Hot compaction of nanocrystalline TiO 2 (anatase) ceramics. Mechanisms of densification: Grain size and doping effects A. Weibel, R. Bouchet, P. Bouvier and P. Knauth MADIREL (UMR 6121), Université de Provence-CNRS, Centre St Jérôme, 13397 Marseille Cedex 20, France LEPMI (UMR 5631), Université Joseph Fourier-INPG-CNRS, 38402 St Martin d’Hères Cedex, France Abstract The hot compaction of nanocrystalline TiO 2 anatase powders is investigated using dilatometry. The constant rate of heating (CRH) method is applied to determine effective activation energies of the processes involved during sintering. Grain size and doping effects are studied, using dopant cations of different radius and charge: Zn 2+ , Al 3+ , Si 4+ , Nb 5+ . The results are interpreted by a mechanism including superplastic deformation and boundary diffusion. The former is predominant for small particles and low temperature, whereas the latter is more important for larger particles and higher temperature. Dopant effects on densification kinetics are discussed in view of defect chemistry. Keywords: Dilatometry; Sintering; Diffusion; Superplastic deformation; Defect chemistry 1. Introduction 2. Experimental 3. Results and discussion 3.1. Influence of particle size 3.2. Effective activation energies 3.3. Influence of doping 3.4. Defect chemistry 4. Conclusion References