A NEW POLYMORPH OF LITHIUM ZINC PHOSPHATE WITH THE CRISTOBALITE-TYPE FRAMEWORK TOPOLOGY

A new form of lithium zinc phosphate has been prepared under high temp erature and high pressure. The structure consists of lithium, zinc, an d phosphorus atoms tetrahedrally coordinated to oxygen atoms. The thre e-dimensional framework structure can be described as belonging to the family of stuffed cristobalite structures with zinc and phosphorus at oms as framework tetrahedral atoms and lithium as extra-frame-work, ch arge-balancing cations, The cristobalite framework is derived from tha t of the diamond type, with the insertion of oxygen atoms between tetr ahedral atoms. It is constructed from the stacking of hexagonal layers in the ABC sequence and consists of six-ring channels propagating in directions significantly offset from the stacking directions of layers . Crystal data for LiZnPO4: M = 167.28, space group Cc (No. 9), a = 17 .2962(1) Angstrom, b = 9.7753(1), c = 16.1989(2) Angstrom, beta = 98.9 53(1)degrees, V = 2705.47(5) Angstrom(3), Z = 32, D-c = 3.285 g cm(-3) , MoK alpha, mu = 7.573 mm(-1), 2 theta(max) = 56.52 degrees, R(F) = 2 .35% for 506 parameters and 6219 reflections with I > 2 sigma(I), (C) 1998 Academic Press.