Low-temperature phase transformations in weakly doped quantum paraelectrics: novel features and quantum reentrant dipolar glass state in KTa0.982Nb0.018O
Autor(en): | Trepakov, VA Prosandeev, SA Savinov, ME Galinetto, P Samoggia, G Kapphan, SE Jastrabik, L Boatner, LA |
Stichwörter: | Chemistry; Chemistry, Multidisciplinary; CRITICAL-BEHAVIOR; DISORDER; KTA1-XNBXO3; KTAO3; LIGHT-SCATTERING; ORDER; Physics; Physics, Condensed Matter; RAMAN-SCATTERING; SOFT-MODE; TRANSITIONS; TRANSPORT | Erscheinungsdatum: | 2004 | Herausgeber: | PERGAMON-ELSEVIER SCIENCE LTD | Journal: | JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS | Volumen: | 65 | Ausgabe: | 7 | Startseite: | 1317 | Seitenende: | 1327 | Zusammenfassung: | An unusual sequence of phase transitions (PT) and reentrant dipole glass-like phase formation at low temperatures was found recently in KTaO3 weakly doped with Li and Nb (K0.9986Li0.0014Ta0.976Nb0.024O3) [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, KTa1-xNbxO3 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-C similar to 27 K revealed properties inherent to the reentrant glass-type state at lower temperatures. The substitution of Nb for Ta influences the TOI 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 epsilon'(T) behaviour and dipole glass-like formation were found below T-C (at similar to 15 K), which is attributed to the randomness of the Nb distribution. A crossover to the Iona-range order was found under a dc bias field. (C) 2004 Elsevier Ltd. All rights reserved. |
ISSN: | 00223697 | DOI: | 10.1016/j.jpcs.2004.02.012 |
Zur Langanzeige
Seitenaufrufe
1
Letzte Woche
0
0
Letzter Monat
0
0
geprüft am 23.05.2024