Rational combination of multiple structural groups on regulating nonlinear optical property in hexagonal Ln3MGeS7 polar crystals

Non‐Linear Optical Properties of the (RE)3CuGeS7 Family of Compounds

“…Such property enhancements were not only observed for NLO materials, [22] but also for thermoelectrics [23,24] . We hypothesize, that the NLO performance of ( RE ) 3 CuGeS 7 can be further improved by fine tuning of the cation sizes, i. e. by formation of solid solutions, such as Gd 3−δ ( RE ) δ CuGeS 7 [14,25,26] …”

“…[18] Diffraction peaks corresponding to admixtures are labeled as ("*" = Ce 3 Ge 1.5 S 7 ) for the composition with Ce and as (" + " = Cu 5 Ge 0.5 S 4 ) for composition with Y. improved by fine tuning of the cation sizes, i. e. by formation of solid solutions, such as Gd 3À δ (RE) δ CuGeS 7 . [14,25,26]…”

“…La 3 CuGeS 7 was previously identified as a promising NLO material with good SHG and LDT properties compared to its analogues with T= Si or Sn and other transition metals [12] . Using a principle of composition optimization in this prototype structure, it is possible to synthesize phases with better NLO properties [14] . By substituting La for rare‐earth metals with smaller ionic radii (Y, Ce, Sm, and Gd), a change in the bond length and angles of the underlying polyhedral structure was observed, resulting in Gd 3 CuGeS 7 having the best combination of SHG (1.6× AgGaS 2 at 88–105 μm particle size) and LDT (3× AgGaS 2 ) and being phase matchable.…”

“…[12] Using a principle of composition optimization in this prototype structure, it is possible to synthesize phases with better NLO properties. [14] By substituting La for rare-earth metals with smaller ionic radii (Y, Ce, Sm, and Gd), a change in the bond length and angles of the underlying polyhedral structure was observed, resulting in Gd 3 CuGeS 7 having the best combination of SHG (1.6 × AgGaS 2 at 88-105 μm particle size) and LDT (3 × AgGaS 2 ) and being phase matchable. Based on changes in bond lengths and angles in various polyhedra, we propose that an optimal structure would have coplanar [CuS 3 ] units with Cu being situated right in the center of the [CuS 3 ] triangle.…”

Synthesis of chiral high-entropy sulfides for non-linear optical applications

“…21 We have previously identified La 3 CuGeS 7 (La 6 Cu 2 Ge 2 S 14 ) as a potential NLO material with good LDT and SHG properties. 21 Then, following the principle of composition optimization within this prototype structure, 23 we attempted to synthesize phases with better NLO properties by changing La to other rare-earth metals: Y, Ce, Sm, and Gd. 24 Rare-earth cation variation caused changes to the bond lengths and angles of the underlying polyhedral structure.…”