| Autor: |
Colodrero, Rosario M. P., Salcedo, Inés R., Bazaga-García, Montse, Milla-Pérez, Diego F., Durán-Martín, Jonatan D., Losilla, Enrique R., Moreno-Real, Laureano, Rius, Jordi, Aranda, Miguel A. G., Demadis, Konstantinos D., Olivera-Pastor, Pascual, Cabeza, Aurelio |
| Předmět: |
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| Zdroj: |
Pure & Applied Chemistry; Jan2017, Vol. 89 Issue 1, p75-87, 13p |
| Abstrakt: |
The structural variability of two series of Mg2+- and Zn2+- 2-hydroxyphosphonoacetates have been studied in the range of 25-80 °C and 95 % relative humidity in order to correlate the structure with the proton conductivity properties. In addition to selected previously reported 1D, 2D and 3D materials, a new compound, KZn6(OOCCH(OH)PO3)4(OH)·5H2O (KZn6-HPAA-3D), has been prepared and thoroughly characterized. The crystal structure of this solid, solved ab initio from synchrotron X-ray powder diffraction data, consists of a negatively charged 3D framework with K+ ions, as compensating counterions. It also contains water molecules filling the cavities in contrast to the potassium-free 3D anhydrous NH4Zn(OOCCH(OH)PO3) (NH4Zn-HPAA-3D). In the range of temperature studied, the 1D materials exhibit a 1D → 2D solid-state transition. At 80 °C and 95 % RH, the 2D solids show moderate proton conductivities, between 2.1 x 10 -5 S·cm-1 and 6.7 x 10-5 S·cm-1. The proton conductivity is slightly increased by ammonia adsorption up to 2.6 x 10-4 S·cm-1, although no ammonia intercalation was observed. As synthesized KZn6-HPAA-3D exhibits a low proton conductivity, 1.6 x 10-6 S·cm-1, attributed to the basic character of the framework and a low mobility of water molecules. However, this solid transforms to the 2D phase, Zn(OOCCH(OH)PO3H)·2H2O, upon exposure to dry HCl(g), which enhances the proton conductivity with respect to the as-synthesized 2D material (4.5 x 10-4 S·cm-1). On the other hand, NH4Zn-HPAA-3D exhibited a higher proton conductivity, 1.4 x 10-4 S·cm-1, than the K+ analog. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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