Cationic transport properties and structural aspects of solid Na2WO4

Cahen, H.T.; Bottelberghs, P.H.; Broers, G.H.J.

doi:10.1016/0025-5408(77)90128-3

Cited by 4 publications

(2 citation statements)

References 7 publications

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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: 65%

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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Section: Ionic Conductivitymentioning

confidence: 65%

Ionic conductivity and solid phase transitions in Na₂SO₄–Cs₂SO₄ system

Macdonald¹,

Maclean²,

Secco³

1988

Can. J. Chem.

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“…According to Cahen et al, the Na 2 WO 4 was reported as a Na + conductor. 25 Therefore, it is considered that loading WO 3 into NaNO 2 with proper amount seems not to influence for Na + conduction of the NaNO 2 -based sensing layer. Moreover, it was also found that the device attached with Na 2 WO 4 -NaNO 2 sensing layer could detect NO 2 down to ppb-level ͑20 ppb͒, although it contained no WO 3 in the sensing layer.…”

Section: Resultsmentioning

confidence: 99%

The Enhancement of Response Speed by Loading the Noble Metal into the Sensing Layer for FET-Type NO[sub 2] Sensors

Inoue

Yuasa

Kida

et al. 2011

J. Electrochem. Soc.

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In order to enhance the response speed, noble metal ͑Ru͒ loading into the WO 3 -NaNO 2 sensing layer for the field effect transistor ͑FET͒-based NO 2 sensors was investigated. The sensing layer was prepared by heat-treating the mixture powder of NaNO 2 and noble metal ͑Ru͒-loaded WO 3 at 300°C. The effects of loading amounts of the noble metal on NO 2 sensing performances as well as the microstructure of the sensing layer have been examined. It was found that the optimization of the noble metal loading amount into the sensing layer was important for the improvement of 90% response-and recovery-times. Field emission scanning electron microscopy observations revealed that the sensing layer became porous with increasing noble metal loading amounts. However, extensive addition of Ru ͑above 0.2 wt % to WO 3 ͒ into the sensing layer resulted in the degradation of sensing characteristics, although the sensing layer showed a highly porous structure. According to theoretical analysis based on Knudsen gas diffusion reported by Matsunaga et al., the diffusion of gas molecules into such a porous sensing layer is very fast. Therefore the obtained results suggested that the improvement of the response-and recovery-speeds is owing to the large contribution of noble metal nanoparticle to the electrochemical promotion rather than the diffusion of NO 2 gas into the sensing layer.

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