Paddle-wheel versus percolation mechanism for cation transport in some sulphate phases☆

Andersen, N.H.; Bandaranayake, P.W.S.K.; Careem, M.A.; Dissanayake, M.A.K.L.; Wijayasekera, C.N.; Kaber, R; Lundén, Arnold; Mellander, Bengt-Erik; Nilsson, L.; Thomas, John O.

doi:10.1016/0167-2738(92)90149-j

Cited by 48 publications

(29 citation statements)

References 22 publications

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“…Cations might also jump between 4f and 6h sites. On the other hand, with the presence of XO4 tetrahedra, the transportation of cations might also take advantage from the rotation of XO 4 tetrahedra as is the case for high temperature cubic phase ~-LizSO 4 [27][28][29].…”

Section: Conduction Mechanismmentioning

confidence: 99%

Synthesis and ionic conduction of apatite-type materials

Tao

Irvine

2000

Ionics

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Abstract. Apatite is a mineral with general formula Ml0(XO4)6Z2, where M are metallic elements such as Li § Na +, K*, Ca 2 § Sr z+, Ba 2 § Ln 3 § etc.; X = P, V, S, Si, Ge, Re, Cr etc; Z = F-, CI-, I-, OH-, O z-, S a-etc. Some materials with apatite structure (S.G. P63/m) exhibit quite high cationic (Li § H § etc.) and/or anionic (F-, C1-etc.) conduction. Recently, it was reported that some rare earth silicates, e.g., Lam(SiO4)603, exhibit quite high oxide-ion conductivity. In this paper, we discuss chemical composition, structure, synthetic procedure and ionic conduction of apatite-type materials. Recent improvements are briefly reviewed. High ionic conductivity has been observed for both cation deficient, oxygen stoichiometric La9.33(5iO4)60 a and cation stoichiometric, oxygen excess Lalo(SiO4)603 compositions. Grain boundary conductivity is usually low, which tends to dominate the impedance response. The resistance, particularly the grain boundary resistance is also found to depend on pO a.

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Section: Conduction Mechanismmentioning

confidence: 99%

Synthesis and ionic conduction of apatite-type materials

Tao

Irvine

2000

Ionics

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“…For Li 2 SO 4 the phase transition from the low temperature monoclinic phase, space group P2 1 /a [1], to the high temperature face-centered cubic phase, space group Fm3m [2] takes place at 577 °C. The exceptional high temperature phase of Li 2 SO 4 has been extensively studied as a model example of a rotator phase exhibiting coupling between the motion of the captions and the rotation of the sulphate anions [3]. The monoclinic phase is a more regular ionic solid even if an increasing orientational freedom of the sulphate groups takes place close to the phase transition [4,5].…”

Section: Introductionmentioning

confidence: 99%

Dielectric relaxation in Li ₂ SO ₄ in the intermedia‐temperature regime

Diosa

Vargas

Fernández

et al. 2005

phys. stat. sol. (c)

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The dielectric permittivity of polycrystalline Li 2 SO 4 was measured from 5 Hz to 13 MHz and over the temperature range 235-460 °C. The corrected imaginary part of permittivity, ε", and its real part ε' vs. frequency clearly show a new dielectric relaxation around f max = 2×104 Hz at T = 256 °C, which shifts to higher frequencies (~1 MHz) as the temperatures increases. The relaxation frequency (calculated from the peak position of ε") vs. reciprocal T shows an activated relaxation process with activation energy E a = 0.9 eV, which is very close to that derived from the dc conductivity, E σ (0.87 eV). We suggest that this dielectric relaxation could be due to the Li + jump andSO reorientation that cause distortion and change of the local lattice polarizability inducing dipoles likeLiSO .

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“…Todos estos estudios concluyen que la fase α-Li 2 SO 4 es un superconductor iónico. A partir de los estudios estructurales mencionados anteriormente se han propuesto dos tipos de modelos que describen el mecanismo que origina la conducción iónica; el modelo "Paddle wheel" y el modelo "Percolation" (11).…”

Section: Introductionunclassified

“…El Na 2 SO 4 sufre cuatro transiciones de fase en el rango de temperaturas 700 K -293 K. Los estudios efectuados mediante Análisis Térmico y de Conductibilidad Eléctrica muestran que las temperaturas de transición son a 506, 498, 493 y 483 K medidas mediante un proceso de descenso de temperatura (11)(12)(13). La Fase IV (entre 493 K -483 K) no se observa mediante difracción de rayos-X.…”

Section: Introductionunclassified

Estudio del Sistema Li2SO4 â Na2SO4. Diagrama de fases y caracterización del LiNaSO4

Mata¹,

Soláns²,

Font-Bardı́a³

2004

Bol. Soc. Esp. Ceram. Vidr.

