Dielectric relaxation properties of tysonite-type solid solutions La1−xBaxF3−x

Ionic conductivity in tysonite-type solid solutions La1−xBaxF3−x

“…The present data were recorded well beyond room temperature. The enthalpies as obtained by TSDC (thermally stimulated depolarization current) and DL (dielectric loss) experiments, performed on our samples, are, as expected, in excellent agreement with the present conductivity data [27]. The data of Schoonman et al [ 11 ] indicate a maximum to occur in the isothermal conductivity of the solid solutions for x "" 0.05.…”

“…Furthermore, low-temperature dielectric relaxation measurements [27] indicate that in nominally pure LaF 3 only 0.06 m/o divalent cations are present in impurity-vacancy associates. If this relatively small amount of divalent cations would be responsible for the appearance of the knee, at least 95% of these cations must be associated to a fluoride vacancy at room temperature.…”

“…For the calculations perpendicular For the conductivity region above 415 K, the exchange mode, the pre-exponential factor, o °, can be given by o0 = [VF l q 2a21"og/k exp(z~Sm/k). It will be obvious that for pure LaF 3 we can make a good estimation of the number of fluoride ion vacancies for T> 300 K by using the concentration of O.06 m/o of dipoles as determined by dielectric relaxation measurements at low temperatures [27]. For the doped samples the concentration of fluoride ion vacancies is approximated by the dopant concentration as determined by the analysis.…”

Spectra of divalent samarium in LaF3 crystals

“…It was initially assumed that the charge in the crystals of LaCl 3 -Sm 2+ can be compensated for by interstitial positive ions or the transfer of electrons from the nearest halogens to Sm 2+ [6]. In studying LaF 3 crystals with impurities of divalent alkaline earth metals Ca 2+ , Sr 2+ , and Ba 2+ , it was found that fluorine vacancies can act as charge compensators [8,9]. Adding divalent impurities increases ionic conductivity [8], produces peaks on the curve of the thermally stimulated depolarization, and results in dielectric losses [8] and the splitting of peaks in the spectra of 19 F nuclear magnetic resonance [9].…”

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.…”