Origin of the Crossover Between a Freezing and a Structural Transition at Low Concentration in the Relaxor Ferroelectric K1-xLIxTaO3

Published

April 16, 2015

Author(s)

Ling Cai, Jean Toulouse, Leland Harriger, Robert Gregory Downing, Lynn A. Boatner

Abstract

The origin of the relaxor behavior in K_1-xLi_xTaO₃(KLT) and other disordered perovskites has long been recognized as due to the reorientation of the polar nanodomains (PNDs) which are formed by the correlated disordered dipoles. The thermodynamic properties of the system usually can be categorized into several characteristic temperatures. On decreasing temperature, the individual dipoles become correlated to form nano sized regions at the so-called Burns temperature Τ_B. After further cooling, the slow dynamics of these polar regions induce lattice distortion, and they form polar nanodomain at Τ*(Τ*<Τ_B). For KLT specifically, thres is a critical Li concentration x_c = 0.022 above which the system undergoes a structural transition at T_c, and below which the system freeze into a dipole glass state at T_F. In the present work, we compare two KLT samples with Li concentration x = 0.026 and 0.018 determined by neutron depth profiling. Dielectric and relaxational properties of the two samples. In addition to the phase transition temperatures T_c abd T_F, we identify a critical temperature T_min in the lower concentration sample (x=0.018) this dielectric minimum, which resembles the critical slowing down behavior in many hydrogen bonded ferroelectric systems, can be explained by the progressive of local dipoles in the thermodynamic non-equilibrium state.

Citation

Physical Review B

Volume

91

Issue

13

Pub Type

Journals

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Keywords

relaxor, ferroelectric, disordered perovskites

Citation

Cai, L. , Toulouse, J. , Harriger, L. , Downing, R. and Boatner, L. (2015), Origin of the Crossover Between a Freezing and a Structural Transition at Low Concentration in the Relaxor Ferroelectric K_1-xLI_xTaO₃, Physical Review B, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=917577 (Accessed October 5, 2024)