| Autor: |
O'Brien ES; Department of Chemistry , Columbia University , New York , New York 10027 , United States., Russell JC; Department of Chemistry , Columbia University , New York , New York 10027 , United States., Bartnof M; Department of Mechanical Engineering , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States., Christodoulides AD; Department of Mechanical Engineering , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States., Lee K; Department of Chemistry , Columbia University , New York , New York 10027 , United States., DeGayner JA; Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States., Paley DW; Columbia Nano Initiative , Columbia University , New York , New York 10027 , United States., McGaughey AJH; Department of Mechanical Engineering , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States.; Department of Materials Science and Engineering , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States., Ong WL; College of Energy Engineering, ZJU-UIUC , Zhejiang University , Hangzhou , Zhejiang 310027 , China., Malen JA; Department of Mechanical Engineering , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States.; Department of Materials Science and Engineering , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States., Zhu XY; Department of Chemistry , Columbia University , New York , New York 10027 , United States., Roy X; Department of Chemistry , Columbia University , New York , New York 10027 , United States. |
| Abstrakt: |
Structural phase transitions run in families of crystalline solids. Perovskites, for example, feature a remarkable number of structural transformations that produce a wealth of exotic behaviors, including ferroelectricity, magnetoresistance, metal-insulator transitions and superconductivity. In superatomic crystals and other such materials assembled from programmable building blocks, phase transitions offer pathways to new properties that are both tunable and switchable. Here we describe [Co 6 Te 8 (PEt 3 ) 6 ][C 70 ] 2 , a novel superatomic crystal with two separate phase transitions that drastically transform the collective material properties. A coupled structural-electronic phase transition triggers the emergence of a new electronic band in the fullerene sublattice of the crystal, increasing its electrical conductivity by 2 orders of magnitude, while narrowing its optical gap and increasing its spin density. Independently, an order-disorder transition transforms [Co 6 Te 8 (PEt 3 ) 6 ][C 70 ] 2 from a phonon crystal to a phonon glass. These results introduce a family of materials in which functional phase transformations may be manipulated by varying the constituent building blocks. |
