Chemical and physical characterizations of the n = 1 Ruddlesden–Popper phases: Nd2 − y Sr y Ni1 − x Co x O4 ± δ (y = 1 and 0.1 ≤ x ≤ 0.9)

Tuning the Oxygen Reduction Reactivity of Layered Perovskites Using the Jahn–Teller Effect

“…Observation of an opposite trend here suggests that the inclusion of Sr(II) in the A site leads instead to replacement of Ni(III) with Co(III), effectively compressing the c axis by replacing a d 7 ion with a d 6 ion to decrease the Jahn–Teller expansion. This behavior is similar to that previously reported for Nd 2– x Sr x Ni 1– y Co y O 4 , where the c axis was compressed by 0.1 Å across all values of y . The anisotropic change observed in the unit cell results in a c / a ratio that smoothly decreases to the value observed for the pure Co sample (Figure D).…”

“…This behavior is similar to that previously reported for Nd 2−x Sr x Ni 1−y Co y O 4 , where the c axis was compressed by 0.1 Å across all values of y. 18 The anisotropic change observed in the unit cell results in a c/a ratio that smoothly decreases to the value observed for the pure Co sample (Figure 1D). A minor impurity is seen in Rietveld refinement residual plots for samples with y values between 0.05 and 0.15, where an isolated peak appears at ca.…”

“…This combination introduces properties that have been shown to introduce properties such as oxide conductivity, 6,7 superconductivity, 8,9 magnetism, 10 and catalysis. 3,6,11−16 The diversity of properties that can be installed into this family of materials has led to the identification of many examples, including La 2−x A x CoO 4 (A = Sm 3+ , Gd 3+ , Dy 3+ ), 17 T h i s c o n t e n t i s Nd 2−x Sr x Ni 1−y Co y O4, 18 La 2 Co 1−y Cu y O 4 , 19 La 2 Ni 1−y Co y O 4 , 20 and La 2−x Sr x Ni 1−y Co y O 4 . 21 Their electrochemical behavior, however, has been understudied compared to their classic perovskite analogues, and we find no previous reports on the ability of La 20,22 confirming that both Co(II) and Ni(II) can be accessed in these materials.…”

“…Layered perovskite oxides of the A 2 BX 4 type offer an intriguing ability to interface structural regions with redox activity to regions that are dominated by ionic bonding. This combination introduces properties that have been shown to introduce properties such as oxide conductivity, , superconductivity, , magnetism, and catalysis. ,,− The diversity of properties that can be installed into this family of materials has led to the identification of many examples, including La 2– x A x CoO 4 (A = Sm 3+ , Gd 3+ , Dy 3+ ), Nd 2– x Sr x Ni 1– y Co y O4, La 2 Co 1– y Cu y O 4 , La 2 Ni 1– y Co y O 4 , and La 2– x Sr x Ni 1– y Co y O 4 . Their electrochemical behavior, however, has been understudied compared to their classic perovskite analogues, and we find no previous reports on the ability of La 2– x Sr x Ni 1– y Co y O 4 to catalyze ORR.…”

Short review on recent studies and prospects of application of rare-earth-doped La2NiO4+δ as air electrodes for solid-oxide electrochemical cells

“…According to [72,92,93,113], REE substitution of lanthanum in La2NiO4+δ resulted in an increase in electrical conductivity. This was explained by the fact that the observed decrease in unit cell parameters (and bond lengths) led to an increase in carrier mobility via the small radius polaron mechanism, as it was observed earlier for the RP phases in [115,116]. At low concentration of the dopant (x ≤ 0.4), REE substitution may have an even more pronounced influence on the conductivity of the base oxide compared to some AEE, introducing additional defects due to charge compensation (Figure 6a).…”