III. Order–disorder transitions and electrical conductivity studies in Na2SO4 – Ag2SO4 system

Kumari, Manju; Secco, E. A.

doi:10.1139/v83-483

Cited by 34 publications

(14 citation statements)

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“…To start with, we have chosen the Ag2SO 4-NazSO 4 system because of (i) the existence of solid-solid phase transition over the entire range of compositions and (ii) the formation of the complete solid solution below and above the phase transition [8]. In this system, Kumari and Secco [8] have studied the electrical conductivity of only one composition (i.e. 40 AgzSO4-60Na2SO4).…”

Section: Pacsmentioning

confidence: 99%

“…Binary sulphates containing monovalent cations are highly conducting in the high temperature phase [7], but the mechanism of high conductivity has not yet been probed properly. To start with, we have chosen the Ag2SO 4-NazSO 4 system because of (i) the existence of solid-solid phase transition over the entire range of compositions and (ii) the formation of the complete solid solution below and above the phase transition [8]. In this system, Kumari and Secco [8] have studied the electrical conductivity of only one composition (i.e.…”

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Electrical properties of the Ag2SO4-Na2SO4 binary system

1992

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Binary SystemAbstract. A systematic investigation of the Ag2SO 4-Na2SO 4 binary system which forms a complete solid solution in the entire compositional range reveals the mobility of Ag + as well as Na +. This is concluded on the basis of the appearance of two overlapping semicircles in the complex impedance plane. Transport number measurements using Tubandt and dc polarisation methods support the mobility of both ions. Further, the maximum conductivity for 30 Ag2SO4-70 Na2SO 4 is due to optimum percolating paths resulting from lattice expansion. The decrease in conductivity beyond this, is caused by the increased interaction of Ag + and Na +. 66.30, 61.7, 82.45 Several sulphates form high temperature modifications with cubic or hexagonal structures which are characterised by a higher mobility of the cations than in ordinary solids [1][2][3][4][5]. A special advantage of sulphate based electrolytes is that many mono-and di-valent cations are mobile in their high temperature modifications which increases the choice of anode material [6]. Binary sulphates containing monovalent cations are highly conducting in the high temperature phase [7], but the mechanism of high conductivity has not yet been probed properly. To start with, we have chosen the Ag2SO 4-NazSO 4 system because of (i) the existence of solid-solid phase transition over the entire range of compositions and (ii) the formation of the complete solid solution below and above the phase transition [8]. In this system, Kumari and Secco [8] have studied the electrical conductivity of only one composition (i.e. 40 AgzSO4-60Na2SO4). Such a system is potentially the best from a SO2/SO 3 gas sensor point of view. PACS:In the present paper, we report a systematically carried out investigation on the electrical conductivity over the entire range of compositions belonging to the AgzSO4-Na2SO 4 system.

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Section: Pacsmentioning

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confidence: 99%

Electrical properties of the Ag2SO4-Na2SO4 binary system

1992

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“…The negative conductivity effect accompanying the 400°C phase transition parallels the Pm3m+ Fm3m transition of CsCl (4,5), the V 4 I11 single crystal of Na2S04 (6), the P + a transition of Na2W04 (7), the Ag2S04-K2S04 compositions (8) and the glass transition of Na4U02(S04)3 (9). Similar conductivity behavior occurs in melting AgI (10-12) and Na2UBr6 (5, 13).…”

Section: Ionic Conductivitymentioning

confidence: 64%

Ionic conductivity and solid phase transitions in Na₂SO₄–Cs₂SO₄ system

Macdonald¹,

Maclean²,

Secco³

1988

Can. J. Chem.

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o . Can. J. Chem. 66, 3132 (1988). The ac conductivity and DSC calorimetry data reveal interesting solid state interactions and solid phase transition behavior in the Na2S04-Cs2S04 binary system. The P + a solid transition of NaCsS04 is reported for the first time. 'These data indicate preferential reaction between Cs2S04 and the high temperature phase I of Na2S04, exemplifying the Hedvall effect, to form the compound NaCsS04 which further interacts with excess Na2S04 or excess Cs2S04 to form 1:1 association complexes, viz. NaCsS04:Na2S04 and NaCsS04:Cs1S04. These complexes appear to dissociate at low temperatures reminiscent of spinodal-type decomposition behavior. The reaction enthalpies of NaCsS04, P + a transition of NaCsS04 and complex associations are reported.' The report contains two unexpected results: (i) a subdued higher ionic conductivity relative to its Rb2S04 analogue and (ii) a conductivity drop accompanying the high temperature phase transition which is in strong contrast to all the other Na2S04 -mixed alkali compositions.Can. J. Chem. 66, 3 132 (1988). Les donnCes de conductivitC ca et de calorimCtrie DSC se rapportant au systkme binaire Na2S04-Cs2S04 rCvklent des interactions intkressantes dans 1'Ctat solide et des transitions de phasesolide. On rapporte pour la prernikre fois la transition P+ a du NaCsS04 t i 1'Ctat solide. Ces donnCes indiquent une rCaction prCfCrentielle entre le Cs2S04 et la phase I t i haute tempkrature du Na2S04, mettant en Cvidence I'effect Hedvall, pour former le composC NaCsS04 qui par la suite interagit avec le Na2S04 ou le Cs2S04 en exces pour former des complexes d'association 1: 1 , par exemple NaCsS04-Na2S04 et NaCsS04-CszS04. Ces complexes semblent se decomposer B basses tempkratures ce qui appelle un comportement de type spinodal. On rapporte les ' enthalpies de rCaction du NaCsS04, de la transition p + a du NaCsS04 et des complexes d'association.Cette Ctude comporte deux rksultats inattendus: (i) une plus grande conductivitC ionique douce par rapport a son analogue Rb2S04 et (ii) une chute de conductiviti accompagnant la transition i haute tempCrature qui contraste beaucoup avec celle de tous les autres complexes mCtal alcalin-Na2S04.[Traduit par la revue]

