It is a convenient approximation to regard the frictional forces between two solids as made up of two components: the force required to shear adhering junctions in the region of surface contact and the force required to deform the underlying bulk material.' With an elastic solid, the deformation component may be due mainly to an elastic hysteresis loss; but if plastic flow occurs, the deformati...

high purity fluorapatite (FA) with rod-like and spherical-like morphology was synthesized via sol-gel method. Chemical characterization of FA powders was done by XRD and FTIR analyses. Crystallite samples were calculated using Scherer method. Morphology of FA powders was investigated with TEM and SEM images. The results revealed that increasing the time of hydrolysis of phosphate sols significa...

Ca 10 (PO 4 ) 6 F 2 :xEr 3+ (x = 0.1, 0.3 and 0.5) was synthesized using solid-state powder process (1150 °C, 1h), conventional sintering spark plasma (SPS) techniques min, 50 MPa). XRD analysis revealed that all samples are generally composed of fluorapatite (FAP) containing quartz as a minor phase, the presence Er O 3 peaks is becoming more evident Er-doped increases. In SEM microstructure im...

A Cameca IMS 300 ion analyzer has been used to measure fluorine concentrations in tooth material. Samples of human and shark teeth were studied. Negative oxygen primary ions produce secondary mass spectra in which positive as well as negative fluorine ion peaks are well re­ presented. With constant measuring conditions, the reproducibility of the F/Ca ion ratios is satis­ factory. Fluorine conc...

LLE Review, Volume 90 79 Solid-state laser systems envisioned for inertial fusion energy (IFE) applications will require both high efficiency and high single-beam, on-target uniformity. High efficiency is achieved by diode pumping, and on-target uniformity is achieved by beam-smoothing techniques. One of the most-promising gain media for these high-efficiency lasers is ytterbium-doped strontium...