The small-signal ac response of La1−xBaxF3−x solid solutions

Abstract

The small-signal ac response of single crystals of La,_,Ba,F,_, (0 s x G 0.104) with ionically blocking electrodes has been measured in the frequency range lo-* to 10' Hz, and for temperatures from 293 to 1300 K. At low and moderate temperatures the ac bulk response can be modeled with a Debye circuit. The circuit parameters do not have the temperature dependence associated with dipolar reorientation but rather the opposite, as is characteristic of the behavior of free charge carriers. We have developed a model, in which the theoretically expected dependence of the circuit parameters is concordant to the behavior found experimentally. Thermally stimulated depolarization current (TSDC) spectra exhibit five dielectric relaxation peaks, in addition to a space-charge peak. Two peaks have been analyzed in detail. The reorientation enthalpies are concordant with the conduction activation enthalpies.La rtponse signal-faible par courant altematif de monocrystaux du type La,_,Ba,F,_, (0 G x s 0.104) avec des electrodes de blocage des ions a tti mesuree dans le domaine de frequence lo-' a lo5 Hz, et pour des temperatures entre 293 et 1300 K. A des temperatures basses et modtrees la reponse du volume par courant alternatif put &re represent6 a l'aide du circuit Debye. Les parambtres du circuit ne montrent pas la dtpendance de temperature associee a la reorientation dipolaire mais plut& l'oppost, ce qui est caracttristique du comportement des porteurs de charge libre. Nous avons dtvelopp6 un modtle oh la dependance attendu theoriquement des parametres du circuit s'accorde avec le comportement trouvt en experiment. Thermally stimulated depolarization current (TSDC) spectres montrent cinq pits de relaxation dielectrique et en plus un pit de charge d'espace. Deux pits ont BtC analysts en detail. Les enthalpies de reorientation s'accordent avec les enthalpies de l'activation de la conduction.

TSDC spectroscopy of relaxational and interfacial phenomena

“…A variety of natural minerals, such as amethyst [94], sapphire [95], stilbite [96], calcite, dolomite, quartz [97], clays [98], mordenites [99,100], cretaceous strata [101], and synthetic solids, such as ceramics doped with CuO, FeO and TiO 2 [102], silicas, silicates and other compounds with silica [103][104][105][106], different crystals [107][108][109][110][111][112] and polycrystalline structures [113,114], disordered materials [115], thin films [116][117][118][119][120][121], ferrites [122], metal fluorides [123][124][125][126][127][128][129] and solid solutions based on fluorides [130][131][132][133][134][135], was investigated by the TSDC method.…”

Electrical properties of the Ag2SO4-Na2SO4 binary system

“…Ravain and Souquet [21] for the first time included the CPE element in the equivalent circuit to describe the depression in semicircular arc in the complex plane for amorphous materials. Later, it has been applied to polycrystalline ion conductors [22][23][24].…”

Electrochemical performance of microwave synthesized Nd1.8Ce0.2CuO4±δ cathode for intermediate temperature solid oxide fuel cell applications

“…Later Raistrick et al have applied it to polycrystalline solid electrolyte [34]. Subsequently, CPE element has been frequently used in parallel with geometrical capacitance, C, and electrolytic bulk resistance, R [35,36]. Detailed theoretical description and electrical equivalent circuit for distributed relaxation time (depression in complex impedance plots) have been given in literature [29].…”