期刊
NANO LETTERS
卷 11, 期 12, 页码 5531-5536出版社
AMER CHEMICAL SOC
DOI: 10.1021/nl203409s
关键词
Lead telluride; high pressure; phase transformation; pressure-induced amorphization; in situ X-ray diffraction; reversed Hall-Petch effect
类别
资金
- NSF [DMR-0731382, DMR-0936384]
- New York State Office of Science Technology and Innovation
- Empire State Development Corporation
Using an in situ synchrotron X-ray diffraction technique, a pressure-induced phase transformation of PbTe nanocrystals with sizes of 13 and 5 rim up to similar to 20 GPa was studied. Upon an increase of pressure, we observed that the 13 nm PbTe nanocrystals start a phase transformation from rocksalt structure to an intermediate orthorhombic structure and finally CsCl-type structure at 8 GPa, which is 2 GPa higher than that in bulk PbTe. In contrast, the 5 nm PbTe nano crystals do not display the same type of transition with a further increased transition pressure as expected. Instead of orthorhombic or CsCl-type structure, the 5 rim PbTe nanocrystals turn to amorphous phase under a similar pressure (8 GPa). Upon a release of pressure, the 13 nm PbTe nanocrystals transform from high pressure CsCl-type structure directly to rocksalt structure, whereas the 5 nm PbTe nanocrystals remain their amorphous phase to ambient conditions. The structure stability of rocksalt-type PbTe shows a significant reversal of Hall-Petch effect. On the basis of such an observation with a critical size determination of similar to 9 nm, PbTe nanocrystals appear as the first class of material that demonstrates a pressure-induced structural change from order to disorder. By sharing the insight of this reversed Hall-Petch effect with associated transition types, we tuned our experimental protocol and successfully synthesized a sample with high-pressure metastable structure, amorphous phase at ambient pressure. This integrative study provides a feasible pathway to understand nucleation mechanism as a function of particle size and to explore novel materials with high-pressure metastable structure and unique properties under lab-accessible conditions.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据