Structural Evolution of MoO3 Thin Films Deposited on Copper Substrates upon Annealing: An X-ray Absorption Spectroscopy Study

Condensed Matter

Ivan Davoli¹  Salvatore Macis¹  Giannantonio Cibin²  Jessica Scifo³  Bruno Spataro³  Augusto Marcelli³  Javad Rezvani³  Luigi Faillace⁴ 

[1] Department of Physics, Università di Roma Tor Vergata, via della Ricerca Scientifica 1, 00133 Rome, Italy;Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK;Istituto Nazionale Fisica Nucleare, Laboratori Nazionali di Frascati, via Enrico Fermi 40, 00044 Frascati, Italy;Istituto Nazionale Fisica Nucleare, Sezione di Milano, Via Celoria 16, 20133 Milano, Italy;

关键词: molybdenum;    TM oxides;    XAFS;    thin films;   

DOI  :  10.3390/condmat4020041

来源: DOAJ

【 摘 要 】

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.

【 授权许可】

Unknown