Preparation and Structure of the Non-centrosymmetric Hydrated Borate: K2Ca[B4O5(OH)4]2·8H2O

Abstract

Single crystal of hydrated borate K₂Ca[B₄O₅(OH)₄]₂·8H₂O (KCB) has been grown with sizes up to 30 mm × 10 mm × 5 mm under the condition of water solution. The structure is determined by X-ray diffraction, IR and SEM. It crystallizes in the orthorhombic space group P2₁2₁2₁,with a = 16.59700(Å), b = 12.46900(Å), c = 11.56900(Å), z = 4. In the structure, Ca and K atoms are disordered on different 4a sites. The fundamental building units are K-O polyhedra, Ca-O polyhedral and [B₄O₅(OH)₄]^2- polyborate anions, with the new coordination number of K₁⁺, K₂⁺ and Ca²⁺ is 9, 7, 6. And we fit the crystal structure and ideal shape integrallty.