Elastic-plastic transition in MBE-grown GaSb semiconducting crystal examined by noindentation

The present paper concerns the elastic-plastic nanodeformation of Te-doped GaSb crystals grown by molecular beam epitaxy on the n-type of GaSb substrate. The conventional analysis of nanoindentation data obtained with sharp triangular (Berkovich) and spherical tip revealed the elastic modulus (E = 83:07 1:78 GPa), hardness (H = 5:19 0:25 GPa) and “true hardness” (HT = 5:73 0:04 GPa). The registered pop-in event which indicates the elastic–plastic transition in GaSb crystal points towards the corresponding yield strength ( Y = 3:8 0:1 GPa). The origin of incipient plasticity in GaSb crystal is discussed in terms of elastic-plastic deformation energy concept

Mechanisms of the potassium stabilization in K2Fe22O34

Effect of potassium stabilization in K2Fe22O34, the principal phase of styrene catalyst is caused by doping Cr and Ce. The effect was investigated by means of potassium ion and neutral atom thermal desorption. The kinetics for K+ and K emission from undoped and Ce-, Cr-doped b-K2Fe22O34 is studied with the field reversal technique and steady-state mode in high vacuum conditions. Two main mechanisms of the stabilization were developed depending on the dopant location. Chromium is located in the structure of β-ferrite and slows down the diffusion potassium ion. Cerium segregated at the basal planes favoring the cationic state of potassium inhibits the probability of potassium atoms to leave the K2Fe22O34 surface via work function increase