ChemInform Abstract: Superconductive Properties of Solid Solutions of Ba(Pb1‐xLax)O3 and ( Ba1‐xLax)PbO3.

Abstract

Superconductive Properties of Solid Solutions of Ba(Pb1-xLax)O3 and ( Ba1-xLax)PbO3.-The title ceramics Ba(Pb1-xLax)O3 (0 ≤ x ≤ 0.5) and (Ba1-xLax)PbO3 (0 ≤ x ≤ 0.6), obtained by solid phase synthesis from BaO2, PbO2, and La2O3, reveal a metal-dielectric type transition. The conditions for the transition into the superconductive state are analyzed. -(OL'KHOVIK, I. V.; POLITOVA, E. D.; MITIN, A. V.; PRUTCHENKO, S. G.; FEDOTOVA, M. V.; Neorg. Mater. 30 (1994) 3, 402-405; Nauchno-issled. fiz.-khim. inst. im. Karpova, Moskva, Russia; RU)

Room-temperature ferromagnetism in transparent Mn-doped BaSnO3epitaxial films

“…Because the BSMO films were deposited at a low oxygen pressure and are apt to contain oxygen vacancies, the low valence state of the Mn ions can maintain the charge balance. The low valence state also gives rise to a large average diameter of Mn ions (Mn 2+ : R ef = 0.80 Å, Mn 3+ : R ef = 0.58 Å), 32) which is consistent with the observed lattice expansion.…”

Optical and transport properties of lanthanum-doped stannate BaSnO3

“…For Ba 0.98 La 0.02 SnO 3 , a increases even though the ionic radius of La 3+ (136 pm) is lower than that of Ba 2+ (161 pm) in 12-fold coordination [18]. The partial reduction of Sn 4+ (r Sn 4+ = 69 pm) to Sn 2+ (r Sn 2+ = 112 pm) 4 in the octahedral site, induced by La-substitution to keep the electro neutrality, is responsible for this evolution. Generally, the oxides with a Jahn-Teller ion bearing an inert electron pair crystallize in distorted structures with a low coordination environment and a limited composition range.…”

“…The thermal variation of the molar susceptibility χ M (T ) is temperature independent (∼1.7 × 10 −5 emu cgs mol −1 ) down to ∼70 K, with dχ/dT equal to −1.4 × 10 −8 emu cgs mol −1 K −1 (figure 2); below 70 K the sharp upturn may be due to a localized paramagnetic impurity. SnO 2 is expected to be diamagnetic; however the thermal variation of its susceptibility follows the Curie law, electron paramagnetic resonance (EPR) measurements have shown that they were Fe 3+ ions, detected owing to the dilution effect; from 4 The nature of the lone pair Sn 2+ occupying irregular oxygen polyhedra made it impossible to define precise ionic radii and given values in the literature are somewhat variable. In the present case, the radius of Sn 2+ was taken from [19].…”

“…This is due to the broad anti-bonding conduction band (CB) arising from Pb : 6s-O : 2p orbitals owing to the close energy that tolerates large perturbations [3]. In this prospect, some superconducting copperless oxides with oxygen deficient perovskites or perovskite intergrowth would appear as multi valence state systems [4]. For this purpose, we need central cations that exhibit various electronic configurations.…”