Teilprojekt 7
TP7
Acoustic loss and electromechanical properties of LiNb1-xTaxO3
The solid solution of lithium niobate-lithium tantalate (LNT, LiNb1-xTaxO3) crystals offers high thermal stability and piezoelectric coefficient, thus opening up new prospects for next-generation high-temperature sensing and actuator applications. In this respect, it is of paramount importance to understand the role of point defects, domain walls, and their effect on electromechanical properties. The understanding of related phenomena such as the acoustic loss are anticipated in this subproject of the research unit.
The losses are predominantly determined by the composition and the domain structure. Both parameters offer numerous options for tailoring the crystal properties. In this context, acoustic losses, the electrical conductivity of domains and domain walls, and the coercive field strength at high temperatures are to be determined and correlated with the composition, the type and density of point defects, and the domain wall density and charge, so that atomistic origins for the losses can be assigned. These findings will lead to a better elucidation of minimizing acoustic loss, either through doping or the introduction of a suitable domain structure.
Objectives
- Determination of electrical conductivity, piezoelectric, dielectric and elastic constants as well as domain wall conductivity.
- The dominant acoustic loss mechanism will be correlated with the electrical conductivity, the type and concentration of point defects, and the domain structures.
- Optimal combination of properties for high temperatures sensor and actuator applications under harsh environments.
