Paula M Jardim

Publications (2)4.57 Total impact

• Article: Large scale combustion synthesis of single-walled carbon nanotubes and their characterization.

  Henning Richter, Meri Treska, Jack B Howard, John Z Wen, Sebastien B Thomasson, Arthur A Reading, Paula M Jardim, John B Vander Sande
  [show abstract] [hide abstract]
  ABSTRACT: Since its invention in 1991, premixed combustion synthesis of fullerenic materials has been established as the major industrial process for manufacturing of these materials. Large-scale production of fullerenes such as C60, C70 and C84 has been implemented. More recently, combustion technology has been extended to the targeted synthesis of single-walled carbon nanotubes (SWCNT). Addition of catalyst precursor and operation at well-controlled fuel-rich but non-sooting conditions are required. Extensive parametric studies have allowed for the optimization of the formation of high-quality SWCNT. Purification techniques previously reported in the literature have been adjusted and used successfully for the nearly complete removal of metal and metal oxide. Material has been characterized using Raman spectroscopy, scanning (SEM) and transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Correlations between process conditions and nanotube properties such as length have been established. Product reproducibility and process scalability of the combustion process have been demonstrated. Sample preparation was found to affect significantly the apparent characteristics of nanotubes as seen in electron microscopy images.
  Journal of Nanoscience and Nanotechnology 12/2008; 8(11):6065-74. · 1.56 Impact Factor
• Article: Precipitate crystal structure determination in melt spun Mg-1.5wt%Ca-6wt%Zn alloy.

  Paula M Jardim, Guillermo Solórzano, John B Vander Sande
  [show abstract] [hide abstract]
  ABSTRACT: A melt-spun Mg-1.5%wtCa-6wt%Zn alloy was analyzed by means of transmission electron microscopy, energy dispersive X-ray spectroscopy, and scanning transmission electron microscopy. The as-solidified alloy exhibited both spherical matrix precipitates and elongated precipitates at the grain boundaries (grain-boundary films). After heat treatment, the alloy showed faceted precipitates (cuboidal shape), mostly on dislocations. It was found that the observed precipitates are the same compound, Ca2Mg6Zn3. As there was no crystallographic data for this compound in the literature, its crystal structure was investigated by comparison of experimental and simulated selected-area electron-diffraction patterns and high-resolution electron microscopy images. This study indicated that Ca2Mg6Zn3 is a trigonal compound with space group P 3 1c and lattice parameters a = 0.97 nm, c = 1.0 nm.
  Microscopy and Microanalysis 01/2003; 8(6):487-96. · 3.01 Impact Factor