Noncentrosymmetric K_(2)Mn_(3)(SO_(4))_(3)F_(2)·4H_(2)O and Rb_(2)Mn_(3)(SO_(4))_(3)F_(2)·2H_(2)O with pseudo-KTP structures

摘要

Two fluoride sulfates,K_(2)Mn_(3)(SO_(4))_(3)F_(2)·4H_(2)O(Ⅰ) and Rb_(2)Mn_(3)(SO_(4))_(3)F_(2)·2H_(2)O (Ⅱ) are obtained by water solution method.Single-crystal X-ray diffraction analysis indicated that they crystallize in space groups of Cmc2_(1.)Their structures feature a pseudo-KTP structure consisting of interconnecting[Mn_(3)(SO_(4))3F_(2)(H_(2)O)2]_(∞) layers,which are further packing along the a axis with alkali metal cations balancing the charges.The structure relationships between the two compounds are discussed.Secondharmonic generation measurements manifest that Ⅰ and Ⅱ have similar second-harmonic generation responses of about 0.2 and 0.25 times that of KH_(2)PO_(4).