The purpose of this study was to investigate the effect of cation substitutions on the formation of Aurivillius phases at various annealing temperatures using solid-state synthesis. The phase formation of lanthanide bismuth ferrotitanates with the Aurivillius phase structure Ln(2)Bi(3)FeTi(3)O(15), where Ln = Tb, Ho, Er, Yb, has been studied. The obtained samples were characterized by X-ray diffraction, infrared spectroscopy, differential thermal and thermogravimetric analysis, and their elemental composition was studied. The predominant formation of a phase with a pyrochlore structure was revealed in the entire series studied in the chosen synthesis conditions. The exception was the sample containing ytterbium(III) cations, in which phases of the pyrochlore type and layered perovskite with the Aurivillius structure coexist. The main pyrochlore-type phase in all samples crystallizes in the cubic syngony. It is shown that in the Ln(2)Bi(3)FeTi(3)O(15) samples, where Ln = Tb, Ho, Er, the crystal lattice parameters decrease due to a decrease in the cationic radius of the Ln(III) ions. However, in the last sample of the studied series Yb2Bi3FeTi3O15, this pattern is violated because of Yb(III) ions distribution between the perovskite and pyrochlore phases. It has been established that the thermal effects observed in the samples Ln(2)Bi(3)FeTi(3)O(15), where Ln = Tb, Ho, Er, can be attributed to an order-disorder phase transition in the pyrochlore structure. When studying the temperature behavior of a two-phase sample of Yb2Bi3FeTi3O15, two reversible phase transitions were revealed: a low-intensity thermal effect characterizes changes in the pyrochlore-type structure, and a more intense thermal effect can be attributed to a ferroelectric phase transition in the structure of a layered perovskite of the Aurivillius family.

N-salicyloyl-N'-(3,5-ditertbutyl-2-hydroxy)benzylidene hydrazine (H3sahz) and its complex with VO(III) have been synthesized. The molecular and crystal structure of the [(VO)2(sahz)2(C2H5O)2(C2H5OH)] complex by X-ray diffraction, as well as IR and electronic spectra, EPR spectrum etc., have been studied. The structure of the investigated VO(III) complex consists of binuclear units in which the monomeric complex molecules are linked to each other through vanadyl oxygen atom. Monomeric complexes differ between themselves in the character of coordination. Both vanadium atoms have a distorted octahedral environment. The biological activity of this compound has been studied. Lastly, the activities of the studied ligand against various enzyme proteins including acetylcholinesterase (AChE), butrylcholinesterase (BChE) and alpha-glycosidase (alpha-Gly) enzyme were compared. ChE inhibitory activities of the new complex against alpha-Gly, AChE and BChE were determined by Tao and Ellman's methods. The new complex was shown to have IC50 values of 42.60 mu M for BChE, 91.43 mu M for AChE, and 196.49 mu M for alpha-glycosidase.

In this study, (E)-N'(3,5-di-tert-butil-2-hedroxybenzilidene)-2-hydroxybenzohydrazide (H3sahz) 2 and its copper (II) complex has been synthesized and evaluated by methods FTIR, UV-Vis, EPR, and single crystal X-ray analysis. It has been shown, that H3sahz crystallizes as a dimer through hydrogen bonds. H3sahz with copper nitrate forms [Cu(H(2)sahz)(NO3)(H2O)] complex, which according to X-ray diffraction analysis has a distorted square pyramidal structure. The complex was screened for alpha-glucosidase (alpha-Glu), acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) inhibitory abilities. Results displayed that IC50 and K-i values of the novel complex for AChE, BChE, and aGlu enzymes were obtained at 0.93-2.14, 1.01-2.03, and 73.86-102.65 mu M, respectively. The molecular docking outcomes have shown that the synthetic complex has a lower affinity for aglucosidase compared to acarbose. But the inhibition ability of H(3)sahz for acetylcholinesterase and butyrylcholinesterase enzymes was greater than that of tacrine. These findings indicate that the (H(3)sahz)(2) complex may be considered a possible candidate for the development and discovery of compounds effective in inhibiting the relevant enzymes.

