Structural and thermoelectric properties of Gd Sr2-CoO4 layered perovskites

Switching from antiferromagnetism to ferromagnetism in nanocrystalline La1−xSr1+xCoO4 (x = 0.0, 0.2, 0.4 and 0.6) layered perovskite oxides: effects of mixed valence states of Co on their magnetic, optical and photocatalytic properties

“…5(d) illustrates a high-resolution XPS scan of the Co 2p lines in all the synthesized phases, demonstrating two main peaks located at 795.08 and 780.06 eV, corresponding to Co 2p 1/2 and Co 2p 3/2 , respectively. 58 Furthermore, the obtained XPS spectra were fitted using the XPSPEAK41 program. 59 To refine the experimental spectra, we meticulously adjusted them with a combination of Lorentz–Gaussian functions to resolve the overlapping peaks, which is crucial for accurately determining the content of mixed valence states of cobalt such as Co 3+ and Co 4+ in the samples.…”

“…6, revealed the mixed valence state of cobalt, i.e., the presence of Co 3+ and Co 4+ at binding energies of 780.01 and 781.58 eV, respectively. 58,60,61 3+ and Co 4+ in terms of percentage for all the prepared phases obtained from the analysis of XPS spectra. It has been observed that the introduction of Sr 2+ ions as dopants leads to significant changes in the concentration of Co 3+ and Co 4+ ions.…”

Structural and Thermoelectric Properties of Gd2−2xSr1+2xMn2O7 Double-Layered Manganites

“…However, works on the high-temperature TE properties of RE 2−2 x Sr 1+2 x Mn 2 O 7 to take advantage of their intrinsic superlattice structures are very scarce. During the course of our systematic research on the phase diagram of the Gd–Sr–Co/Mn–O systems [ 22 , 23 ], a Gd 2−2 x Sr 1+2 x Mn 2 O 7 solid solution was found. Our magnetic measurements of the Gd 2−2 x Sr 1+2 x Mn 2 O 7 samples in the temperature range of 2–350 K under an applied magnetic field of 0.02 T show two ferromagnetic transitions, which is in analogy to the temperature-dependent magnetizations of La 1.2 Sr 1.8 Mn 2 O 7 [ 24 ] and La 1.4 Sr 1.6 Mn 2 O 7 [ 25 ].…”