K2ZnMoP2O10: a novel nonlinear optical molybdophosphate with a strong second harmonic generation response and moderate birefringence

Abstract

Designing new nonlinear optical (NLO) materials with a strong second harmonic generation (SHG) response, wide transparent range and moderate birefringence is a significant but addressable challenge. By introducing Mo⁶⁺ and Zn²⁺ cations into phosphates, a prospective non-centrosymmetric (NCS) phosphate, K₂ZnMoP₂O₁₀, has been rationally designed. Physical property measurements indicate that K₂ZnMoP₂O₁₀ exhibits a strong SHG response (∼6.8 × KDP), a moderate birefringence (0.0534@450.2 nm), a wide transparent range (0.38–4.5 μm) and a high laser-damage threshold (>910 MW cm⁻²). In addition, a high quality K₂ZnMoP₂O₁₀ single crystal with a size of 14 × 8 × 4 mm³ has also been grown using a top-seeded solution growth method, which is the first large-size crystal of molybdophosphates reported to date. These results indicate that K₂ZnMoP₂O₁₀ is a potential NLO material. The discovery of K₂ZnMoP₂O₁₀ also suggests that introducing various types of NLO-active structural units is helpful for balancing the SHG response and birefringence of materials.