Studies of CdI2-Bi3 microstructures with optical methods, atomic force microscopy and positron annihilation spectroscopy

Abstract

Results of the comprehensive morphological study of CdI 2 -BiI 3 layered crystals are presented. Direct AFM observations of micro-and nanostructures formed in the volume of the crystals confirm the predictions made on the basis of positron annihilation spectroscopy studies. The model explaining the possible pores formation mechanism is proposed and validated by the results of luminescence measurements at 8 K.

Long-term evolution of luminescent properties in CdI2 crystals

“…The transformation of CdI 2 photoluminescence spectra over time, as supported by atomic force microscopy results, may be connected with the creation of nanostructures on the crystal surface [4,[22][23][24] and with the modification of the crystal structure: the annihilation of moving defects and the appearance of PbI 2 nanophases.…”

“…A notable feature of MX 2 crystals is their layered structure formed by a hexagonal close packing of iodine atoms, while a half of octahedral interstices in the lattice are filled with cadmium atoms. The principal structural element of the lattice is a 2+ 4-6 [Cd I ] − octahedral complex formed by 2+ Cd in an octahedral interstice [1][2][3][4]. Previous investigations of CdI 2 crystals have been performed both theoretically [5][6][7][8] and experimentally [9][10][11][12][13][14][15].…”

Positron annihilation characterization of free volume in micro- and macro-modified Cu0.4Co0.4Ni0.4Mn1.8O4 ceramics

“…As it was shown in Table 1 and Table 2 τ b ), and ratio represents the nature of these defects (τ 2 /τ b ) [21,42] remain unchanged. Obviously, pores of large examination by SEM and Hg-porosimetry do not modify significantly the measured positron lifetime spectra, testifying in a favor of correctness of the performed measuring and fitting procedures.…”

“…PAL measurements for Cu 0.4 Co 0.4 Ni 0.4 Mn 1.8 O 4 ceramics were performed using ORTEC spectrometer at temperature of 20 °C and relative humidity of ~35 % [26,29,41,42]. The isotope 22 Na was used as positron source.…”

Water-Sorption Effects near Grain Boundaries in Modified MgO-Al2O3 Ceramics Tested with Positron-Positronium Trapping Algorithm

“…* corresponding author; e-mail: klymha@yahoo.com Porous structure of functional materials are studied using traditional methods such as X-ray diffraction, electron microscopy and different porosimetry methods, etc. [12,13]. However, porosimetry techniques provide information on open pores with radii over 2 nm [13], whereas processes of capillary condensation in such ceramics depend also on nanopores smaller than 2 nm [14].…”