Probing bipyramid microstructure of pure and Dy-doped HoMnO3 using high pressure and low temperature studies.

Autor: Roy, Arkadev, Bhatt, Himal, Srihari, V, Poswal, H K, Vishwakarma, S R
Zdroj: Bulletin of Materials Science; Dec2022, Vol. 45 Issue 4, p1-13, 13p
Abstrakt: Bipyramidal distortions play the governing role in physical properties of RMnO3 multiferroics. We have carried out angle-dispersive high pressure synchrotron X-ray diffraction experiments on hexagonal HoMnO3 to find the evolution of bipyramidal parameters upon external compression. It is found that the average bond-lengths and bond-angles between Mn and O atoms depict significant reduction, which results in the distortion in MnO5 bipyramidal structure at high pressures. Further, since subtle variations in these distortions are used to compare the properties of hexagonal RMnO3 manganite series, in-situ low temperature infrared spectroscopic studies of 10% Dy-doped HoMnO3 have been carried out to study the effect of further increase in R-site cationic radius on MnO5 deformations. It is found that the phonon modes specifically related to the motion of Mn and O atoms in ab-plane display irregularities near magnetic transition temperatures (TN and TSR) via spin phonon coupling. Even a small increase in average ionic radius of rare-earth atom suppresses this anomalous behaviour and follows the trend of undoped hexagonal rare-earth manganites. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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