Polyferrocenylsilanes Enable NIL-Fabricated Magneto-Ceramic Composite Nanorod Arrays
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more, which has become possible in the past few years, may produce FETs with a different gating mechanism and perhaps dramatically better characteristics than those made with more common 67% to
75% semiconducting mixes. Further characterization of field-modulated transport between metallic and semiconducting tubes, or through semiconducting tubes crossed by metallic tubes, will be important
in determining whether the predominantly semiconducting networks really are better.” STEVEN TROHALAKI
Polyferrocenylsilanes Enable NIL-Fabricated Magneto-Ceramic Composite Nanorod Arrays
use of aluminum-backed AAO templates to imprint patterns into PFS at elevated temperatures (150°C). Once raised above its glass transition temperature, the polymer melt was able to infiltrate the AAO template. The research team found that the extent of template filling was dependent on the temperature ramping rate. Under fast ramping conditions (15°C/min), the polymer partially filled the template but was able to completely fill the channels under slower ramping conditions (2°C/min). In order to form magnetic patterned ceramic features, the group melt-filled the AAO with polymer under N 2/H 2 (95%/5%) to avoid the formation of iron oxides. After cooling the template and removing the aluminum backing, the researchers heated the filled template to between 500°C and 800°C. They removed the AAO template by dissolution in NaOH to reveal the patterned magnetic
ceramic material. Of the three PFSs studied, only the polymer containing the acetylenic substituent gave a high enough ceramic yield (85%) to provide shape retention. At elevated temperatures, pyrolysis of PFS forms α-Fe nanoparticles that have a theoretical domain size of 14 nm. The researchers found that they were able to tune the magnetic properties of the particles by varying the diameter of the AAO template. When pyrolyzed in templates with 55 nm pores, the resulting particles had an average size of 8.2 nm ± 2.4 nm and exhibited superparamagnetic behavior; whereas, polymer pyrolyzed in templates with 95 nm pores resulted in particles with average diameters of 20.9 nm ± 4.9 nm and exhibited ferromagnetic behavior. The group hypothesizes that the “growth of the nanoparticles was confined by the diameter of the nanochannels.” KEVIN P. HERLIHY
lateral spatial resolution of 145 nm at λ 0 = 1.3 μm, which represents a resolution of ~λ 0/9, as they reported in the April 15 issue of Optics Letters (DOI: 10.1364/ OL.34.001261; p. 1261). The confocal microscopy setup the researchers developed is a single-path, reflection-mode fiber-optical scanning microscope that uses a single mode fibercoupled laser diode emitting at 1.3 μm and a 2 × 2 optical coupler. The researchers coupled the light in and out the single mode fiber with a collimating objective with matching NA and illuminated the sample and the NAIL using a second objective with NA = 0.26, the same objective that collected the reflected signal. The NAIL consisted of an undoped silicon hemisphere with radius of 1.61 mm. The images were gener
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