The Effect of Zr-Doping and Crystallite Size on the Mechanical ...

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III. Results <strong>and</strong> Discussion multipoint-method was used to determine the specific surface area according to Brunauer, Emmet <strong>and</strong> Teller (BET). <strong>The</strong> samples synthesized via sol-gel process are mainly colorless powders, excluding samples with nominally 100 mol% <strong>Zr</strong>O2, which are always dark grey or black <strong>and</strong> thus, contain small amounts <strong>of</strong> carbon (
III. Results <strong>and</strong> Discussion with a pore volume <strong>of</strong> 0.16 cm 3 /g, which is typical for sol-gel materials (Figure 17). <strong>The</strong> type 1 isotherm indicates a microporous network with an average pore diameter <strong>of</strong> around 1.8 nm. Figure 17: N2-sorption <strong>of</strong> sol-gel sample with 50 mol-% TiO2. <strong>The</strong> pore size distribution (left) shows a highly porous material with a pore volume <strong>of</strong> 0.16cm³/g, the isotherm (right) indicates an average pore diameter <strong>of</strong> 1.8 nm. <strong>The</strong> results <strong>of</strong> the TGA <strong>and</strong> DTA/TG experiments are presented in Figure 18. <strong>The</strong> total overall mass loss up to 1000°C is 6 wt% <strong>and</strong> can be separated in two temperature regimes. <strong>The</strong> first, major mass loss until 250°C <strong>of</strong> ~5 wt% is directly associated with a broad endothermic DTA signal due to the evaporation <strong>of</strong> adsorbed water in the micropores. <strong>The</strong> minor mass loss at T=250-1000°C <strong>of</strong> ~1 wt% may be explained by decomposition reactions <strong>of</strong> organic residues or the continued condensation <strong>of</strong> OH-groups within the material. At a temperature <strong>of</strong> 717°C, the DTA data show a large exothermic signal (onset at T=714°C), indicating the crystallization <strong>of</strong> srilankite from the amorphous phase. It can be concluded that the total amount <strong>of</strong> carbon + H2O <strong>of</strong> the sol-gel samples produced is samller than 1 wt%. A st<strong>and</strong>ard drying procedure at 250°C for 24 h was used to reduce the water content <strong>of</strong> the powders. <strong>The</strong> overall mass loss was reduced to ~3%, as can be seen from the differential thermal DTA/TG experiments (Figure 18). However, it has to be noted that still a minor endothermic vaporization <strong>of</strong> water occurs. Also the small weight loss at temperatures >250°C is still present. 49
Page 1 and 2: The Effect
Page 3 and 4: Content Content Zusammenfassung ...
Page 5 and 6: Zusammenfassung Experimentelle Meth
Page 7 and 8: Zusammenfassung Berechnungen des Gr
Page 9 and 10: Summary Experimental Methods <stron
Page 11 and 12: Summary generalized gradient approx
Page 13 and 14: I. Introduction Because rutile is r
Page 15 and 16: I. Introduction 1.2. Polymorphs <st
Page 17 and 18: I. Introduction enthalpy of
Page 19 and 20: I. Introduction 2. TiO2-Zr<
Page 21 and 22: I. Introduction 3. Technical Applic
Page 23 and 24: I. Introduction 4. Tuning o
Page 25 and 26: I. Introduction polyhedra a
Page 27 and 28: I. Introduction 5. Computational Wo
Page 29 and 30: II. Methods and In
Page 47: III. Results and D
Page 51 and 52: III. Results and D
Page 97 and 98: Conclusions In contrast, the compre
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Conclusions Table 12: Pressure indu
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Acknowledgments Acknowledgments Thi
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Bibliography [16] J. Haines <strong
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Bibliography [52] M. Latroche, L. B
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Bibliography and p
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Bibliography [121] M. Mikami, S. Na
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Bibliography [154] G.Y. Shen, V.B.
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Bibliography [191] S. Ananta, R. Ti
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Erklärung Erklärung Hiermit erkl
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