Temperature stable dielectric properties for Pb(Mg1/3Nb2/3)O3-BaTiO3-PbTiO3 system ceramics

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

A new type of ordering in Ba(Zn1/3 Ta2/3)O3 ceramics

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Characterization of (Bi1/2Na1/2)TiO3 using electric modulus spectroscopy

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Effect of high pressure on the dielectric properties of relaxor compositions [Pb(Fe1/2Nb1/2)O3]1-x-y-[Pb(Zn1/3Nb2/3)O3]x- [BaTiO3]y

Abstracts are not published in this journal     

Multiple-toughening behaviour in SiC platelet-reinforced TZP/Al2O3 ceramic composites

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Synthesis and superconducting properties of the composite in the system (1_x).YBa2Cu3Oy − x.Ba(Y1/2Nb1/2)O3

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Structural order in Ba(Zn1/3Ta2/3)O3, Ba(Zn1/3Nb2/3)O3 and Ba(Mg1/3Ta2/3)O3 microwave dielectric ceramics

The process and nature of structural ordering and the factors that influence them have been investigated in the microwave dielectric perovskites, barium zinc tantalate (BZT), barium zinc niobate (BZN), and barium magnesium tantalate (BMT), sintered at various temperatures. The samples were characterized mainly by X-ray powder diffraction and transmission electron microscopy. The results show that short-range 1 : 1 B-site order features strongly in the early stages of ordering in BZT and BZN, but it is extremely rare in BMT, for which most grains commence with 1 : 2 order. As sintering progresses, 1 : 1 order is replaced by 1 : 2 long-range order in BZT and by disorder in BZN. Orientational variants of the ordered domains within grains occur in similar numbers when order is fine-scale, but their distribution is less homogeneous in well-ordered samples. Local inhomogeneities in the degree of order within grains, which will affect dielectric properties, correlate with both residual non-stoichiometry and the presence of dislocations. Incompletely reacted starting materials which may persist to late stages of sintering can also strongly influence order. Anomalously large ordered domains at grain boundaries are attributed to grain-boundary migration accompanied by enhanced diffusion. The results indicate that with starting materials that are well-mixed and homogeneous at the nanoscale, tailoring of physical properties should be possible by controlling the type and degree of order through chemical composition. This revised version was published online in November 2006 with corrections to the Cover Date.     

Stabilization of the perovskite phase in Pb(Zn1/3, Nb2/3)O3 ceramics modified by Ba(Zn1/3, Nb2/3)O3 and BaTiO3

Stabilization of the perovskite phase in PZN-BT-BZN ceramics prepared by solid-state sintering was investigated. With the addition of BT and/or BZN, the amounts of perovskite phase in PZN ceramics increased, but the amount of pyrochlore phase decreased. Optimum calcination conditions for this system, to obtain PZN ceramics with the minimum amount of the pyrochlore phase, are a temperature range between 950 and 1000°C and a sintering time of 2–4 h. The perovskite phase of these systems could be 100% stabilized by the addition of more than 7 mol% BT, 8 and 10 mol% BTZN and BZN, respectively. This revised version was published online in November 2006 with corrections to the Cover Date.     

Multiple-toughening behaviour in SiC platelet-reinforced TZP/Al2O3 ceramic composites

Abstracts are not published in this journal     

Hybrid plasma chemical vapour deposition of aluminium nitride from Al and NH3/N2 mixtures

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Magnetic properties of quaternary compounds on the Cu2GeSe3-Cr2Se3 join of the Cu2Se-GeSe2-Cr2Se3 system

We have synthesized two quaternary compounds, Cu₂GeCr₄Se₉ and Cu₂GeCr₆Se₁₂, with compositions on the Cu₂GeSe₃-Cr₂Se₃ join of the Cu₂Se-GeSe₂-Cr₂Se₃ system. Their composition stability limits and the lattice parameters of Cu₂GeCr₄Se₉ have been determined, and their magnetic properties (magnetic moments, temperatures and types of magnetic transitions) have been investigated. Ferromagnetic samples with Curie temperatures from 95 to 135 K have been identified in the homogeneity ranges of the two compounds. Original Russian Text ? T.G. Aminov, G.G. Shabunina, E.V. Busheva, 2009, published in Neorganicheskie Materialy, 2009, Vol. 45, No. 3, pp. 283–287.     

