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Scientists Unveil Unusual Crystal Behavior on Heating

2024-10-16

In a groundbreaking discovery, scientists at the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore, have observed an unexpected reduction in local crystal symmetry when heated. This finding challenges traditional theories that suggest crystal symmetry typically increases with temperature due to entropy. Published in Advanced Materials, the research holds potential applications in phononics, thermoelectrics, and solar thermal conversion.

Led by Prof. Kanishka Biswas, the team, including researchers Ivy Maria and Paribesh Acharyya, studied the behavior of the all-inorganic two-dimensional halide perovskite Cs?PbI?Cl?. Surprisingly, while the global symmetry remained unchanged, the local symmetry decreased with rising temperatures. The researchers coined the term "Emphanisis" to describe this phenomenon.

The study employed advanced synchrotron X-ray techniques, allowing the team to simultaneously observe both local and global structures. The experiments were conducted at DESY, Hamburg, under the India-DESY collaboration, supported by India's Department of Science & Technology (DST). This discovery could revolutionize the design of materials for efficient heat management systems.