INFORMATION:
This work was financially supported by the Russian Science Foundation (Project No. 20-73-10242).
Scientists developed energy saving ceramic phosphors for high power LED systems
2021-01-26
(Press-News.org) Materials scientists of Far Eastern Federal University (FEFU), in collaboration with an international research team, have advanced the design of composite ceramic materials (Ce3+:YAG-Al2O3), i.e. solid-state light converters (phosphors) that can be applied in-ground and aerospace technologies. The LED systems based on the developed materials to save 20-30 percent more energy compared to commercial analogues. A related article was published in Materials Characterization.
Over 15% of the total global electricity production or about $ 450 billion annually spent on lighting. According to the photonics development roadmap run in Russia, the development of LED technology with an efficiency of more than 150 lm/W will allow to release up to 30% of electricity by 2025.
Based on the developed ceramic light converters, it is possible to produce both compact energy-efficient white light-emitting diodes (wLEDs) and high-power (high brightness) systems. The new material is in demand for many photonic applications from portable projectors and endoscopes to laser TVs with a diagonal of more than 100 inches, lighting devices for auto and aircraft construction, megastructures, etc.
"The consumption of white LEDs is more than half of the total consumption of high brightness LEDs. Some peculiarities of the technology for the production of organic phosphors for modern commercial white LEDs lead to the quick aging of the light-emitting diode that loses brightness and quality of color rendering. We get around the problem by creating completely inorganic light converters in the form of composite ceramics based on yttrium aluminum garnet, activated by cerium ions Ce3+:YAG, and a thermally stable phase of aluminum oxide Al2O3", says Anastasia Vornovskikh, a Junior Researcher at the REC for "Advanced Ceramic Materials" of the FEFU Polytechnic Institute (school, PI).
The new materials are characterized by high values of thermal strength and thermal conductivity, endure high pumping power, and generate bright white light without obvious thermal quenching of the photoluminescence intensity. This makes it possible to reduce the operating temperature of the LED device down to 120-70°C, more than 2 times in comparison with commercial samples of Ce3+:YAG.
"We synthesized materials by vacuum reactive sintering of initial oxide powders of aluminum, yttrium, cerium, and gadolinium. Particular attention we paid to the identification of the quantitative relationship between the main scattering centers that are residual pores and Al2O3 crystallites and the spectroscopic properties of ceramic phosphors. Our light converters meet all the requirements for new generation wLEDs. They have a long lifespan, high luminous efficacy and color rendering index while maintaining the requirements for the environmental friendliness and material dimensions", says project manager Denis Kosyanov, Director of the REC for "Advanced Ceramic Materials", of the Industrial Safety Department of FEFU PI.
In the study took part researchers from Far Eastern Federal University (FEFU); Shanghai Institute of Ceramics, the Shanghai Technological Institute, the University of the Chinese Academy of Sciences; Institute of Chemistry of the Far Eastern Branch of the Russian Academy of Sciences; Institute of Solid State Chemistry and Mechanochemistry of the Siberian Branch of the Russian Academy of Sciences.
[Attachments] See images for this press release:
ELSE PRESS RELEASES FROM THIS DATE:
Roadblocks to success for PhD grads could mean missed opportunities for Canada
2021-01-26
Canada could be sitting on a significant untapped resource, as the number of PhD holders in this country rises, but persistent barriers make it hard for them to put their skills to work. According to a new expert panel report from the Council of Canadian Academies (CCA), PhD graduates play a critical role in the Canadian economy, but many are missing out on important opportunities to contribute their expertise and bolster growth and innovation.
"The growing number of PhD graduates in Canada could represent a significant opportunity to drive innovation and increase our competitiveness in a global economy," said M. Elizabeth Cannon, O.C., PhD, FRSC, FCAE, Chair of the Expert Panel. "The difficulties graduates face raise important questions about the nature of PhD ...
Corona vaccination: Approach receives approval
2021-01-26
"74 percent of the respondents consider the national vaccination strategy to be appropriate," says BfR-President Professor Dr. Dr. Andreas Hensel. "This indicates that the strategy is accepted."
