Achieving balanced UV SHG responses, optical band gaps and birefringence in rare earth compounds Ln(IO3)(SO4)·3H2O (Ln = Y, Gd, Er, Ho, Dy, Eu)

A combination of tetrahedral [SO 4 ] with trigonal pyramidal [IO 3 ] units leads to a series of rare earth compounds Ln(IO 3 )(SO 4 )·3H 2 O (Ln = Y, Gd, Er, Ho, Dy, Eu) with balanced UV SHG responses, optical band gaps and birefringence.