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Synthesis and physical chemical properties of Ca-substituted LaTiO2N |
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| Authors: | D. Logvinovich, A. B rger, M. D beli, S.G. Ebbinghaus, A. Reller,A. Weidenkaff |
| Affiliation: | aEmpa, Swiss Federal Laboratories for Materials Testing and Research, Solid State Chemistry and Catalysis, Ueberlandstr. 129, CH-8600 Duebendorf, Switzerland bTechnical University of Braunschweig, D-38106 Braunschweig, Germany cETH, CH-8093 Zürich, Switzerland dUniversity of Augsburg, Festkörperchemie, Institut für Physik, Universitätstr. 1, D-86159 Augsburg, Germany |
| Abstract: | Oxynitrides with the general formula La1−xCaxTiO2+xN1−x (x = 0, 0.3, 0.5, 0.7, 1.0) were synthesized by thermal ammonolysis of oxide precursors produced with a soft chemistry method. The crystallographic structure, optical properties and the thermal stability of the compounds were studied with X-ray diffraction, UV–vis spectroscopy and thermal analysis. All materials crystallize in perovskite-type pseudo-cubic unit cell. It was found that the lattice parameter decreases with increasing Ca content, while the optical band gap width increases with increasing x. Thermal reoxidation studies of the synthesized materials reveal the formation of nitrogen rich intermediates. The decomposition rate of the intermediates was correlated with the structure of the final products. TEM studies show a preferred insertion direction of the nitrogen into the crystal lattice of the starting oxides. Ammonolysis with flux significantly changed the microstructure of the obtained oxynitrides. |
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