Microstructure of Al2O3-ZrO2 nanocomposites prepared by combustion process

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Preparation of Al--Al2O3 in-situ particle composites by addition of Fe2O3 particles to pure Al melt

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Mössbauer study of amorphous Al2O3:Eu3+

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Phase diagram of the binary system PbO-Ga2O3

The phase diagram of the binary system PbO-Ga₂O₃ was determined by means of DTA and X-ray measurement. The existence of compound PbGa₂O₄ in the investigated system was confirmed. The compounds Pb₂Ga₂O₅ and PbGa₁₂O₁₉ recently published were not found.     

Synthesis and study of compounds A 2I (UO2)2Si5O13 · 3H2O (AI = Na, K)

Sodium and potassium diuranyl pentasilicates were prepared by precipitation from a solution followed by hydrothermal treatment. The structure, properties, and thermal behavior of these compounds were studied by X-ray diffraction, IR spectroscopy, and thermal analysis. Original Russian Text ? N.G. Chernorukov, A.V. Knyazev, A.A. Sazonov, 2007, published in Radiokhimiya, 2007, Vol. 49, No. 2, pp. 114–115.     

Highly oriented structure of hot-extruded Tl2Ba2Ca2Cu3 oxides prepared from MG powders

Abstracts are not published in this journal This revised version was published online in November 2006 with corrections to the Cover Date.     

Effect of doping with Co2O3, TiO2, Fe2O3, and Mn2O3 on the properties of Ce0.8Gd0.2O2?δ

The effects of Co, Fe, Mn, and Ti oxide additions on the sinterability and crystal-chemical, thermal, and electrical properties of Ce_0.8Gd_0.2O_2−δ have been studied. The results indicate that these oxides enhance the sinterability of the mixed oxide, regardless of whether they were introduced before or after synthesis. The most effective sintering aid is Co₂O₃. The lattice parameters of Ce_0.8Gd_0.2O_2−δ samples containing different metal oxide additions (1 mol %) are refined in space group Fm3m. The temperature-dependent thermal expansion data are used to determine the linear thermal expansion coefficients of the samples. Manganese oxide additions reduce the electrical conductivity of Ce_0.8Gd_0.2O_2−δ, whereas the other dopants increase it in the order Ti < Fe < Co. The activation energy for conduction increases in the order Co < Ti < Fe < Mn. Original Russian Text ? E.Yu. Pikalova, A.N. Demina, A.K. Demin, A.A. Murashkina, V.E. Sopemikov, N.O. Esina, 2007, published in Neorganicheskie Material, 2007, Vol. 43, No. 7, pp. 830–837.     

Physicochemical characterization of WO3/ZrO2 and WO3/Nb2O5 catalysts and their photoactivity for 4-nitrophenol photooxidation in aqueous dispersion

Two different photo-catalysts consisting of tungsten oxide supported on zirconia and niobia have been studied. The photoactivity of the samples has been investigated in both the absence and presence of H2O2 for the photo-oxidation of 4-nitrophenol in aqueous suspensions and compared to that of WO3 and of the pure ZrO2 and Nb2O5 supports. Both catalysts were found to be photoactive, although no beneficial influence of the presence of tungsten oxide on the reaction rate was observed in the absence of H2O2. The presence of hydrogen peroxide was observed to be beneficial for all of the samples. Scanning electron microscopy, X-ray diffraction, diffuse reflectance and laser Raman spectroscopies, surface area and porosity determination, as well as Fourier transform infra-red spectroscopy monitoring of surface acidity were used to characterize the catalysts. This revised version was published online in November 2006 with corrections to the Cover Date.     

Time dependence of dielectric constants of Pb(Mg1/3Nb2/3)O3-BaTiO3-PbTiO3 ferroelectric ceramics for X7R MLCs

The isothermal ageing behaviour of Pb(Mg_1/3Nb_2/3)O₃-BaTiO₃-PbTiO₃ ceramics, promising high dielectric (ε_25°C = 4574) materials for X7R multilayer ceramic capacitors (MLCs) was studied over a wide range of frequencies. During ageing, the dielectric constants and loss tangents decreased linearly with the logarithm of ageing time. The ageing rates were evidently influenced by the test frequencies. The maximum value, within the range 0.1 to 1000 kHz, was about 1.7% per decade (time) and meets the corresponding ageing specifications for X7R ceramic dielectrics. This revised version was published online in July 2006 with corrections to the Cover Date.