Oxygen-ionic conductors based on substituted bismuth molybdates with column-type structural fragments

Abstract

Abstract-The possibility of synthesizing oxygen ionic conductors from substituted bismuth molybdates containing columns, MoO 4 tetrahedra, and isolated Bi ions in their structure was studied. The specifics of their structure and electric conductivity were investigated. The general formula of the solid solu tions can be recorded as Bi 13 Mo 5 -x Me x O 34 -δ , where Me is the four or five valent d metal (Ti, Zr, V, Nb). The electric conductivity of doped bismuth molybdates considerably increased compared with that of the matrix compound. The electric conductivity reached 5.5 × 10 -3 S cm -1 at 700°C and 1.8 × 10 -4 S cm -1 at 350°C for the zirconium doped compound with x = 0.4. The porosity of the ceramics was less than 5%; the thermal expansion coefficient was of the order of 14 × 10 -6 K -1. Based on the set of their characteristics, these compounds are recommended as materials for membranes of electrochemical devices.

Crystal Structure and Characterization of La1-xBixMnO3+δ

“…The obtained precursors were annealed at 600°С and 1100°С (x=0.1-0.5) and 1200°С (x=0.0). Bismuth-containing electrolytes Bi 4 V 1.7 Fe 0.3 O 11 , Bi 13 Mo 5 O 34 and Bi 3 Nb 0.8 W 0.2 O 7.1 were synthesized using the solid-state method described elsewhere (1)(2)(3) to study their chemical compatibility with La 1-x Bi x MnO 3+δ electrodes. X-ray powder diffraction (XRD) patterns were collected using CuK α radiation on a D8 ADVANCE diffractometer equipped with a VÅNTEC position-sensitive detector and a β-filter, and on an Equinox 3000 Enel diffractometer.…”

“…An excess of Mohr's salt (~0.71 g) was added to the solution. Mn 4+ and Mn 3+ ions present in La 1-x Bi x MnO 3+δ react with Fe 2+ ions from Mohr's salt according to chemical equations [1] and [2]:…”

“…Mn 3+ +Fe 2+ → Mn 2+ +Fe 3+ [ 2 ] Red-Ox titration was performed using automatic titrator (ATP -02, Akvilon, Russia) with 0.1 N K 2 Cr 2 O 7 solution as the titrant. The unreacted Fe 2+ ions from Mohr's salt after finishing reactions [1] and [2] was oxidized by Cr 2 O 7 2ions to get Fe 3+ according to the reaction [3]:…”

“…An excess of Mohr's salt (~0.71 g) was added to the solution. Mn 4+ and Mn 3+ ions present in La 1-x Bi x MnO 3+δ react with Fe 2+ ions from Mohr's salt according to chemical equations [1] and [2]: Mn 4+ +2Fe 2+ → Mn 2+ +2Fe 3+ [ 1 ] Mn 3+ +Fe 2+ → Mn 2+ +Fe 3+ [ 2 ] Red-Ox titration was performed using automatic titrator (ATP -02, Akvilon, Russia) with 0.1 N K 2 Cr 2 O 7 solution as the titrant. The unreacted Fe 2+ ions from Mohr's salt after finishing reactions [1] and [2] [ 4 ] n -quantity of gram-equivalent of manganese; ν -quantity of mol manganese; N -normality of K 2 Cr 2 O 7 (gram-equivalent/liter); V -volume of K 2 Cr 2 O 7 (liter).…”

Crystal structure and conductivity of bismuth-containing complex oxides

“…The features of synthesis for each particular case are described in [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”