Heat-shrinking materials benefit from cleaner production methods using lower temperatures

On July 8, 2026, researchers at the Institute of Science Tokyo unveiled a groundbreaking method for producing heat-shrinking materials, specifically BiNi₁₋ₓFeₓO₃, which exhibits negative thermal expansion (NTE). This new production route utilizes lower temperatures and finer particles, significantly enhancing safety and environmental sustainability during manufacturing.

Innovative Production Techniques for Functional Oxides

The research team, led by Specially Appointed Assistant Professor Takumi Nishikubo, collaborated with experts from Northwestern University and the Kanagawa Institute of Industrial Science and Technology. Their findings, published in the Journal of the American Chemical Society on June 18, 2026, propose a safer and more effective synthesis method for functional oxide materials.

Traditionally, the production of functional oxides involves harsh chemicals and high temperatures, which can pose significant safety risks and lead to harmful environmental byproducts. By addressing these challenges, the new method not only improves safety but also reduces the carbon footprint associated with these materials.

Enhanced Synthesis Process Using Amorphous Precursors

The innovative process combines reverse coprecipitation with oxidation in a single step. By introducing a metal nitrate solution into an alkaline sodium hypochlorite solution, researchers created a highly oxidized amorphous precursor containing high-valent ions such as Bi 5+ and Ni 3+. This precursor demonstrates exceptional elemental dispersion, making it ideal for synthesizing the desired oxide.

Professor Nishikubo remarked, "This process eliminates the need for oxidizing agents and avoids the emission of NO x gases, making the synthesis significantly safer and cleaner." The precursor's high oxidation level allows for the final material to be synthesized without additional oxidants.

Direct Crystallization and Tailored Particle Sizes

The research revealed that under high-pressure conditions, the amorphous precursor crystallizes directly into the perovskite phase at about 750°C (1,380°F) in under one minute. This direct crystallization process contrasts sharply with conventional methods, which often require temperatures nearing 950°C (1,740°F) and multiple intermediate phases.

• Conventional methods: High temperatures, multiple steps
• New method: Direct crystallization, lower temperatures
• Particle sizes reduced from 15 μm to 5 μm

This efficiency not only saves energy but also enables precise control over particle sizes, enhancing the material's functionality without compromising its NTE capacity. The fine particles produced exhibit stable behavior across a wider temperature range, demonstrating the potential for improved processability.

The research highlights a versatile approach that can extend beyond just BiNi₁₋ₓFeₓO₃, potentially benefiting other functional oxides, including Cu 3+-based materials related to superconductivity. This advancement could pave the way for the next generation of materials in electronics, thermal management, and energy technologies while minimizing environmental impact.