Lithium niobate (LiNbO 3 ) fibers, obtained from the heat treatment of composite fibers (polymer/inorganic precursors), were successfully prepared by using the blow-spinning technique. A chemical solution containing Li and Nb ions, added to poly(vinyl pyrrolidone) solution, was used as precursor solution. The best condition for producing composite fibers was determined. The morphology of green and crystallized fibers was characterized by scanning electron microscopy (SEM) and revealed fibrous structure with an average diameter around 800 nm. X-ray diffraction (XRD) measurement revealed a pure LiNbO 3 (LN) phase formation. Detailed studies of dielectric response at various frequencies and temperatures exhibited a dielectric anomaly at 364 ℃. The electrical properties (impedance, modulus, and conductivity) of the fibers were studied using impedance spectroscopy technique. The contributions of grain and grain boundary effects were observed in the LN fibers. The activation energy of the composite fibers was found to be 1.5 eV in the high temperature region (325-400 ℃).

In this paper we propose a simple experimental apparatus that can be used to show quantitative and qualitative results of resonance in a driven damped harmonic oscillator. The driven oscillation is made by a servo motor, and the oscillation amplitude is measured by an ultrasonic position sensor. Both are controlled by an Arduino board. The frequency of free oscillation measured was campatible with the resonance frequency that was measured.

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A novel approach to distinguish soybean seed vigor based on Fourier Transform infrared spectroscopy (FTIR) associated with chemometric methods are presented. Batches with high and low vigor soybean seeds were...

Flexible nanocomposite films derived from castor-oil polyurethane (PUR) and conductive fillers of activated carbon nanopowder (CNP) and carbon black (CB) nanoparticles were prepared by casting and characterized by scanning electron microscopy (SEM) as well as direct (dc) and alternate current (ac) electrical conductivity measurements. The fillers exhibited spherical morphology with diameters ranging between 40 and 60 nm. Compared to CNP, CB was dispersed better in the matrix. Based on the classical percolation theory, different universal exponents were obtained from the conductivity curve analysis. The PUR/CNP nanocomposite obeyed the universal percolation theory, while the PUR/CB nanocomposite did not obey it. The PUR/ CNP nanocomposites exhibited a higher percolation threshold (p c 5 29.3 vol%) and lower dc conductivity compared to PUR/CB nanocomposites (p c 5 5.7 vol%). This difference is related to the physics and chemical characteristics of the CNP and CB filler dispersed in the matrix. The ac conductivity of the nanocomposites was described by the Jonscher power law confirmed that conduction occurs through a hopping mechanism between localized hopping. POLYM. COMPOS., 00:000-000,