| Autor: |
Sadhu A; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) , Kolkata, Mohanpur 741246, India., Salunke HG; Technical Physics Division, Bhabha Atomic Research Centre , Trombay, Mumbai 400085, India., Shivaprasad SM; International Centre for Materials Science & Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore 560064, India., Bhattacharyya S; Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) , Kolkata, Mohanpur 741246, India. |
| Abstrakt: |
The alterations in physical property across different space groups of the same material are sometimes conveniently reflected by the crystal structure as a function of temperature. However, mirroring the physical property and crystal parameters over a wide range of temperatures within the same space group is quite unusual. Remarkably, Rietveld analyses of the X-ray diffraction patterns of PrMn0.9O3 (ABO3) nanoparticles (NPs) with a constant Pnma space group from 300 to 10 K could successfully predict the four magnetic phases, viz. paramagnetic, antiferromagnetic (AFM), ferromagnetic (FM), and spin-glass-like ordering. The increase in Mn-O-Mn bond angles and tolerance factor leads to FM ordering below ∼100 K in usually AFM PrMn0.9O3 NPs. The concurrent decrease of lattice cell volume and Mn-O-Mn bond angles near the AFM to FM transition temperature (Tc) suggests that the AFM character increases just above Tc due to atomic deformations and reduced Mn-Mn separation. The predictions from crystal structure refinement were successfully verified from the cooling path of the temperature-dependent field-cooled magnetization measurements. A mechanism involving incoherent spin reversal due to competition between the neighboring spins undergoing antiparallel to parallel spin rotations was suggested. The structure-property parallelism was cross-checked with the A-site vacant Pr0.9MnO3.2 NPs. |
