Dislocation etch tunnels in Nd xY 1-xP 5O 14 crystals

Abstract

Defects in single N x Y 1− x P 5 O 14 and NdP 5O 14 crystals grown by a flux evaporation method using phosphoric acid are studied by etching. An interesting etching characteristic observed is the formation of etch tunnels which propagate into the crystal from etch pit apices on the as-grown crystal faces. The etch tunnel distribution indicates that the dislocations appearing in the form of these tunnels extend from the nucleation site of the crystal to the outcrops on the crystal faces. These are grown-in dislocations. Etch tunnels connected to growth hillocks on the crystal faces are found to be probably due to dislocations having a screw component.