SYNCHROTRON MONOCHROMATOR CRYSTAL GROWTH

SYNCHROTRON RADIATION FACILITIES ARE BEING USED INCREASINGLYFOR ADVANCED MATERIALS RESEARCH. THE EFFECTIVENESS OF THIS RESEARCH IS NOW COMPROMISED BY A SHORTAGE OF SUITABLE CRYSTALS TO MAKE DEVICES FOR LONG WAVELENGTH SPECTROSCOPY INTHE SOFT X-RAY REGION OF 6 TO 30 ANGSTROM. THE CRYSTAL, YTTRIUM BORIDE (YB66), HAS BEEN IDENTIFIED AS A POTENTIAL MONOCHROMATOR FOR DISPERSING SYNCHROTRON RADIATION. KEY PROPERTIES OF THIS COMPOSITION INCLUDE (1) A MELTING TEMPERATURE OF 2100 DEGREES CENTIGRADE, (2) STABILITY TO SYNCHROTRON RADIATION, (3) A CELL PARAMETER OF 23.44 ANGSTROM, (4) A TWO-DIMENSIONAL SPACING OF 11.76 ANGSTROM (400 REFLECTION), AND (5) NO ABSOPRTION EDGES FROM BORON OR YTTRIUM IN THE 100 TO 2,000 EV WINDOW. UNFORTUNATELY, A LACK OF COMMERCIAL SUPPLIERS OF SINGLE CRYSTAL YB66 MATERIALEXISTS BECAUSE OF THE DIFFICULTY OF GROWING CRYSTALS AT TEMPERATURES HIGHER THAN 2,000 DEGREES CENTIGRADE. THIS PROBLEM IS BEING ADDRESSED BY THE USE OF A NOVEL GRADIENT TEMPERATURE CONTROL. BY APPLYING THIS CONTROL TO THE GROWING OF REFRACTORY CRYSTALS, THE CAPABILITY OF QUICKLY BECOMING A SUPPLIER OF YB66 CRYSTALS TO X-RAY SYNCHROTRON FACILITIES AND INTERESTED OTHERS WILL BE DEVELOPED. DURING PHASE I OF THIS PROJECT, SEVERAL CRYSTALS OF YB66 ARE BEING GROWN AND CHARACTERIZED. IN PHASE II, THE CRYSTAL GROWTH PROCESS IS TO BE OPTIMIZED, AND CRYSTALS ARE TO BE SUPPLIED TO DOE.