Optical and electrical characterization of titanosilicate ETS-10 thin films: photochromism and ionic conductivity

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2015
Galioğlu Özaltuğ, Sezin
Zeo-type Engelhard titanosilicate (ETS-10) crystals were synthesized by using Ti source of P25 and titanium (IV) isopropoxide. Using different Ti sources resulted in ETS-10 crystals with different particle morphology and particle size. The investigation of the titanosilicate ETS-10 crystals was done by FE-SEM, XRD and Raman analyses. The analyses showed that the samples contain only pure ETS-10 phase without any titanosilicate ETS-4 and quartz phases in our ETS-10 samples. Ag+ ions and Ag0 nanoparticles were incorporated to submicrometer-sized ETS-10 crystals that were synthesized by using Ti source of P25 and characterized by using advanced analytical methods including ICP-OES, XRD, XPS, FE-SEM, TEM, HRTEM, DR-UV-vis, Raman spectroscopies and N2 adsorption-desorption technique. Although maintaining of structural integrity of host material had been monitored for Ag+-ETS-10, detailed Raman analyses of Ag0-ETS-10 samples showed significant changes in the titanate quantum wires of ETS-10 framework depending on the silver vi loading. To figure out the role of 1D TiO32- quantum wires in the ETS-10 crystals, Ag+ ions were incorporated into ETS-10 matrix by ion-exchange of extra framework cations (i.e., Na+ and K+) to form Ag+ ion-exchanged ETS-10. Afterwards, partially reversible photochromic behavior of Ag0 nanoparticle incorporated titanosilicate ETS-10 films was achieved for the first time. The resulting Ag0-ETS-10 films and also Ag+-ETS-10 crystals had been characterized by ICP-OES, XRD, XPS, FE-SEM, HR-TEM, UV-vis spectroscopies. Partial restoration of color was achieved after second thermal treatment, which implies reversibility of the photochromic process. In the second part of the current thesis study, different techniques to obtain ETS-10 thin films were deeply investigated by spin-coating and secondary growth methods for the purpose of testing the obtained films in different applications. To attach the silver incorporated ETS-10 particles to the substrate, Ag+ ion-exchanged ETS-10 crystals were suspended in acetone and coated on regular glass substrates by spin coating method in order to investigate its photochromic property. Further investigation was carried out to obtain firmly attached ETS-10 films on conducting ITO glass and non-conducting α-alumina substrates by using secondary growth of seed crystals. After that, long-range ionic conductivity properties of zeo-type ETS-10 films prepared via secondary growth method was investigated by using impedance spectroscopy for the first time at Central Laboratory, METU. The Na+ and K+ ions within the framework of as-synthesized ETS-10 films were ion-exchanged with Li+, Ca2+, and Zn2+ ions to figure out the effect of cation site occupancy on conduction. The current studies reveal the long-range ionic conductivity of titanosilicate ETS-10 films prepared by secondary growth method for the first time. These results might open new gateways for ion-exchange, fuel cells, and sensor applications.

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Citation Formats
S. Galioğlu Özaltuğ, “Optical and electrical characterization of titanosilicate ETS-10 thin films: photochromism and ionic conductivity,” Ph.D. - Doctoral Program, Middle East Technical University, 2015.