Dopant boosts carbon nanotubes’ conductivity tenfold

Good news!

"Doping carbon nanotubes with tetrachloroaluminate ions can increase their electrical conductivity around tenfold without harming the nanotube structures, researchers in Spain have shown. The research helps explain the chemistry of nanotube doping, and could potentially lead to applications such as lighter, stronger cables for electricity distribution. ...

exposed commercial double-walled carbon nanotubes with an initial conductivity of around 1.4MS/m to an atmosphere of aluminium trichloride and excess chlorine for 24 hours, causing tetrachloroaluminate ions to diffuse into the structure. Spectroscopic analysis indicated that, rather than entering the nanotubes’ centres, the ions intercalated between the walls. The researchers observed no significant expansion of the nanotubes. They showed that the fact that the nanotubes are wrapped concentrically creates a greater gap between the carbon atoms than in multilayer graphene, ... ‘Therefore, it can host the dopant without distorting the bundle.’ ..."

From the editor's summary and abstract:

"Editor’s summary

Translating the outstanding individual properties of carbon nanotubes, such as their electrical and thermal conductivity, into bulk materials that retain those properties remains a challenge.

de Isidro-Gomez et al. demonstrated controlled vapor-phase intercalation of tetrachloroaluminate (AlCl₄−) ions within intertube channels to make macroscopic double-walled carbon nanotube fibers.

The fibers showed high electrical conductivity approaching 40% of the value of copper at room temperature.

On a per-weight basis, the cables exceeded both the conductivity and strength of conventional overhead cables. Furthermore, they showed excellent dry stability and reasonable moisture tolerance when protected by a polymer sheath. ...

Abstract

Translating the conductivity of individual carbon nanotubes into practical, macroscopic conductors remains a challenge.

We report highly aligned fibers of double-walled carbon nanotubes intercalated with chains of tetrachloroaluminate anions (AlCl4−) in the intertube channels. The AlCl4− intercalant acts as a noncovalent dopant, accepting 0.65 electrons per anion, mostly from the outer nanotube layer.

Combined with a 17% intercalant volume fraction, it produces an increase in room-temperature conductivity to values as high as 24.5 mega-Siemens per meter, which is 41% of that of copper.

Specific conductivity values reach 17,345 Siemens-meter squared per kilogram, which is superior to that of metals.

These fibers are five times stronger and half the weight of conventional overhead cables while remaining stable in dry conditions and retaining 80% of their conductivity protected from moisture by a cable polymer sheath."

Dopant boosts carbon nanotubes’ conductivity tenfold | Research | Chemistry World

Intercalated carbon nanotube fibers with high specific electrical conductivity (no public access)

The tetrachloroaluminate ions are positioned in interstitial channels between the double-walled carbon nanotubes

Salty ice produces electricity when bent comparable to the best piezoelectric materials

Amazing stuff!

"... Every solid exhibits some amount of electric response to being bent or deformed, called flexoelectricity. Most of these responses are far too weak to exploit ... 

But when researchers turned to ice, a prevalent solid on Earth and one of the most common solids in space, the story was different. 

Adding table salt (NaCl) created a solid where every ice particle was surrounded by a few nanometers of briny liquid. When the salty ice was bent and unbent, this fluid sloshed back and forth, creating a current of ions that conferred a flexoelectrical effect around 1000 times larger than that of pure ice and on par with specially designed materials.

Salty ice has plenty of advantages in the real world, such as being 

moldable (just think of fun-shaped ice trays), 

non-toxic, and 

requiring no trace elements, as found in typical electronics.

The simple solid could be incorporated into engineering projects in polar areas where sunlight is too low for solar power and water threatens soft robotics’ wiring and batteries, though it’s not a great candidate for deep space applications since the key briny liquid freezes at -70ºC. ..."

"... discovered that, despite not being piezoelectric, ice can generate electricity when unevenly deformed, thanks to a phenomenon known as flexoelectricity.

Building on this first discovery, the researchers have now achieved a new breakthrough: adding salt to ice significantly enhances its ability to generate electricity, opening up a wide range of potential technological applications. ..."

From the abstract:

"Despite 10% of the Earth’s surface being covered by ice, ice power remains untapped. 

Although ice is known to generate electricity upon bending via flexoelectricity, the generated electric polarization per curvature, that is, the flexoelectric coefficient, is too small (~1–10 nC m−1) to be utilized for electromechanical devices. 

Here we demonstrate that doping ice with NaCl can enhance its flexoelectric coefficient 1,000-fold, to ~1–10 μC m−1. We find that this enhancement is due to the bending-induced streaming current along ice grain boundaries.

On the basis of this mechanism, we fabricated flexural devices with an effective piezoelectric coefficient of ~4,000 pC N−1, which is comparable to that of the best piezoelectric materials. 

