LiMII(IO3)3 (MII=Zn and Cd): Two Promising Nonlinear Optical Crystals Derived from a Tunable Structure Model of α‐LiIO3

Excellent nonlinear optical materials simultaneously meet the requirements of large SHG response, phase‐matching capability, wide transparency windows, considerable energy band‐gap, good thermal stability and structure stability. Herein, two new promising nonlinear optical (NLO) crystals LiMII(IO3)3 (MII=Zn and Cd) are rationally designed by the aliovalent substitution strategy from the commercialized α‐LiIO3 with the perfect parallel alignment of IO3 groups. Compared with parent α‐LiIO3 and related AI2MIV(IO3)6, the title compounds exhibit more stable covalent 3D structure, and overcome the racemic twinning problem of AI2MIV(IO3)6. More importantly, both compounds inherit NLO‐favorable structure merits of α‐LiIO3 and show larger SHG response (≈14× and ≈12×KDP), shorter absorption edge (294 and 297 nm) with wider energy band‐gap (4.21 and 4.18 eV), good thermal stability (460 and 430 °C), phase‐matching behaviors, wider optical transparency window and good structure stability, achieving an excellent balance of NLO properties. 3D structure: Two promising nonlinear optical (NLO) crystals LiMII(IO3)3 (MII=Zn and Cd) are rationally designed by the aliovalent substitution strategy. They achieve a suitable balance of excellent properties of larger second‐harmonic generation (SHG) response, wider energy band‐gap and optical transparency window, high large optical‐damage thresholds (LDT), and good stability.