Synergistic effect of2[V2P2O14]∞layers and hydrogen bonds inducing large birefringence in M(VO)2(PO4)2·4H2O (M = Ca, Sr, Ba) systems

The parallel alignment of zigzag 2 [V 2 P 2 O 14 ] ∞ layers and the binding force of hydrogen bonds result in the large birefringence of M(VO) 2 (PO 4 ) 2 ·4H 2 O (M = Ca, Sr, Ba) compounds.