Synthesis and properties of Co–Pt alloy silica core-shell particles

  • Y. Kobayashi
  • H. Kakinuma
  • D. Nagao
  • Y. Ando
  • T. Miyazaki
  • M. Konno
Original Paper


This paper describes a method for fabrication of silica-coated Co–Pt alloy nanoparticles in a liquid phase process. The Co–Pt nanoparticles were prepared from CoCl2 (4.2 × 10−5 M), H2PtCl6 (1.8 × 10−5 M), citric acid (4 × 10−4 M) and NaBH4 (1.2 × 10−2 M) with a Co:Pt mole ratio of 7:3. The silica coating was performed in water/ethanol solution with a silane coupling agent, 3-aminopropyltrimethoxysilane (8 × 10−5 M), and a silica source, tetraethoxyorthosilicate (7.2 × 10−4 M) in the presence of the Co–Pt nanoparticles. Observations with a transmittance electron microscope and a scanning transmission electron microscope revealed that the Co-rich and Pt-rich nanoparticles were coated with silica. According to X-ray diffraction measurements, core particles were crystallized to metallic Co crystallites and fcc Co–Pt alloy crystallites with annealing in air at 300–500 °C. Magnetic properties of the silica-coated particles were strongly dependent on annealing temperature. Maximum values of 11.4 emu/g-sample for saturation magnetization and 365 Oe for coercive field were obtained for the particles annealed at 300 and 500 °C, respectively. Annealing at a temperature as high as 700 °C destroyed the coating structures because of crystallization of silica shell, resulting in reduction in saturation magnetization and coercive field.


Particle Alloy Co–Pt Silica Core-shell Sol–gel Coating Magnetic properties 



This research was partially supported by a Grant-in-Aid for Science Research (No. 15656163) and by the COE project, Giant Molecules and Complex Systems from the Ministry of Education, Culture, Sports, Science and Technology of Japan.


