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  • 1. Solid State Reaction: General - Reaction between the solids Advantages 1. Simple apparatus (ball milling, A+B rotatory evaporator) 2. Inexpensive (cost-effective) Disadvantages 1. Wide particle-size distribution 2. Coarse particle size ( ≥1µm) 3. Contamination during mixing 4. High temperature is required for reaction especially when the particle size is large C+A+B or when the mixing is insufficient 5. Compositional fluctuation due to the incomplete reaction 6. Difficult to control the particle shape Advanced Electronic Ceramics I (2004) Rotatory evaporator http://www.buchi-analytical.com/file/2/ct_1120_ctDownload1.pdf Advanced Electronic Ceramics I (2004)
  • 2. Solid State Reaction AO BO2 Starting powder Incomplete reaction Proper reaction Strong bond due to excessive reaction ABO3 A+ AO BO2 AO BO2 L ∝ t1/2 B2+ L Ceramic Processing: Powder Preparation and Forming, Ceramic Society of Japan (1984) Advanced Electronic Ceramics I (2004) Solid State Reaction: Particle size (1) coarse particles AO AO ABO3 BO2 BO2 L ∝ t1/2 (2) fine particles AO ABO3 BO2 For complete reaction, t1 = 4t2 Ceramic Processing: Powder Preparation and Forming, Ceramic Society of Japan (1984) Advanced Electronic Ceramics I (2004)
  • 3. Solid State Reaction: Particle-size distribution At the presence of a coarse particle in a fine matrix particles AO ABO3 BO2 BO2 Strong bond between particles can be occurred when the reaction time increased in order to achieve complete reaction Ceramic Processing: Powder Preparation and Forming, Ceramic Society of Japan (1984) Advanced Electronic Ceramics I (2004) Solid State Reaction: mixing (1) good mixing AO BO2 AO ABO3 BO2 (2) bad mixing AO ABO3 BO2 Ceramic Processing: Powder Preparation and Forming, Ceramic Society of Japan (1984) Advanced Electronic Ceramics I (2004)
  • 4. Solid State Reaction: other parameters 1. Compaction or filling state - The reaction occurs and the contact points between two phase 2. Temperature - the temperature dependence of diffusion coefficient D = Do exp (-E/RT) Ceramic Processing: Powder Preparation and Forming, Ceramic Society of Japan (1984) Advanced Electronic Ceramics I (2004) Solid State Reaction: BaTiO3 Fig. In-situ X-ray diffraction BL: γ-BaCO3, BH: β-BaCO3, T: TiO2, B2T: Ba2TiO4, BT: BaTiO3, BT3: BaTi3O7, BaCO3: BT4: BaTi4O9, TiO2 B2T formation from ~800oC BT formation from ~900oC The completion of BT formation : ~1200oC Temperature (oC) Ceramic Processing: Powder Preparation and Forming, Ceramic Society of Japan (1984) Advanced Electronic Ceramics I (2004)
  • 5. Solid State Reaction: BaTiO3 Fig. In-situ X-ray diffraction BL: γ-BaCO3, BH: β-BaCO3, T: TiO2, B2T: Ba2TiO4, BT: BaTiO3, BT3: BaTi3O7, BT4: BaTi4O9, BaCO3: TiO2 Avg. size of BaTiO3: 1 µm (A) avg. size of TiO2: 6.5 µm (B) avg. size of TiO2: 2.0 µm (C) avg. size of TiO2: 0.05 µm In the case of fine powder, - small B2T formation - BT formation Temperature (oC) at low temperature Ceramic Processing: Powder Preparation and Forming, Ceramic Society of Japan (1984) Advanced Electronic Ceramics I (2004) Solid State Reaction: BaTiO3 Fig. In-situ X-ray diffraction BL: γ-BaCO3, BH: β-BaCO3, T: TiO2, B2T: Ba2TiO4, BT: BaTiO3, BT3: BaTi3O7, BT4: BaTi4O9, BaCO3: TiO2 The curves for the co-precipitated BaTiO3 powder - almost no intermediate reaction - low temperature formation Temperature (oC) Ceramic Processing: Powder Preparation and Forming, Ceramic Society of Japan (1984) Advanced Electronic Ceramics I (2004)
  • 6. Solid State Reaction: BaTiO3 1. Reaction at the contact points In order to avoid the incomplete reaction, - smaller particle size - good mixing - narrow particle-size distribution - good compaction between particles 2. Reaction at relatively high temperature - frequently results the milling the powder aggregates for further process - involves the contamination during ball milling Ceramic Processing: Powder Preparation and Forming, Ceramic Society of Japan (1984) Advanced Electronic Ceramics I (2004)