User:OrganoMetallurgy/Drafts/Barium bismuthate

OrganoMetallurgy/Drafts/Barium bismuthate

Names
Other names BBO, BaBiO3
Identifiers
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

non-chembox sections

Barium bismuthate(III)(V), BaBiO₃, is a mixed valence semiconductive oxide with a perovskite structure which becomes superconductive at low temperatures when suitably hole doped.

Properties

Semiconductive Losses some oxygen at high temperatures.

Crystal structure

BaBiO₃ is a perovskite, there are two distinct bismuth sites It is monoclinic, space group I2/m at room temperature. At temperatures between 430 and 820 K it is rhombohedral with the space group R3, above 820 K it is cubic, space group Fm3m. Below 140 K it is monoclinic with the space group P21/n.

Synthesis

Electrocrystallization
Melt and anneal under high oxygen pressure

Superconductivity

Potassium barium bismuth oxide (Ba_1-xK_xBiO₃)

Potassium barium bismuth oxide is a superconductor from x ≈ 0.3 to 0.45 the maximum T_c is around 32 K at the approximate composition Ba_0.6K_0.4BiO₃. The superconductive phase is cubic, space group Fm3m, at room temperature, and tetragonal, space group I4/mcm, at low temperatures.
The different bismuth sites become more equivalent?/disordered?/less distinct with increasing hole doping.

BaPb_1-xBi_xO₃

See the article of barium plumbate for more information.
BaPb_1-xBi_xO₃ is a superconductor in the composition range x = 0.15 to 0.30 with a maximum T_c of ~12 K at x ≈ 0.25