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Category: materials – Page 59

A new theory has finally deciphered the physical mechanisms of fracture in soft materials. This discovery could soon lead to new, defect-free materials that are more resistant and durable as well as environmentally friendly. The article “Elastic instability behind brittle fracture” was recently published by Physical Review Letters.

“We have revealed that fracture propagates from the free surface of the material, starting from an elastic instability that breaks the symmetry of the object. Then, the drastically extends with an intricate network of cracks spreading like a turbulence phenomenon similar to what we observe in fluids, like during vortex formation,” explains Pasquale Ciarletta from the MOX Laboratory, Department of Mathematics at Politecnico di Milano.

This discovery stimulates significant applications in various technological sectors. For instance, in the production of micro and nano devices, where materials need to be extremely resistant and defect-free.

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A groundbreaking study has demonstrated the use of liquid crystals for efficient and tunable spontaneous parametric down-conversion (SPDC), expanding the potential of quantum light sources beyond traditional solid materials.

Spontaneous parametric down-conversion (SPDC), a key method for generating entangled photons used in quantum physics and technology, has traditionally been restricted to solid materials. However, researchers at the Max Planck Institute for the Science of Light (MPL) and the Jozef Stefan Institute in Ljubljana, Slovenia, have recently achieved a breakthrough by demonstrating SPDC in a liquid crystal for the first time. Their findings, published in Nature, pave the way for the development of a new generation of quantum sources that are both efficient and tunable by electric fields.

The splitting of a single photon in two is one of the most useful tools in quantum photonics. It can create entangled photon pairs, single photons, squeezed light, and even more complicated states of light which are essential for optical quantum technologies. This process is known as spontaneous parametric down-conversion (SPDC).

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To take a picture, the best digital cameras on the market open their shutter for around around one four-thousandths of a second.

To snapshot atomic activity, you’d need a shutter that clicks a lot faster.

With that in mind, scientists have unveiled a way of achieving a shutter speed that’s a mere trillionth of a second, or 250 million times faster than those digital cameras. That makes it capable of capturing something very important in materials science: dynamic disorder.

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An international collaborative research team has developed an image recognition technology that can accurately determine the elemental composition and the number of charge and discharge cycles of a battery by examining only its surface morphology using AI learning.

Professor Seungbum Hong from the Korea Advanced Institute of Science and Technology (KAIST) Department of Materials Science and Engineering, in collaboration with the Electronics and Telecommunications Research Institute (ETRI) and Drexel University in the United States, has developed a method to predict the major elemental composition and charge-discharge state of NCM cathode materials with 99.6% accuracy using (CNN).

The paper is published in the journal npj Computational Materials.

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Researchers have successfully controlled the quantum mechanical properties of Andreev bound states in bilayer graphene-based Josephson junctions using gate voltage. Their research is published in Physical Review Letters. The research team includes Professors Gil-Ho Lee and Gil Young Cho from the Department of Physics at Pohang University of Science and Technology (POSTECH) in South Korea in collaboration with Dr. Kenji Watanabe and Dr. Takashi Taniguchi from National Institute for Materials Science (NIMS) in Japan.

Superconductors are materials that exhibit zero under specific conditions such as extremely low temperatures or high pressures. When a very thin normal is placed between two superconductors, a supercurrent flows through the normal conductor due to the proximity effect where superconductivity extends into the normal conductor. This device is known as a Josephson junction.

Within the normal conductor, new quantum states called Andreev bound states are formed, which are crucial for mediating the supercurrent flow.

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The propagation of charged particles in a medium at a speed exceeding the phase speed of light in the medium (this speed also called superluminal) leads to the generation of radiation. The diagram of generated radiation during this process has a conical structure. This effect, called the Cherenkov effect, has many fundamental and applied applications, and its explanation was awarded the Nobel Prize in Physics in 1958.

The oblique incidence of light on the between two media is a similar phenomenon; in this case, a wave of secondary radiation sources is formed along the interface, which propagates at a exceeding the phase speed of light.

The and reflection of light from an interface is the result of the addition of the amplitudes of waves from all sources formed during light incidence. If one considers the interface with photo emissive material—the cathode, on which light is incident obliquely and causes of electron emission—then an electron density wave will form along the cathode surface at superluminal speed.

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Graphene, composed of layers of carbon atoms arranged in a honeycomb pattern, is recognized as a supermaterial due to its exceptional conductivity and mechanical advantages. These properties are key to advancing flexible electronics, innovative batteries, and composite materials for aerospace applications. Despite these benefits, creating elastic and durable films has been difficult. In a recent edition of Angewandte Chemie, researchers have proposed a solution by connecting graphene nanolayers through extendable bridging structures, potentially overcoming previous limitations.

The special capabilities of microscopic graphene nanolayers often drop off when the layers are assembled into foils, because they are only held together by relatively weak interactions—primarily hydrogen bonds. Approaches that attempt to improve the mechanical properties of graphene foils by introducing stronger interactions have only been partially successful, leaving particular room for improvement in the stretchability and toughness of the materials.

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Wei Zhang, Qing Liang, Xiujuan Li, Lai-Peng Ma, Xinyang Li, Zhenzhen Zhao, Rui Zhang, Hongtao Cao, Zizhun Wang, Wenwen Li, Yanni Wang, Meiqi Liu, Nailin Yue, Hongyan Liu, Zhenyu Hu, Li Liu, Qiang Zhou, Fangfei Li, Weitao Zheng, Wencai Ren, Meng Zou, Discovery of natural few-layer graphene on the Moon, National Science Review, 2024;„ https://doi.org/10.1093/nsr/nwae211.

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