The present study was aimed at revealing the influence of the mechanical stress induced by water molecule adsorption on the composition of crystalline phases in the ZrO2 + 3 mol% Y2O3-nanoparticles. ...Three basic methods were used to determine the phase transition: neutron diffraction, Raman microspectroscopic scanning, and X-ray diffraction. The fact of reversible phase-structural β → α transformation and the simultaneous presence of two polymorphic structural modifications (β is the phase of the tetragonal syngony and α of monoclinic syngony in nanosized particles (9 nm)) under normal physical conditions was established by these methods. An assumption was made regarding the connection of the physical mechanism of transformation of the extremely nonequilibrium surface of nanoparticles with electronic exchange of the material of the near-surface layer of nanoparticles with the adsorption layer through donor–acceptor interaction. The principal possibility of creating direct-acting hydroelectric converters based on nanoscale YSZ (Yttria-Stabilized Zirconia) systems due to the reversible character of the considered effect was shown.
The present study was aimed at revealing the influence of the mechanical stress induced by water molecule adsorption on the composition of crystalline phases in the ZrO
+ 3 mol% Y
O
-nanoparticles. ...Three basic methods were used to determine the phase transition: neutron diffraction, Raman microspectroscopic scanning, and X-ray diffraction. The fact of reversible phase-structural β → α transformation and the simultaneous presence of two polymorphic structural modifications (β is the phase of the tetragonal syngony and α of monoclinic syngony in nanosized particles (9 nm)) under normal physical conditions was established by these methods. An assumption was made regarding the connection of the physical mechanism of transformation of the extremely nonequilibrium surface of nanoparticles with electronic exchange of the material of the near-surface layer of nanoparticles with the adsorption layer through donor-acceptor interaction. The principal possibility of creating direct-acting hydroelectric converters based on nanoscale YSZ (Yttria-Stabilized Zirconia) systems due to the reversible character of the considered effect was shown.
The paper considers the new effects of the nanoscale state of matter, which open up prospects for the development of electronic devices using new physical principles. The contacts of chemically ...homogeneous nanoparticles of yttrium-stabilized zirconium oxide (ZrO2—x mol% Y2O3, x = 0, 3, 4, 8; YSZ) with different sizes of 7.5 nm and 9 nm; 7.5 nm and 11 nm; and 7.5 nm and 14 nm, respectively, was studied on direct current using nanostructured objects in the form of compacts obtained by high-hydrostatic pressure (HP-compacts of 300MPa). A unique size effect of the nonlinear (rectifying-type contact) dependence of the electrical properties (in the region U < 2.5 V, I ≤ 2.7 mA) of the contact of different-sized YSZ nanoparticles of the same chemical composition is revealed, which indicates the possibility of creating semiconductor structures of a new type (homogeneous electronics). The electronic structure of the near-surface regions of nanoparticles of studied oxide materials and the possibility of obtaining specifically rectifying properties of the contacts were studied theoretically. Models of surface states of the Tamm-type are constructed considering the Coulomb long-range action. The discovered energy variance and its dependence on the curvature of the surface of nanoparticles made it possible to study the conditions for the formation of a contact potential difference in cases of nanoparticles of the same radius (synergistic effect), different radii (doped and undoped variants), as well as to discover the possibility of describing a group of powder particles within the Anderson model. The determined effect makes it possible to solve the problem of diffusion instability of semiconductor heterojunctions and opens up prospects for creating electronic devices with a fundamentally new level of properties for use in various fields of the economy and breakthrough critical technologies.
Abstract
Neutron activation analysis of the Pleurotus ostreatus showed that adding of solid solution of ZrO
2
-Y
2
O
3
hydroxide and oxide (3 mol % Y
2
O
3
) nanoparticles of size 4 and 9 nm at a ...concentration of 0.2 weight percent in a nutrient medium (Czapek) alters the character of physiological processes in the biological tissues of the mushrooms. This is manifested in the form of a significant change in morphological and physiological characteristics of the mushrooms and the elemental composition of the dry biomass. In particular, it is shown that the intercalation of nanoparticles into the tissues of the mushrooms leads to an increase of 1.3-1.4 times (more than 2.6 g/dm
3
) of biomass accumulation (industrial strain HK 35) and decrease of 1.7-1.8 times (below 1.7-2.5 mg/mm
3
) of concentrations of extracellular proteins into the culture fluid at a substantially constant value of the acidity. It is shown that the addition of ZrO
2
+3 mol % Y
2
O
3
nanoparticles of sizes 4 or 9 nm into tissue of mushroom at step of the mother mycelium in very small concentrations can alter effectively the chemical composition of the substances produced by the cells and consequently, its physiological activity. It is shown that the use of low concentrations of ZrO
2
nanoparticles allow to increase the yield and resistance of crops to diseases up to 1.2-1.5 times, as well as in the long term can be used in biomedical technologies for the treatment of cancer diseases.
Presented in this paper is theoretical studying redistribution of electric charges in the layer of a tetragonal plate of yttrium-stabilized zirconia based on the position of yttrium atom in the ...crystal lattice for both dry and humid ambient atmosphere. The density functional theory with local density approximation (DFT-LDA) has been employed for this modelling. Calculations have been performed for layer-by-layer electron density distribution over the thickness of an infinite plate 001 of yttrium-stabilized tetragonal zirconium dioxide, which show that a change in the position of stabilizing yttrium atom and its symmetry in the layer leads to changing the total energy of zirconium dioxide both for the dry 001 surface and for the hydrated one. It has been ascertained that the surface charge density for the 001-surface of an infinite tetragonal zirconia plate increases in proportion to the degree of hydration.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Correlation between observed kinetic effects of phase-transfer catalytic reaction of the alkaline hydrolysis of 4-nitrophenyl ester of N-benzyloxycarbonylglycine-4 in the two-phase system ...chloroform-borate buffer pH = 10 and a content of ionic forms of catalyst was investigated. The phosphonium salts QX (X = Cl¯, Br¯, I¯) shows high catalytic reactivity. Dependence of the reaction kinetics discussed in the framework of the extraction mechanism with a competitive extraction of a nucleophile ОН¯, nucleofuge 4-NO
O¯ and anion X¯ of the phase-transfer catalyst.
Zbadano korelację pomiędzy obserwowanym efektem kinetycznym przejścia fazowego katalitycznej reakcji zasadowej hydrolizy estru 4-nitrofenylowego N-benzyloksycarbonylglycyny-4 w dwufazowym układzie chloroform-bufor boranowy, pH = 10, z zawartością jonowych form katalizatora. Sole fosfoniowe QX (X = Cl¯, Br¯, I¯) wykazują wysoką aktywność katalityczną. Zależności kinetyki reakcji przeanalizowano w ramach mechanizmu ekstrakcji z konkurencyjną ekstrakcją nukleofilu ОН¯, grupą odchodzącą 4-NO
O¯ i anionem X¯ katalizatora przejścia fazowego.
PDF
