SKM 2023 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 13: Polar Oxide Crystals and Solid Solutions I

KFM 13.2: Vortrag

Donnerstag, 30. März 2023, 10:20–10:40, POT 106

Crystal growth and thermal analysis of Li(Nb,Ta)O3 solid solutions — •Umar Bashir Ganie — IKZ, Berlin

This work presents the growth and thermal analysis of Lithium Niobate Tantalate (Li(Nb,Ta)O3, LNT) single crystals for different LiTaO3 (LT) mole fractions (xLT), (xLT = nLT/(nLT+nLN)). Our crystal growth experiments show that growth of LNT single crystal over the entire LT mole fraction is not only possible but can be achieved with weaker constituent segregation and therefore higher degree of homogeneity than considered previously. Our differential thermal analysis (DTA) measurements show that the melting temperature increases with increasing fraction of LT and follow the behavior of a (pseudo)binary phase diagram as published previously [1]. Thorough evaluation of the DTA results allows to propose an improved version of the LN-LT phase diagram that is not only thermodynamically stringent but also allows to explain the component distribution observed in LNT single crystals and to design growth experiments yielding crystals of higher homogeneity. We also performed specific heat capacity measurements of single crystals of LNT solid solutions. The aim was to investigate the variation of ferroelectric Curie temperature with composition. We observed that the ferroelectric Curie temperature decreases linearly with growing Ta composition in the LNT solid solution crystals.