Environmental barrier coating material and coating structure and ceramic structure using the same

4An environmental barrier coating material comprising one or more constituents selected from a group consisting of hafnia; hafnia stabilized by one or more rare-earth oxides and/or silica; zirconia-containing hafnia; and zirconia-containing hafnia stabilized by one or more rare-earth oxides and/or silica, which when formed as a coating structure for covering a substrate which has a low thermal expansion coefficient, has hafnon (HfSiO) serving as a first layer directly formed on the substrate, and hafnia with which the first layer is coated as a second layer.