Monoclinic to cubic structural transformation, local electronic structure, and luminescence properties of Eu-doped HfO2

• Published in: Applied physics. A, Materials science & processing Vol. 129; no. 10
• Main Authors: Kumar, Rajesh, Kumar, Jitender, Kumar, Ramesh, Kumar, Akshay, Sharma, Aditya, Won, S. O., Chae, K. H., Singh, Mukhtiyar, Vij, Ankush
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.10.2023; Springer Nature B.V
• Subjects: Applied physics; Characterization and Evaluation of Materials; Color; Condensed Matter Physics; Density functional theory; Electronic structure; Emission analysis; Emission spectra; Europium; Excitation; Hafnium oxide; Luminescence; Machines; Manufacturing; Materials science; Nanoparticles; Nanotechnology; Optical and Electronic Materials; Optical properties; Phase transitions; Photoluminescence; Physics; Physics and Astronomy; Processes; Purity; Surfaces and Interfaces; Thin Films; Wavelengths; HfO; DFT; PL; XANES; Phase transition
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-023-06997-0

We report the photoluminescence (PL) properties of Eu 3+ doped HfO 2 nanoparticles prepared using co-precipitation method and annealed at 600 °C. X-ray diffraction results revealed the monoclinic phase in undoped HfO 2 and show mixed phase formation at lower concentration and a dominant cubic phase achieved at 5 mol% doping of Eu in HfO 2 . The phase transition anticipated by the density functional theory is in excellent agreement with experimental findings. The oxygen K-edge XANES spectra clearly depicts the diverse hybridization of O 2p orbitals in M–O7 (for monoclinic) and M–O8 (for cubic) polyhedra of HfO 2 . Hf L-edge XANES confirms Hf 4+ ions in cubic and monoclinic structured HfO 2 . The Eu 3+ ions are dominantly present in the Eu-doped HfO 2 nanoparticles. PL study demonstrates the emission in red region with high color purity under different excitation wavelengths from near UV to blue light. PL emission spectra show four emission bands at 594 nm, 609 nm, 650 nm, and 716 nm corresponding to 4f–4f transitions of Eu 3+ under excitation wavelengths of 361 nm, 383 nm, 394 nm and 465 nm. The reddish PL emission with high color purity under different excitation wavelengths from near-UV to blue region may be exploited in solid state lighting-based applications.