Enhanced thermal stability of silica-encapsulated metal nanoshells

A silica-encapsulating layer of a 60–70 nm thickness is fabricated around composite nanoparticles consisting of a silica core and a gold shell (metal nanoshells). The outer silica layer provides greatly enhanced thermal stability to the nanoparticle, effectively raising its melting temperature by 300° relative to uncoated nanoshells. Both spectroscopic and microscopic structural evaluations are used to assess changes in the nanostructure when subjected to potentially destructive heating cycles. This encapsulation method may prove valuable in enhancing the thermal stability of other types of assembled nanostructures and nanoscale photonic materials.

[1]  Michael Vollmer,et al.  Optical properties of metal clusters , 1995 .

[2]  Naomi J. Halas,et al.  Surface enhanced Raman scattering in the near infrared using metal nanoshell substrates , 1999 .

[3]  P. Buffat,et al.  Size effect on the melting temperature of gold particles , 1976 .

[4]  Naomi J. Halas,et al.  Nanoengineering of optical resonances , 1998 .

[5]  S. L. Westcott,et al.  Infrared extinction properties of gold nanoshells , 1999 .

[6]  L. Liz‐Marzán,et al.  Stabilization of CdS semiconductor nanoparticles against photodegradation by a silica coating procedure , 1998 .

[7]  W. Jesser,et al.  Thermodynamic theory of size dependence of melting temperature in metals , 1977, Nature.

[8]  R. Vanfleet,et al.  Thermodynamics of melting and freezing in small particles , 1995 .

[9]  Choi,et al.  Size-dependent melting temperature of individual nanometer-sized metallic clusters. , 1990, Physical review. B, Condensed matter.

[10]  Naomi J. Halas,et al.  Light scattering from dipole and quadrupole nanoshell antennas , 1999 .

[11]  W. Stöber,et al.  Controlled growth of monodisperse silica spheres in the micron size range , 1968 .

[12]  Paul Mulvaney,et al.  Controlled Method for Silica Coating of Silver Colloids. Influence of Coating on the Rate of Chemical Reactions , 1998 .

[13]  Jooho Moon,et al.  Preparation of Ag/SiO2 nanosize composites by a reverse micelle and sol-gel technique , 1999 .

[14]  M. Natan,et al.  Hydroxylamine Seeding of Colloidal Au Nanoparticles. 3. Controlled Formation of Conductive Au Films , 2000 .

[15]  Naomi J. Halas,et al.  Plasmon Resonance Shifts of Au-Coated Au 2 S Nanoshells: Insight into Multicomponent Nanoparticle Growth , 1997 .

[16]  G. Mie.  Beiträge zur Optik trüber Medien, speziell kolloidaler Metallösungen , 1908 .

[17]  D. Balding,et al.  HLA Sequence Polymorphism and the Origin of Humans , 2006 .

[18]  L. Liz‐Marzán,et al.  Silica-coated metals and semiconductors. Stabilization and nanostructuring , 2000 .

[19]  S. L. Westcott,et al.  Temperature-sensitive polymer-nanoshell composites for photothermally modulated drug delivery. , 2000, Journal of biomedical materials research.

[20]  Paul Mulvaney,et al.  Synthesis of Nanosized Gold−Silica Core−Shell Particles , 1996 .

[21]  Andreoni,et al.  Melting of small gold particles: Mechanism and size effects. , 1991, Physical review letters.

[22]  R. A. Bayles,et al.  Small particle melting of pure metals , 1986 .

[23]  Milton Kerker,et al.  Scattering of Electromagnetic Waves from Two Concentric Spheres , 1951 .