Structural and Magnetic Characterizations of Gold and Silica Doubly Coated $\gamma $-Fe$_{2}$O$_{3}$ Nanoparticles

ORAL

Abstract

An extensive structural and magnetic characterization has been carried out on the gold (Au) and silica (SiO$_{2})$ doubly coated $\gamma $-Fe$_{2}$O$_{3}$ nanoparticles. The phase of the uncoated and Au/SiO$_{2}$ coated nanoparticles were studied by powder x-ray diffraction (XRD) and x-tray absorption spectroscopy (XAS), which show that the iron oxide particles before and after coating have the phase of $\gamma $-Fe$_{2}$O$_{3. }$The transmission electron microscopy (TEM) results indicate that the average sizes of the $\gamma $-Fe$_{2}$O$_{3.}$cores, the Au/SiO$_{2}$ coated Fe$_{2}$O$_{3 }$ nanoparticles, and the Au nanoparticles in the Au nanoshells are about 12 nm, 92 nm, and 7 nm, respectively. We have the following observations from the magnetization measurements: (i) both the uncoated and coated nanoparticles are superparamagnetic at room temperature (T), and the Au nanoparticles are diamagnetic at all temperatures, (ii) the blocking temperature is decreased by the Au/SiO$_{2}$ double coating, and (iii) the coercivity for both the uncoated and coated nanoparticles decreases almost linearly with T$^{ \raise.5ex\hbox{$\scriptstyle 1$}\kern-.1em/ \kern-.15em\lower.25ex\hbox{$\scriptstyle 2$} }$ with the latter decreasing faster than the former.

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Authors

  • Gan Liang

    Sam Houston State University

  • Kevin Boos

    Angelo State University, Texas State University, San Marcos, SEMATECH, Texas State University, University of Texas at Brownsville, Abilene Christian University, Texas Tech University, University of Texas at Austin, Maypearl High School, Birdville ISD, South Texas Chapter, Health Physics Society, Sam Houston State University, NASA Johnson Space Center, Dept. of Physics, U. de Buenos Aires, Argentina, Dept.of Physics, ESFM-IPN, Mexico City, University of Texas M.D. Anderson Cancer Center, Rutgers University, Texas A\&M University, Istanbul University, University of North Texas, University of Texas at El Paso, Texas Christian University, Lee College, Southern University and A\&M College, Austin Community College, Rapoport Academy, Texas A\&M University, Kingsville, The University of Texas at Arlington, Tyler Junior College, Tarleton State University, Tolar High School, Granbury High School, Lake Highlands High School

  • Kevin Boos

    Angelo State University, Texas State University, San Marcos, SEMATECH, Texas State University, University of Texas at Brownsville, Abilene Christian University, Texas Tech University, University of Texas at Austin, Maypearl High School, Birdville ISD, South Texas Chapter, Health Physics Society, Sam Houston State University, NASA Johnson Space Center, Dept. of Physics, U. de Buenos Aires, Argentina, Dept.of Physics, ESFM-IPN, Mexico City, University of Texas M.D. Anderson Cancer Center, Rutgers University, Texas A\&M University, Istanbul University, University of North Texas, University of Texas at El Paso, Texas Christian University, Lee College, Southern University and A\&M College, Austin Community College, Rapoport Academy, Texas A\&M University, Kingsville, The University of Texas at Arlington, Tyler Junior College, Tarleton State University, Tolar High School, Granbury High School, Lake Highlands High School

  • Kevin Boos

    Angelo State University, Texas State University, San Marcos, SEMATECH, Texas State University, University of Texas at Brownsville, Abilene Christian University, Texas Tech University, University of Texas at Austin, Maypearl High School, Birdville ISD, South Texas Chapter, Health Physics Society, Sam Houston State University, NASA Johnson Space Center, Dept. of Physics, U. de Buenos Aires, Argentina, Dept.of Physics, ESFM-IPN, Mexico City, University of Texas M.D. Anderson Cancer Center, Rutgers University, Texas A\&M University, Istanbul University, University of North Texas, University of Texas at El Paso, Texas Christian University, Lee College, Southern University and A\&M College, Austin Community College, Rapoport Academy, Texas A\&M University, Kingsville, The University of Texas at Arlington, Tyler Junior College, Tarleton State University, Tolar High School, Granbury High School, Lake Highlands High School

  • Kevin Boos

    Angelo State University, Texas State University, San Marcos, SEMATECH, Texas State University, University of Texas at Brownsville, Abilene Christian University, Texas Tech University, University of Texas at Austin, Maypearl High School, Birdville ISD, South Texas Chapter, Health Physics Society, Sam Houston State University, NASA Johnson Space Center, Dept. of Physics, U. de Buenos Aires, Argentina, Dept.of Physics, ESFM-IPN, Mexico City, University of Texas M.D. Anderson Cancer Center, Rutgers University, Texas A\&M University, Istanbul University, University of North Texas, University of Texas at El Paso, Texas Christian University, Lee College, Southern University and A\&M College, Austin Community College, Rapoport Academy, Texas A\&M University, Kingsville, The University of Texas at Arlington, Tyler Junior College, Tarleton State University, Tolar High School, Granbury High School, Lake Highlands High School

  • Kevin Boos

    Angelo State University, Texas State University, San Marcos, SEMATECH, Texas State University, University of Texas at Brownsville, Abilene Christian University, Texas Tech University, University of Texas at Austin, Maypearl High School, Birdville ISD, South Texas Chapter, Health Physics Society, Sam Houston State University, NASA Johnson Space Center, Dept. of Physics, U. de Buenos Aires, Argentina, Dept.of Physics, ESFM-IPN, Mexico City, University of Texas M.D. Anderson Cancer Center, Rutgers University, Texas A\&M University, Istanbul University, University of North Texas, University of Texas at El Paso, Texas Christian University, Lee College, Southern University and A\&M College, Austin Community College, Rapoport Academy, Texas A\&M University, Kingsville, The University of Texas at Arlington, Tyler Junior College, Tarleton State University, Tolar High School, Granbury High School, Lake Highlands High School

  • Kevin Boos

    Angelo State University, Texas State University, San Marcos, SEMATECH, Texas State University, University of Texas at Brownsville, Abilene Christian University, Texas Tech University, University of Texas at Austin, Maypearl High School, Birdville ISD, South Texas Chapter, Health Physics Society, Sam Houston State University, NASA Johnson Space Center, Dept. of Physics, U. de Buenos Aires, Argentina, Dept.of Physics, ESFM-IPN, Mexico City, University of Texas M.D. Anderson Cancer Center, Rutgers University, Texas A\&M University, Istanbul University, University of North Texas, University of Texas at El Paso, Texas Christian University, Lee College, Southern University and A\&M College, Austin Community College, Rapoport Academy, Texas A\&M University, Kingsville, The University of Texas at Arlington, Tyler Junior College, Tarleton State University, Tolar High School, Granbury High School, Lake Highlands High School