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Se presenta un estudio exhaustivo del diagrama de fase del sistema binario Li 2 SO 4 -Na 2 SO 4 . El diagrama de fases se determinó mediante termo-difractometría de rayos-X en muestras de polvo y calorimetría ATD. Se obtiene una nueva fase de fórmula Li 2-x Na x SO 4 , con 1 ≤ x ≤ 1.22. La estructura cristalina de β-LiNaSO 4 se determinó por difracción de rayos-X sobre un monocristal. Este estudio muestra que los cristales usualmente se maclan cuando el crecimiento es por solución, lo cual explica la baja polarización espontánea. Se explica la dispersión Raman de los compuestos Li 2 SO 4 , Na 2 SO 4 y LiNaSO 4 , a partir de los datos estructurales. Las medidas experimentales se han efectuado a diferentes velocidades de calentamiento y enfriamiento.Palabras Clave: Cerámicas ferroeléctricas, LiNaSO 4 , caracterización estructural, difracción de rayos X, espectroscopía Raman. An exhaustive study of the phase diagram of binary system Li 2 SO 4 -Na 2 SO 4 is presented. Phase diagram was determined using thermo-X-ray diffraction in powder samples and calorimetry ATD. A new phase with formula Li 2-x Na x SO 4 has been obtained, with 1 ≤ x ≤ 1.22. The crystal structure of β-LiNaSO 4 was determined from single-crystal X-ray diffraction. This study shows that the crystals usually become twinned when the growth is by solution; which explains the poor spontaneous polarization. The Raman dispersion of Li 2 SO 4 , Na 2 SO 4 and LiNaSO 4 compounds is explained from the structural data. The measurements have been made at different heating and cooling rate. 4 , structural characterization, x-ray diffraction, Raman spectroscopy. Study of the System Li Keywords: Ferroelectric ceramics, LiNaSO INTRODUCCIÓNEl estudio de materiales susceptibles de ser utilizados como electrolitos o electrodos a alta temperatura en baterías de estado sólido, fundamentalmente de iones de litio, es en la actualidad de gran interés. Entre los materiales estudiados podemos citar a los compuestos derivados de la estructura tipo perovskita como los son los sulfatos de elementos monovalentes, donde la especie móvil, el litio, ocupa diferentes posiciones en la estructura. Algunos de estos sulfatos presentan superconductividad iónica a alta temperatura, como ocurre en el sistema Li 2 SO 4 -Na 2 SO 4 . El primer estudio sobre el diagrama de fase de este sistema fue elaborado por Nacken (1) y posteriormente fue redeterminado por Schroeder (2,3). En este diagrama de fase se observa la formación de un compuesto intermedio; LiNaSO 4 . En (1) y (2) se considera que la descomposición del α-LiNaSO 4 da lugar a α-Li 2 SO 4 + α-Na 2 SO 4 durante el proceso de enfriamiento, mientras en (3) se considera la existencia de una transición de fase entre la fase α y la fase β.El Li 2 SO 4 sufre una transición de fase a 851 K (4). La estructura de la fase a alta temperatura, llamada fase α ha sido determinada a 908 K (5), 883 K (6) y 873 K (7). La fase de baja temperatura; llamada fase β fue determinada a temperatura ambiente (8). Se han realizado diferentes estudios; térmicos (...

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Paddle-wheel versus percolation mechanism for cation transport in some sulphate phases☆

Cited by 48 publications

References 22 publications

Synthesis and ionic conduction of apatite-type materials

Synthesis and ionic conduction of apatite-type materials

Dielectric relaxation in Li ₂ SO ₄ in the intermedia‐temperature regime

Estudio del Sistema Li<sub>2</sub>SO<sub>4</sub> â Na<sub>2</sub>SO<sub>4</sub>. Diagrama de fases y caracterización del LiNaSO<sub>4</sub>

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Paddle-wheel versus percolation mechanism for cation transport in some sulphate phases☆

Cited by 48 publications

References 22 publications

Synthesis and ionic conduction of apatite-type materials

Synthesis and ionic conduction of apatite-type materials

Dielectric relaxation in Li 2 SO 4 in the intermedia‐temperature regime

Estudio del Sistema Li<sub>2</sub>SO<sub>4</sub> â Na<sub>2</sub>SO<sub>4</sub>. Diagrama de fases y caracterización del LiNaSO<sub>4</sub>

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Dielectric relaxation in Li ₂ SO ₄ in the intermedia‐temperature regime

Estudio del Sistema Li<sub>2</sub>SO<sub>4</sub> â Na<sub>2</sub>SO<sub>4</sub>. Diagrama de fases y caracterización del LiNaSO<sub>4</sub>