The phase formation in the series Ln(2)Bi(3)FeTi(3)O(15) (Ln = La, Pr, Nd, Sm, Gd) was studied. It was found that the layered perovskite structure was formed after annealing at 1000 degrees C. Further increase in the synthesis temperature to 1100 degrees C did not affect the phase composition, excluding Gd-containing sample, where perovskite structure was partially destroyed to form the pyrochlore phase based on Bi2Ti2O7. Reversible anomalies obtained by differential thermal analysis indicate the phase transitions with a change in the crystal lattice symmetry in case of a perovskite-like phase and a transition of the order-disorder type in case of a pyrochlore structure.

Phase formation in the series of Bi3Nd2Fe1 + yTi3 – 2yNbyO15 and Bi3Tb2Fe1 + yTi3 – 2yNbyO15 (y = 0.0–0.6 and Δy = 0.2) samples is studied. When Bi3Nd2Fe1 + yTi3 – 2yNbyO15 solid solutions (ss) are doped with niobium(V) ions, the formation of Bi3Nd2FeTi3O15 layered perovskite, a member of the Aurivillius phase family of general formula Am – 1Bi2BmO3m + 3 (m = 4), is not dominant in samples where y ≥ 0.2. Bi4Ti3O12 (m = 3) and NdFeO3 phases are formed in the course of phase interaction under the chosen conditions. With higher niobium(V) amounts, a Bi2Ti2O7-base pyrochlore ss phase is formed in the Bi3Tb2Fe1 + yTi3 – 2yNbyO15 multicomponent system. Dielectric spectroscopy shows that the phases in samples of both series where y > 0.0 undergo structural alterations associated with magnetic and electric ordering.

— Al- and Zr-containing sols intended for producing Al 2 O 3 and ZrO 2 nanocoatings, respectively, were prepared by a sol–gel process using N , N -dimethyloctylamine (DMOA) and acetylacetone (acacH). Aluminum and zirconyl nitrates were used as metal precursors. The DMOA/Al and DMOA/Zr molar ratios were 1 and 2, respectively, and the acacH/DMOA molar ratio was 1.5 in both cases. The sols were synthesized at a temperature of 80–90°C and then were evaporated at 90–95°C to a gel state. The resultant gels were characterized by differential thermal analysis, differential scanning calorimetry, and electron impact mass spectrometry. Measurements in the temperature range 20–500°C in air and Ar showed that the Zr-containing material was more thermally stable (decomposition temperature of 304–308°C) than its Al-containing analog (decomposition temperature of 225–230°C). According to the mass spectrometry analysis data, the gels contained metals as acetylacetonate complexes having strong M–O bonds and coordinated molecular DMOA. The nature of the metal was shown to influence both the thermal stability of the gel in which it is present in a chemically bound state and the mechanisms of the processes involved in its thermolysis.

The influence of BiFeO3 on phase formation, crystal structure, and dielectric properties of solid solutions close to the Morphotropic Phase Boundary in the (Na0.5Bi0.5)TiO3 - (K0.5Bi0.5)TiO3 TiO3 system was studied. The formation of samples with pure perovskite structure was proved, increase in the unit cell parameters and in the T-m value while decrease in elelctroconductivity and dielectric loss stimulated by the BiFeO3 addition were revealed.

The phase formation of solid solutions Bi 4– y Tb y Ti 3 O 12 , where y = 0.0, 0.2, 0.4, 0.6, and 0.8, was studied, and a scheme of this process in an oxide reaction mixture was proposed. The thermal stability of the obtained solid solutions was investigated, and the phase composition and structural parameters were explored in detail by the Rietveld method. It was found that, within the tested concentration range, Bi 4– y Tb y Ti 3 O 12 samples crystallize in the orthorhombic system, and the concentration evolution of the unit cell parameters was traced. It was determined that the temperature of the ferroelectric phase transition decreases with increasing y, as the concentration limit of the existence of the rhombic modification of Bi 4– y Tb y Ti 3 O 12 is approached.

Phase formation, crystal structure parameters, dielectric and ferroelectric properties of ceramic solid solutions in the (1-y)[(1-x)(Na0.5Bi0.5)TiO3-x(K0.5Bi0.5)TiO3]-yBiFeO(3) system with x = 0.25, y = 0 - 0.6 has been studied. Pure samples with the pseudocubic perovskite structure were obtained by the solid state reaction method. Addition of BiFeO3 stimulated a monotonous increase in the unit cell volume and in the Curie temperature T-m value. With increasing the BiFeO3 content, nonmonotonous behaviour of the dielectric permittivity, a decrease in the T-ph value, a decrease in total electroconductivity and dielectric loss at the room temperature were revealed.

