Sr2SiO4螢光材料由於具有優異的化學與熱穩定性，可望取代商業化白色發光二極體之YAG螢光粉。目前工業上量產Sr2SiO4粉末，仍以需要較高反應溫度之固態反應法為主，容易造成粉末之凝聚且耗能，因此，降低粉末之熱處理溫度成為未來必然之趨勢，此外Sr2SiO4反應機構至今仍未被明確的探討。
本研究以二氧化矽披覆於碳酸鍶之表面，欲建立以核殼構造結合之反應物系統，並且探討Sr2SiO4粉末之固態反應機制。此外，利用適當之披覆製程條件，嘗試於較低溫度合成Sr2SiO4粉末。
實驗結果顯示，以二氧化矽披覆於碳酸鍶之表面，可以有效增加反應物之間的接觸面積與混合均勻性，縮短反應所需之擴散距離，達到促進介面反應進行之效益；另一方面，較低溫(600～800℃)之Sr2SiO4生成反應過程，推測為矽離子擴散所主導，當反應溫度高達到純碳酸鍶足以分解之溫度，反應才由碳酸鍶之分解所主導。本研究成功於800℃熱處理條件下，得到接近純相之Sr2SiO4粉末。

The Sr2SiO4 can replace YAG as a phosphor material for white light emitting diodes (LEDs) due to its excellent chemical and thermal stability. Presently, Sr2SiO4 powder is mainly mass-produced using a solid-state reaction from SrCO3 and SiO2. But, the conventional high-temperature solid-state reaction easily leads to coarsening and particle agglomerations. On the other hand, the reaction mechanism between SrCO3 and SiO2 for formation of the Sr2SiO4 is not well understood so far. In this study, the SrCO3 -SiO2 core-shell structure was prepared to reduce the heat treatment temperature and the Sr2SiO4 formation mechanism was discussed.
The experimental results indicate that the surface coating SrCO3 with SiO2 raises the contact area and mixture homogeneity of reactants, which promotes the interfacial reaction to from Sr2SiO4 and reduces Sr2SiO4 formation temperature drastically due to the decrease of the diffusion distance. Since the reaction temperature is too low to result in the decomposition of SrCO3, the mechanism in this stage is suggested to be dominated by the silicon diffusion. However, when the reaction temperature is higher than the decomposition temperature of pure SrCO3, the mechanism can be dominated by the strontium diffusion. Using the SrCO3 -SiO2 core-shell structure, the Sr2SiO4 powder can be successfully prepared at a temperature as low as 800℃.

1. M. Catti, G. Gazzoni and G. Ivaldi , “Structures of Twinned β-Sr2SiO4 and of α'-Sr1.9Ba0.1SiO4,” Acta. Cryst., C39 29-34 (1983).
2. R .D. Shannon, “Revised Effective Ionic Radii and Systematic Studies of Interatomic Distances in Halides and Chalcogenides,”Acta. Cryst., A32 751–767 (1976).
3. S. H. M. Poort, W. Janssen and G. Blasse, “Optical Properties of Eu2+-activated Orthosilicates and Orthophosphates,”J. Alloys Compd., 260 93-97 (1997).
4. N. Lakshminarasimhan and U. V. Varadaraju, “White-Light Generation in Sr2SiO4：Eu2＋, Ce3＋ under Near-UV Excitation,”J. Electrochem. Soc., 152 [9] H152-H156 (2005).
5. A. Nag and T.R.N. Kutty, “The Light Induced Valence Change of Europium in Sr2SiO4： Eu involving Transient Crystal Structure,”J. Mater. Chem., 14 1598-1604 (2004).
6. J. K. Park, M. A. Lim, C. H. Kim and H. D. Park, “White Light-Emitting Diodes of GaN-Based Sr2SiO4：Eu and the Luminescent Properties,”Appl. Phys.Lett., 82, number 5 (2003).
7. J. K. Park, K. J. Choi, S. H. Park, C. H. Kim and H. K. Kim, “Application of Ba2＋．Mg2＋ Co-doped Sr2SiO4：Eu Yellow Phosphor for White-Light-Emitting Diodes, ”J. Electrochem. Soc., 152 [8] H121-H123 (2005).
