A. L. Podkorytov

Synthesis and properties of (Sr1-xMx)2Nb2O7 (M = Cu, Ni) solid solutions

Abstract(Sr1 – xMx)2Nb2O7 (M = Cu, Ni) layered perovskite solid solutions were synthesized, and their stoichiometry ranges were determined. The electrical properties of the solid solutions were compared with those of Sr2Nb2O7 .

Synthesis and electrochemical properties of Pb3 − xMxNb2O8 (M = Sr, Ba) solid solutions

Pb3 − xMxNb2O8 (M = Sr, Ba) solid solutions have been synthesized and their properties have been studied. The composition ranges of the solid solutions have been determined by X-ray diffraction and their electrical conductivity has been measured as a function of temperature. The results suggest that lead-containing niobates can in principle be used as electrode-active materials for lead-selective electrodes.

Phase equilibria, charge transport, and mass transport in Sr4Nb2O9-“M4Nb2O9” (M = Cd, Cu, Ni, and Zn) systems

AbstractHomogeneous fields of Sr4 − xMxNb2O9 (M = Cd, Cu, Ni, or Zn) solid solutions were determined using powder X-ray diffraction. Phase fields were plotted proceeding from the tolerance factor t and electronegativity ratio

Kinetics of solid-state synthesis and properties of lead-containing niobate pyrochlores

\bar k_A /\bar k_B

Synthesis and Properties of Phases in the System BaCO3–PbO–Nb2O5

with a satisfactory fit of experimental results. Thermogravimetry was used to establish the major kinetic laws of solid-phase synthesis (conversion, rate-controlling stage, and effective activation energy) in (4 − x)SrCO3 + xMO + Nb2O5 powdery mixtures. Direct radiometry was used to determine 90Sr, 63Ni, and 65Zn self-diffusion coefficients in solid solutions based on the Sr4Nb2O9 phase. Electrical conductivity was measured as a function of temperature for all Sr4Nb2O9-“M4Nb2O9” samples. The conductivity of Sr4 − xMxNb2O9 (M = Cd, Cu, Ni, or Zn) solid solutions has a mixed ion-electron character.

SYNTHESIS AND PROPERTIES OF NICKEL-CONTAINING NIOBATES

Lead-selective film electrodes with solid contact with membranes on the basis of niobates and vanadates of compositions Sr2.75Pb0.25La(VO4)3, Ba3.8Pb0.2Nb2O9, Ba3.5Pb0.5Nb2O9, Pb3NiNb2O9, and Pb2Nb2O7 are constructed and studied. Basic electrochemical characteristics of ion-selective electrodes, such as linearity region and steepness of the electrode function, working pH interval, type of electrode function, and reproducibility are determined. The electrode with a membrane on the basis of Pb3NiNb2O9 is tested and recommended as an indicator in the method of potentiostatic titration. The optimum titrant for assaying ions of lead(II) in solution is potassium chromate.

Pyrochlore solid solution (Pb1-xMx)2Nb2O7 (M = Sr, Ba)

The main features of the synthesis of (Pb1-xSrx)2Nb2O7 and (Pb1-xBax)2Nb2O7 pyrochlore solid solutions were determined using isothermal thermogravimetry in tandem with formal-kinetic analysis. The stability and electron-transport properties of the triple niobates were studied, which allowed us to test them as electrode-active materials for membranes in ion-selective electrodes (ISEs).

Solid-state synthesis of strontium titanate niobates

Ca3−xPbxNb2O8 and (Pb1−xMx)2Nb2O7 (M = Sr, Ba, Ca) solid solutions have been synthesized and identified by x-ray diffraction, their isomorphic capacity has been assessed theoretically, and the theoretical predictions have been compared with experimental data. The formation kinetics and mechanisms of the alkaline-earth-doped lead niobates have been analyzed in detail. The electrical conductivity of the synthesized niobates has been measured, and their chemical stability in acid solutions has been shown to be rather high.