β Scribed by J.B. Newkirk; A.H. Geisler
No coin nor oath required. For personal study only.
In a verl' recent note, Frank1 and Read [O] report that the!. measured the changes of the internal friction of SaCl when F-centers were introduced and removed. Their result leads to the same conclusion as can be drawn from that of Podnscheu:sk>.'s experiment, i.e., the mobility of dislocations is greatly decreased b\r the formation of F-centers and does not recover jvhen the Fcenters are bleached at room temperature. Frank1 and Read proposed the h)-pothesis that the dislocations are pinned down b-the attachment of positive-ion vacancies, which arc freed by the formation of F-centers from vacancy-pairs.
Hardness tests by the author show that Knopp hardness number increases remarkably by the introduction of F-centers from 17 for annealed SaCl crystal plates to 31 for the same specimens irradiated by X-rays. (The longitudinal axis of the diamond indentor is set in parallel with the crystal cubic edges.
π SIMILAR VOLUMES
Structural evolution during the phase transition from h (hexagonal)-to c (cubic)boron nitrides (BN) under high pressure (6.5-7.7 GPa) at high temperature (1,700-2,150Β°C) was examined by using high-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS). At th