2026 Volume 94 Issue 6 Pages 067001
Anion doping is a promising approach for controlling material functionalities. However, precise control of anion concentration remains challenging. In this study, we experimentally evaluated the effects of reaction conditions on F concentration and distribution in topochemical F doping to La0.6Sr0.4CoO3−δ thin films by simply varying F sources, reaction temperatures, and reaction times. Comparative experiments using MgF2, BiF3 and PVDF as F sources suggested that the equilibrium F2 activity of the F source is the primary factor governing the F concentration in the product. Meanwhile, the choice of F source also significantly affects the homogeneity of F distribution. Temperature-dependent experiments showed that maximum F incorporation was achieved at 300 °C, while higher temperatures led to F release and decreased F concentration. Time-dependent experiments demonstrated that F concentration increases with prolonged reaction time. Notably, uniform F distribution throughout the entire film thickness (100–150 nm) was achieved within just 1-hour treatment at 240 °C when using MgF2 as the F source, indicating that the topochemical F-doping process is governed by surface reaction kinetics rather than bulk diffusion. These findings enable precise control of anion composition in topochemical anion doping and contribute to the rational design of functional materials by anion doping.
