First-principles calculations of the dielectric and vibrational properties of ferroelectric and paraelectric BaAl2O4

• BaAl2O4 has much weaker permittivity than classical ferroelectrics.
• Paraelectric BaAl2O4 has higher permittivity than ferroelectric BaAl2O4.
• BaAl2O4 has good transmittance in the light range from UV to near-IR.

First-principles calculations have been conducted to study the structural, dielectric, and vibrational properties of ferroelectric and paraelectric BaAl2O4. High-frequency and static dielectric constants, and phonon frequencies at the Brillouin zone center are reported. Both BaAl2O4 polymorphs are promising infrared-transparent materials due to their low electronic dielectric constants. The ferroelectric and paraelectric BaAl2O4 have much smaller permittivity compared to the classical ferroelectric materials. From an atomic nanostructure standpoint, the abnormally low permittivity of BaAl2O4 polymorphs is mainly related to low coordination numbers of Ba (9) and Al (4).