Second harmonic generation and thermally stimulated depolarization current investigation of K1-xLixTaO3

Autor(en): Voigt, P
Kapphan, S
Oliveira, L
Li, MS
Stichwörter: FIELD; GLASS; K1-xLixTaO3; KTAO3; Nuclear Science & Technology; PHASE-TRANSITION; Physics; Physics, Condensed Matter; Physics, Fluids & Plasmas; second harmonic generation; solid-solid phase transition; STATE; thermally stimulated depolarization current
Erscheinungsdatum: 1995
Herausgeber: GORDON BREACH SCI PUBL LTD
Journal: RADIATION EFFECTS AND DEFECTS IN SOLIDS
Volumen: 134
Ausgabe: 1-4
Startseite: 229
Seitenende: 232
Zusammenfassung: 
the incipient ferroelectric KTaO3 small substitutional Li-ions are known to induce dipolar microgregions due to their off-center dipole moment. A sensitive method to observe the appearance of non-inversion symmetric regions in K1-xLixTaO3 is based upon monitoring the second harmonic intensity (SHG) of Nd: YAG laser light. At low temperatures a considerable SHG intensity (calibrated with respect to LiNbO3) is observed with a characteristic temperature-, field- and Li-concentration dependence. The time and temperature dependence of the electric field induced SHG intensity change shows an Arrhenius-like behavior with fast and slow relaxation processes. For concentrations larger that x approximate to 0.02 the slow relaxation process with an activation energy of E(A) approximate to 86 meV has been interpreted as a reorientation of mainly antiparallel ferroelectric domains. Measurements of the thermally stimulated depolarization current (TSDC), performed after removing the bias field at LHe-temperature, yield for a x = 0.028 sample a broad current peak with a maximum at approximate to 60 K. A good fit to the experimental data can be reached for a distribution of relaxing dipoles according to a Havriliak-Negami model with a mean activation energy Delta A = 178 meV. The difference in activation energies will be discussed in terms of different reorientation processes.
Beschreibung: 
7th Europhysical Conference on Defects in Insulating Materials (Eurodim 94), ECOLE NORMALE SUPIRIEURE LYON, LYON, FRANCE, JUL 05-08, 1994
ISSN: 10420150
DOI: 10.1080/10420159508227220

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