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Oriented Co[sub x]Ni[sub 1-x] nanoparticles were synthesized by sequential implantation of 90 keV Co and Ni ions at room temperature in the near surface of an yttria-stabilized zirconia single crystal. Transmission electron microscopy and a superconducting quantum interference device magnetometer as well as a vibrating sample magnetometer were utilized to characterize the structural and magnetic properties of the implanted layer. Typical nanoparticles range from 3 to 10 nm in diameter, and some elongated precipitates as long as 25 nm were formed by joining the nanoparticles with nanotwins. Hysteresis loops were measured at both 300 and 10 K, and showed coercivity of 100 or 250 Oe, respectively. Magnetization versus temperature in zero-field-cooled and field-cooled fields was measured. No obvious superparamagnetism was detected below 300 K. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

High magnetocrystalline anisotropy CoPt particles with an average size of 8 nm were synthesized by the superhydride reduction of CoCl2 and Pt(acac)2 at a high temperature. As-made particles showed a disordered face-centered cubic lattice and were superparamagnetic. Upon heat treatment at temperatures above 600 °C, the particles transformed to the L10 phase, as indicated by the appearance of the superlattice peaks in the x-ray diffraction and high magnetocrystalline anisotropy. The temperature dependence of the coercivity of nanoparticles annealed at 650 °C was measured from 10 to 300 K and analyzed using a Sharrock formula. After annealing at 650 °C, the anisotropy of the nanoparticles was K∼1.7×107 erg/cm3. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report the high temperature reaction of iron acetylacetonate in phenyl ether in the presence of oleic acid and oleylamine that was used to synthesize monodisperse Fe3O4 nanoparticles. X-ray diffraction profile and high-angle annular dark-field images give evidence of self-assembled arrays with nanoparticle size of 4 nm. Magnetization versus temperature in the temperature range 2.5–160 K was measured in zero-field-cooled and field-cooled experiments and a blocking temperature Tb=20 K was obtained. Above Tb the nanoparticles show superparamagnetic behavior and the magnetization versus field for various temperature follows the Langevin function. M-H curves below Tb indicate the ferromagnetic behavior with Hc=60–400 Oe for temperature T=2.5–18.5 K. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this letter, we coupled nanodiamonds (NDs) with gold nanoparticles of different sizes using two complementary DNA sequences. After hybridizing the gold nanoparticles on the NDs, we observed the enhancement of the photoluminescence (PL) signals originating from the nitrogen-vacancy (N-V) center of the ND. The enhancement was attributed to the plasmon field created by the gold nanoparticles. The line shape of the enhanced PL spectra was also affected by the sizes of the attached nanoparticles due to their different resonant plasma frequencies. The signal enhancement can be used as an indexing tool for biosensing applications. [ABSTRACT FROM AUTHOR]