Electronic structure of BaPbO₃and Ba₂PbO₄

Abstract

The electronic structure of BaPbO3 and Ba2PbO4 was investigated using photoemission, x-ray diffraction (XRD) and tight binding linear muffin tin orbital (TB-LMTO) band structure techniques. BaPbO3 is a base material for all Pb based superconductors. Rietveld analysis of the XRD data suggested that BaPbO3 is an orthorhombically distorted perovskite with Imma space group and Ba2PbO4 possesses tetragonal structure with I4/mmm space group. LMTO calculations indicated an insulating ground state for Ba2PbO4 with a band gap of 1.3 eV and a metallic ground state for BaPbO3. Ultraviolet photoemission results agree well with the LMTO calculations. The Pb–O1–Pb bond angle in the basal plane is a key parameter in deciding the electronic structure of these compounds. The Pb 4f and O 1s core levels of BaPbO3 exhibited asymmetry on the high binding energy side of the peak, indicating that both Pb and O contribute to the density of states at the Fermi edge. The core levels of Ba2PbO4 did not exhibit asymmetry. Core level asymmetry can be used to probe the local density of states at EF.

Systematic Band Gap Tuning of BaSnO3 via Chemical Substitutions: The Role of Clustering in Mixed-Valence Perovskites

“…It is worthwhile to note that the Ba−Pb−O system has many possible stable compounds, including Ba 2 PbO 4 and Ba 2 PbO 6 , and Pb ions may also have a stable valence state of 2+. 48,49 It has been reported that the oxygen vacancies can enable the partial reduction of Pb 4+ to Pb 2+ and the change in the Pb−O bonding angle, which is responsible for the semiconducting behavior of BaPbO 3 . 50,51 In one possible theoretical scenario, Pb 2+ enters the A site, which leads to a situation similar to what is observed with Sr: a small decrease in the lattice constant (<1%) and disordered reduction of octahedral sizes.…”

“…Theoretical calculations of the energetics for A-site or B-site occupancy provide very similar results and do not discriminate between the two cases. It is worthwhile to note that the Ba–Pb–O system has many possible stable compounds, including Ba 2 PbO 4 and Ba 2 PbO 6 , and Pb ions may also have a stable valence state of 2+. , It has been reported that the oxygen vacancies can enable the partial reduction of Pb 4+ to Pb 2+ and the change in the Pb–O bonding angle, which is responsible for the semiconducting behavior of BaPbO 3 . , …”

Reduction of anatase TiO[sub 2] on Si(111) by ion beam sputtering

“…The peak deconvolution of Ti 2p spectra was carried out using the Asymmetric Gassian Lorentzian sum function [10] defined as,…”

Feeble Metallicity and Robust Semiconducting Regime in Structurally Sensitive Ba(Pb, Sn)O$_3$ Alloys

“…Weakly correlated oxide perovskites of the form ABO 3 , where A is an alkali or alkaline earth element and B = Sn, Pb, Bi, have shown diverse structural polymorphs and electronic properties, including metal-insulator transition, superconductivity, and nontrivial topological phases [1][2][3][4][5][6][7][8] . Among these, the emerging superconducting properties, similar to that exhibited by cuprates, have been investigated extensively in their pristine form or with substitution at A and/or B sites [9][10][11] . BaPb 1−x B x O 3 is one such member in this family which exhibits Drude kind of metallic behaviour in its pristine form (x=0) and superconducting phase upon Bi (0<x≤0.3) substitution at T c = 13 K [12][13][14][15][16][17] .…”