Family of low dimensional materials with ternary elements Ta₂Ni_xSe_y: Growth strategy for Ta₂NiSe₅ and Ta₂NiSe₇

In the ternary Ta-Ni-Se materials group, the conditions for selectively synthesizing Ta₂NiSe₅ and Ta₂NiSe₇ that exhibit a low-dimensional layered structure (due to van der Waals bonding between layers) were studied. Control of both the stoichiometric ratio of selenium and synthesis temperature facilitated the selective growth of high-quality Ta₂NiSe₅ and Ta₂NiSe₇ crystals. The synthesized low-dimensional materials could be exfoliated in a layered form, with the Ta₂NiSe₅ and Ta₂NiSe₇ layers having semiconductor and metallic electrical characteristics, respectively, as verified through the change in electrical resistance with temperature. The synthesized materials are expected to expand the repertoire of semiconducting and conducting building blocks for use in various low-dimensional devices.