SYNTHESIS AND STRUCTURE OF A NEW VARIETY OF INDIUM PHOSPHATE BETA-INPO4

A new high-temperature allotropic form of indium phosphate, beta-InPO4 , has been obtained through quenching of an amorphous InPO4 phase heat ed for one hour at 1300 degrees C. The two precursor amorphous phases, prepared according to two different soft chemistry procedures, lead t o the same beta derivative. The beta-InPO4 structure is the same as th e high-temperature varieties presented by MgSO4 and CoSO4, with an ort horhombic cell and the parameters a = 8.8800(1) Angstrom, b = 6.8983(1 ) Angstrom, c = 4.8082(1) Angstrom, V = 294.56(1) Angstrom(3) and Z = 4. The space group is Pnma. The structure was refined using the Rietve ld method (R-p = 0.041, R-wp = 0.056 and chi(2) = 2.63). It is built F rom [InO6] octahedra sharing edges to constitute [InO4] chains running in one direction and linked by [PO4] tetrahedra. The alpha and beta s tructures are compared and discussed.