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Multi-phase ceramics based on ZrB2, TiB2 and doped with CrB2 and SiC were prepared by powder metallurgy and hot pressing to explore the possibility of obtaining multi-scale microstructures by super-saturation of complex (Zr,Ti,Cr)B2 solid solutions. Core–shell structures formed in TiB2 grains, whereas ZrB2 appeared to form a homogeneous solid solution with the other metals. Precipitation of nano-inclusions within both micron-sized borides was assessed by transmission electron microscopy and thermodynamics elucidated the preferential formation of boride inclusions due to the specific sintering atmosphere. In addition, atomic size factors explicated the precipitation of CrB2 nano-particles into ZrB2-rich grains and of ZrB2 nano-particles into TiB2-rich grains. The hardness of the constituent phases measured by nanoindentation ranged from 36 to 43 GPa., Peer Reviewed, Postprint (published version)

The structural characteristics of polymer nanocomposites with functionalized multiwall carbon nanotubes (MWCNTs) in poly(methyl methacrylate) matrix have been studied in relation to nanofiller loading and surface functionality. Different functional groups have been covalently attached on the MWCNTs sidewalls in order to induce interfacial interactions at nanofiller/polymer interface, which resulted in an improved nanomechanical features. Structural properties of nanocomposites, studied with XRD and Raman analysis, indicated the most pronounced decrease in a degree of amorphousness for samples containing 0.5 and 1 wt% of MWCNTs functionalized with dapsone (dapson-MWCNT) and diethyl malonate (dem-MWCNT). SEM and TEM micrographs confirmed improved dispersibility of the MWCNTs modified with aromatic structure of dapsone inside PMMA matrix. A significant increase in a glass transition temperature of over 60 degrees C has been found for the 1 wt% dapson-MWCNT nanocomposite. Additional modification of dapson-MWCNT by further increasing aromaticity and voluminosity of attached moiety (fid-MWCNT), showed 30 degrees C increases in a glass transition temperature at 4 wt% of nanofiller loading, which is similar to shift of 37 degrees C with loading of MWCNTs modified with ester terminal group. A maximum increase of 56% of reduced modulus and 86% of hardness was obtained for 1 wt% loading of dapson-MWCNT nanofiller.

Commercially available ZnO powder was mechanically activated in a planetary ball mill. In order to investigate the specific surface area, pore volume and microstructure of non-activated and mechanically activated ZnO powders the authors performed N-2 physisorption, SEM and TEM. Crystallite size and lattice microstrain were analyzed by X-ray diffraction method. XRD patterns indicate that peak intensities are getting lower and expend with activation time. The reduction in crystallite size and increasing of lattice microstrain with prolonged milling time were determined applying the Rietveld's method. The difference between non-activated and the activated powder has been also observed by X-ray photoelectron spectroscopy (XPS). XPS is used for investigating the chemical bonding of ZnO powder by analyzing the energy of photoelectrons. The lattice vibration spectra were obtained using Raman spectroscopy. In Raman spectra some changes along with atypical resonant scattering were noticed, which were caused by mechanical activation.

In this article the influence of ball miling process on structure of MgO-TiO2 system, as well as the electrical properties of samples after sintering, was investigated. The mixtures of MgO-TiO2 powders were mechanically activated in a planetary ball mill for the time period from 0 to 120 min. The influence of mechanical activation and sintering on the lattice vibrational spectra was studied by Raman spectroscopy at room temperature. Structural investigations have been performed on produced powders. Nitrogen adsorption method was used to determine the BET specific surface area and pore size distribution. Unusual results have been obtained: specific surface area continuosly decreased up to 40 min of activation and increased after that, reaching its minimun value of 5.5 m(2)/g. The Raman spectra of activated powders have shown that anatase modes have been decreasing in intensity and broadening as the time of activation extended. Also, the additional modes attributed to TiO2 II, srilankite and rutile phases started to appear as a consequence of activation. The small differences noticed in the Raman spectra of sintered samples have been explained by structural modification of MgTiO3 phase due to the presence of defects. The effects of activation and sintering process on microstructure were investigated by scanning electron microscopy (SEM). The electrical measurements showed difference in dielectric constant (epsilon(r)), loss tangent (tg delta) and specific resistance (rho) as a function of time of mechanical treatment.