A phase transition material, VO 2 , with a semiconductor-to-metal transition (SMT) near 341 K (68 °C) has attracted significant research interest because of drastic changes in its electrical resistivity and optical dielectric properties. To address its application needs at specific temperatures, tunable SMT temperatures are highly desired. In this work, effective transition temperature ( T c ) tuning of VO 2 has been demonstrated via a novel Pt : VO 2 nanocomposite design, i.e. , uniform Pt nanoparticles (NPs) embedded in the VO 2 matrix. Interestingly, a bidirectional tuning has been achieved, i.e. , the transition temperature can be systematically tuned to as low as 329.16 K or as high as 360.74 K, with the average diameter of Pt NPs increasing from 1.56 to 4.26 nm. Optical properties, including transmittance ( T %) and dielectric permittivity ( ε ′) were all effectively tuned accordingly. All Pt : VO 2 nanocomposite thin films maintain reasonable SMT properties, i.e. sharp phase transition and narrow width of thermal hysteresis. The bidirectional T c tuning is attributed to two factors: the reconstruction of the band structure at the Pt : VO 2 interface and the change of the Pt : VO 2 phase boundary density. This demonstration sheds light on phasemore »
Temperature dependence of photophysical properties of a dinuclear C^N-cyclometalated Pt(
ii ) complex with an intimate Pt–Pt contact. Zero-field splitting and sub-state decay rates of the lowest triplet
The temperature dependence (1.7 K < T < 100 K) of emission decay is reported for the first time for a type of di-nuclear Pt complex featuring a metal–metal-to-ligand charge transfer (MMLCT) lowest energy transition that arises from a strong Pt–Pt interaction. The effect of local variation of the host/guest cage in a polymer matrix upon the phosphorescence decay time constants is characterized by the Kohlrausch–Williams–Watts function. The temperature dependence of the average decay time constants is fit by a Boltzmann-type expression to obtain the average zero-field splittings and individual sublevel decay rates of the photoluminescent triplet excited state.
- Award ID(s):
- Publication Date:
- NSF-PAR ID:
- Journal Name:
- Physical Chemistry Chemical Physics
- Page Range or eLocation-ID:
- 25096 to 25104
- Sponsoring Org:
- National Science Foundation
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