TY - JOUR

T1 - In-situ Mössbauer studies of 57Fe-doped Ruddlesden-Popper type lanthanum nickel oxides

AU - Klande, Tobias

AU - Cusenza, Salvatore

AU - Gaczyński, Piotr

AU - Becker, Klaus Dieter

AU - Dörrer, Lars

AU - Borchardt, Günter

AU - Feldhoff, Armin

N1 - Funding Information: Financial support from the State of Lower Saxony in the frame of NTH bottom-up project No. 21-71023-25-7/09 is gratefully acknowledged. We like to thank Hannes Töpfer and Mladen Zec (TU Ilmenau) for the helpful discussions and for the FEM calculations of the four-point geometry of the conductivity measurements.

PY - 2012/8/20

Y1 - 2012/8/20

N2 - The Ruddlesden-Popper (RP) phases La 2Ni 1 - xFe xO 4 + δ (x = 0.02, 0.1) and La 4Ni 3 - xFe xO 10 - δ (x = 0.3, 0.9) were successfully synthesized via the sol-gel route. Even though X-ray diffraction did not show any secondary phases for La 2Ni 0.9Fe 0.1O 4 + δ, approximately 5-10% of the higher order RP phase La 4Ni 2.1Fe 0.9O 10 - δ were detected in backscattered electron contrast imaging, whereas La 2Ni 0.98Fe 0.02O 4 + δ exhibits no foreign phases. This was also confirmed by transmission electron microscopy (TEM). Furthermore, the oxygen permeation performance and electrical conductivity of La 2Ni 1 -xFe xO 4 + δ were found to decrease slightly with increasing iron content. The Mössbauer spectra of La 2Ni 1 -xFe xO 4 + δ (x = 0.02, 0.1) are dominated by a quadrupole-split doublet. With increasing temperature, however, a minority iron species is detected. The dominating doublet reveals an unusual high-temperature behavior of quadrupolar interactions, which was observed by in-situ Mössbauer measurements at high temperatures and different oxygen partial pressures. This is most likely related to ordering phenomena of oxygen.

AB - The Ruddlesden-Popper (RP) phases La 2Ni 1 - xFe xO 4 + δ (x = 0.02, 0.1) and La 4Ni 3 - xFe xO 10 - δ (x = 0.3, 0.9) were successfully synthesized via the sol-gel route. Even though X-ray diffraction did not show any secondary phases for La 2Ni 0.9Fe 0.1O 4 + δ, approximately 5-10% of the higher order RP phase La 4Ni 2.1Fe 0.9O 10 - δ were detected in backscattered electron contrast imaging, whereas La 2Ni 0.98Fe 0.02O 4 + δ exhibits no foreign phases. This was also confirmed by transmission electron microscopy (TEM). Furthermore, the oxygen permeation performance and electrical conductivity of La 2Ni 1 -xFe xO 4 + δ were found to decrease slightly with increasing iron content. The Mössbauer spectra of La 2Ni 1 -xFe xO 4 + δ (x = 0.02, 0.1) are dominated by a quadrupole-split doublet. With increasing temperature, however, a minority iron species is detected. The dominating doublet reveals an unusual high-temperature behavior of quadrupolar interactions, which was observed by in-situ Mössbauer measurements at high temperatures and different oxygen partial pressures. This is most likely related to ordering phenomena of oxygen.

KW - Electrical conductivity

KW - In-situ Mössbauer spectroscopy

KW - Oxygen permeation

KW - Ruddlesden-Popper phases

KW - Transmission electron microscopy

UR - http://www.scopus.com/inward/record.url?scp=84864063409&partnerID=8YFLogxK

U2 - 10.1016/j.ssi.2012.06.019

DO - 10.1016/j.ssi.2012.06.019

M3 - Article

AN - SCOPUS:84864063409

VL - 222-223

SP - 8

EP - 15

JO - Solid State Ionics

JF - Solid State Ionics

SN - 0167-2738

ER -