Metallic Nano Particles Embedded in Sapphire
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Metallic Nano Particles Embedded in Sapphire A. Crespo-Sosa, P.E. Mota-Santiago, J.L. Jiménez-Hernández, H.G. Silva-Pereyra, E.V. GarcíaRamírez, O. Sánchez-Dena, J.A. Reyes-Esqueda, A. Oliver. Instituto de Fisica, Universidad Nacional Autónoma de México, A.P. 20-364, 01000 México, D.F., Mexico. ABSTRACT Sapphire is best known for its hardness that makes it ideal for many mechanical and optical applications, but its resistance to radiation damage and its optical properties, combined with metallic nano-particles, make it promising for future opto-electronic and plasmonic devices. In this paper, we present an overview of our work on the fabrication of metallic nano-particles embedded in synthetic sapphire by means of ion implantation, thermal annealing and high energy ion irradiation. We show that we can have control over the amount and size of the nano particles formed inside the matrix by carefully choosing the parameters during the preparation process. Furthermore, we show that anisotropic nano particles can be obtained by an adequate high energy ion irradiation of the originally spherical nano particles. We also have studied the linear and non-linear optical properties of these nano-composites and have confirmed that they are large enough for future applications. INTRODUCTION Sapphire has been studied for many reasons for many years due to its very interesting physical and chemical properties. Amongst the most technologically useful of them are its hardness, high melting point, its resistance to radiation damage and luminescence due to defects and impurities [1]. Metallic nano particles in transparent dielectrics have also been studied because of the appearance of the local surface plasmon resonance (SPR) in the visible region of the electromagnetic spectrum. Associated with this resonance are many interesting nonlinear optical properties that promise to have a wide range of applications in technological devices like sensors or optoelectronic chips [2,3]. Perhaps the most ambitious research is in the accomplishment of plasmonic devices that could have the size of today's electronic devices but the speed of optical ones [4]. For this purpose, the full control and coupling of the surface plasmons is required. And it is well known that their properties depend strongly on their size, shape and assembly. Most of the work on this topic has been done, however, on metallic nano particles embedded in SiO2 and little on other matrixes [5]. Elongation of metallic nano particles has also been studied in SiO2 with a variety of ions and a good understanding of the underlying mechanism has been achieved, but unfortunately not proven in other systems [6,7]. In the process of elongation, the formation of an ion track as well as a difference in thermal stress have been assumed. These assumptions are, of course, in agreement with the SiO2 systems. As mentioned above, sapphire is known to have a large formation track threshold, as well as a high expansion coefficient. That means that elongation of
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