Pressure-induced structural evolutions and electronic properties of Eu3+ and Pr3+ doped yttrium oxide crystals: a comparative study.

Rare-earth-doped yttrium oxide (Y2O3) is a promising optoelectronic material due to its outstanding optical characteristics, including the efficient red emission of Eu3+ and the lattice-sensitive luminescence of Pr3+. The crystal lattice and structural information have aroused widespread interest. However, clarifying the structural evolution and local structures in doped systems under high pressure remains challenging. In this work, we systematically investigate the structural evolution and electronic properties of Y2O3:Eu3+ and Y2O3:Pr3+ under the pressure range of 0-40 GPa. The ground-state structures are identified for the first time. Eu3+ and Pr3+ substitute Y3+ sites with a doping concentration of 3.125%. At ambient pressure, the structure of Y2O3:Eu3+ exhibits a trigonal structure with the R3̄ space group while Y2O3:Pr3+ exhibits a monoclinic configuration with the P2 space group. LDA + U + SOC calculations reveal narrowed band gaps of 1.884 and 3.326 eV for Y2O3:Eu3+ and Y2O3:Pr3+, respectively, indicating an insulator-to-semiconductor transition. Under pressure, Y2O3:Eu3+ shows higher sensitivity in lattice and electronic properties than Y2O3:Pr3+. Pressure enhances intrinsic 4f-electron differences, leading to divergent evolution trends. The 4f configuration serves as a key controller of high-pressure behavior. These findings could not only provide important information for further investigations of rare-earth-doped systems, but also help to gain more insights into designing a new generation of laser materials under extreme conditions.