Teilprojekt 1
TP1
Crystal Growth an Basic Properties of Lithium Niobate-Lithium Tantalate Solid Solution Crystals
This project is focussed on the growth of Li(Nb,Ta)O3 single crystals from the melt. The today only vaguely known phase diagram of the system LiNbO3–LiTaO3 will be assessed be thermoanalytical means. Single crystals will be grown for different compositions covering the entire solid solution range evenly. During growth an electric field will be applied to the crystal to achieve in-situ orientation of the dipoles in the ferroelectric phase. Depending on the type of the field, crystals with either monodomain or periodically poled regions are expected to be obtained. The applied electric field is further expected to affect segregation of components and dopants during crystallization. Therefore, elemental distribution in the grown crystals will be investigated on both, macro and micro scale. Numerical modeling will be utilized calculate the temperature field in the setup to gain a closer insight into the transport processes in the melt. Growth parameters will be optimized with respect an improved structural perfection and chemical homogeneity of the growth solid solution crystals.
Objectives
- Thermodynamic assessment of the pseudobinary system LiNbO3–LiTaO3
- Development of quantitative segregation models for relevant dopants
- Numerical modeling of the mass and heat transport during crystal growth
- Growth of solid solution crystals of high homogeneity, low defect density and defined domain structure
