Luminescence and energy transfer processes in Gd_0.99Er_0.01Al_0.995Cr_0.05O₃

Area of Science:

• Materials Science
• Solid-state Chemistry
• Luminescence Spectroscopy

Background:

• Gadolinium Aluminum Oxide (GdAlO3) is a promising host material for luminescent applications.
• Doping with rare-earth ions like Erbium (Er3+) and transition metals like Chromium (Cr3+) can modify its optical properties.
• Understanding energy transfer pathways is crucial for designing advanced phosphors.

Purpose of the Study:

• To synthesize and characterize GdAlO3 doped with Er3+ and co-doped with Cr3+.
• To investigate the structural and optical properties, including photoluminescence.
• To elucidate the energy transfer mechanisms between Er3+ ions, intrinsic defect centers, and Cr3+ ions.

Main Methods:

• Solid-state reaction method for sample synthesis.
• X-ray diffraction for structural analysis.
• Derivative absorption spectrum fitting (DASF) and first-derivative reflectance (dR/dλ) for band gap determination.
• Photoluminescence (PL) spectroscopy for emission analysis.

Main Results:

• Samples crystallized in an orthorhombic structure (Pbnm space group) with wide band gaps (~5.9 eV).
• Gd0.99Er0.01AlO3 exhibited green emission from Er3+ and red lines from intrinsic defects.
• Gd0.99Er0.01Al0.995Cr0.05O3 showed reduced green/red emission due to energy transfer to Cr3+.
• Cr3+ ions were identified as the primary source of red emission at 697 nm and 726 nm.

Conclusions:

• The synthesized materials possess wide band gaps and exhibit distinct luminescent properties.
• Efficient energy transfer from Er3+ and defect centers to Cr3+ ions was confirmed.
• Cr3+ ions play a significant role in the red emission of the co-doped GdAlO3 system, indicating potential for tunable luminescence.