ABSTRACT
Data on thermally stimulated depolarization current (TSDC) study of the same poled glass in the temperature range 100-1000 K are analyzed. Four specific temperature ranges in the TSDC spectrum of this glass are identified, with each range being attributed to the charge relaxation processes of different natures. During linear heating in the temperature range 100-250 K, charge relaxation is related to the adsorption/desorption of particles from the atmosphere, supposedly water cluster ions H+(H2O)n. The next TSDC band, which is observed at room temperature and above, is related to the disordering of the polar structural entities. The TSDC band in the temperature range 500-750 K is attributed to the relaxation of spatial charge by the diffusion mechanism. The TSDC band in the temperature range 750-1000 K is attributed to the relaxation of spatial charge by the viscous flow mechanism. All these data allowed drawing a schematic TSDC spectrum of silicate glasses in the full temperature range.
ABSTRACT
We present a new method for the deposition of colloidal Au nanoparticles on the surface of silicon substrates based on short-time Ar plasma treatment without the use of any polymeric layers. The elaborated method is compatible with molecular beam epitaxy, which allowed us to carry out the detailed study of GaAs nanowire synthesis on Si(111) substrates using colloidal Au nanoparticles as seeds for their growth. The results obtained elucidated the causes of the difference between the initial nanoparticle sizes and the diameters of the grown nanowires.
ABSTRACT
Nanocorrugation of 2D crystals is an important phenomenon since it affects their electronic and mechanical properties. The corrugation may have various sources; one of them is flexural phonons that, in particular, are responsible for the thermal conductivity of graphene. A study of corrugation of just the suspended graphene can reveal much of valuable information on the physics of this complicated phenomenon. At the same time, the suspended crystal nanorelief can hardly be measured directly because of high flexibility of the 2D crystal. Moreover, the relief portion related to rapid out-of-plane oscillations (flexural phonons) is also inaccessible by such measurements. Here we present a technique for measuring the Fourier components of the height-height correlation function H(q) of suspended graphene which includes the effect of flexural phonons. The technique is based on the analysis of electron diffraction patterns. The H(q) is measured in the range of wavevectors q≈0.4-4.5nm(-1). At the upper limit of this range H(q) does follow the T/κq(4) law. So, we measured the value of suspended graphene bending rigidity κ=1.2±0.4eV at ambient temperature T≈300K. At intermediate wave vectors, H(q) follows a slightly weaker exponent than theoretically predicted q(-3.15) but is closer to the results of the molecular dynamics simulation. At low wave vectors, the dependence becomes even weaker, which may be a sign of influence of charge carriers on the dynamics of undulations longer than 10nm. The technique presented can be used for studying physics of flexural phonons in other 2D materials.
