Dielectric relaxation properties of tysonite-type solid solutions La /SUB 1-x/ Ba /SUB x/ F /SUB 3-x/
Dielectric relaxation properties of solid solutions La /SUB 1-x/ Ba /SUB x/ F /SUB 3-x/ (xless than or equal to0.105) have been studied by thermally stimulated depolarization current (TSDC)- and a.c. dielectric loss (DL) techniques. For x<3.0 x 10/sup -3/ the dielectric spectra show a relaxation peak which is ascribed to a simple associate of a substitutional dopant ion and a fluoride ion vacancy (Ba /SUB La/ V /SUB F/ ) /SUP x/ in nearest-neighbour position, the vacancy being confined to the B sublattice. For x values of about 1.3 x 10/sup -2/ a relaxation peak appears which is tentatively attributed to a similar type of defect associate with the vacancy now confine to the A sublattice of the tysonite anion array. One broad relaxation peak dominates the TSDC and DL spectra over the whole concentration range. This peak is due to the relaxation of macroscopic space charge i.e. ionic conductivity. The low-temperature ion conductivity has been determined for several solid solutions, and extrapolates to the high-temperature conductivity determined previously with impedance spectroscopy. Below liquid-nitrogen temperature three relaxations are observed, and ascribed to electronic transitions in cerium impurities. A computer programme has been developed to analyse TSDC relaxation peaks, taking dipole-dipole interactions into account. Relaxation parameters and dipole concentrations ar presented.
- Research Organization:
- Solid State Department, Physics Laboratory, Utrecht University, Utrecht
- OSTI ID:
- 6394095
- Journal Information:
- J. Polym. Sci.; (United States), Vol. 46:6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BARIUM FLUORIDES
DIELECTRIC PROPERTIES
RELAXATION
LANTHANUM FLUORIDES
ALTERNATING CURRENT
CERIUM
COMPUTER CALCULATIONS
DEPOLARIZATION
ELECTRIC DIPOLES
ELECTROCHEMISTRY
HEATING
IMPURITIES
SOLID SOLUTIONS
VACANCIES
VANADIUM COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHEMISTRY
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
CURRENTS
DIPOLES
DISPERSIONS
ELECTRIC CURRENTS
ELECTRICAL PROPERTIES
ELEMENTS
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
LANTHANUM COMPOUNDS
METALS
MIXTURES
MULTIPOLES
PHYSICAL PROPERTIES
POINT DEFECTS
RARE EARTH COMPOUNDS
RARE EARTHS
SOLUTIONS
TRANSITION ELEMENT COMPOUNDS
360104* - Metals & Alloys- Physical Properties