Polymorphism in BaPb1−xBixO

Field-tuned superconductor-insulator transition in BaPb1−xBixO3Giraldo-Gallo1, Lee2, Zhang3 et al. 2012Phys. Rev. B231340View full textAdd to dashboardCite

“…1). This behavior is consistent with results previously found in polycrystalline samples 14 , though with a reduced maximum volume fraction, possibly due to the different conditions and cooling rates used to grow single crystal samples. Figure 2 shows curves of electrical resistivity vs. temperature at zero field for representative samples of different Bi compositions.…”

Lone Pair Effect, Structural Distortions, and Potential for Superconductivity in Tl Perovskites

“…BaPb 1−x Bi x O 3 (BPBO) is superconducting for 0.05 < x < 0.3 and its maximum T c is 13 K for x = 0.25 where there is a mixture of orthorhombic and tetragonal polymorphs. 11 In both systems, BKBO and BPBO, the maximum T c is close to a metal to semiconductor transition. When BaBiO 3 is hole doped, more Bi 5+ is present and the average Bi-O distance consequently decreases.…”

Stripe-like nanoscale structural phase separation in superconducting BaPb1−xBixO3

“…On doping, the insulating CDW phase disappears, giving rise to a metallic phase, where superconductivity appears at (maximum) temperatures below 30 and 11 K for K-doping and Pb-doping, respectively2324. For the case of BaPb 1– x Bi x O 3 , superconducting compositions are found to be dimorphic25. The nature of the associated structural phase separation, and its effect on the superconducting properties, has, however, not previously been addressed.…”

“…For the insulating end-member compound BaBiO 3 ( x =1), and down to x =0.9, the unit cell space group is monoclinic I2/m (coming from a a 0 b − c − tilt, in Glazer's notation); for the metallic end-member compound BaPbO 3 ( x =0) and up to x ≈0.15, and again for 0.35< x <0.9, the unit cell space group is orthorhombic Ibmm (coming from a a 0 b − b − tilt, as shown in Fig. 1a); however, for the region of 0.15< x <0.35, which is also the range of compositions for which the material is superconducting, the material is polymorphic, with a fraction of its volume with orthorhombic Ibmm symmetry and the rest with tetragonal I4/mcm symmetry (coming from a a 0 a 0 c − tilt)25. The superconducting volume fraction peaks at the same Bi composition where the tetragonal-to-orthorhombic ratio is maximum, leading to the conclusion that the tetragonal polymorph is the one responsible for superconductivity in this material2528.…”

“…1a); however, for the region of 0.15< x <0.35, which is also the range of compositions for which the material is superconducting, the material is polymorphic, with a fraction of its volume with orthorhombic Ibmm symmetry and the rest with tetragonal I4/mcm symmetry (coming from a a 0 a 0 c − tilt)25. The superconducting volume fraction peaks at the same Bi composition where the tetragonal-to-orthorhombic ratio is maximum, leading to the conclusion that the tetragonal polymorph is the one responsible for superconductivity in this material2528. This Bi composition is also the one for which the material has the maximum T c , that is, the optimal doping composition.…”