Transport Properties of La<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">F</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

Sher, A.; Solomon, R.; Lee, K.; Müller, Michael

doi:10.1103/physrev.144.593

Cited by 137 publications

(50 citation statements)

References 14 publications

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“…19F NMR investigations on LaF 3 show that fluoride ions are the migrating species [8,21,26]. As outlined before, Schottky defects are the most probable intrinsic point defects in LaF 3 , and a vacancy mechanism for anion conduction is therefore most likely.…”

Section: Discussionmentioning

confidence: 97%

“…Thermal expansion measurements indicate the bulk volume to expand faster than the unit cell volume. This suggests that the thermal formation of point defects in LaF 3 occurs primarily by the Schottky mechanism [8]. Furthermore, calculations using structural data of LaF 3 [13], reveal that the interstitial sites (V x ) in LaF 3 allow ions with a radius up to 0.84 A.…”

Section: Crystal Structure and Possible Conduction Pathsmentioning

confidence: 99%

“…Previous investigations of the electrical conductivity of LaF 3 [8][9][10][11][12] reveal clearly a lack of consistency in the ionic transport parameters. LaF3, and its solid solutions are known to react with oxygen and water vapour at elevated temperatures.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 1984

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The ionic conductivity of single crystals of tysonite-type solid solutions Lal_xBaxFa_x(O • x • 0.095) has been studied parallel and perpendicular to the crystallographic c axis in the temperature range 293-1300 K. Three regions can be discerned in the compositional dependence of the ionic conductivity: (i) the "pure" crystal, in which at room temperature no exchange occurs between different types of anion sites in the tysonite structure; (ii) an intermediate region (0 < x < 7 X 10 -2) which reveals changes in both the conductivity activation enthalpy and the magnitude of the conductivity; (iii) a concentrated solid-solution region (x > 7 X 10-2), where fluoride ions interchange easily among the different anion sublattices. Diffusion coefficients calculated from ionic conductivity results, are in good agreement with those calculated from 19F NMR measurements. Using the present data, along with 19F NMR data, dielectric relaxation data and structural considerations, mechanisms governing the ionic conductivity are proposed.

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Section: Discussionmentioning

confidence: 97%

Section: Crystal Structure and Possible Conduction Pathsmentioning

confidence: 99%

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

et al. 1984

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“…This is at least partly due to the tendency of LaF 3 crystals to form oxygen-rich surface layers, which interfere with the determination of the bulk electrical properties. Experimental plots [ 14,15] of log oT against 1/T show a change in slope at about 100°C for the pure single crystal and dilute solid solutions Lal_xBaxF3_ x. Sher et al [15] interpret the change in slope as due to the dissociation of impurity-vacancy pairs, with the impurity being either oxygen or a divalent cation. Schoonman et al [ 14], however, discount this interpretation on the basis of their measurements on the solid solution up to x = 0.05.…”

Section: + Pe/p1mentioning

confidence: 99%

“…The elements R 1 and C 1 describe the behavior of a macroscopic bulk polarization arising from the inequality of the jump probabilities. If we set P3 = 0, a = b, and P = P1 = P2 so that all nearest-neighbor jumps are equivalent, we fred R 1 -~ oo, C 1 ~ 0 and R b ~Rb0, with Rb0 = lk T/e2coPo a2 , (15) so that the equivalent circuit reduces to the geometric capacitance and bulk resistance in parallel. The appearance of the Debye length in the expression for C 1 is consistent with a polarization arising from the motion of free charge carriers, and represents the screening of the internal field by the mobile charges.…”

Section: Model and Equivalent Circuitmentioning

confidence: 99%

Bulk conductivity and polarization of ionic crystals exhibiting defect exchange between inequivalent sites

Franceschetti

Shipe

1984

Solid State Ionics

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The bulk conductivity of ionically conducting crystals in which Schottky or Frenkel defects jump between inequivalent sites can be appreciably more complex than that of simpler materials. An equivalent electrical circuit is derived to describe the bulk ac response of crystals of the tysonite type. The circuit has the form of a two-component Maxwell-Wagner capacitor and includes a capacitative element which represents a frequency-dependent bulk polarization not associated with dipolar complexes. The application of the model to LaF3 is discussed.

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Diffraction and Thermal Expansion of Solids

Tyagi

Achary

2010

Thermodynamic Properties of Solids

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Thermal expansion of materials is a topic of age-old interest to mankind in view of the chronological development of several devices and technologies [1,2]. The concept of thermal expansion and knowledge of thermal expansion coefficient of materials remain important for any structural materials experiencing a temperature gradient. The structural materials include any material used in technology to build a mechanically or electronically integrated physical entity. In particular, the thermal properties are of interest when any structural assembly faces a temperature variation. Thermal expansion effects have been well considered right from the metals and ceramic parts of cookwares to the highly sophisticated mechanical structures, such as buildings, bridges, air/spacecraft, vessels, kilns, furnaces, and so on. In particular, metals such as steel, copper, and so on that are important structural parts show a significant expansion with temperature. Thus, in all these materials, thermal expansion was exploited either to enhance or to nullify any temperature-induced dimensional instability, for example, the utilization of thermal expansion in automatic cut-off switch using bimetals is well known. The discovery of Invar (an alloy of 35% Ni and 65% Fe) and subsequent modified compositions as Elinvar, Kovar, Alnico, and so on have found immense applications in modern technologies, such as design of high-accuracy clocks, shadow mask in television screen, and so on [3]. In addition, low thermal expansion in fused silica and controllable thermal expansion in materials with glass and glass-ceramic compositions have been discovered and used in precise optical instruments, mirror substrates, glass-metal junctions [4,5]. A large number of crystalline materials with low thermal expansion are also discovered [6]. Thermal expansion data of ceramics have been a prime consideration in the designing of electrolyte and electrodes of solid oxide fuel cells [7]. Similarly, thermal expansion data of nuclear fuel materials are significant in preventing detrimental effects of fuel-clad interaction and unwanted swelling of fuel pins [8]. Nuclear reactor performance is mainly restricted by the thermal expansion and thermal conductivity of the fuel pellets under irradiation conditions. In these j197 applications, the material property is more significant than the structural assembly and hence the structural materials are tuned as per their thermal expansion behavior. However, the thermal expansion behavior of electronic materials causing temperature-induced dimensional instability leading to circuit failure also needs to be dealt with. Considering such aspects, several Invar-type alloys and metal matrix composites are developed in recent years [9]. Thus, the thermal expansion data of any material are the first requisite for the development of most of the technologies.In general, it is known that all materials expand or contract with the rise or fall of temperature. The thermal expansion of any material is explained as a relative change in dimens...

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Transport Properties of LaF3

Cited by 137 publications

References 14 publications

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

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

Bulk conductivity and polarization of ionic crystals exhibiting defect exchange between inequivalent sites

Diffraction and Thermal Expansion of Solids

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