Niobium compounds in acoustics and electro-optics

Niobium containing oxide crystals generally are ferroelectrics with useful applications in acoustics, nonlinear optics and electro-optics. Crystal growth technology for lithium niobate has reached a state where 125mm diameter wafers are easily available. This material is used mostly in surface acoustic wave filters for TV IF filters. Much growth in demand for lithium niobate wafers is seen from the manufacturing of high speed digital modulators for telecommunication systems. Other uses such as birefringent prisms, bulk acoustic transducers are also discussed. The other niobates typically crystallize in the perovskite structure, and growth is much more challenging because of structural phase-transitions and the absence of a congruent composition. Some of the crystals studied include potassium niobate (KN) or KLN for blue light generation, SBN or KN for photorefractive applications, and relaxor ferroelectric crystals for highly efficient actuators and ultrasonic transducers. (AU)