Novel topotactic conversion of an organically templated vanadyl phosphate framework into layered structures
Novel topotactic conversion of an organically templated vanadyl phosphate framework into layered structures
Date
2005
Authors
Asnani, Minakshi
Sharma, Sanjeev
Lofland, Samuel E
Ramanujachary, Kandalam V
Buffat, Philippe A
Ramanan, Arunachalam
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Abstract
This paper reports a novel topotactic exchange reaction of the ethylenediammonium intercalated mixed-valent vanadyl phosphate, (H3NCH2CH2NH3)0.5[V4+ 0.45V5+ 0.55O2PO4- {P(OH)2}0.483], with monovalent cations at room temperature. Alkali metal ions and other monovalent cations (e.g. K+, Rb+, Tl+, NH4+) behave similarly, leading to intercalated layered vanadyl phosphates (basal spacing about 6.3−6.5A° ). The amount of cations incorporated between the layers is essentially dictated by the charge present on the layers (equivalent to the amount of V4+ present). The present approach has enabled us to obtain a new phase, Tl0.45VOPO4·0.33H2O, under ambient conditions. All the layered solids show low-temperature magnetic behaviour similar to hydrothermally synthesised products. Treatment with silver ions resulted in a new silver vanadium(V) phosphate Ag3.5VP1.5O8 [monoclinic; a = 22.557(4), b = 7.973(3), c = 12.430(3) A° and β = 112.26(2)°] coated with silver metal nanospheres (ca. 15 nm) which, on heating above 400 °C, yielded a 2:1 mixture of two thermodynamically stable phases, Ag2VO2PO4 and Ag3PO4.
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Keywords
vanadium, intercalation, deintercalation, phosphorus, alkali metals, silver, thallium