Lattice defects in lithium tantalate

Lattice defects in lithium tantalate single crystals and their possible effect on the performances of piezoelectric devices are investigated. These defects have been characterized by various techniques and especially by transmission electron microscopy (TEM). It is found that the density of as-grown defects should not induce any appreciable decrease of the piezoelectric performance except for some dislocations that generate nonremovable ferroelectric domains around them. Such dislocations can also be accidentally introduced by matching operations; in this case their density can be much larger and an appreciable decrease of the piezoelectric performances may result. The techniques used for sawing and polishing are thus very important for getting high-performance devices.<>