A Room-Temperature Transition in Polytetrafluoroethylene

Non-equilibrium heat capacity of polytetrafluoroethylene at room temperature

Polytetrafluoroethylene can be considered as a model for calorimetric studies of complex systems with thermodynamics transitions at ambient temperature. This polymer exhibits two phase transitions of different nature at 292 K and 303 K. We show that sensitive accalorimetry measurements allow us to study the thermodynamic behaviour of polytetrafluoroethylene when it is brought out of thermodynam...

Electronic transition above room temperature in CaMn7O12 films

We report on the electronic phase transition in CaMn7O12 quadruple perovskite films synthesized by oxide molecular beam epitaxy on SrLaAlO4 and La0.3Sr0.7Al0.65Ta0.35O3 substrates. We use x-ray diffraction and transmission electron microscopy to confirm that the CaMn7O12 phase has been realized. Temperature dependent resistivity measurements reveal a signature of a charge ordering phase transit...

Transition Metal-Doped Oxide Semiconductor Exhibiting Room-Temperature Ferromagnetism

"Nok": a phytosterol-based amphiphile enabling transition-metal-catalyzed couplings in water at room temperature.

The third-generation designer amphiphile/surfactant, "Nok" (i.e., SPGS-550-M; β-sitosterol methoxypolyethyleneglycol succinate), soon to be commercially available from Aldrich, can be prepared in two steps using an abundant plant feedstock and β-sitosterol, together with succinic anhydride and PEG-550-M. Upon dissolution in water, it forms nanomicelles that serve as nanoreactors, which can be c...

A phase transition close to room temperature in BiFeO3 thin films.

BiFeO3 (BFO) multiferroic oxide has a complex phase diagram that can be mapped by using appropriately substrate-induced strain in epitaxial films. By using Raman spectroscopy, we conclusively show that films of the so-called supertetragonal T-BFO phase, stabilized under compressive strain, display a reversible temperature-induced phase transition at about 100 °C, and thus close to room temperat...