Phys.org July 26, 2022 Mechanoluminescence (ML) materials emit light in response to mechanical stimulation. However, most of today’s ML materials are polycrystalline ceramics or ceramic particle composites, which puts constraints on their bulk processability, material homogeneity and optical transparency. Researchers in Germany created a glass-ceramic material with mechanoluminescence properties by developing an exceptionally fast and stable crystallization process that allows the tiny chromium-doped zinc gallate (ZGO) crystals to precipitate homogeneously inside the glass after it has been shaped. They demonstrated it by using the ball-drop methos to show that the mechanoluminescence response was reproducible and rechargeable and that it exhibited […]
Tag Archives: S&T Germany
How ultrathin polymer films can be used for storage technology
Phys. org July 18, 2022 Researchers in Germany showed that precisely applied mechanical pressure can improve the electronic properties of a widely used ferroelectric semi-crystalline polymer material polyvinylidene fluoride (PVDF). However, PVDF’s structure, unlike crystals, is not completely ordered. They discovered that atomic force microscopy can be used to establish a certain electric order in the material. They scanned the material sample with a tip only a few nanometers in size. Using a laser they measured, evaluated the vibrations that were produced, and analyzed the material’s surface structure at the nano level. They discovered that this also changed the electrical […]
Photovoltaics: Fully scalable all-perovskite tandem solar modules
Science Daily July 14, 2022 Researchers in Germany have developed a prototype for fully scalable all-perovskite tandem solar modules which have an efficiency of up to 19.1 percent with an aperture area of 12.25 square centimeters. The improved efficiency was realized with optimized light paths, high-throughput laser scribing, and the use of established industrial coating methods. Perovskite solar cells with a tunable band gap are ideal tandem partners for solar cells made of other materials and for all-perovskite tandem solar cells. They were able to scale up individual perovskite cells with an efficiency of up to 23.5 percent .They feature […]
Acoustic sensors to pinpoint shooters in an urban setting
Phys.org May 23, 2022 Instead of a sound propagation-based approach, researchers in Germany focused on an information theoretical analysis using the Cramér-Rao bound to predict the achievable shooter localization accuracy. They showed that accounting for incomplete and heterogeneous acoustic measurement data sets leads to maximization of the fusion gain and consequently to improved achievable localization accuracy. They validated the match between predicted and actual experimental performance in free-field measurements with supersonic gunshots including varying sensor-to-shooter geometries, weapon types, and various measurement types. By measuring signatures of impulsive gas cannon shots in urban terrain, they analyzed the effect of buildings to […]
Secure communication with light particles that sidesteps the reliance on polarization
Phys.org May 25, 2022 Researchers in Germany have created a scalable star-shaped quantum-key-distribution (QKD) optical-fiber network using WDM of broadband photon pairs to establish key exchange between multiple pairs of participants. They demonstrated simultaneous bipartite key exchange between any possible combination of participants and showed that the quantum bit error rate (QBER) itself can be used to stabilize the phase in the interferometers by small temperature adjustments. The key distribution is insensitive to polarization fluctuations in the network, enabling key distribution using deployed fibers even under challenging environmental conditions. They demonstrated that the network could be extended to 34 participants […]
More efficient optical quantum gates
Phys.org May 13, 2022 Progress in optical quantum information processing is hampered by the low efficiency of the two-qubit quantum gates realized so far. Researchers in Germany demonstrated an optical two-qubit gate with an average efficiency above 40%, thus outperforming the previous record by a factor of almost 4. They accomplished this with electromagnetically induced transparency. Incoming photons are converted into polaritons in highly excited Rydberg state. Any two atoms in such a state have a strong interaction, even at large separations. When two photons enter the resonator, both become polaritons and their Rydberg components interact. When the excitations leave […]
Intense laser light modifies the pairing of electrons
Phys.org April 12, 2022 Researchers in Germany have realized a method to affect and measure the effective exchange interaction between several electrons bound in a molecule with two differently colored laser pulses. Using soft X-ray light, they excited an electron deeply bound to the sulfur atom in a sulfur hexafluoride molecule, thereby extending its radius of motion to the entire molecule for a short time before it leaves the molecule. Due to the spin-orbit interaction of the deeply bound electrons remaining there, the hole formed at the sulfur atom thereby produces a characteristic double structure of two lines measurable in […]
Converting body heat into electricity: A step closer towards high-performance organic thermoelectrics
Science Daily April 4, 2022 Researchers in Germany investigated the charge and thermoelectric transport in modulation-doped large-area rubrene thin-film crystals with different crystal phases. They showed that modulation doping allows achieving superior doping efficiencies even for high doping densities when conventional bulk doping runs into the reserve regime. Modulation-doped orthorhombic rubrene achieved much improved thermoelectric power factors. Modulation doping technique avoid impurity scattering in the highly ordered undoped narrow bandgap semiconductor allowing both carrier concentration and mobility to be independently maximized. The work paves new ways to achieve flexible thermoelectric devices to directly generate electrical power from heat in an […]
Heat storage: Scientists develop material that is stable, efficient, and eco-friendly
Phys.org March 29, 2022 Researchers in Germany have developed shape-stabilized phase change material which can absorb large amounts of heat by changing its physical state from solid to liquid. The stored heat is then re-released when the material hardens. They describe the steps involved in creating the structure of the material and how the different chemicals influence each other. Large panels of the material could be integrated into walls. These would then absorb heat during the sunny hours of the day and release it again later when the temperature goes down. Under the right conditions it could store up to […]
Physicists create compressible optical quantum gas
Phys.org March 24, 2022 The compressibility of a medium, quantifying its response to mechanical perturbations is a fundamental property determined by the equation of state. For gases of material particles studies of the mechanical response are well established in fields from classical thermodynamics to cold atomic quantum gases. Researchers in Germany demonstrated the measurement of the compressibility of a two-dimensional quantum gas of light in a box potential and obtained the equation of state for the optical medium. The experiment was carried out in a nanostructured dye-filled optical microcavity. They observed signatures of Bose-Einstein condensation at high phase-space densities in […]