engleski

Design and synthesis of new lead-free ferroelectrics

Ferroelectrics are ubiquitous materials used in daily life and industrial production, as memories, transducers, capacitors, sensors, and so forth. The main feature of ferroelectrics is spontaneous polarization that can be reversed by the application of an electric field larger than the coercive field. By far the most studied and used electroceramic with ferroelectric properties is lead zirconate titanate, which is nowadays becoming an increasingly serious problem in terms of the environment, costs, and energy.[1] Due to the overall superior performance of lead-based ferroelectrics finding alternatives has proven to be challenging. Herein preparation of two new lead-free ferroelectric systems will be presented, both based on chemical solution synthesis. First, the block copolymer–templated mesostructured LiNbO3 thin films prepared by evaporation induced self-assembly will be presented and their ferroelectric performance will be discussed in terms of different device construction, ie. top and bottom electrodes.[2] The efficiency of ferroelectric materials is related to the way they are prepared because characteristics such as chemical purity, crystallinity, and morphology are important in the obtained materials. Porous electroceramics typically exhibit lower polarizability than their dense counterparts, but they offer much more possibilities for structuring, especially when it comes to producing multifunctional and multicomponent systems and tuning/tailoring of properties. Another approach for the preparation of new ferroelectric systems relies on the chemical design of molecular compounds. Chirality that certain molecules possess is a very convenient feature especially important for the design of polar structures. Using this strategy we have chosen naturally occurring chiral alkaloids of the Cinchona plants: quinine and cinchonidine, in reactions with chlorocobaltate(II) anions to prepare complexes of the formula ACoCl3 (A = alkaloid), that reveal exciting structural and electric properties.

ferroelectrics ; polar structures ; lead-free

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