Embodiments of the present disclosure are directed to an article and methods of forming the article. The article includes a thermal barrier coating disposed on a substrate. The thermal barrier coating includes a thermal barrier material and partially filled surface-connected columnar voids. The partially filled surface-connected columnar voids are interspersed with the thermal barrier material in the thermal barrier coating. At least some of the partially filled surface-connected columnar voids include a calcium-magnesium-aluminum-silicon-oxide (CMAS)-reactive material disposed within, such that the CMAS-reactive material is physically separated from the substrate by a columnar cavity having an aspect ratio greater than 3.