The high flexoelectricity of saline ice brings the vision of harnessing ice power one step closer to reality, and may also be relevant to the electrical activity of ice-covered terrestrial regions and icy ocean worlds such as Europa or Enceladus.

In addition, the model for coupling between strain gradients and streaming currents is not limited to ice and provides a general framework for extracting electromechanical activity from liquid-infused porous solids."

ScienceAdviser

Salty Ice: a New Way to Generate Electricity in Extreme Conditions (original news release)

Streaming flexoelectricity in saline ice (no public access)

Bending polycrystalline salty ice drives the flow of ions from one side to the other through small channels, generating an electrical current. 

‘Strange metals’ point to a whole new way to understand electricity

Recommendable! Amazing stuff! This is a long overview article.

"... a compound of ytterbium, rhodium, and silicon ... The sample belongs to a class of materials that physicists call “strange metals.” For 4 decades, they’ve puzzled over the fact that in these compounds, the standard theory of electricity just doesn’t work.

Recent experiments ... suggest that in strange metals, electrons lose their individuality. ... Instead, electric charge appears somehow to pass through the metal as a diffuse amorphous blob—like water without individual H2O molecules. Researchers are still debating the microscopic details of this bizarre picture. But it’s already clear that the stakes are higher than just understanding a dozen or so oddball materials. “It’s really a mysterious state with big consequences ...

The hallmark of strange metals is electrical resistivity that climbs higher than that of ordinary metals when they are warmed from low temperatures. They also lose their resistivity altogether, becoming superconductors, at lower ­temperatures—though above those of conventional superconductors. Some researchers believe this ­high-temperature ­superconductivity is simply the flip side of strange metallicity—that they’re two manifestations of the same underlying phenomenon. ...

A theory that explains strange metals may force a fundamental rethinking of how electricity works in all materials. It might subsume the standard theory the way general relativity, with its curved spacetime, subsumed Isaac Newton’s theory of gravity—and prove just as unsettling. Strange metals are forcing physicists to ask whether the very idea of an electron, or any particle for that matter, is an oversimplification of what’s really going on. ..."

‘Strange metals’ point to a whole new way to understand electricity | Science | AAAS

Caterpillars Detect Predators Using Electrostatic Charge

Amazing stuff!

Steering high voltage electric sparks (plasma) through the air with ultrasound pulses

Amazing stuff! Let the sparks fly!

"... Scientists in Europe and Canada have now managed to guide sparks through thin air and even around obstacles using ultrasound waves. ...

The method allows sparks to be directed so precisely that they can bend around obstacles, and hit specific spots on a material even if it isn’t conductive. ...

When a spark ignites, it heats up the air around it. This warmer air expands, which reduces its density. Since electricity prefers to travel through lower density air, the spark moves in that direction. The ultrasound pulses move this hotter, lower-density air around, which in turn guides the electricity with surprising precision. ..."

From the abstract:

"Electric plasma forms sparks in midair that transfer electrical current. This current can power high-voltage electronics, kill bacteria, produce tactile sensations, or be used for welding.

However, the formation of the spark is chaotic and hard to control.

Laser pulses can guide discharges but require high power and are disruptive and cumbersome to control.

Here, we show that ultrasonic fields can guide plasma sparks, even around obstacles. The ultrasonic beams can be directed dynamically and within milliseconds, enabling precise, non-dangerous, and fast control of high-voltage sparks. This phenomenon can be used for applications in high-voltage switching and plasma treatments."

Steering electricity through the air with ultrasound pulses

Making an invisible electric wire: guiding electricity with sound (original news release)

Electric plasma guided with ultrasonic fields (open access)

Fig. 3. Guidance of the spark along a curved acoustic field created with two focal points coming from two rings of emitters.

Electrostatic Motors Challenge Electromagnetic Motors

Amazing stuff!

"... But “an electrostatic motor doesn’t need windings, doesn’t need magnets, and it doesn’t need any of the critical materials that a conventional machine needs.”

... C-Motive Technologies, to build macro-scale electrostatic motors. “We make our machines out of aluminum and plastic or fiberglass,” he says. Their current prototype is capable of delivering torque as high as 18 newton meters and power at 360 watts (0.5 horsepower)—characteristics they claim are “the highest torque and power measurements for any rotating electrostatic machine.” ...

