N. C. Das¹, N. K. Sahoo¹, D. Bhattacharyya¹, S. Thakur¹, D. Nanda², S. Hazra³, J. K. Bal³, J. F. Lee⁴, Y. L. Tai⁴, C. A. Hsieh^4
1Applied Spectroscopy Division, Bhabha Atomic Research Centre, Mumbai 400085, India
²Coolant System Laboratory, Raja Rmanna Centre for Advanced Technology, Indore 452013, India
³Surface Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064, India
⁴National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Sience Park, Hsinchu 30076, Taiwan, R. O. C.

In the present work we have reported the results of investigations on local structures of e-beam evaporated (Gd₂O₃-SiO₂) composite thin films by synchrotron based EXAFS measurements. The evolution of local structure in the case of the Gd₂O₃-SiO₂ system is found to be different from the HfO₂-SiO₂ system reported by us earlier. The EXAFS analysis has shown that the Gd-O bond length decreases monotonically as SiO₂ content in the films increases. Also the amplitudes of the peaks in the FT-EXAFS spectra of the samples, which depend jointly on the coordination numbers as well as the Debye-Waller factors (measure of disorder) are found to decrease monotonically with increase in SiO₂ contents in the Gd₂O₃ matrix. Atomic force microscopy (AFM) measurements of the samples also show continuous evolution of amorphous-like denser microstructure with increase in SiO₂ content in the films. Hence incorporation of SiO₂ in the Gd₂O₃ matrix, results in a continuous change in oxygen coordination yielding a change in the Gd-O bond length and also results in a continuous increase in amorphousness and a smoother morphology of the samples and, unlike the HfO₂-SiO₂ system, does not show any maximum for a particular SiO₂ concentration.