Papers by Author: B.B. Das

Abstract: Studies on xCuO-(1-x)As2O3-0.7B2O3(0.01≤x≤0.05) (G1-G5: x = 0.01, 0.02, 0.03, 0.04, 0.05) glasses were done using varieties of structure sensitive techniques. The powder X-ray diffraction (XRD) studies show the formation of glasses in the composition. The IR spectral results show the presence of Cu-O bond, planar [BO3/2] and [BO3 -n](n=1, 2, 3) units and tetrahedral {BO4/2]- units. The magnetic susceptibility results show Curie-Weiss behaviour in the range 4.2-400 K. The calculated values of the exchange integral from the Weiss constant obtained form the linear fit of the Curie-Weiss law are found to be in the range 5.22-29.50 meV. From the trend of the gmatrices of gơ>g⊥>ge (ge =2.0023) obtained from electron paramagnetic resonance (EPR) lineshapes simulation we conclude that the paramagnetic site in these glasses is Cu2+(3d9) which is in a tetragonally elongated octahedron [O1/2-CuO4/2-O1/2] exhibiting Jahn-Teller distortion having D4h symmetry with orbital singlet 3dx2-y2 (2B1g) as the ground state.

Abstract: Studies on ZnxCu1-xBi2O4(0≤ x ≤0.6) spinels (S1-S5: x = 0.0, 0.15, 0.3, 0.45, 0.6) were done using varieties of structure sensitive techniques. The powder X-ray diffraction (XRD) studies shows formation of cubic phase, a=10.6023 Ǻ, space group, Ia3, Z=3 in all the samples. The IR spectral results show the presence of octahedral[CuO6/2] or [BiO6/2] units and Bi-O, Cu-O, and Zn-O bonds in the samples. From the trend g║>g┴>ge(ge=2.0023) obtained from electron paramagnetic resonance(EPR) lineshapes simulation we conclude that the paramagnetic site in these glasses is Cu2+(3d9) which is in a tetragonally elongated octahedron [O1/2-CuO4/2-O1/2] exhibiting Jahn-Teller distortion having D4h symmetry with orbital singlet 3dx 2-y 2(2B1g) as the ground state.