Synthesis and Characterization of Alloys and Bimetallic Nanoparticles of CuNi Prepared by Sol-Gel Method
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Synthesis and Characterization of Alloys and Bimetallic Nanoparticles of CuNi Prepared by Sol-Gel Method E.L. de León-Quiroz1*, D. Vázquez Obregón1, A. Ponce Pedraza3, E. Larios-Rodríguez3, M. José-Yacaman3 and L.A. García-Cerda2*
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1 Instituto Tecnológico de Saltillo, Blvd. V. Carranza No. 2400, Saltillo, Coah., México Centro de Investigación en Química Aplicada), Blvd. Enrique Reyna No. 140, Saltillo, Coah., C.P. 25294, México 3 University of Texas at San Antonio. One UTSA Circle. San Antonio, TX. 78249 Corresponding authors: [email protected], [email protected]
ABSTRACT Recently, bimetallic nanostructures and nanoalloys have received special interest due to their promising chemical and physical properties. Specifically, Cu-Ni nanoparticles have been investigated for biomedical and catalytic applications. This work reports the synthesis of alloys and bimetallic nanoparticles of CuxNi100-x (x = 20, 40, 50, 60 and 80) by sol-gel method, and their morphological, structural and magnetic characterization. A precursor material was prepared using a standard Pechini method and then CuNi nanoparticles were obtained by calcination treatments of the precursor in H2/N2 atmosphere at 600 and 700°C for 15 minutes. The resulting nanoparticles were characterized by X-ray diffraction (XRD), which reveals that this method led to the formation of CuNi substitutional nanoalloys and bimetallic nanoparticles with good cristallinity related with the calcination temperatures and Cu:Ni weight ratios. Transmission electron microscopy (TEM) shows nearly monodisperse and uniform spherical nanoparticles with sizes between 40 and 70 nm. The magnetic properties were studied using SQUID magnetometry, according with these results, the CuNi nanoparticles showed a ferromagnetic behavior, the magnetization value increases as a function of the weight percentage of Ni. INTRODUCTION Nanoparticles are aggregates from a few to many millions of atoms or molecules. These may be formed of the same atoms or molecules, or by two or more different species, these can be studied in different media, such as vapor, colloidal suspensions, or isolated in different matrices [1,2]. The interest in nanoparticles arises in part because they are a new type of material which may have different properties from individual atoms and molecules or bulk material. A major reason for this interest is the evolution of their size-dependent properties and structure [2]. In fact, both the geometry and the energy stability of the groups may change dramatically with size. From the point of view of applications, there is a continuing interest in these materials due to their potential applications in fields such as catalysis and nanoelectronics [2]. Moreover, the range of properties can be expanded to metallic systems if these are mixed with other elements to generate intermetallic compounds and/or alloys. In many cases, there is an improvement in the specific properties of the metallic alloys due to synergistic effects and a rich variety of compositions, structures and properties w
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