Diameter control of K3Li2-xNb5+xO15+2x single-crystal fibers

Potassium lithium niobate, K3Li2-xNb5+xO15+2x (KLN) single-crystal fibers have been grown using the laser-heated pedestal growth (LHPG) technique. Ceramic source rods of K3.00Li1.70Nb5.30O15.6 (KLN53) and K3.00Li1.85Nb5.15O15.3 (KLN51.5) were adapted to grow the fibers with the: same compositions. The diameter deviations at various growth rates were estimated. For the (110) oriented KLN53 fibers, increase of the growth rate decreased the diameter deviation and the minimum root mean square diameter deviation was 1.8% when the growth rate was 66 mm/h. For the (110) oriented KLN51.5 fibers, the minimum diameter deviation was 1.7% when the growth rate was 40 mm/h. From the dielectric properties along the grown fiber, the fiber without diameter deviation was determined to have homogeneous composition along the fiber. However, the Curie temperature measurements revealed that the composition of the KLN51.5 fiber did not coincide with that of the ceramic source rods.