Temperature dependent structural properties of Mn_1.90M_0.10O₃(M = Cr and Fe)

Area of Science:

• Materials Science
• Solid State Physics
• Crystallography

Background:

• Manganese oxide (Mn2O3) exhibits complex magnetic and structural properties, including antiferromagnetic transitions and a cubic to orthorhombic structural transition.
• Investigating the effects of substituting other transition metals into the Mn2O3 lattice is crucial for understanding structure-property relationships.

Purpose of the Study:

• To investigate the impact of chromium (Cr) and iron (Fe) substitutions on the magnetic and structural properties of Mn2O3.
• To determine the temperature-dependent magnetic and structural transitions in Mn1.90Cr0.10O3 (MCO) and Mn1.90Fe0.10O3 (MFO) polycrystalline samples.

Main Methods:

• Polycrystalline samples of MCO and MFO were synthesized.
• Temperature-dependent magnetic measurements were performed.
• Synchrotron X-ray Powder Diffraction (SXRD) was used for structural analysis at room temperature and across a temperature range.

Main Results:

• Both MCO and MFO samples crystallize in cubic symmetry at room temperature.
• Cr and Fe substitutions significantly affect the magnetic and structural properties of Mn2O3.
• Both substituted samples exhibit two antiferromagnetic transitions, similar to pristine Mn2O3, occurring around ~77 K/80 K and ~40 K.
• The cubic to orthorhombic structural transition temperature shifts to lower values (around 240 K for MCO and 260 K for MFO) compared to pristine Mn2O3 (~310 K).
• A symmetry change from centrosymmetric Pcab to non-centrosymmetric Pca2 was observed at the ferroelectric ordering temperature for MCO.

Conclusions:

• Cr and Fe substitutions effectively modify the magnetic and structural behavior of Mn2O3.
• The observed shift in structural transition temperature and the induced ferroelectric ordering highlight the potential for tuning material properties through substitution.