Synthesis And Investigation Of Magnetic Properties Of Substituted Ferrite Nanoparticles Of Spinel System Mn1-XZnX[Fe2-YLY]O4

Superparamagnetic nanoparticles of the spinel ferrite four-element system Mn1-xZnx[Fe2-yLy]O4 (where L:Gd3+, La3+, Ce3+, Eu3+, Dy3+, Er3+,Yb3+) were synthesized by the co-precipitation method. The magnetic moments of the 10 nm diameter nanoparticles were comparable to the ones of Fe3O4 nanoparticles. A comparatively low TC (∼52-72 °C) was observed for some of the compositions. The heating mechanism of the superparamagnetic particles in the AC magnetic field at radiofrequency range is discussed and especially the absence of the hysteresis loop in the M-H curve at room temperature. One possible explanation-spontaneous particle agglomeration-was experimentally verified. © 2006 Elsevier B.V. All rights reserved

Terahertz Spectroscopy Of Tnt For Explosive Detection

Transmittance spectra of solid and vapor samples of trinitrotoluene (TNT) in the spectral range 0.6 to 10 THz at resolutions up to 1 GHz are reported. Uniform solid samples of ∼100 μrn thickness gave stronger absorption and more resolved structure than previous studies. New absorption lines for TNT solid below 100 cm-1 are reported. A heated 10 m multpass White cell was used for spectroscopy of the vapor. Strong absorption bands yield unexpectedly large absorption cross sections for the anticipated saturated vapor pressure at the cell temperature, leaving their assignment to TNT in doubt. These results indicate that path lengths exceeding 10 m and temperatures higher than 40 C, or significantly higher instrumental sensitivity, are needed for sensing of TNT vapor in the spectral range 0.6 to 10 THz