Rb2Na(NO3)3: A Congruently Melting UV-NLO Crystal with a Very Strong Second-Harmonic Generation Response

Hyung Kim,Chensheng Lin,Hongil Jo,Guohong Zou,Kang Ok

doi:10.3390/cryst6040042

Abstract

Crystals of congruently melting noncentrosymmetric (NCS) mixed alkali metal nitrate, Rb2Na(NO3)3, have been grown through solid state reactions. The material possesses layers with NaO8 hexagonal bipyramids and NO3 triangular units. Rb+ cations are residing in the interlayer space. Each NaO8 hexagonal bipyramid shares its corners and edges with two and three NO3 units, respectively, in order to fulfill a highly dense stacking in the unit cell. The NaO8 groups share their six oxygen atoms in equatorial positions with three different NO3 groups to generate a NaO6-NO3 layer with a parallel alignment. The optimized arrangement of the NO3 groups and their high density in the structure together produce a strong second-harmonic generation (SHG) response. Powder SHG measurements indicate that Rb2Na(NO3)3 has a strong SHG efficiency of five times that of KH2PO4 (KDP) and is type I phase-matchable. The calculated average nonlinear optical (NLO) susceptibility of Rb2Na(NO3)3 turns out to be the largest value among the NLO materials composed of only [NO3]− anion. In addition, Rb2Na(NO3)3 exhibits a wide transparency region ranging from UV to near IR, which suggests that the compound is a promising NLO material.

Highlights

Nonlinear optical (NLO) crystals, especially those producing coherent ultraviolet (UV) light, are continuously attracting enormous attention, attributed to their auspicious applications in laser science and technology [1,2,3,4,5,6,7,8,9,10,11,12,13,14]
Crystals [15,16,17,18,19,20,21,22] revealing a variety of structural possibilities and considerably large microscopic second-order susceptibility with moderate birefringence based on the anionic group theory have been reported [23,24,25]
We report phase pure synthesis, structure determination, characterization, and calculations of a promising UV-NLO material, Rb2 Na(NO3

Summary

Introduction

Nonlinear optical (NLO) crystals, especially those producing coherent ultraviolet (UV) light, are continuously attracting enormous attention, attributed to their auspicious applications in laser science and technology [1,2,3,4,5,6,7,8,9,10,11,12,13,14].

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