MnSiP₂: A New Mid-IR Ternary Phosphide with Strong SHG Effect and Ultrabroad Transparency Range

Abstract

Mid-infrared (MIR) nonlinear optical (NLO) crystals are crucial in generating MIR lasers, which are important in civilian and military applications. Compared to the extensively investigated ternary and quaternary chalcogenide NLO crystals, ternary phosphide crystals have a large nonlinearity coefficient and a wide transparency range. For instance, the well-known ternary chalcopyrite phosphide NLO crystal, ZnGeP 2 , possesses a large nonlinearity coefficient (d eff = 75 pm/ V) and a broad transmittance range of 0.75−12 μm. However, its applications in the far-infrared laser range were hindered by its strong absorption near 9 and 10−12 μm. Here, considering that Mn 2+ not only makes contributions to large secondharmonic generation (SHG) response but also extends the transparency wavelength range, a new ternary chalcopyrite phosphide crystal, MnSiP 2 (MSP), was rationally designed by substituting a II-site metal (Zn or Cd) for Mn in the II-Si-P 2 family. In this work, the synthesis and single-crystal growth of MSP were systematically investigated. The theoretical and experimental characterizations demonstrated that MSP exhibits a good balance between strong SHG behavior (6 × AgGaS 2 ) and large laser damage threshold (about 70 MW/cm 2 ). Specifically, the long-wavelength MIR cutoff edge of MSP is 18.2 μm, and the outstanding terahertz (THz) transmittance covers the range of 0.4−2.0 THz, indicating the ultrabroad transparency range. This work may provide a feasible strategy and impel one to search for promising outstanding MIR NLO crystals in the ternary phosphide family.

Noncentrosymmetric Tetrel Pnictides RuSi4P4 and IrSi3P3: Nonlinear Optical Materials with Outstanding Laser Damage Threshold

“…Specifically, when compared at the 54–88 µm particle size, RuSi 4 P 4 (1.4 × AGS) and IrSi 3 P 3 (1.6 × AGS) both outperform the recently discovered MgSiAs 2 (0.6 × AGS) [ 19 ] and Ba 2 Si 3 P 6 (0.9 × AGS) [ 13 ] phases measured at identical conditions and versus identical standard, but are not as strong as MnSiP 2 (6 × AGS), despite the latter was measured under different excitation conditions. [ 11 ] Moreover, stronger SHG response is expected under longer wavelength irradiation (such as 10.6 µm of CO 2 laser), as reported for CdGeAs 2 with large nonlinear optical efficiency (236 pm V −1 ) at a longer wavelength (>2.5 µm). [ 63 ] Both RuSi 4 P 4 and IrSi 3 P 3 compounds are expected to be promising infrared NLO materials under suitable excitation sources.…”

“…Additionally, SiP 4 tetrahedra are capable of forming networks by sharing corners and edges, similar to SiO 4 tetrahedra seen in silicates. [ 9–11 ] Distinct from silicates, the formation of Si–Si and P–P bonds are also possible, as is exhibited in A‐Si‐P systems, A = alkali or alkaline‐earth metals. [ 12–18 ] Unlike large electropositive cations, transition metals may form strong covalent bonds with Si and P, thus higher chemical, thermal, and radiation stability is expected.…”

“…Recent discoveries of NCS ternary tetrel pnictides (Ba 2 Si 3 P 6 , MgSiAs 2 , and MnSiP 2 ) [ 11,13,19 ] demonstrate promise in nonlinear optical (NLO) applications in the infrared region of the electromagnetic spectra due to strong second harmonic generation (SHG) activity and exceptional laser damage threshold (LDT). NLO materials can upconvert incoming frequencies of light.…”

“…The landscape of ternary transition metal tetrel pnictides remain understudied for NLO applications, regardless of the many reported NCS structures in this family of M‐Si‐P compounds and despite the promising properties recently reported for MnSiP 2 . [ 11 ] For example, while multiple phases and crystal structures were reported for late 4 d and 5 d transition metal silicon phosphides where M = Ru, Rh, Os, Ir, Ag, Pt, Au, [ 29–32 ] single phase syntheses were not developed and properties were not characterized. Among this group of silicon phosphides, RuSi 4 P 4 and IrSi 3 P 3 are particularly promising due to their reddish color, indicating a relatively large bandgap (about 2 eV).…”

Flux Growth of Phosphide and Arsenide Crystals

“…The volatility of P and As has resulted in poor exploration of many metal-phosphorus (arsenic) phase diagrams in the areas of high pnictogen content. Nevertheless, compounds with substantial P(As) content often exhibit interesting chemistry and useful practical properties, with potential applications as heat conductors, thermoelectrics, catalysts, and non-linear optical materials (Soheilnia et al, 2007;Lindsay et al, 2013;Dolyniuk et al, 2017;Nuss et al, 2017;Pöhls et al, 2017;Li et al, 2018;Owens-Baird et al, 2018, 2019Woo et al, 2018;Coleman et al, 2019;Mark et al, 2019;Yu et al, 2019).…”