Growth, Properties, and Theoretical Analysis of M2LiVO4 (M = Rb, Cs) Crystals: Two Potential Mid-Infrared Nonlinear Optical Materials

Abstract

Mid-Infrared nonlinear optical (Mid-IR NLO) crystals with excellent performances play a particularly important role for applications in areas such as telecommunications, laser guidance, and explosives detection. However, the design and growth of high performance Mid-IR NLO crystals with large NLO efficiency and high laser-damage threshold (LDT) still face numerous fundamental challenge. In this study, two potential Mid-IR NLO materials, Rb2LiVO4 (RLVO) and Cs2LiVO4 (CLVO) with noncentrosymmetric structures (Orthorhombic, Cmc21) were synthesized by high-temperature solution method. Thermal analysis and powder X-ray diffraction demonstrate that RLVO and CLVO melt congruently. Centimeter sized crystals of CLVO have been grown by the top-seeded solution growth method. RLVO and CLVO exhibit strong second harmonic generation (SHG) effects (about 4 and 5 times that of KH2PO4, respectively) with a phase-matching behavior at 1.064 μm, and a wide transparency range (0.33–6.0 μm for CLVO). More importantly, RLVO and CLVO possess a high LDT value (~28 × AgGaS2). In addition, the density functional theory (DFT) and dipole moments studies indicate that the VO4 anionic groups have a dominant contribution to the SHG effects in RLVO and CLVO. These results suggest that the title compounds are promising NLO candidate crystals applied in the Mid-IR region.

Two Polar Molybdenum(VI) Iodates(V) with Large Second-Harmonic Generation Responses

“…The SHG responses of compounds 1 and 2 are consistent with those of dipole moment calculations (Table S5). Considering that both compounds 1 and 2 crystallize in polar space groups, i.e., Pna 2 1 and Cc , respectively, the dipole moments of the [IO 3 ] − , [IO 4 ] 3– , and [MoO 6 ] 6– polyhedra in compounds 1 and 2 were calculated by the Debye equation. , The directions of the dipole moments of the [IO 3 ] − , [IO 4 ] 3– , and [MoO 6 ] 6– polyhedra are assigned in Figure . As results show in Table S5, the magnitudes of the dipole moments of the [IO 3 ] − and [IO 4 ] 3– units in title compounds are more than 10 times those of the [MoO 6 ] 6– units, which can be regarded as the main source of SHG of compounds 1 and 2 .…”

Unprecedented mid-infrared nonlinear optical materials achieved by crystal structure engineering, a case study of (KX)P2S6 (X = Sb, Bi, Ba)

“…[10][11][12][13][14][15] Now the major strategy to achieve a large bandgap is through the investigation of oxides, with good examples of Cs 4 V 8 O 22 , 16 La 3 SnGa 5 O 14 , 17 LiCd(IO 3 ) 3 , 18 Li 2 MTeO 6 (M ¼ Ti, Sn), 19 and M 2 LiVO 4 (M ¼ Rb, Cs). 20 Compared with oxygen, which has intrinsic vibration modes within the infrared spectrum range, suldes constituted from heavier sulfur atoms can have better performance. [21][22][23][24] For sulde MIR NLO materials, they currently remain in a vacuum without a promising material to balance d ij , Dn, and LDT with a bandgap breaking through the "3.5 eV wall".…”

Rational design of a promising oxychalcogenide infrared nonlinear optical crystal

“… 22 But the poor IR transparency and relatively weak SHG responses make their application limited within 5 μm. 23 Therefore, it is clear that chalcogenides can exhibit larger SHG response and better IR transmission, while metal oxides have advantages in band-gaps and LDTs. Therefore, combining two types of anions may be an expectant strategy for designing high-performance IR NLO crystals with balanced properties.…”