RESUMO
Thin films of double perovskite ruthenates, viz., Ba2DyRuO6 (BDRO) and Sr2DyRuO6 (SDRO), have been successfully grown on a SrTiO3 substrate using the pulsed laser deposition technique. The BDRO samples crystallizes in cubic structure, while SDRO exhibits monoclinic structure as revealed in their X-Ray diffraction examination. Temperature-dependent magnetization measurements suggest the presence of ferromagnetism in BDRO, while paramagnetism is present for the SDRO thin film. Surprisingly, both films show canted antiferromagnetism at â¼T = 5 K as revealed in their isothermal magnetization curves. The inverse susceptibility has been fitted to the Curie-Weiss law for the SDRO sample, where the Curie temperature (TC â¼ -336.6 K) has been obtained, thus suggesting the prevalence of antiferromagnetic interactions. The existence of the canted magnetism at a lower temperature may be attributed to the Dzyaloshinskii-Moriya (D-M) interactions in the monoclinic SDRO sample due to structural distortion. However, the emergence of canted antiferromagnetism at lower temperatures (5 K) in the BDRO sample with cubic symmetry having no D-M interactions may be attributed to the various modifications at the surface of the thin films. Overall, a comparison made between the magnetic properties of both the thin films i.e., BDRO & SDRO, reveals the suppression of bulk magnetic ordering when compared to their bulk counterparts. The possible reason for the absence of any magnetic ordering in these thin films may be due to any modifications in superexchange interactions, any exchange bias, stress-strain, or uncompensated spins present in these types of thin films. UV-visible measurements for both the samples reveal a direct influence of the A-site element (Sr/Ba) on their band gaps, i.e., 3.66 eV and 2.59 eV for BDRO and SDRO samples, respectively, hence suggesting their insulating nature. We have also carried out first principles calculations with DFT using the CASTEP software to gain more insights into the experimental data. These thin films with insulating-antiferromagnetic properties may be crucial for "spintronics devices".
RESUMO
The exploration of an anthranilic acid based Schiff base SB as a "Turn-ON" fluorescent probe for the detection of highly toxic selenite (SeIV) and arsenite (AsIII) species in an aqueous medium is described. The selectivity of SB towards SeIV and AsIII in the presence of other ions was investigated by some spectrofluorimetric and 1H NMR spectroscopic experiments. The studies revealed the interaction between SB and AsIII via the deprotonation of phenolic -OH, which enhanced the conjugation in phenolate ion and in turn enhanced the emission response. The SB has analytical prospects for the quantification of AsIII and SeIV with good sensitivity (LODs; 5.15 ppb for SeIV and 3.12 ppb for AsIII calculated by S/N = 3σ/K). Furthermore, it can be used to evaluate real and synthetic samples for the presence of SeIV and AsIII species as well as the fabrication of on-spot recognition devices (in the form of silica gels SB@SiO2 and silica coated TLC aluminium strips SB@SiO2@Al).
