ITC technique as a tool to monitor a new phase nucleation in LiF-Ti single crystals

Author

Capelletti, Rosanna ; Mora, Carlo ; Prato, Stefano ; Földvári, Lstvan

Author_Institution

Dept. of Phys., Parma Univ., Italy

Volume

27

Issue

4

fYear

1992

fDate

8/1/1992 12:00:00 AM

Firstpage

787

Lastpage

794

Abstract

Thermal treatment of LiF:Ti³⁺ at temperatures close to the melting point in moist atmosphere causes the growth of new phase occlusions. Optical and electron microscopy and X-ray diffraction have shown that they are parallelepipeds and cubes of a FCC phase coherent with the host matrix. ITC spectra (in the range 100 to 380 K) support that the crystal behaves as a heterogeneous dielectric: in fact the occlusion growth is accompanied by the appearance of new ITC bands at the expense of the band due to the reorientation of dipoles built by Ti ³⁺ and two cation vacancies. OH ions play a key role in such a process as supported by isotopic substitution experiments with OD and by infrared absorption spectra. The nucleation kinetics have been studied in such a way, and the Maxwell-Wagner-Sillars model has been applied, to interpret the new ITC bands

Keywords

crystal microstructure; electron microscope examination of materials; heat treatment; impurity and defect absorption spectra of inorganic solids; inclusions; infrared spectra of inorganic solids; lithium compounds; nucleation; optical microscopy; solid-state phase transformations; thermally stimulated currents; titanium; 100 to 380 K; FCC phase; ITC bands; ITC spectra; LiF:Ti single crystals; Maxwell-Wagner-Sillars model; OH ions; X-ray diffraction; cubes; electron microscopy; heterogeneous dielectric; infrared absorption spectra; isotopic substitution experiments; moist atmosphere; nucleation kinetics; occlusion growth; optical microscopy; parallelepipeds; phase nucleation; phase occlusions growth; Atmosphere; Dielectrics; Electron microscopy; Electron optics; FCC; Monitoring; Optical diffraction; Optical microscopy; Temperature; X-ray diffraction;

fLanguage

English

Journal_Title

Electrical Insulation, IEEE Transactions on

Publisher

ieee

ISSN

0018-9367

Type

jour

DOI

10.1109/14.155799

Filename

155799