Growth and evaluation of some urea derivative crystals

Looking for compounds with optical properties comparable or better than those of urea we have performed crystallization tests on phenylurea, 1,1-dimethylurea and 1,3-dimethylurea. Appreciable results have been obtained for 1,3-dimethylurea grown by the normal freezing method. The ingots display good keeping and mechanical properties. Phase matching has been achieved with an encouraging doubling efficiency.