High-pressure research on nanostructured materials has been of considerable interest owing to the quantum confinement effect and intrinsic defects in the nanocrystals. Here, we report a pressure-induced reversible structural phase transition in nanostructured Bi 2 Te 3 hierarchical architectures (HAs) that were prepared via a facile solution-phase method. Therein, distinct phases I−IV by respectively adopting crystal structures of rhombohedral (I), monoclinic (II, III), and cubic (IV) were experimentally identified with increasing pressure up to 20.2 GPa in a diamond anvil cell (DAC). It is worthwhile to notice that nanostructured Bi 2 Te 3 HAs ultimately evolved into a fascinating Bi−Te substitutional nonmetallic alloy at pressure even as low as 15.0 GPa, approximately 10 GPa lower than that of the corresponding bulk counterpart. The synergistic effect involving large volume collapse and the unique one-dimensional nanostructures with intrinsic antisite defects was proposed to be responsible for the reduction of transition pressure that is contrary to the general model for most nanomaterials. Our findings may pave a potential pathway for developing future multifunctional nanoalloys that are composed of nonmetallic elements.
■ INTRODUCTIONAlloys have been anticipated to be widely utilized in engineering and industry owing to their extraordinary properties, such as much stronger hardness and toughness, depressed electric and thermal conductivity, and lower melting point than each separated constituent alone. 1,2 These unique characteristics of an alloy are able to render people manufacture the target material with desired properties for a given practical application. However, most alloys are composed of metal elements; thus, searching for other alternatives of new and enhanced functional alloys as well as their prepared strategy is of great interest and remains challenging.Applications of high pressure have proven to be a powerful tool in tailoring the material's properties, especially since the development in the 1950s of the diamond anvil cell (DAC), which made it possible to generate pressures even above 100 GPa. 3−6 Intriguingly, nanomaterials subjected to high-pressure conditions can greatly increase opportunities of exploring novel physical phenomena because of the quantum confinement effect and intrinsic defects yielded by the stark decrease in size. 7−13 In this respect, Tolbert and Alivisatos, as pioneers in 1994, systematically investigated in situ high-pressure structural phase transition of monodispersed CdSe nanoparticles by applying DAC apparatus. 14 Inspired by the size effect of nanomaterials, Wang et al. have recently reported a critical sizedependent amorphization of nanoscale Y 2 O 3 particles at high pressure. 15 Meanwhile, Fan's group further developed high pressure as a potential means for morphology regulation of noble metal nanocrystals. 16−18 Our group has also made a progress in high-pressure nanomaterial studies over the different stabilities and phase transition routines for nanosized YP...