports on
studies of the development of this instability in order to define the
conditions for the stable growth of crystals of this material for non-
linear optical devices.