Interplay of 4f-3d Magnetism and Ferroelectricity in DyFeO3

DyFeO3 exhibits a weak ferromagnetism (TNFe ~ 645 K) that disappears below a spin-reorientation (Morin) transition at TSRFe ~ 50 K. It is also known that applied magnetic field induces ferroelectricity at the magnetic ordering temperature of Dy-ions (TNDy ~ 4.5 K). Here, we show that the ferroelectricity exists in the weak ferromagnetic state (TSRFe < T < TN,C) without applying magnetic field, indicating the crucial role of weak ferromagnetism in inducing ferroelectricity. 57Fe M\"ossbauer studies show that hyperfine field (Bhf) deviates from mean field-like behaviour that is observed in the weak ferromagnetic state and decreases below the onset of spin-reorientation transition (80 K), implying that the Bhf above TSR had additional contribution from Dy-ions due to induced magnetization by the weak ferromagnetic moment of Fe-sublattice and below TSR, this contribution decreases due to collinear ordering of Fe-sublattice. These results clearly demonstrate the presence of magnetic interactions between Dy(4f) and Fe(3d) and their correlation with ferroelectricity in the weak ferromagnetic state of DyFeO3.Comment: 5 pages, 6 figures, published in EP

Biodegradability study to develop longer life jute geotextiles for road applications

To enhance the life of jute geotextiles (JGTs) for road applications, new types of JGT fabrics were developed following two different routes, viz., (a) rot-proof treatment of 100% JGT fabric and (b) preparation of jute–polypropylene blended JGT fabrics. The biodegradability behavior of these fabrics along with grey JGTs was studied for different durations up to 12 months in three categories of saturated soils, namely, Guwahati Lateritic Red soil, Kolkata Alluvial Silty soil and Andhra Pradesh Black Cotton soil and water separately. Biodegradability assessment was done through residual tensile strength study and microscopic study. The experimentation reveals that rate of biodegradation of the JGTs is different in the three experimental saturated soils and water. Saturated Black Cotton soil was found to be the most detrimental medium. Studies were also carried out to understand this differential degradation behavior of JGTs in different soils. This indicates that the pH of soil media and microbial population growing capability of the respective soils both affect the level of degradation of the JGT fabrics. Jute–synthetic blended JGT is essential for Black Cotton soil road-subgrade, while grey JGT and treated JGT can be used in Lateritic soil and Silty soil, respectively.by Mahuya Ghosh, Guda Rao Venkatappa, Syamal Kanti Chakrabarti, Supriya Pal and Uma Sankar Sarm