TY - JOUR
T1 - Fundamental material property trends in the La0.8-xNdxCa0.2FeO3-δ series: crystal structure and thermal expansion
AU - Berger, Christian
AU - Bucher, Edith
AU - Lammer, Judith
AU - Nader, Christina
AU - Sitte, Werner
PY - 2021/2/25
Y1 - 2021/2/25
N2 - Compounds from the series La0.8-xNdxCa0.2FeO3-δ (0.1 ≤ x ≤ 0.7) were synthesised by a sol–gel route. X-ray diffraction and Rietveld analysis showed that materials with 0 ≤ x ≤ 0.6 crystallize as single-phase orthorhombic perovskites. The smaller ionic radius of Nd3+ compared to La3+ leads to a decrease in unit cell volume with increasing x. Elemental mapping by high-resolution scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy confirms the homogeneous distribution of the A-site elements (La, Nd and Ca) in the perovskite (ABO3) lattice. The thermal expansion behaviour of La0.8-xNdxCa0.2FeO3-δ (0 ≤ x ≤ 0.6) was characterized by dilatometry at 30 ≤ T/°C ≤ 1000 and 1 × 10–3 ≤ pO2/bar ≤ 1. The thermal expansion coefficients of La0.8-xNdxCa0.2FeO3-δ, which were determined in regions I (40–530 °C) and II (530–990 °C), respectively, are almost independent of the Nd concentration in the range of (0 ≤ x ≤ 0.6) and increase slightly with decreasing pO2. The transition from orthorhombic to trigonal modification, which is observed for La0.8Ca0.2FeO3-δ at approx. 740 °C, is suppressed for all Nd-substituted compounds with x ≥ 0.1.
AB - Compounds from the series La0.8-xNdxCa0.2FeO3-δ (0.1 ≤ x ≤ 0.7) were synthesised by a sol–gel route. X-ray diffraction and Rietveld analysis showed that materials with 0 ≤ x ≤ 0.6 crystallize as single-phase orthorhombic perovskites. The smaller ionic radius of Nd3+ compared to La3+ leads to a decrease in unit cell volume with increasing x. Elemental mapping by high-resolution scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy confirms the homogeneous distribution of the A-site elements (La, Nd and Ca) in the perovskite (ABO3) lattice. The thermal expansion behaviour of La0.8-xNdxCa0.2FeO3-δ (0 ≤ x ≤ 0.6) was characterized by dilatometry at 30 ≤ T/°C ≤ 1000 and 1 × 10–3 ≤ pO2/bar ≤ 1. The thermal expansion coefficients of La0.8-xNdxCa0.2FeO3-δ, which were determined in regions I (40–530 °C) and II (530–990 °C), respectively, are almost independent of the Nd concentration in the range of (0 ≤ x ≤ 0.6) and increase slightly with decreasing pO2. The transition from orthorhombic to trigonal modification, which is observed for La0.8Ca0.2FeO3-δ at approx. 740 °C, is suppressed for all Nd-substituted compounds with x ≥ 0.1.
UR - https://rdcu.be/cGhdY
U2 - 10.1007/s10853-021-05851-z
DO - 10.1007/s10853-021-05851-z
M3 - Article
SN - 0022-2461
VL - 56.2021
SP - 10191
EP - 10203
JO - Journal of materials science
JF - Journal of materials science
IS - February
ER -