Dr. Tamara Petkova, Professor, Head of Solid state electrolytes department, Institute of electrochemistry and energy systems, Bulgarian Academy of sciences, Acad.G.Bonchev str.Bl.10, 1113 Sofia, BULGARIA

Biography: Tamara Petkova completed her PhD in physical chemistry at Central Laboratory of Optical Storage & Processing of Information of the Bulgarian Academy of Sciences. Her doctoral thesis involved the investigation of new chalcogenide materials as optical storage media. She became Research Associate of the Institute of electrochemistry and Energy Systems -BAS. After a postdoctoral appointment at the University of Patra, Greece in the field of solid state physics, she has been promoted and currently is Head of Solid State Electrolytes department in IEES. Her research interests include investigation of amorphous and crystalline materials for application in energy conversation and storage.

Speech Title: Study of urea-silicate composites
Abstract: Development of innovative hybrid organic-inorganic materials with controllable properties is an essential for fundamental and technological achievements. By varying the conditions of preparation, the relationship composition-structure-properties of the material can be modified, making these materials promising candidates for various applications.
The hybrid materials, based on organic-inorganic ureasilicates, are obtained by sol-gel approach. The structure of the ureasilicates can be represented as disordered network consisting of "hard" silicon containing silica nano-domains (inorganic component) linked to "soft" polymer chains (organic component). Such type of structure allows the materials to tolerate elastic deformations within certain limits, hence to be deposited on non-planar surfaces. In order to obtain material with predefined properties - transparent in the visible region of the spectrum, elastic and thermally stable, the synthesis algorithm is modified. Addition of different fillers derived from an in situ reaction by hydrolysis and condensation of different alkoxides can reinforce the relative weakness of the materials. Several alkoxy-compounds are tested in order to clarify the influence of the ratio between organic and inorganic component on the properties of the material and its possible structure is suggested. The structure of the material is studied using spectroscopic and diffraction methods. Additional information about the structure and in particular the distribution of defects is obtained by positron annihilation in the temperature range of 50-300 K.
Optical research in the visible and ultraviolet part of the spectrum defines the areas of transmittance and absorption and possibilities for material’s application as a medium for different kind of optical functionalities.
Keywords: composites, urea –silicate matrix, properties.