Category Physics

A layered ruthenate Ca2RuO4-y ceramic body contracts on heating, or exhibits negative thermal expansion (NTE). The sintered-body structure shows colossal NTE when extremely anisotropic thermal expansion of the crystal grains produces deformation, consuming open spaces (voids) on heating. The total volume change related to NTE reaches 6.7 percent at most, the largest reported so far. Credit: Koshi Takenaka

Machines and devices in modern industry are required to withstand harsh conditions. When environmental temperature changes, the volume of the materials used to make these devices usually changes slightly, typically by <0.01%. Although this may seem trivial, over time this thermal expansion can seriously degrade the performance of industrial systems and equipment.

Materials that contract o...

Array of low-power light-emitting diodes. Failure of a single LED does not affect the overall system. (Photo: KIT)

Researchers of Karlsruhe Institute of Technology (KIT) have developed a novel type of LED street light of increased efficiency. Compared to conventional LEDs, power consumption may be reduced by up to 20%. This will also decrease costs and CO2 emission. Conventional high-power diodes are replaced by a special array of LEDs. This enhances efficiency, increases service life and safety, and produces a better light.

Parallel connection of a large number of LEDs is difficult, as failure of a single diode will cause failure of the overall system or section...

1. How to make ceramic foam ink 2. Close up image of one node of the triangular honeycomb. The structure, which consists of air surrounded by ceramic, can be designed with specific porosity. (Image courtesy of James Weaver/Wyss Institute)

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being compressed. The plant’s hardiness comes from a combination of its hollow, tubular macrostructure and porous, or cellular, microstructure. These architectural features work together to give grass its robust mechanical properties. Harvard SEAS, Wyss Institute and MIT have developed a new method to 3D print materials with independently tunable macro-and microscale porosity using a ceramic foam ink...

Terahertz wireless links to spaceborne satellites could make gigabit-per-second connection speeds available to anyone anytime, anywhere on the face of the earth, on the ground or in flight.

A Terahertz (THz) transmitter capable of transmitting digital data at a rate >100 gigabits (= 0.1 terabit) per second over a single channel using the 300-GHz band has been developed. This technology enables data rates 10X or more, faster than that offered by the fifth-generation mobile networks (5G), expected to appear around 2020. The THz band is a new and vast frequency resource expected to be used for future ultrahigh-speed wireless communications.

The research group has developed a transmitter that achieves a communication speed of 10Gb/s using the frequency range from 290 – 315 GHz...