Synthesis and characterisation of fluorinated epitaxial films of BaFeO₂F: tailoring magnetic anisotropyviaa lowering of tetragonal distortion

Abstract

Fluorination of epitaxially grown thin films of BaFeO2.5 to BaFeO2F results in increased magnetic anisotropy.

Structural and Magnetic Properties of BaFeO2.667 Synthesized by Oxidizing BaFeO2.5 Obtained via Nebulized Spray Pyrolysis

“…At around 300 K, the magnetization curves show a ferromagnetic-like transition, which is probably due to weak ferromagnetism on top of the dominant antiferromagnetic order, as the magnetization measurements (Figure 6b) do not show any saturation or hysteresis at 250 K. Below the transition at around 300 K, the FC and ZFC curves diverge notably, confirming a weak ferromagnetic (or a spin-glass-like) behavior, which is common in oxygen defect materials with canted or locally uncompensated spins. 81 At about 55 K, there is a maximum visible in the ZFC curve and to a lesser extent in the FC curve (which both are not found for BaFeO 2.81 ), which could be related either to gradual strengthening of the magnetic order with the decreasing temperature or presence of the magnetic coercivity. Indeed, at low temperatures, magnetic hysteresis was observed in the magnetization curves, with coercivity reaching about 0.7 T at 10 K, as shown in the inset in Figure 6b.…”

Strain-Induced Anion-Site Occupancy in Perovskite Oxyfluoride Films

“…For example, biaxial strains of ±3% are now routinely imposed in epitaxial oxide films that are tens of nanometers in thickness without loss of coherence with the substrate . The development of topochemical approaches − to convert perovskite oxide films to oxyfluorides has enabled the realization of numerous families of epitaxial oxyfluorides including ferrites, − manganites, , ruthenates, , chromates, cobaltites, and nickelates . The thin film nature of these samples has been exploited for functionality not accessible to bulk polycrystalline oxyfluorides, for instance, through reversible insertion and removal of F in NdNi­(O, F) 3−δ films and lateral patterning of SrFeO 2.5 /SrFeO 2 F heterostructures through spatially controlled topochemistry .…”

On the Impact of the Degree of Fluorination on the ORR Limiting Processes within Iron Based Catalysts: A Model Study on Symmetrical Films of Barium Ferrate

“…The films and powder were kept at a temperature of 450 • C under argon for 20 h to enable interdiffusion and compositional equilibration between powder and film. In contrast, fully fluorinated BaFeO 2 F|YSZ8|BaFeO 2 F was prepared by utilizing the vapor transport related technique [33]. The films and the polymer polyvinylidene fluoride (PVDF) were put into a tube furnace (Sigma Aldrich, Saint Louis, MO, USA) at an elevated temperature of 450 • C and an argon gas stream.…”