Noncentrosymmetric versus Centrosymmetric: Influence
of the Na<sup>+</sup> Substitution on Structural Transition and Second-Harmonic
Generation
Property
Shujuan Han
Ying Wang
Shilie Pan
Xiaoyu Dong
Hongping Wu
Jian Han
Yun Yang
Hongwei Yu
Chunyan Bai
10.1021/cg4019103.s007
https://acs.figshare.com/articles/dataset/Noncentrosymmetric_versus_Centrosymmetric_Influence_of_the_Na_sup_sup_Substitution_on_Structural_Transition_and_Second_Harmonic_Generation_Property/2310088
A series
of K<sub>3–<i>x</i></sub>Na<sub><i>x</i></sub>B<sub>6</sub>O<sub>10</sub>Br (0.5 ≤ <i>x</i> ≤ 1.2) polycrystalline samples have been synthesized
by the standard solid-state reaction method. Four stoichiometric crystals
K<sub>3–<i>x</i></sub>Na<sub><i>x</i></sub>B<sub>6</sub>O<sub>10</sub>Br (<i>x</i> = 0.13, 0.67,
1.30, 2.20) have been successfully grown from the high-temperature
solution, and the crystal structures were determined by single-crystal
X-ray diffraction. Interestingly, the Na<sup>+</sup> concentration
plays a profound role to influence the crystal structure. Up to about
23% (<i>x</i> = 0.7) K<sup>+</sup> ions can be substituted
by Na<sup>+</sup> ions with the same noncentrosymmetric (NCS) crystal
structure of K<sub>3</sub>B<sub>6</sub>O<sub>10</sub>Br (space
group <i>R</i>3<i>m</i>) being retained, while a higher Na concentration
would lead to it crystallizing in the centrosymmetric (CS) space group <i>Pnma</i>. Meanwhile, the second-harmonic generation (SHG) response
of K<sub>3–<i>x</i></sub>Na<sub><i>x</i></sub>B<sub>6</sub>O<sub>10</sub>Br (<i>x</i> ≤
0.7) is about 2.8 times that of KDP, while the SHG response decreases
sharply when <i>x</i> > 0.7 (the SHG response is zero
at <i>x</i> = 1.3). After careful structural analysis, we
believe
that the different Br-M (M = K/Na, K, or Na) lattices, which are influenced
by the coordination environments of the cations, are responsible for
the structural changes from NCS to CS.
2014-04-02 00:00:00
space group R 3m
space group Pnma
Na
KDP
SHG response decreases
CS
crystal structure
concentration
ion
NCS