Defect structure and electrical conductivity in the pseudo-binary system Bi3TaO7–Bi3NbO7

The exchange interactions and the state of manganese atoms in the solid solutions in Bi3NbO7 of cubic and tetragonal modifications

“…Such a conclusion agrees with the assumption about clustering of niobiumoxygen octahedra advanced as the result of examining the superstructure in cubic and tetragonal bismuth niobate and in the solid solutions [3,8,9,[17][18][19][20][21]. The formation of dimers rather than more complex clusters or chains of paramagnetic atoms seems to be associated with a low concentration of paramagnetic atoms in the solid solutions under study.…”

“…Solid electrolytes on the basis of bismuth oxide have a high oxygen conductivity and are promising as materials for fuel cells, oxygen sensors and oxygen-conducting membranes of catalytic reactors [1][2][3]. Ionic conductivity, necessary for practical application, in a cubic high-temperature phase of bismuth oxide (δ-Bi 2 O 3 ) is reached at 730°С and is equal to 1.0 S/cm [4].…”

Microwave Dielectric Properties, Crystal Structure, and Microstructure of the Bi3Nb1−xTaxO7 Solid Solution

“…The trend of increasing Q × f values with increasing Ta content in the solid solubility of the commensurate‐tetragonal Bi 3 Nb 1− x Ta x O 7 , 0.1 ≤ x ≤ 0.6, was not surprising, taking into consideration that the Ta–O bonds have a greater covalency than the Nb–O bonds and thus the Ta exhibited a greater tendency to harden the framework. These observations are in agreement with Struzik et al ,. who reported that the electrical conductivity of the ceramic system increases with the increasing Nb content.…”

“…However, any practical application of this material in fuel‐cell technologies has been restricted because of its limited range of stability (from 729°C to 835°C) and the mechanical stresses that are built up during the phase transitions . To obtain the same fluorite‐related structure and the outstanding intrinsic conductive properties at much lower temperatures, extensive investigations have attempted to stabilize the δ‐Bi 2 O 3 phase using a variety of cation substitutions . Among the wide choice of cations that can be used to stabilize δ‐Bi 2 O 3 , Nb, and Ta were found to be of particular interest because the Bi 2 O 3 –Nb 2 O 5 and Bi 2 O 3 –Ta 2 O 5 solid solutions are as follows: (i) thermodynamically stable polymorphs of δ‐Bi 2 O 3 , even at room temperature, and (ii) have the largest compositional range of stability .…”

“…3 To obtain the same fluoriterelated structure and the outstanding intrinsic conductive properties at much lower temperatures, extensive investigations have attempted to stabilize the d-Bi 2 O 3 phase using a variety of cation substitutions. [4][5][6][7][8] Among the wide choice of cations that can be used to stabilize d-Bi 2 O 3 , Nb, and Ta were found to be of particular interest because the Bi 2 O 3 -Nb 2 O 5 and Bi 2 O 3 -Ta 2 O 5 solid solutions are as follows: (i) thermodynamically stable polymorphs of d-Bi 2 O 3 , even at room temperature, and (ii) have the largest compositional range of stability. 8 In addition to the research on the ionconductivity behavior, fluorite-like solid solutions, and nitrogen-doped bismuth-based compounds were also found to be promising materials for photocatalysts [9][10][11] and as important alternatives for low-temperature co-fired ceramic (LTCC) technology.…”