Study on variable temperature Mössbauer spectra of GdFe_0.5Cr_0.5O₃ perovskite

Quantitative Calculation of the Clustering Behavior of Fe‐Rich and Cr‐Rich REFepCr1−pO3 Crystals

“…The Curie–Weiss law [ 29 ] χ = C /( T − θ ) has been used to fit the data between 80 and 125 K and above 250 K. The results indicate that the susceptibility follows the Curie–Weiss law. Above 250 K, the primary component is nearly paramagnetism, confirming the Mössbauer spectral results from our earlier work, [ 17 ] while the Curie–Weiss behavior between 80 and 125 K is puzzling because the Mössbauer spectrum test at 120 K indicates a strong magnetic state rather than a paramagnetic state. In fact, the Curie–Weiss behavior is the principal cause of the strong paramagnetic contribution of Gd 3+ to the system.…”

“…This is the result of the competition between Fe 3+ –O–Cr 3+ and Fe 3+ –O–Fe 3+ /Cr 3+ –O–Cr 3+ or the random occupation of Fe/Cr. The bifurcation of ZFC/FC at 300 K shows that the system is in a strong frustration state at room temperature (RT), contrary to the previous Mössbauer spectral phenomenon [ 17 ] : no Zeeman sextet was observed in the Mössbauer spectrum at 300 K, indicating there is no competition of superexchange interaction. It is worth noting that the shape of spectrum at 250 K is characteristic of Fe atoms in the superparamagnetic state, [ 28 ] which shows that the temperature range of 250–300 K is likely to be the dynamic change stage of superparamagnetic relaxation.…”

“…Mössbauer spectra are used to analyze the charge environment around Fe nuclei in order to support the calculated results. Figure 7c,d shows the Mössbauer spectra fitted by seven sextets at 120 and 12 K. Data previously analyzed by us in ref [17]. for fitting were used in this article.…”

“…The synthesis method, X‐ray diffraction, and Mössbauer spectrum characterization of the sample were described in ref. [17]. The lattice parameters, the volume of the unit cell, and average grain size of were calculated by Bragg formula and Scherrer formula, a = 5.3325 Å, b = 5.5599 Å, c = 7.6395 Å, V = 226.5 Å 3 , and D = 73.4 nm.…”

“…[ 15,16 ] Likewise, we have previously held that Fe 3+ –O–Cr 3+ is AFM superexchange. [ 17 ] Typically, this is primarily attributable to the lattice distortion caused by Cr 3+ doping, which reduces the bond angle of Cr 3+ –O–Fe 3+ to less than 180°, and also significantly weakens the FM interaction, and boosts the AFM interaction. Further, such arguments exist regarding other rare‐earth perovskites.…”