For this quest he and his team found inspiration in a lesser-known accomplishment of one of the United States’ founding fathers. “The fact is that Benjamin Franklin built and demonstrated a macroscopic electrostatic motor in 1747,” says Krein. “He actually used the motor as a rotisserie to grill a turkey on a riverbank in Philadelphia” ...
C-Motive is now testing a 750-watt (1 hp) motor in applications with potential customers. Their next machines will be in the range of 750 to 3,750 watts (1 to 5 hp), he adds. "

Electrostatic Motors Challenge Electromagnetic Motors - IEEE Spectrum "It turns out that Benjamin Franklin was on to something in 1747"

C-Motive’s 360-watt motor has a half dozen each of rotors and stators, shown in yellow in this cutaway illustration.

Thermoelectric Effect Seen at the interface of two metal Liquids for the First Time

Amazing stuff! Could this be a breakthrough!

"Based on physics first observed over 200 years ago, thermoelectric devices can convert thermal energy into electrical energy and vice versa. ... Liquid thermoelectrics could be used to create new devices for scavenging energy from waste heat, and insights from the research could help improve the design of liquid-metal batteries.  ...
liquid thermoelectricity could be harnessed in new, highly efficient devices that convert waste heat into electricity. ...

team hypothesizes that these effects might be contributing to Jupiter’s magnetic field. The planet’s core is surrounded by a large region of metallic hydrogen, which is covered by an atmosphere of liquid molecular hydrogen. The planet’s equator is warmer than its poles, creating a temperature gradient along the metallic-liquid hydrogen interface. ..."

"The thermoelectric effect describes an energy transformation in which heat is converted into electricity and vice versa. This captivating interaction has long intrigued physicists, as it offers insight into the complex relationship between energy, temperature and matter. Thermoelectric materials generally involve an interface between two different solid semiconductors, and have a wide variety of applications: temperature sensors, refrigeration, environmentally-friendly power generation, etc.
 Researchers at the Laboratoire de Physique de l’Ecole Normale Supérieure de Paris (LPENS) have obtained the first proof of thermoelectricity between two liquids. The experiment involves superimposing two immiscible metals, mercury and gallium, liquid at room temperature, in a cylindrical container. When a large radial temperature difference is imposed between the two cylindrical walls containing the liquid metals, an electric current flows across the interface between the two liquids. ..."

From the significance and abstract:

"Significance

The Seebeck effect is the conversion of heat into electricity, usually achieved by thermoelectric devices using solid electrical conductors or semiconductors. Here is reported evidence of this effect at the interface between two metals that are liquid at room temperature, gallium and mercury. The liquid nature of the interface significantly alters the usual temperature distribution, leading to an abnormally high current density near the boundaries. In the bulk, the thermoelectric current interacts with a magnetic field to produce efficient thermoelectric pumping of fluids. This effect may be of prime importance in several industrial and astrophysical systems, such as the promising liquid-metal batteries and Jupiter’s magnetic field.

Abstract

We present experimental evidence of a thermoelectric effect at the interface between two liquid metals. Using superimposed layers of mercury and gallium in a cylindrical vessel operating at room temperature, we provide a direct measurement of the electric current generated by the presence of a thermal gradient along a liquid–liquid interface. At the interface between two liquids, temperature gradients induced by thermal convection lead to a complex geometry of electric currents, ultimately generating current densities near boundaries that are significantly higher than those observed in conventional solid-state thermoelectricity. When a magnetic field is applied to the experiment, an azimuthal shear flow, exhibiting opposite circulation in each layer, is generated. Depending on the value of the magnetic field, two different flow regimes are identified, in good agreement with a model based on the spatial distribution of thermoelectric currents, which has no equivalent in solid systems. Finally, we discuss various applications of this effect, such as the efficiency of liquid metal batteries."

Thermoelectric Effect Seen in Liquids for the First Time - IEEE Spectrum The insight could lead to breakthroughs in liquid-metal batteries

Liquid thermoelectricity (original press release)

Thermoelectricity at a gallium–mercury liquid metal interface (no public access)

Schematic 3D visualization of the thermoelectric interaction between two liquid metals. The gallium in the upper part is made transparent to better visualize the abnormally strong electric currents (in blue) and the associated magnetic field (in yellow).

Quantum treatment sheds fresh light on triboelectricity

Until now we did not even understand how the ancient well known phenomenon of electric charge generated by friction works! However, daily propaganda and demagoguery about Global Warming/Climate Change wants us to believe we could predict climate over the next 100 years! Global Warming is a hoax, an ideology, and a religion!

"Thanks to Alicki and his colleague Alejandro Jenkins of the Universidad de Costa Rica, the mystery surrounding triboelectricity (as the “charging by rubbing” effect is known) may be clearing up. According to Alicki and Jenkins, a major barrier to understanding triboelectricity is that physicists tend to view the phenomenon in terms of electrostatic potentials, even though “from a potential effect, you are never going to sustain a current that is going around a circuit,” Jenkins says. “It’s like the problem of perpetual motion.”"

Quantum treatment sheds fresh light on triboelectricity – Physics World