  1. 1.
    Wagner J, Autenrieth T, Hempelmann R (2002) J Magn Magn Mater 252:4CrossRefGoogle Scholar
  2. 2.
    Wu M, Zhang YD, Hui S, Xiao TD (2002) Appl Phys Lett 80:4404CrossRefGoogle Scholar
  3. 3.
    Mehta RV, Upadhyay RV, Charles SW, Ramchand CN (1997) Biotechnol Technol 11:493CrossRefGoogle Scholar
  4. 4.
    Zhang YD, Wang SH, Xiao DT, Budnick JI, Hines WA (2001) IEEE Trans Magn 37:2275CrossRefGoogle Scholar
  5. 5.
    Weller D, Moser A (1999) IEEE Trans Magn 35:4423CrossRefGoogle Scholar
  6. 6.
    Shang H, Wang J, Liu Q (2007) Mater Sci Eng A 456:130CrossRefGoogle Scholar
  7. 7.
    Upadhyay C, Verma HC, Sathe V, Pimpale AV (2007) J Magn Magn Mater 312:271CrossRefGoogle Scholar
  8. 8.
    Duong GV, Turtelli RS, Thuan BD, Linh DV, Hanh N, Groessinger R (2007) J Non-Cryst Solids 353:811CrossRefGoogle Scholar
  9. 9.
    Gul IH, Abbasi AZ, Amin F, Anis-ur-Rehman M, Maqsood A (2007) J Magn Magn Mater 311:494CrossRefGoogle Scholar
  10. 10.
    Baldi G, Bonacchi D, Innocenti C, Lorenzi G, Sangregorio C (2007) J Magn Magn Mater 311:10CrossRefGoogle Scholar
  11. 11.
    Duong GV, Hanh N, Linh DV, Groessinger R, Weinberger P, Schafler E, Zehetbauer M (2007) J Magn Magn Mater 311:46CrossRefGoogle Scholar
  12. 12.
    Maaz K, Mumtaz A, Hasanain SK, Ceyla A (2007) J Magn Magn Mater 308:289CrossRefGoogle Scholar
  13. 13.
    Park S-J, Kim S, Lee S, Khim ZG, Char K, Hyeon T (2000) J Am Chem Soc 122:8581CrossRefGoogle Scholar
  14. 14.
    Racka K, Gich M, Ślawska-Waniewska A, Roig A, Molins E (2005) J Magn Magn Mater 290–291:127CrossRefGoogle Scholar
  15. 15.
    Osuna J, de Caro D, Amiens C, Chaudret B, Snoeck E, Respaud M, Broto J-M, Fert A (1996) J Phys Chem 100:14571CrossRefGoogle Scholar
  16. 16.
    Giersig M, Hilgendorff M (1999) J Phys D 32:L111CrossRefGoogle Scholar
  17. 17.
    Ely TO, Amiens C, Chaudret B, Snoeck E, Verelst M, Respaud M, Broto J-M (1999) ChemMater 11:526Google Scholar
  18. 18.
    Cordente N, Respaud M, Senocq F, Casanove M-J, Amiens C, Chaudret B (2001) Nano Lett 1:565CrossRefGoogle Scholar
  19. 19.
    Sun Y-P, Rollins HW, Guduru R (1999) Chem Mater 11:7CrossRefGoogle Scholar
  20. 20.
    Tyson TA, Conradson SD, Farrow RFC, Jones BA (1996) Phys Rev B 54:R3702CrossRefGoogle Scholar
  21. 21.
    Weller D, Brändle H, Chappert C (1993) J Magn Magn Mater 121:461CrossRefGoogle Scholar
  22. 22.
    Grange W, Maret M, Kappler J-P, Vogel J, Fontaine A, Petroff F, Krill G, Rogalev A, Coulon J, Finazzi M, Brookes N (1998) Phys Rev B 58:6298CrossRefGoogle Scholar
  23. 23.
    Weller D, Brändle H, Gorman G, Lin C-J, Notarys H (1992) Appl Phys Lett 61:2726CrossRefGoogle Scholar
  24. 24.
    Lin C-J, Gorman GL (1992) Appl Phys Lett 61:1600CrossRefGoogle Scholar
  25. 25.
    Shapiro AL, Rooney PW, Tran MQ, Hellman F, Ring KM, Kavanagh KL, Rellinghaus B, Weller D (1999) Phys Rev B 60:12826CrossRefGoogle Scholar
  26. 26.
    Chang G, Lee Y, Rhee J, Lee J, Jeong K, Whang C (2001) Phys Rev Lett 87:067208CrossRefGoogle Scholar
  27. 27.
    Ely TO, Pan C, Amiens C, Chaudret B, Dassenoy F, Lecante P, Casanove M-J, Mosset A, Respaud M, Broto J-M (2000) J Phys Chem B 104:695CrossRefGoogle Scholar
  28. 28.
    Carpenter EE, Seip CT, O’Connor CJ (1999) J Appl Phys 85:5184CrossRefGoogle Scholar
  29. 29.
    Liou SH, Huang S, Klimek E, Kirby RD, Yao YD (1999) J Appl Phys 85:4334CrossRefGoogle Scholar
  30. 30.
    Thielen M, Kirsch S, Weinforth A, Carl A, Wassermann EF (1998) IEEE Trans Magn 34:1009CrossRefGoogle Scholar
  31. 31.
    Yamada Y, Suzuki T, Abarra EN (1998) IEEE Trans Magn 34:343CrossRefGoogle Scholar
  32. 32.
    Park J-I, Cheon J (2001) J Am Chem Soc 123:5743CrossRefGoogle Scholar
  33. 33.
    Yu ACC, Mizuno M, Sasaki Y, Kondo H, Hiraga K (2002) Appl Phys Lett 81:3768CrossRefGoogle Scholar
  34. 34.
    Shevchenko EV, Talapin DV, Schnablegger H, Kornowski A, Festin Ö, Svedlindh P, Haase M, Weller H (2003) J Am Chem Soc 125:9090CrossRefGoogle Scholar
  35. 35.
    Sobal NS, Ebels U, Möhwald H, Giersig M (2003) J Phys Chem B 107:7351CrossRefGoogle Scholar
  36. 36.
    Gibot P, Tronc E, Chanéac C, Jolivet JP, Fiorani D, Testa AM (2005) J Magn Magn Mater 290–291:555CrossRefGoogle Scholar
  37. 37.
    Du X, Inokuchi M, Toshima N (2006) J Magn Magn Mater 299:21CrossRefGoogle Scholar
  38. 38.
    Ohmori M, Matijeviç E (1992) J Colloid Interface Sci 150:594CrossRefGoogle Scholar
  39. 39.
    Ohmori M, Matijeviç E (1993) J Colloid Interface Sci 160:288CrossRefGoogle Scholar
  40. 40.
    Philipse AP, van Bruggen MPB, Pathmamanoharan C (1994) Langmuir 10:92CrossRefGoogle Scholar
  41. 41.
    Correa-Duarte MA, Giersig M, Kotov NA, Liz-Marzán LM (1998) Langmuir 14:6430CrossRefGoogle Scholar
  42. 42.
    Liu Q, Xu Z, Finch JA, Egerton R (1998) Chem Mater 10:3938Google Scholar
  43. 43.
    Tago T, Hatsuta T, Miyajima K, Kishida M, Tashiro S, Wakabayashi K (2002) J Am Ceram Soc 85:2188CrossRefGoogle Scholar
  44. 44.
    Lu Y, Yin Y, Mayers BT, Xia Y (2002) Nano Lett 1:183CrossRefGoogle Scholar
  45. 45.
    Kobayashi Y, Horie M, Konno M, Rodríguez-González B, Liz-Marzán LM (2003) J Phys Chem B 10:7420CrossRefGoogle Scholar
  46. 46.
    Kobayashi Y, Horie M, Nagao D, Ando Y, Miyazaki T, Konno M (2006) Mater Lett 60:2046CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • Y. Kobayashi
    • 1
    • 2
  • H. Kakinuma
    • 1
  • D. Nagao
    • 1
  • Y. Ando
    • 3
  • T. Miyazaki
    • 3
  • M. Konno
    • 1
  1. 1.Department of Chemical Engineering, Graduate School of EngineeringTohoku UniversitySendaiJapan
  2. 2.Department of Biomolecular Functional Engineering, College of EngineeringIbaraki UniversityHitachiJapan
  3. 3.Department of Applied Physics, Graduate School of EngineeringTohoku UniversitySendaiJapan

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