Plasma-assisted chemical vapor deposition of F-doped MnO2 nanostructures on single crystal substrates

MnO2 nanostructures were fabricated by plasma assisted-chemical vapor deposition(PA-CVD) using a fluorinated diketonate diamine manganese complex, acting as single-sourceprecursor for both Mn and F. The syntheses were performed from Ar/O2 plasmas on MgAl2O4(100),YAlO3(010), and Y3Al5O12(100) single crystals at a growth temperature of 300°C, in order to investigatethe substrate influence on material chemico-physical properties. A detailed characterization throughcomplementary analytical techniques highlighted the formation of highly pure and oriented F-dopedsystems, comprising the sole beta-MnO2 polymorph and exhibiting an inherent oxygen deficiency.Optical absorption spectroscopy revealed the presence of an appreciable Vis-light harvesting, ofinterest in view of possible photocatalytic applications in pollutant degradation and hydrogenproduction. The used substrates directly affected the system structural features, as well as the resultingmagnetic characteristics. In particular, magnetic force microscopy (MFM) measurements, sensitive tothe out-of-plane magnetization component, highlighted the formation of spin domains and long-rangemagnetic ordering in the developed materials, with features dependent on the system morphology.These results open the door to future engineering of the present nanostructures as possible magneticmedia for integration in data storage devices.