THE GROWTH OF LARGE UREA SINGLE CRYSTALS FROM METHANOL SOLUTION USING A NOVEL TURBINE SEED RACK.

SINGLE CRYSTAL UREA HAS BEEN DEMONSTRATED TO BE A USEFUL NONLINEAR OPTICAL MATERIAL. ITS MOST PROMISING APPLICATION IS AS THE BASIS OF THE FIRST PRACTICAL, ALL SOLID STATE, BROADLY TUNABLE LASER. CURRENTLY, HOWEVER, ITS USE IS SEVERELY RESTRICTED BECAUSE NO ONE HAS YET RELIABLY GROWN LARGE, OPTICAL GRADE MATERIAL. PAST CRYSTAL GROWTH ATTEMPTSHAVE CONCENTRATED ON GROWING ALONG THE 110 DIRECTION WITH LOW STIRRING RATES FROM METHANOL SOLUTION OR BY SUBLIMATION AND VAPOR TRANSPORT. THE OBJECTIVE OF THIS PROPOSAL IS TO INVESTIGATE THE GROWTH OF UREA FROM METHANOL SOLUTION ALONG THE 001 (Z-AXIS) WITH LOCALIZED HIGH STIRRING RATES AT THE SEEDED CRYSTAL. A NOVEL TURBINE BASED SEED RACK WILL GENERATE THE FAST SOLUTION FLOW RATES. THE TURBINE WILL BE USED IN CONJUNCTION WITH A SLIGHTLY MODIFIED HOLDEN TEMPERATURE LOWERING CRYSTALLIZER. TO BE SUCCESSFUL UREA GROWTH RATES ALONG THE Z-AXIS OF 1-2MM/DAY AND MINIMUM OCCURRENCE AND GROWTH OF SPURIOUS NUCLEI SHOULD TAKE PLACE. THIS RESEARCH COULD LAY THE BASIS FOR A COMMERCIAL UREA CRYSTAL GROWTH METHOD ALLOWING THE GROWTH OF VERY LARGE 5CM/SIDE CRYSTALS.