Partial exchange of the Li+, Na+ and K+ alkaline cations in the HNi(PO4)·H2O layered compound
| Autor: | José L. Mesa, María I. Arriortua, Teófilo Rojo, Begoña Bazán, José L. Pizarro, Jaione Escobal |
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| Rok vydání: | 2006 |
| Předmět: |
Ion exchange
Inorganic chemistry Infrared spectroscopy Condensed Matter Physics Alkali metal Electronic Optical and Magnetic Materials Inorganic Chemistry Crystallography chemistry.chemical_compound chemistry Transition metal X-ray crystallography Octahedral molecular geometry Materials Chemistry Ceramics and Composites Hydroxide Physical and Theoretical Chemistry Powder diffraction |
| Zdroj: | Journal of Solid State Chemistry. 179:3768-3775 |
| ISSN: | 0022-4596 |
| DOI: | 10.1016/j.jssc.2006.08.019 |
| Popis: | The exchange of the Li+ (1), Na+ (2) and K+ (3) alkaline cations in the layered HNi(PO4)·H2O was carried out starting from a methanolic solution containing the Li(OH)·H2O hydroxide for (1) and the M(OH) (M=Na and K) hydroxides together with the (C6H13NH2)0.75HNiPO4·H2O phases for (2) and (3). The compounds are stable until, approximately, 280 °C for (1) and 400 °C for phases (2) and (3), respectively. The IR spectra show the bands belonging to the water molecule and the (PO4)3− oxoanion. The diffuse reflectance spectra indicate the existence of Ni(II), d8, cations in slightly distorted octahedral geometry. The calculated Dq and Racah (B and C) parameters have a mean value of Dq = 765 , B = 905 and C = 3895 cm - 1 , respectively, in accordance with the values obtained habitually for this octahedral Ni(II) cation. The study of the exchange process performed by X-ray powder diffraction indicates that the exchange of the Li+ cation in the lamellar HNi(PO4)·H2O phase is the minor rapid reaction, whereas the exchange of the Na+ and K+ cations needs the presence of the intermediate (C6H13NH2)0.75HNiPO4·H2O intercalate in order to obtain the required product with the sodium and potassium ions. The Scanning electronic microscopy (SEM) images show a mean size of particle of 5 μm. The Li+ exchanged compound exhibits small ionic conductivity (Ω cm−1 is in the 10−8–10−9 range) probably restrained by the methanol solvent. Magnetic measurements carried out from 5 K to room temperature indicate antiferromagnetic coupling as the major interaction in the three phases. Notwithstanding the Li and K phases show a weak ferromagnetism at low temperatures. |
| Databáze: | OpenAIRE |
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