April 24, 2019
A rare earth metal is the key to improving the performance of energy-harvesting piezoelectric crystals. And it's up to The Avengers to keep it safe! The first sentence is true, I made up the second one. Science is truly awesome! And The Avengers are almost as awesome. It's very close.
Learn about this and more interesting stories from the scientific community in today's issue.
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*-- Rare metal improves performance of energy-harvesting piezoelectric crystals --*
Researchers have discovered that the addition of a rare earth metal significantly improves the performance of piezoelectric crystals.
Piezoelectric crystals are used in sensors, including underwater sonars and medical ultrasound imaging devices. These technologies use perovskite oxide crystals, or PMN-PT crystals.
Scientists have also tried to use piezoelectric crystals, which convert mechanical oscillations into electricity, to power wearable electronics and other types of novel technologies.
An international team of scientists from Australia, China and the United States found a way to improve the performance of PMN-PT crystals. Scientists added samarium atoms during the crystal growth process -- one samarium atom per thousand atoms of the parent crystal -- and found the additive created more homogeneous piezoelectric properties inside the crystal, boosting the crystal's performance.
The piezoelectric coefficient, quantified in picocoulombs per Newton, describes the efficiency of a material's piezoelectric properties. More efficient piezoelectric crystals do more with less.
In lab tests, scientists confirmed that conventional PMN-PT crystals feature a piezoelectric coefficient between 1,200 and 2,500 pC/N. PMN-PT crystals enhanced with samarium produced 3,400 to 4,100 pC/N.
Scientists also noted that the addition of samarium granted the crystals more uniform, or homogeneous, physical properties.
"These crystals are ideal for a variety of sensing applications and could reduce cost by eliminating waste," researchers wrote in their study, published this week in the journal Science.
*-- Physicists aim to catch slow-decaying dark particle inside LHC --*
Scientists at the Large Hadron Collider have developed a new strategy for tracking down dark matter.
Dark matter is apparently everywhere, binding galaxies together. But astronomers can only intimate dark matter's presence by measuring its gravitational effect on regular matter. As such, dark matter and dark energy remains poorly understood.
"We know for sure there's a dark world, and there's more energy in it than there is in ours," LianTao Wang, a researcher at LHC and a professor of physics at the University of Chicago, said in a news release.
To gain insights into this dark world, Wang and his colleagues are trying to isolate the dark particle that they estimate occasionally interacts with normal matter. Researchers predict the elusive particle is heavier and longer-lived than other subatomic particles.
Wang and his research partners suggest that every once in a while -- once or twice a decade, maybe -- this mysterious dark particle gets tangled in the violent mashup of protons produced by the LHC.
"One particularly interesting possibility is that these long-lived dark particles are coupled to the Higgs boson in some fashion -- that the Higgs is actually a portal to the dark world," said Wang. "It's possible that the Higgs could actually decay into these long-lived particles."
When looking for a new kind of elusive particle, scientists face the same problem they always do. It's very difficult to locate a tiny particle inside the violent explosion of subatomic particles created inside LHC's underground tunnels.
However, scientists estimate the dark particle's properties will make it stand out more than others.
"If it's that heavy, it costs energy to produce, so its momentum would not be large -- it would move more slowly than the speed of light," said Fermilab scientist Zhen Liu.
Physicists could simply tweak their algorithms to isolate particles that live and decay more slowly than the rest of subatomic shrapnel. Scientists would be searching for a time difference measuring less than a a billionth of a second, but Wang, Liu and their colleagues are confident LHC's sensors are sensitive enough to do the job.
Scientists are now working to program the LHC's instruments to search for slow-decaying particles when the collider turns back on in 2021. Researchers described their plans for the new dark matter trap this month in the journal Physical Review Letters.
"We anticipate this method will increase our sensitivity to long-lived dark particles by more than an order of magnitude -- while using capabilities we already have at the LHC," Liu said.