@article{Moencke_Dussauze_Kamitsos_Varsamis_Ehrt_2009, title={Thermal poling induced structural changes in sodium borosilicate glasses}, volume={50}, ISSN={1753-3562}, archiveLocation={Ινστιτούτο Θεωρητικής και Φυσικής Χημείας (ΙΘΦΧ) - Επιστημονικό έργο}, url={https://hdl.handle.net/10442/12682}, abstractNote={Inorganic glassy materials can exhibit large second order nonlinear optical (NLO) coefficients, chi((2)), after thermal poling. Sodium borosilicate glasses with various SiO(2) contents and constant Na(2)O:B(2)O(3) ratio of 0.2, which characterises the boric oxide anomaly, were thermally poled under argon. The second harmonic generation signal was measured for different poling parameters. Structural changes between poled and unpoled glasses were observed by infrared reflectance and Raman spectroscopy. It was found that under poling Na(+) ions migrate from the anode to the cathode side. This displacement of cations from the anode side is compensated by structural rearrangements of the glassy network, which lead eventually to the release of oxygen anions from the anode side. Both effects are facilitated by the conversion of borate tetrahedra into neutral trigonal borate units. The reverse transformation occurs at the cathode side, where borate tetrahedra are formed together with electron centres, also known as oxygen vacancies. The presence of vacancies was revealed by optical and EPR spectroscopy.}, number={3}, journal={Physics and Chemistry of Glasses-european Journal of Glass Science and Technology Part B}, publisher={Society Glass Technology}, author={Moencke, D. and Dussauze, M. and Kamitsos, Efstratios I. and Varsamis, Christos-Platon E. and Ehrt, D.}, year={2009}, month={Jun}, pages={229–235} }