Structural modification of Pr3+-/Zr4+doped HfO2:Eu3+and the resulting luminescence and dielectric properties

초록

Incorporating a minute amount of rare earth ions has been suggested to improve the functionality of electronic materials through the introduction of luminescence properties. HfO2-based materials have received significant attention owing to their high dielectric permittivity (k), excellent thermodynamic stability, and ferroelectricity. In this study, we fabricated luminescent high-k materials by co-doping Pr3+/Zr4+ and Eu3+ into HfO2, i.e., Hf1xPrxO2-delta:Eu for x = 0.00, 0.01, 0.03, 0.05, 0.07, and 0.09, and into Hf1-yZryO2:Eu for y = 0.00, 0.10, 0.50, and 0.90 via the solid-state reaction method. The doping concentration of Eu3+ is 0.4 mol%. Rietveld refinement based on the X-ray diffraction pattern of Hf1-xPrxO2-delta:Eu shows that HfO2 undergoes structural transformation from monoclinic (P21/c) to cubic (Fm3m) as x increases, along with an increase in its dielectric constant. Although the structures of Hf1-yZryO2:Eu maintain the P21/c phase of HfO2 even with Zr4+ doping, their dielectric constants increase with y, which is associated closely with an increase in the grain size. The photoluminescence (PL) spectra of Hf1-xPrxO2-delta:Eu and Hf1-yZryO2:Eu under 396 nm excitation show the typical orange-red emission of Eu3+ ions. As x increases, the PL intensity of Hf1-xPrxO2-delta:Eu decreases because of its higher local structural symmetry. However, the PL intensity of Hf1-yZryO2:Eu increases with y because of its larger grain size. Our experiments suggest that Hf1-xPrxO2-delta:Eu and Hf1-yZryO2:Eu are promising candidates as multifunctional luminescent high-k materials.

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