0000000000643274
AUTHOR
Tom Hörlin
Synthesis, structure and conductivity of Ag2ZnSiO4, Ag2ZnGeO4 and Ag2BeSiO4
Abstract The compounds Ag2MM′O4 with MM′ = ZnSi, ZnGe and BeSi have been synthesised by reacting the corresponding Na compounds with molten AgNO3. The crystal structures of Ag2ZnSiO4 and Ag2ZnGeO4 have been refined from Cu K α1 powder diffractometer data by the Rietveld technique to RF = 3.3 and 7.1%, respectively. They are isostructural with monoclinic Na2ZnSiO4. The powder pattern of Ag2BeSiO4 indicates that it is isostructural with orthorhombic Na2BeSiO4. The conductivity of the compounds has been determined using ac impedance measurements. Ag2ZnSiO4 and Ag2BeSiO4 are ionic conductors, with conductivities that are very similar to those of their corresponding isostructural Na compounds. A…
Ionic conductivity in monophasic Ag2xNa2(1 − x)ZnSiO4 materials with 0 ≤ x ≤ 1
Abstract Solid solution samples Ag 2 x Na 2(1 − x ) ZnSiO 4 with 0 ≤ x ≤ 1 have been prepared by heat treating powder mixtures of Na 2 ZnSiO 4 and Ag 2 ZnSiO 4 at 300 °C and characterised by X-ray powder diffraction. The ionic conductivity of the solid solution has been determined as a function of composition and temperature by means of impedance measurements. The ionic conductivity of the mixed-mobile ion compositions (0 ≤ x ≤ 1) shows no substantial deviation from the mutually similar conductivities of the end compositions Na 2 ZnSiO 4 and Ag 2 ZnSiO 4 , and neither activation energy nor conductivity pre-factor varies significantly with composition. The results indicate that the mixed-alk…
Synthesis and structural and ionic conductivity studies of Na2ZrSi4O11
The compound Na 2 ZrSi 4 O 1 1 has been prepared both by solid state synthesis and by the sol-gel technique via alkoxides. The structure of Na 2 ZrSi 4 O 11 was investigated by the Rietveld method using X-ray diffractometer data. The powder diffraction data show evidence for a triclinic distortion of the basic monoclinic structure. The ionic conductivity has been determined in the temperature interval 130-560°C using a.c. impedance measurements. The Na + ion mobility is limited, with E a =1.04 eV and σ(300°C)= 2-9 10 7 S/cm. Samples with Ta partially substituted for Zr, according to the formula Na 2-x (Zr 1-x Ta x )Si 4 O 11 with x ≤0.2, showed the same evidence for a triclinic distortion. …