Intermediate states on the way to edge-sharing BO4 tetrahedra in M6B22O39·H2O (M=Fe, Co).

The new borates Fe(II)(6)B(22)O(39)·H(2)O (colourless) and Co(II)(6)B(22)O(39)·H(2)O (dichroic: red/bluish) were synthesised under the high-pressure/high-temperature conditions of 6 GPa and 880 °C (Fe)/950 °C (Co) in a Walker-type multi-anvil apparatus. The compounds crystallise in the orthorhombic space group Pmn2(1) (Z=2) with the lattice parameters a=771.9(2), b=823.

Synthesis and crystal structure of the new high-pressure phase CdB2O4.

The use of high-pressure/high-temperature conditions (7.5 GPa and 1100 degrees C; Walker-type multianvil apparatus) led to the synthesis of a new cadmium borate CdB2O4, starting from stoichiometric mixtures of the oxides. The crystal structure was determined on the basis of single crystal X-ray diffraction data, to reveal the hexagonal space group P6(3) with a=885.