Methodological Approach to the High-Pressure Synthesis of Nonmagnetic Li₂B⁴⁺B′⁶⁺O₆ Oxides

High-pressure solid-state synthesis advances boost discoveries of new materials and unusual phenomena but endures stringent recipe conditions, poor yield, and high cost. A methodological approach for accelerated and precisely high-pressure synthesis is therefore highly desired. Here, we take the exotic double-perovskite-related nonmagnetic Li2B+4B′+6O6 as an example to show the pipeline of data-mining, high-throughput calculations, experimental realization, and chemical interception of metastable phases. A total of 140 compounds in 7 polymorph categories were initially screened by the convex hull, which left ∼50% candidates in chemical space on the phase diagram of pressure-dependent polymorph evolution. Li2TiWO6 and Li2TiTeO6 were singled out for experimental testing according to the predicted map of crystal structure, function, and synthesis parameters. Computation on surface energy effect and interfacial chemical strain suggested that the as-made high-pressure R3-Li2TiTeO6 polymorph cannot be intercepted below a critical nanoscale but can be stabilized in heterojunction film on a selected compressive substrate at ambient pressure. The developed methodology is expected to accelerate the big-data-driven discovery of generic chemical formula-based new materials beyond perovskites by high-pressure synthesis and shed light on the large-scale stabilization of metastable phases under mild conditions.