Heterocationic strategy to design a nonlinear optical crystal with a polar anti-perovskite structure

Le résumé fourni par la source

The rational design of noncentrosymmetric (NCS) inorganic materials remains a longstanding challenge due to unpredictable solid-state reactions and stringent requirements on symmetry breaking. Although perovskites have been widely used as structural templates for NCS materials, their anti-perovskite counterparts remain unexplored. Here, by incorporating Cs+ and Cd2+ ions into a centrosymmetric Na3Cl[MoO4] template, we introduce a heterocationic strategy tailored for anion-centered anti-perovskites that, modifying the conventional BX6 octahedra, yields the polar molybdate Cs2NaCd2Cl3(MoO4)2. The heterocationic sublattice induces pronounced octahedral distortion, breaks inversion symmetry, and aligns the [MoO4] tetrahedra, resulting in a wide band gap of 4.37 eV, a broad transparency window (0.26–5.42 μm and 6.25–10.46 μm), an SHG coefficient twenty times larger than KH2PO4 (d15 = 9.31 pm/V) and a congruent-melting dynamics, enabling single-crystal growth. This work unveils the potential of heterocationic engineering in anion-centered frameworks demonstrating the design of NCS and polar functional materials with excellent nonlinear optical properties. Perovskites are widely used as templates for designing noncentrosymmetric materials, whereas their anion-centred counterparts have not been extensively explored. Here, authors develop a strategy to design heterocationic anti-perovskite materials with a noncentrosymmetric structure, yielding outstanding nonlinear optical properties.

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