| Abstract [eng] |
This PhD thesis aimed to synthesize single-phase multicomponent oxides by an aqueous sol-gel method and to investigate the thermal decomposition mechanism of the prepared gel precursors. For the first time, the aqueous tartaric acid-assisted sol-gel synthesis technique was successfully proposed for the preparation for La2Mo2O9, Ca1-xSrxMoO4 and M0.05Eu0.05Ca0.9MoO4 (M= Li, Na, K, Rb. Cs) ceramics. The oxalic acid-assisted sol-gel synthesis was successfully applied for the preparation for Ce0.9Gd0.1O1.95 ceramic. It had been demonstrated that the thermal analysis is a powerful technique, which allowed the estimation of both the decomposition processes for synthesized organometallic compounds and the formation behavior of the final inorganic phases. It was found that the mechanism of thermal decomposition of CaMoO4 systems remains identical despite additional ions, and the similar tendencies are mainly caused by the coordination ability of MoO42– anion. Raman studies allowed estimating the molar ratio of individual metals in the Ca1-xSrxMoO4 system. The influence of different alkali metals on the optical properties of M0.05Eu0.05Ca0.9MoO4 oxides were also investigated in detail. The electrical properties of La2Mo2O9 were evaluated by the impedance spectroscopy. Studies have shown that the phase transition of La2Mo2O9 from β-phase to α-phase takes place under slightly more favorable conditions than the opposite process. The influence of the heating temperature on the surface morphology for Ce0.9Gd0.1O1.95 ceramic was determined by the SEM method. |