8. J. Y. Kuang and Y. L. Liu, “White-Emitting Long-lasting Phosphor Sr2SiO4:Dy3＋,” Chem. Lett., 34 [4] (2005).
9. L. Zhang, X. Zhou, H. Zeng, H. Chen and X. Dong, “White-Light Long-Lasting Phosphor Sr2SiO4:Pr3+,”Mater. Lett., 62 2539–2541 (2008).
10. W. R. Blumenthal and D. S. Philips, “High-Temperature Deformation of Single-Crystal Yttrium-Aluminum Garnet (YAG),”J. Am. Ceram. Soc., 79 [4] 1047 (1996).
11. 李盼來,楊志平,王志軍,熊志軍,郭慶林,“Sr2SiO4：Eu3+發光材料的製備及其光譜特性, ”Acta. Phys.- Chim. Sin., 24 (1) 179-182 (2008).
12 H. S. Kang, S. K. Hong, Y. C. Kang, K. Y. Jung, Y. G. Shul and S. B. Park, “The Enhancement of Photoluminescence Characteristics of Eu-doped Barium Strontium Silicate Phosphor Particles by co-doping Materials,”J.Alloys Compd.402 246-250 (2005).
13. M. Pechini, U. S. Patent 3, 330, p697 (1967).
14 I. Nettleship, J. L. Shull and W. M. Kriven, “Chemical Preparation and Phase Stability of Ca2SiO4 and Sr2SiO4 Powders”J.Euro. Ceram. Soc., 2 291-198 (1993).
15. J. S. Benjamin, “Dispersion Strengthened Superalloys by Mechanical Alloying,” Metall. Trans, 10 pp.2943 (1970).
16. N. Stehr,, Recent Developments in Stirred Ball Milling, Int.J.Mineral Processing, 22, pp.431 (1988).
17. K. Sakurai and X. Guo, “Mechanical Solid-State Formation of Y1-xCexAlO3 and Its application as an X-ray Scintillator,”Mater. Sci. Eng. A304– 306 403– 407 (2001).
18. L. B. Kong, J. Ma and H. Huang, “Low Temperature Formation of Yttrium Aluminum Garnet from Oxides via a High-Energy Ball Milling Process,”Mater. Lett. 56 [3] 344-348 (2002)
19. V. Berbenni, A. Marini and G. Bruni, “Effect of Mechanical Milling on Solid State Formation of BaTiO3 From BaCO3-TiO2 (rutile) Mixtures,” Thermochimica Acta, 374 [2] 151-158 (2001).
20. M. T. Buscaglia, V. Buscaglia and R. Alessio, “Coating of BaCO3 Crystals with TiO2：Versatile Approach to the Synthesis of BaCO3 Tetragonal Nanoparticles,” Chem. Mater, 19 711-718 (2007).
21. 趙承琛編著，界面科學基礎，復文書局，中華民國89 年10 月。
22. A. Banerjee, T. R. Ramamohan and M. J. Patni, “Smart Technique for Fabrication of Zinc Oxide Varistor,” Mater. Res. Bull., 36 1259-1267 (2001).
23. D.J. Shaw, Introduction to Colloid and Surface Chemistry, Butterworth-Heinemann, Oxford, 4th ed. (1992)
24. R.J. Hunter, Introduction to Modern Colloid Science, Oxford University Press Inc., New York,(1993).
25. W.D. Kingery, H.K. Bowen, and D.R. Uhlmann, Introduction to Ceramics,
John Wiley & Sons, New York, 2nd ed. (1976).
26. 黃聖哲，SiO2 對奈米級錳鋅鐵氧磁體粉末燒結及燒結體性質之影響。國立成功大學材料科學及工程學系碩士論文、(2002)。
27. C. L. Chang and H. S. Fogler, “Kinetics of Silica Particle Formation in Nonionic W/O Microemulsions from TEOS,” AIChE J., 42[11], 3153 (1996).
