* Electro negativity Difference: Barium (Ba) is a highly electropositive element with an electronegativity of 0.89, while oxygen (O) is highly electronegative with an electronegativity of 3.44. The difference in electronegativity between barium and oxygen is 2.55, indicating a significant difference in their tendencies to attract electrons.

* Metallic and Non-metallic Nature: Barium is a metal, and metals tend to lose electrons, while oxygen is a non-metal, and non-metals tend to gain electrons. This difference in their nature further contributes to the ionic character of the bond.

* Ionic Bonding: The large electronegativity difference leads to the transfer of electrons from barium to oxygen. Barium loses two electrons to form a Ba²⁺ cation, and oxygen gains two electrons to form an O²⁻ anion. These oppositely charged ions then attract each other electrostatically, forming an ionic bond.

Therefore, due to the significant electronegativity difference, the metallic and non-metallic nature of the elements, and the formation of ions, barium oxide exhibits a high ionic character.