Phys.org March 1, 2022 An international team of researchers (USA – PNNL, UT Arlington) tested germanium in combination with a specialized thin crystalline film of lanthanum-strontium-zirconium-titanium-oxide (LSZTO) using hard X-ray photoelectron spectroscopy which can penetrate the material and generate information at the atomic level. They found that the oxygen atoms near the interface donate electrons to the LSZTO film, creating holes in the germanium within a few atomic layers of the interface. These specialized holes resulted in behavior that totally eclipsed the semiconducting properties of both n- and p-type germanium in the different samples they prepared. According to the researchers […]
Category Archives: Materials science
How to look thousands of kilometers deep into the Earth
Phys.org February 21, 2022 To understand how Earth has cooled and produced a solid mantle and crust, we need to know the physical properties of molten rocks at extreme pressure. An international team of researchers (Germany, UK) used the brightness of reflection from a multicolor laser to measure the refractive index of SiO2 glass and the path length of the laser inside the sample at pressures of up to 110 gigapascals, pressures similar to that at the depth of more than 2000 km in the Earth. These measurements yielded the refractive index of SiO2 glass and provided key information to […]
Versatile ‘nanocrystal gel’ could enable advances in energy, defense, and telecommunications
Science Daily February 18, 2022 By using reversibly bonded molecular linkers, gelation can be realized in nanocrystal gels that can be made into responsive and tunable materials. However, there is no experimental means to monitor linking leading to gelation. Researchers at UT Austin developed a metal coordination linkage with a distinct optical signature that allowed them to quantify linking in situ and establish structural and thermodynamic bases for assembly. Because of coupling between linked indium tin oxide nanocrystals, their infrared absorption shifted abruptly at a chemically tunable gelation temperature. They quantified bonding spectroscopically and used molecular simulation to understand temperature-dependent […]
Researchers combine piezoelectric thin film and metasurfaces to create lens with tunable focus
EurekAlert February 17, 2022 Using metasurfaces researchers in Norway designed a device in which a metasurface is suspended on a membrane ring made of a thin-film lead zirconate titanate (PZT) film, which allows the PZT to move the metasurface when a voltage is applied. To demonstrate how MEMS-metasurfaces could function as a varifocal lens doublet, they placed a second metasurface lens after the MEMS-metasurface. Varying the separation distance between the lenses through MEMS displacement allowed researchers to tune the focal point of the lens doublet on the fly. The researchers showed that applying 23 volts allowed the PZT membrane to […]
Researchers identify mechanism by which fatigue cracks grow
Phys.org February 16, 2022 Over the past century a succession of mechanisms has been hypothesized for structural failures resulting from prolonged low-amplitude loading. By atomistic modeling researchers at Cornell University have shown that sustained fatigue crack growth in vacuum requires emitted dislocations to change slip planes prior to their reabsorption into the crack on the opposite side of the loading cycle. By harnessing a new implementation of a concurrent multiscale method, they assess the validity of long-hypothesized material separation mechanisms thought to control near-threshold fatigue crack growth in vacuum and reconcile reports of crack growth in atomistic simulations at loading […]
A star in the world of ceramic engineering
Science Daily February 10, 2022 A team of researchers in the US (Virginia Polytechnic Institute and State University, Bowdoin College, Harvard University) investigated the complex and highly ordered mineralized skeletal system of sea star from the tropical Indo-Pacific region. The skeleton consists of many millimeter-sized skeletal elements called ossicles which connect with soft tissue, allowing the animal to be flexible and move. Each ossicle is constructed of a microlattice structure so uniform that it can be described mathematically. They found that it is essentially a single crystal structure at atomic level which allows a sea star to reinforce its skeleton […]
Scientists discover a mysterious transition in an electronic crystal
Phys.org February 7, 2022 Hysteresis underlies many phase transitions in solids, giving rise to exotic metastable states that are otherwise inaccessible. An international team of researchers (USA – MIT, UC Berkeley, Stanford University, SLAC Linear Accelerator Laboratory, Cornell University, Argonne National Laboratory, Clemson University, China, Russia, Germany) reported an unconventional hysteretic transition in a quasi-2D material, EuTe4. They observed that the hysteresis loop has a temperature width of more than 400 K, setting a record among crystalline solids. The transition has an origin distinct from known mechanisms, lying entirely within the incommensurate charge density wave (CDW) phase of EuTe4 with […]
Impossible material made possible inside a graphene sandwich
Nanowerk January 20, 2022 So far, only a few dozen 2D crystals have been extracted from materials that exhibit a layered phase in ambient conditions, omitting entirely the large number of layered materials that may exist at other temperatures and pressures. An international team of researchers (Austria, Germany, Slovakia, Belgium, France) synthesized 2D cuprous iodide that was stabilized in a graphene sandwich, as the first example of a material that does not otherwise exist in normal laboratory conditions. It normally only occurs in layered form at elevated temperatures between 645 and 675 K. The synthesis utilizes the large interlayer spacing […]
Changing the properties of ferroelectric materials by vacating a single oxygen atom
Phys.org January 3, 2022 In ferroelectric materials, a slight shift of the atoms causes significant changes in the electric field and in the contraction or expansion of the material. An international team of researchers (Israel, USA – UCLA) succeeded in deciphering the atomic structure and electric field deployment in domain walls at the atomic scale. They corroborate the assumption that domain walls allow for the existence of a two-dimensional border between domains as a result of partial oxygen vacancy in areas that are common to two domains, thus enabling greater flexibility in the deployment of the local electric field. They […]
Suiting up with Al-Mg-Si: New protective coating for steel in ships and marine and coastal facilities
Phys.org January 5, 2022 Improving the corrosion resistance of steel by coating it with aluminum for marine applications is limited because of chloride ions in sea water on aluminum. Researchers in South Korea fabricated alloy films with excellent corrosion resistance by depositing an Mg film on Al-Si coated steel sheets and applying heat treatment. The fabricated Al-Mg-Si alloy film formed a corrosion product film composed of two layers, showing an excellent barrier effect against corrosion factors. The Mg in the film fabricated by heat treatment for 5 min was widely distributed in a dissolved state on the AI phase and […]