Macro-dipoles in soft/hard expanded-polytetrafluoroethylene + fluoroethylenepropylene (ePTFE + FEP) fluoropolymer-film systems for high-output piezoelectric ferroelectret-transducer applications

Multi-layer ferroelectrets consisting of fluoroethylenepropylene (FEP) copolymer and open-porous expanded polytetrafluoroethylene (ePTFE) films exhibit stable internal electret charges, high piezoelectric coefficients and heat resistance, making them promising candidates for wearable sensors or nanogenerators in body-area networks. Here,...

Design of efficient magnetocaloric materials for energy conversion

The magnetocaloric effect (MCE) is a magneto-thermodynamic phenomenon in which a temperature change of a material is caused by exposing the material to a changing magnetic field under adiabatic conditions. There are two main applications based on the MCE. One application is magnetic refrigeration, which can expel heat in a magnetic field cycle....

Development of Quantitative electron nano-diffraction

This thesis is a step towards development of quantitative parallel beam electron nano-diffraction (PBED). It is focused on the superstructure determination of zig-zag and zig-zig NaxCoO2 and analysis of charge distribution in the two polymorphs Nb12O29 using PBED. It has been shown that quantitative electron nano-diffraction (parallel beam) has...

Opto-electronic properties of charged conjugated molecules

The aim of this thesis is to provide fundamental insight into the nature and opto-electronic properties of charge carriers on conjugated oligomers and polymers. Electronic structure, optical absorption properties and distribution of charge carriers along the chains of different conjugated materials are central issues of this thesis. In order to...