HIGH-RESOLUTION SOLID-STATE MAGIC-ANGLE-SPINNING NUCLEAR-MAGNETIC-RESONANCE STUDIES ON THE THERMAL-DECOMPOSITION OF THE LAYERED ANTIMONY HYDROGEN PHOSPHATE, HSB(PO4)(2)CENTER-DOT-2H(2)O

The antimony hydrogen phosphate, HSb(PO4)(2) . 2H(2)O, was synthesised using an ion-exchange method from the crystalline KSb(PO4)(2) precurs or. The synthesised H1SbP2 . 2H(2)O material was then studied using P- 31 and H-1 Magic-angle Spinning Nuclear Magnetic Resonance (MAS NMR) t echniques. MAS NMR indicated that the synthesised phosphate consisted of Q(3)-type phosphate tetrahedra (i.e.; PO4) which were protonated in all cases. This was thought to be caused by the dynamic equilibrium b etween the mobile interlayer water and the protons randomly attached t o alternate phosphate groups as H-O-(PO3)-R groups in the structure. S imultaneous TG and DTA thermogravimetry revealed a constant mass loss up to a temperature of 600 degrees C in the TG curve and a series of w ell defined thermal events in the DTA curve. Scanning electron microsc opy revealed that the KSb(PO4)(2) was formed by the so-called 'deck of cards' mechanism. This technique also revealed that the ion-exchange to HSb(PO4)(2) . 2H(2)O resulted in delamination of the phosphate. BET (N-2) analysis of the synthesised material suggested a surface area o f ca. 6.8 m(2) g(-1) and a range of pore sizes.