Physico-chemical, structural and electric properties of Aurivillius phases SrBi2-xSmxNb2O9 and SrBi2-ySmyTa2O9 with x = 0.0 and 0.4 obtained in muffle and microwave furnace have been investigated by the X-ray diffraction, DTA, FTIR-spectroscopy and dielectric spectroscopy methods. The perovskite-like structure of solid solutions obtained is characterized by the orthorhombic symmetry. The assumption about the non-statistical distribution of Sm(III) cations crystal structure of Aurivillius phases was made according to the obtained results. It has been found that Sm(III) cations introduction does not influence on T-C of SrBi2-xSmxNb2O9 solid solutions.

Phase formation, structural and electric properties of bismuth layered perovskite like ferroelectric ceramics Sr[Bi1 - xTbx](2)[Nb0.9Fe0.05Cr0.05](2)O9 - delta (1) and Sr[Bi1 - xTbx](2)[Ta0.9Fe0.05Cr0.05](2)O9 - delta (2) have been investigated. It has been determined that single phase solid solutions are formed at 0.00 <= x <= 0.04 (1) and 0.00 <= x <= 0.30 (2). The perovskite-like structure of all solid solutions obtained is characterized by the orthorhombic symmetry. The volume of the unit cell and T-C of solid solutions 1 and 2 has been found to decrease with x increasing. (C) 2012 Elsevier B.V. All rights reserved.

The effect of the cationic composition on the formation of perovskite solid solutions based on bismuth ferrite(Bi1 − x/3□ x/3)[Fe1 − x Ti x ]O3 with x = 0.00–0.48, Δx = 0.03, has been studied. The homogeneity range of the perovskite phase under the conditions of the solid-phase synthesis of solid solutions has been determined, and the effect of the cationic composition on the physicochemical properties of solid solutions has been studied.

Ceramic solid solutions (Bi1-yLay)(4)(V1-xMex)(2)O11-y with x, y < 0.2 Me-Zr, Ga, Fe, Cu, have been prepared by the solid state reaction method. Crystal structure parameters, phase transitions, dielectric and transport properties of ceramic samples have been studied. Concentration and temperature stability regions of monoclinic alpha-, orthorhombic beta- and tetragonal gamma- or gamma'- polymorph modifications have been determined. Annealing of samples, containing large amount of Cu and/or La dopants, at 973 K in the reducing atmosphere resulted in their decomposition, though compositions containing low content of La, Ga or Zr dopants, remained pretty stable. (C) 2010 Elsevier B.V. All rights reserved.

J.N. Torba, N.V. Golubko, E.A. Fortalnova, G.M. Kaleva, M.G. Safronenko, N.U. Venskovskii and E.D. Politovaa,∗ Karpov Institute of Physical Chemistry, Vorontsovo Pole St., 10, 105064, Moscow, Russia Peoples’ Friendship University of Russia, Ordzhonikidze St., 3, 117198, Moscow, Russia Ceramic composites (100− n)Bi4V2O11−z–nCe0.9Gd0.1O1.9 with n = 0÷ 25 wt% were prepared and studied by the X-ray diffraction, dielectric spectroscopy, and impedance methods. Slight increase in the unit cell volume accompanied by monotonous decrease in temperatures and broadening of the α–β and β–γ phase transitions with increasing fluorite content was observed in the composites studied. Increase in melting temperatures of composites with n ≥ 10 with the retention of their high ionic conductivity was also proved.

Phase formation of Bi 4 (V 1 − x Cu x ) 2 O 11 − z solid solutions (BICUVOX) with x = 0.00–0.20 and Δ x = 0.02 was studied. The concentration stability ranges were determined for the α, β, and γ polymorphs of BICUVOX solid solutions at room temperature, and their unit cell parameters were revised. The following was found to occur as x rises: the α ai β phase transition temperature between the monoclinic and orthorhombic phases shifts down, the β ai γ phase transition temperature to the high-temperature tetragonal phase shifts down, and the order-disorder phase transition temperature between γ′ ai γ tetragonal phases shifts up.