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Structural evolution of MoO3 thin films deposited on copper substrates upon annealing: an X-ray absorption spectroscopy study

DOI: 10.3390/condmat4020041 DOI Help

Authors: Salvatore Macis (Università di Roma Tor Vergata; Istituto Nazionale Fisica Nucleare) , Javad Rezvani (Istituto Nazionale Fisica Nucleare) , Ivan Davoli (Università di Roma Tor Vergata) , Giannantonio Cibin (Diamond Light Source) , Bruno Spataro (Istituto Nazionale Fisica Nucleare) , Jessica Scifo (Istituto Nazionale Fisica Nucleare) , Luigi Faillace (Istituto Nazionale Fisica Nucleare) , Augusto Marcelli (Istituto Nazionale Fisica Nucleare; Rome International Centre for Material Science Superstripes, RICMASS)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Condensed Matter , VOL 4

State: Published (Approved)
Published: April 2019

Open Access Open Access

Abstract: Structural changes of MoO3 thin films deposited on thick copper substrates upon annealing at different temperatures were investigated via ex situ X-Ray Absorption Spectroscopy (XAS). From the analysis of the X-ray Absorption Near-Edge Structure (XANES) pre-edge and Extended X-ray Absorption Fine Structure (EXAFS), we show the dynamics of the structural order and of the valence state. As-deposited films were mainly disordered, and ordering phenomena did not occur for annealing temperatures up to 300 °C. At ~350 °C, a dominant α-MoO3 crystalline phase started to emerge, and XAS spectra ruled out the formation of a molybdenum dioxide phase. A further increase of the annealing temperature to ~500 °C resulted in a complex phase transformation with a concurrent reduction of Mo6+ ions to Mo4+. These original results suggest the possibility of using MoO3 as a hard, protective, transparent, and conductive material in different technologies, such as accelerating copper-based devices, to reduce damage at high gradients.

Journal Keywords: molybdenum; TM oxides; XAFS; thin films

Subject Areas: Materials

Facility: ESRF

condensedmatter-04-00041 (1).pdf