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“…Electrical conductivity measurements were made on compressed polycrystalline sample in a stainless steel conductivity cell following the procedure described earlier (3,11). The AgZS04-rich samples were in the form of a disc, I mm thick and 100 m' in surface area; other compositions were I mm thick and -75 mm' in surface area of the crack-free portion recovered from the compressed disc.…”

Section: Methodsmentioning

confidence: 99%

“…(i) layer structure as in p-alumina and (ii) channel structure as in a-AgI or in NASICON where an open network or skeleton framework of anions facilitates cation mobility (1). This paper is part of a continuing effort (2)(3)(4) to probe the nature of the phase transition, the structure of the high temperature phase and the effects of guest ions relating to the mechanism of fast-ion conductivity in binary sulfate systems.…”

Section: Introductionmentioning

confidence: 99%

IV. Order–disorder transitions: solid state kinetics, thermal analyses, X-ray diffraction and electrical conductivity studies in the Ag₂SO₄–K₂SO₄ system

Kumari¹,

Secco²

1985

Can. J. Chem.

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M. SUNITHA KUMARI and ETALO A. SECCO. Can. J. Chem. 63, 324 (1 985).Order-disorder transitions occurring in the Ag2S04-K2S04 system were investigated by reaction kinetics, thermal analyses, X-ray diffraction, and electrical conductivity techniques. Solid-liquid and solid-solid phase diagrams are reported.The conductivity data in the high temperature phase of the solid resemble superionic conductivity behavior. The higher conductivity of AglS04 with K+ presence relative to pure AgzSOJ and A g , , N a , S 0 4 compositions support a lattice expansion facilitating higher mobility of ions.The reaction kinetics, X-ray diffraction, and electroconductivity results suggest a relatively open periodic S O : sublattice in the high-temperature phase of the sulfate-based systems studied in this series.M. SUNITHA KUMARI et ETALO A. SECCO. Can. J. Chem. 63, 324 (1985). Faisant appel aux cinttiques de rCaction et aux techniques d'analyse thermique, de diffraction de rayons-X et de conductivitC Clectrique, on a Ctudit les transitions ordre-dCsordre qui se produisent dans le systeme Ag2S04-KZS04. On rapporte les diagrammes de phase solide-liquide et solide-solide.Les donnCs de conductivitC thermique de la phase a haute tempkrature ressemblent i un comportement de conductivitC superionique. Le fait que la conductivitk du Ag2S04, en prCsence de K', soit plus ClevCe que celle du Ag2S04 ii 1'Ctat pur ou de celles des compositions AgZ-,Na,S04 milite en faveur d'une expansion du reseau facilitant ainsi une mobilitt plus grande des ions.Les rtsultats observes avec les cinCtiques de rtaction, avec la diffraction de rayons-X et avec 1'ClectroconductivitC suggerent la presence d'un sous-rCseau +riodique d'ions ~~a -~u i est relativement ouvert dans la phase a haute tempirature des systemes a base de sulfates CtudiCs dans cette sCrie.[Traduit par le journal] Introduction Binary sulfates containing monovalent cations are members of a group of compounds which exhibit fast-ion or "superionic" conductivity-in the high temperature phase (I). such compounds are referred to as superionic conductors (SIC'S) or solid electrolytes and have attracted considerable attention because of (i) their promise in applications in high-energydensity batteries and (ii) their unusual transport behavior.The mechanism of fast-ion conduction is not completely understood although proposed models involve basically two structural types, viz. (i) layer structure as in p-alumina and (ii) channel structure as in a-AgI or in NASICON where an open network or skeleton framework of anions facilitates cation mobility (1). This paper is part of a continuing effort (2-4) to probe the nature of the phase transition, the structure of the high temperature phase and the effects of guest ions relating to the mechanism of fast-ion conductivity in binary sulfate systems.Our earlier study on Na' presence in Ag2S0, lattice revealed a decrease in conductivity in Ag2-,Na,SO, compositions attrib-

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III. Order–disorder transitions and electrical conductivity studies in Na₂SO₄ – Ag₂SO₄ system

Cited by 34 publications

References 6 publications

Electrical properties of the Ag2SO4-Na2SO4 binary system

Electrical properties of the Ag2SO4-Na2SO4 binary system

Ionic conductivity and solid phase transitions in Na₂SO₄–Cs₂SO₄ system

IV. Order–disorder transitions: solid state kinetics, thermal analyses, X-ray diffraction and electrical conductivity studies in the Ag₂SO₄–K₂SO₄ system

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III. Order–disorder transitions and electrical conductivity studies in Na2SO4 – Ag2SO4 system

Cited by 34 publications

References 6 publications

Electrical properties of the Ag2SO4-Na2SO4 binary system

Electrical properties of the Ag2SO4-Na2SO4 binary system

Ionic conductivity and solid phase transitions in Na2SO4–Cs2SO4 system

IV. Order–disorder transitions: solid state kinetics, thermal analyses, X-ray diffraction and electrical conductivity studies in the Ag2SO4–K2SO4 system

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III. Order–disorder transitions and electrical conductivity studies in Na₂SO₄ – Ag₂SO₄ system

Ionic conductivity and solid phase transitions in Na₂SO₄–Cs₂SO₄ system

IV. Order–disorder transitions: solid state kinetics, thermal analyses, X-ray diffraction and electrical conductivity studies in the Ag₂SO₄–K₂SO₄ system