The influence of oxygen vacancy on the electronic and optical properties of ABO_3−δ (A = La, Sr, B = Fe, Co) perovskites

Abstract

ABO3−δ (A = La, Sr, B = Fe, Co) perovskites are useful in a wide range of applications, including their recent exploration for application in high-temperature optical oxygen sensing for energy conversion devices such as solid oxide fuel cells.

Effects of Site and Magnetic Disorder on the Oxygen Vacancy Formation and Electronic and Optical Properties of LaxSr1–xCoO3−δ and SrFeyCo1–yO3−δ

“…In the pure LCO, SCO, and SFO systems, the magnetic moments of transition-metal ions in their FM phases are 1. , S = 2) in SFO, which are consistent with the orbital occupations obtained in our previous work. 11 The magnetic moments of Co 4+ and Fe 4+ in the PM SCO and SFO are almost kept unchanged. However, the magnetic moment of Co 3+ in the PM LCO is separated to 0.45 and 2.27 μ B , corresponding to a mixed HS and low-spin (LS) state, which is consistent with the ground HS + LS state in the PM LCO.…”

“…Δh is the correction for calculated errors in O 2 , such as the well-known O 2 overbinding in DFT calculations (Δh = 1.36 eV/O 2 for the PBE method). 30 As described in our previous studies, [10][11][12]31 optical properties can be obtained from the frequency-dependent complex dielectric function ε(ω) = ε 1 (ω) + iε 2 (ω). The imaginary part of the dielectric function ε 2 (ω) can be calculated using the method by Gajdošet al 32 within the single-particle approximation and neglecting local field effects.…”

Doping- and Strain-Dependent Electrolyte-Gate-Induced Perovskite to Brownmillerite Transformation in Epitaxial La1–xSrxCoO3−δ Films

“…While our V̅ Co estimates apply strictly only to the P phase, transport will be dominated by the P phase even in the P−BM and 5, "V g = −0.5 V" corresponds to the "no gel applied" case. 55 Curnan and Kitchin, 54 Deml et al, 56 and Tahini et al 57 are from DFT. In (d), the values of Mefford et al, 59 Pan et al, 60 Takeda et al, 61 and Van Buren et al 62 are from electrochemical chronoamperometry.…”

“…Literature values of the xdependent (c) oxygen vacancy formation energy (E V O ) and (d) 300 K oxygen vacancy diffusion length (l D ) for La 1−x Sr x CoO 3−δ . In (c), the values of Mizusaki et al53 are experimentally measured enthalpies from thermogravimetry, while the values of Jia et al,55 Curnan and Kitchin,54 Deml et al,56 and Tahini et al57 are from DFT. In (d), the values of Mefford et al,59 Pan et al,60 Takeda et al,61 and Van Buren et al62 are from electrochemical chronoamperometry.…”

Defect assisted optical limiting performance of hexagonal boron nitride nanosheets in aqueous suspension and PMMA nanocomposite films

“…Although studies on defect engineering of h-BN samples are in their infancy, results have been obtained indicating that optical features of h-BN can be manipulated by introducing or altering point defects. Optical features can be adjusted potently by vacancy construction and external electric fields [17][18][19]. Vacancy construction yields an exciton emission by introducing localized defect states within the band gap, whereas an external electric field lead to the manipulation of vacancies such as the migration or diffusion of the vacancies yielding the construction of new emission behaviors.…”