**4. Conclusions**

In the present work, the structural and magnetic properties of the Fe-substituted perovskite series were studied in detail. Specifically, the average crystalline grain size of the YFeO3 compound, calculated using the harmonic spherical approach in a Rietveld refinement, was 84 (8) nm, a size where weak ferromagnetism can occur in this compound. In the Fe-substituted YFexCr1−xO3 compounds, X-ray and neutron diffraction patterns collected at RT and 2 K gave a linear increase in the lattice parameters of the orthorhombic structure with increasing Fe concentration, where the c-parameter had the most pronounced increase. This increase obviously translates into an increase in the volume cell and consequently a change in the magnetocrystalline anisotropy of the samples, i.e., a magnetic anisotropy that depends on the Fe concentration. Considering that X-ray and neutron diffraction showed only one crystalline phase for all samples, and the above results of lattice parameters that showed a gradual increase with increasing iron content, we can highlight that autocombustion is a useful method for the synthesis of pure YFeO3 with high stoichiometry. The 90 kOe *M(H)* curves taken at RT and 5 K for all Fe-substituted samples suggest the presence of spin reorientation and magnetization reversal phenomena associated with homogenous (Fe–Fe, Cr–Cr) and non-homogeneous pairs of 3d-ions (Fe–Cr). The dependence of the *HC*, *Mr*, and *σsat* with Fe concentration clearly showed the onset of WFM for x = 0.60–0.80 values. For x = 1.0, the high *HC* value of 46.7 kOe was calculated after subtracting the AFM contribution (linear contribution of the paramagnetic phase). This latter result implies that an enhancement in the WFM is achieved due to chemical inhomogeneity of the YFeO3 phase. Moreover, the values of *Mr* and *σsat* at 300 K are in agreement with the values commonly found in single crystals. The WFC and ZFC *M(T)* curves recorded at low (50 Oe) and high (1000 Oe) probe field analysis allowed the magnetic properties and global magnetic response of the spin reorientation process to be tuned. The high field *M(T)* curves allowed for accurate determination of *TN* values and showed a nonlinear dependence of *TN* on Fe concentration. The sample with x = 0.75 clearly exhibited a higher magnetic disorder, as corroborated by Mössbauer spectra recorded at 77 K and 300 K. The magnetization measurement performed in a low probe field of 50 Oe, for the sample with x = 0.50 showed a diamagnetic-like behavior near the compensation temperature of 245 K, where an inverse magnetization and the most intense remanence and saturation values at 300 K were found compared to the other samples. For the low Fe content (x = 0.25) and pure orthochromite samples, they showed paramagnetic-like behavior at RT, with a magnetic order only below 150 K. Mössbauer spectra allowed us to study the local Fe environment and visualize a weak enhanced ferromagnetism, due to a remarkable high canting angle (13◦), estimated previously from neutron diffraction analysis, and its variation with Fe concentration. At least two octahedral Fe sites were identified in the non-pure Fe-substituted samples, whose evolution of the magnetic hyperfine field (Bhf) can be explained using the results of mean field theory reported in the literature. The sample with x = 0.50 showed good magnetic properties and is a suitable candidate for further study.

**Author Contributions:** Conceptualization, R.S.-R. and J.A.R.-G.; methodology, R.S.-R., N.-R.C.-H. and J.A.R.-G., validation, R.S.-R., N.-R.C.-H., E.C.P., J.-M.G. and J.A.R.-G.; formal analysis, R.S.-R., N.-R.C.-H. and J.A.R.-G.; investigation, R.S.-R., D.A.G., K.M.T., N.-R.C.-H., E.C.P., J.-M.G. and J.A.R.-G.; resources, R.S.-R., N.-R.C.-H. and J.A.R.-G.; data curation, R.S.-R., N.-R.C.-H. and J.A.R.-G.; writing—original draft preparation, R.S.-R. and J.A.R.-G.; writing—review and editing, R.S.-R., E.C.P. and J.A.R.-G.; visualization, R.S.-R. and J.A.R.-G.; supervision, R.S.-R. and J.A.R.-G.; project administration, R.S.-R.; funding acquisition, R.S.-R. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the "Universidad Nacional de Ingeniería-UNI" and the APC was funded by VRI-UNI. The part of this research conducted at ORNL's High Flux Isotope Reactor was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy.

**Data Availability Statement:** The original data related to this research can be requested at any time from the corresponding author at the following email address: rsalazarr@uni.edu.pe.

**Acknowledgments:** We thank LABICER (UNI) for the XRD support and sample preparation analyzes. Juan A. Ramos-Guivar thanks the National Program of Scientific Investigation and Advanced Studies (PROCIENCIA), while Edson C. Passamani thanks FAPES and CNPq for their financial support.

**Conflicts of Interest:** The authors declare no conflict of interest.
