Hydrothermal Synthesis and Crystal Structure of the First Ammonium Indium(III) Phosphate NH4In(OH)PO4 with Spiral Chains of InO4(OH)2

A new rare earth boron-rich compound was found in the Y–B–Si ternary system. The powders were synthesized by solid state reaction method and single crystals were grown by the high temperature solution method with silicon flux. The structure was solved from single crystal x-ray diffraction data with space group R m (No.166) and lattice constants of a=b=10.0841 ? and c=16.4714 ?. Thirty-six parameters refined with 1484 unique reflections gave a residual RF=0.0296. The calculated chemical composition of the new compound is YB17.6Si4.6.