“…Double tungstates and molybdates formulated as AB(YO 4 ) 2 (A: monovalent cation; Li + , Na + or K + , B: trivalent one; Ln 3+ , Y 3+ , or Bi 3+ , Y: Mo 6+ or W 6+ ) have been a significant research interest thanks to their structural and optical features [1,2]. These compounds crystallize in two phases belonging to the monoclinic and tetragonal structures [1].The high refractive index, nonlinear optical characteristics, luminescence properties, wide transmission range and large optical bandwidths make these compounds potential candidates in laser, light emitting diode, optical amplifier, and nonlinear optical device applications [3][4][5]. NaBi(WO 4 ) 2 and NaBi(MoO 4 ) 2 are two members of this group and the device applications of these compounds are increasing in recent years.…”