Study on the mechanical properties of lithium tantalate and the influence on its machinability

As a typical multi-functional single crystal material, lithium tantalate (LiTaO3 or LT) exhibits its excellent electro-optical, piezoelectric properties and has now found many applications, such as electro-optical modulators, pyroelectric detectors, optical waveguide, piezoelectric transducers and SAW (Surface Acoustic Wave) substrates. Although LT is known as a very brittle material, however, detailed summaries of its mechanical properties and machinability are not readily available yet. In order to clarify and understand the fundamental mechanical properties of LT, micro/nano indentation tests are conducted in this study to evaluate elastic modulus, hardness and fracture toughness. Other two typical single crystals of silicon and sapphire are chosen for comparison. The obtained results are analyzed and discussed to understand their behaviors in elastic, plastic (ductile) and brittle regimes, and the influences on their machinability in the machining process.