Striation formation in Ti-doped Y3Al5O12 fibers grown by the laser heated floating zone method

Microscopic dopant distribution has been investigated in 1 mm-diameter single crystal fibers of Ti-doped Y3Al5O12 (YAG) grown by a laser heated floating zone (LHFZ) method. Ln the fibers, a periodic fluctuation in the Ti dopant concentration has been observed along the growth direction, and striations, attributed to variation in dopant concentration, were seen across the diameter of the fiber by two dimensional mapping using an electron probe microanalyser, The dopant concentration was found to vary by as much as 30% from average levels with a spacing of the order of 20 mu m. Microscopic inhomogeneities of Ti are discussed in relation to growth conditions with emphasis on crystal/feed rotation. Effects to minimize segregation effects by annealing are reported.