The electrical conductivity of δ-Bi2O3 stabilized by isovalent rare-earth oxides R2O3

Abstract

The phenomenon of 6-phase stabilization in the systems (Bi,03)o.75(RZ03)0.25 where R = lanthanide metal (including La, but Pm excepted) was investigated. The electrical conductivity of those systems, which did show 6-stabilization, was investigated; the system (BiZ03)1_-X(YbZ03)X was studied in more detail. A Vegard-like relation between the cubic cell-axis and cationic radius of the substituted trivalent metal ion was found. A model is presented which accounts for results of electrical conductivity measurements and thermogalvanic measurements as well.

The bulk electrical conductivity properties of δ-Bi2O3 solid electrolyte system doped with Yb2O3

“…The electrical conductivity in d phase is mainly due to mobile oxygen ions as confirmed by previous studies [18,19,[30][31][32][33][34][35][36][37][38][39]. This type of conductivity can be studied by measuring ionic transference numbers.…”

“…Thus, the crystal formula of pure d-form is Bi 4 O 6 , and it contains two oxygen ion vacancies on the O 2-sublattices which can be ordered or disordered (random) arrangements in the correct directions according to the some assumed crystal structure models. Moreover, this defect crystal structure plays an important role for having a high oxide ionic electrical conduction and a solid electrolyte character of d-Bi 2 O 3 [13][14][15][16][17][18][19][20][21][22][23][24][30][31][32][33][34][35]. According to the XRD results, lattice parameter variations, color changes of fcc-type solid solution, and literature data, the crystal formula of the formed d phases was supposed as seen below;…”

“…As a consequence of this oxidation-reduction and values of x, it was estimated that the obtained solid solution should have a nonstoichiometry character and defect fcc crystal structure. The nonstoichiometry of the formed d-type materials can be regarded as an O 2-ion deficiency type according to the suggested crystal structure models of Gattow, Sillen, or Willis [18][19][20][21][30][31][32][33][34].…”

Structural stability and conductivity of cubic (WO3)x - (Dy2O3)y-(Bi2O3)1−x−y

“…The conductivity-temperature dependence of lanthanide stabilized bismuth oxides exhibit two activation energies [2][3][4][5][6]. At -600 ~ a change in activation energy occurs, with a lower activation energy above -600 ~ and a higher activation energy below -600 ~ This is due to an order-disorder transition of the oxygen sublattice.…”

Thermogalvanic power and fast ion conduction in δ-Bi2O3 and δ-(Bi2O3)1−x(R2O3)x with R = Y, TbLu

“…Besides, two other metastable phases may come into existence: the tetragonal fl phase [5,7,8,14,15] somewhere between 650 and 330°C [2, 4,11,12], and the bee y phase [S,7,8,1 I] somewhere between 640 and 500°C [4,11 ,I 21. Partial replacement of Bi3+ ions by other R3+ ions (R = Y [16-181, Tb-Lu [16,19])canstabilize the 6 phase towards room temperature.…”