28. R. Aelion, A. Loebel and F. Eirich, “Hydrolysis of Ethyl Silicate,” J. Am. Chem.
Soc. 72, 5705 (1950).
29. R. K. Iler, “The Chemistry of Silica,” Woley-Interscience (1979).
30. Z. Z. Vysotskii et al., p.72 in “Adsorption and Adsorbents” No. 1. John Wiley &
Sons (1973).
31. R. K. Iler, “The Chemistry of Silica,” Woley-Interscience (1979).
32. C. Okkerse, “Porous Silica,” Chapter 5, in “Physical Chem. Aspects of Adsorbents
and Catalysis”
33. 阮俊杰，以溶膠-凝膠法製備聚碳酸酯與二氧化矽混成有機/無機奈米複合材料
及性質研究。國立清華大學化學工程學系碩士論文、(2002)。
34. M. W. Colby, A. Osaka and J. D. Mackenzie, “Effect of Temperature on Formation of Silica Gel,”J. Non-cryst. Solids, 82 37-41 (1986).
35. J. Yuan, K. Kajiyoshi, H. Sasaoka and K. Nishimura, “Fabrication and Characterization of Silica Nanocoatings on ZnS phosphor Particles,”Nanotechnology, 18 095607 (5pp) (2007).
36. Infrared and Raman Characteristic Group Frequencies: Tables and Charts, 3rd Edition
37. D. L. Ou and A. B. Seddon, “Near – and Mid – Infrared Spectroscopy of Sol – Gel Derived Ormosils：Vinyl and Phenyl Silicates,”J. Non Cryst. Solids, 210 [2～3] 187-203 (1997).
38. Y. L. Lin, T. J. Wang and Y. Jin, “Surface Characteristics of Hydrous Silica-Coated TiO2 Particles,”Powder Technol., 123 [2] 194-198 (2002).
39. E. Lidén, L. Bergström, M. Persson and R. Carlsson, “Surface Modification and Dispersion of Silicon Nitride and Silicon Carbide Powers,”J. Eur. Ceram. Soc., 7 [6] 361-368 (1991).
40. Y. F. Tang, Z. P. Huang, L. Feng and Y. F. Chen, “Fabrication of α-AlO(OH)-SiO2 with Core-Shell Structures by Heterogeneous Nucleation-and-Growth Processing”Appl. Surf. Sci., 241 412-415 (2005).
41. S. F. Wang, Y. F. Hsu, C. K. Yang, C. M. Chang, Y. Chen, C. Y. Huang and F. S. Yen, “Silica Coating on Ultrafine α-Alumina Particles,”Mater. Sci. Eng., A, 395 148-152 (2005).
42. G. Wang, P. Sarkar and P. S. Nicholson, “Influence of Acidity on the Electrostatic Stability of Alumina Suspensions in Ethanol,”J. Am. Ceram. Soc., 80 [4] 965-972 (1997).
43. 無機物熱力學數據手冊。
44. D. E. Rase and R. Roy, “Phase Equilibria in the System BaO-TiO2,”J. Am. Ceram. Soc., 38 [3] 102-113 (1955).
45. C. H. Lu and P. C. Wu, “Reaction Mechanism and Kinetic Analysis of the Formation of Sr2SiO4 via Solid-State Reaction,”J. Alloys. Compd., 466 457-462 (2008).
46. O. Yamaguchi, K. Yabuno, K. Takeoka and K. Shimizu, “Mechanism of Solid State Reaction between SrCO3 and SiO2,”Chem.lett., 401-404 (1979).
47. J. D. Hancock and J. H. Sharp, “Method of Comparing Solid-State Kinetic Data and its Application to the Decomposition of Kaolinite, Brucite, and BaCO3,”J. Am. Ceram. Soc., 55 74 (1972).
48. I. Arvanitidis, D. Sichen, H. Y. Sohn, and S. Seetharaman, “The Intrinsic Thermal Decomposition Kinetics of SrCO3 by a Nonisothermal Technique,” Metallogr. Mater. Trans., B. 28 [B] 1063-1068 (1997).