Low-Temperature Phase Transformations in Weakly Doped Quantum Paraelectrics: Novel Features and Quantum Reentrant Dipolar Glass State in KTa_0.982Nb_0.018O₃

Journal Article · Wed Dec 31 23:00:00 EST 2003 · Journal of Physics and Chemistry of Solids

DOI:https://doi.org/10.1016/j.jpcs.2004.02.012· OSTI ID:1003432

Trepakov, V. A. ^[1]; Prosandeev, S. A. ^[2]; Savinov, M. E. ^[1]; Galinetto, P. ^[3]; Samoggia, G. ^[3]; Kapphan, S. E. ^[4]; Jastrabik, L. ^[1]; Boatner, Lynn A ^[5]

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1. Institute of Physics, Czech Republic
2. Rostov State University, Russia
3. Universita di Pavia, Italy
4. University of Osnabruck, Osnabruck, Germany
5. ORNL

An unusual sequence of phase transitions (PT) and reentrant dipole glass-like phase formation at low temperatures was found recently in KTaO{sub 3} weakly doped with Li and Nb (K{sub 0.9986}Li{sub 0.0014}Ta{sub 0.976}Nb{sub 0.024}O{sub 3}) [Phys. Rev. B 63 (2001) 172]. We report on detailed low frequency (100 Hz-1 MHz) permittivity and Raman light scattering studies of similar composition, but without Li admixture, KTa{sub 1-x}Nb{sub x}O{sub 3} with x = 0.018 (KTN1.8). The aim of the study is to answer the question if the reentrant dipole glass-like phase exists in KTN1.8 and what is the microscopic origin of this phase. A detailed study of the sharp low-temperature PT observed at T{sub C} {approx} 27 K revealed properties inherent to the reentrant glass-type state at lower temperatures. The substitution of Nb for Ta influences the TO{sub 1} soft lattice mode and leads to PT with the long-range ferroelectric ordering. A crossover to an order-disorder polar microregion dynamics with a non-standard {var_epsilon}(T) behaviour and dipole glass-like formation were found below T{sub C} (at {approx}15 K), which is attributed to the randomness of the Nb distribution. A crossover to the long-range order was found under a dc bias field.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1003432
• Journal Information: Journal of Physics and Chemistry of Solids, Journal Name: Journal of Physics and Chemistry of Solids Journal Issue: 7 Vol. 65; ISSN 0022-3697
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
DIPOLES
DISTRIBUTION
GLASS
LIGHT SCATTERING
ORIGIN
PERMITTIVITY
PHASE TRANSFORMATIONS
RANDOMNESS