Plutonium and Americium Aluminate Perovskites

Area of Science:

• Materials Science
• Nuclear Chemistry
• Solid State Chemistry

Background:

• Perovskite materials, such as AmAlO3 and PuAlO3, are of interest due to their unique structural and chemical properties.
• Understanding the effects of radioactive decay on actinide-based perovskites is crucial for nuclear waste management and materials longevity.

Purpose of the Study:

• To synthesize and characterize AmAlO3 and PuAlO3 perovskites.
• To investigate the structural evolution of AmAlO3 under alpha decay.
• To determine the structural and thermal properties of PuAlO3.

Main Methods:

• Powder X-ray diffraction (XRD) for structural analysis.
• Raman spectroscopy and Fourier transform infrared spectroscopy (FT-IR) for vibrational properties.
• 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy for local atomic environment.
• High-temperature XRD for phase transition studies.

Main Results:

• AmAlO3 perovskite exhibits a rhombohedral structure and undergoes progressive disordering and amorphization upon alpha decay (complete amorphization at 2 × 10^18 α-decays/g).
• PuAlO3 perovskite was successfully synthesized with an orthorhombic structure (Imma), analogous to lanthanide analogues.
• A phase transition from orthorhombic (Imma) to rhombohedral (R3̅c) PuAlO3 was observed between 473 and 573 K.
• Extrapolation suggests a transition to a cubic phase (Pm3̅m) for PuAlO3 around 1850 K.

Conclusions:

• Alpha decay leads to significant structural degradation and amorphization in AmAlO3 perovskite.
• PuAlO3 perovskite presents a new orthorhombic structure with temperature-dependent phase transitions, including a potential cubic phase at high temperatures.
• This study provides fundamental insights into the behavior of actinide perovskites under irradiation and thermal stress.