While some regulations, such as the cancellation of events or the quarantine measures, have always been met with approval in recent months, other measures are now less accepted. Whereas shortly before Christmas, 84 percent of the respondents considered the contact restrictions to be appropriate, 74 percent say so in the current survey. Over the same period, approval of the closure of shops fell by ten percentage points to 56 percent.
In the previous ...
Researchers use nanomaterials to make 2D diamond clusters at room temperature
2021-01-26
BROOKLYN, New York, Monday, January 26, 2021 - Atomically thin, 2D hexagonal boron nitride (h-BN) is a promising material whose protean ability to undergo phase transformations to strong, super lightweight, chemically stable, oxidation-resistant films makes them ideal for protective coatings, nanotechnology thermal applications, deep-UV light emitters, and much more.
The possibilities embodied in different polytypes of h-BN include the ultra-hard diamond phase, a cubic structure (c-BN) with strength and hardness second only to actual carbon diamonds. Key to fabricating such materials is the ability to induce and control the transformation between their various crystalline phases, in a way that is efficient and cost effective enough to allow for economies of scale.
While ...
Reef fish futures foretold
2021-01-26
An international group of scientists is predicting markedly different outcomes for different species of coral reef fishes under climate change - and have made substantial progress on picking the 'winners and losers'.
Associate Professor Jodie Rummer from James Cook University's ARC Centre of Excellence for Coral Reef Studies co-authored a study that exposed two species of coral reef fishes to elevated temperatures and measured their responses over time.
"We collected five-lined cardinalfish and redbelly yellowtail fusilier from the Great Barrier Reef, and under controlled conditions in the laboratory at JCU, slowly raised the temperature ...
When looking at species declines, nuances and long-term data are important
2021-01-26
The scientific process is an iterative and collaborative journey. Research is published, others can weigh in on results, and hypotheses can be corroborated, refuted, or further refined and tested. Though it may seem like second guessing or perhaps become contentious in some cases, this often overlooked aspect of the scientific method makes science better by continuing to challenge scientific assertions, thereby expanding and deepening our understanding.
An example of this process has been published today in Proceedings of the National Academy of Sciences, in a collaboration between researchers from Louisiana State University, the University of Puerto Rico, and UConn. This new paper is a follow-up to an earlier response published in the same journal in 2018 that told of a collapsing ...
Solar hydrogen: Photoanodes made of alpha-SnWO4 promise high efficiencies
2021-01-26
Hydrogen is an important factor in a sustainable energy system. The gas stores energy in chemical form and can be used in many ways: as a fuel, a feedstock for other fuels and chemicals or even to generate electricity in fuel cells. One solution to produce hydrogen in a climate-neutral way is the electrochemical splitting of water with the help of sunlight. This requires photoelectrodes that provide a photovoltage and photocurrent when exposed to light and at the same time do not corrode in water. Metal oxide compounds have promising prerequisites for this. For example, solar water splitting devices using bismuth ...
Intercontinental study sheds light on the microbial life of sourdough
2021-01-26
In a study of 500 sourdough starters spanning four continents, scientists have garnered new insights into the environmental factors that contribute to each sourdough starter's microbial ecosystem, and how different types of microbes influence both a sourdough's aroma and how quickly the sourdough rises. The results may surprise sourdough enthusiasts.
"We didn't just look at which microbes were growing in each starter," says Erin McKenney, co-author of the paper and an assistant professor of applied ecology at North Carolina State University. "We looked at what those microbes are doing, and how those microbes coexist with each other."
"There have been quite a few small studies on microbial ecosystems in sourdough," says Benjamin Wolfe, co-author of the study and ...
Biodegradable displays for sustainable electronics
2021-01-26
In the next years, increasing use of electronic devices in consumables and new technologies for the internet of things will increase the amount of electronic scrap. To save resources and minimize waste volumes, an eco-friendlier production and more sustainable lifecycle will be needed. Scientists of Karlsruhe Institute of Technology (KIT) have now been the first to produce displays, whose biodegradability has been checked and certified by an independent office. The results are reported in the Journal of Materials Chemistry. (DOI: 10.1039/d0tc04627b)
"For the first time, we have demonstrated that it is possible to produce sustainable displays that are largely based on natural ...
Autistic kids may have a harder time recognizing healthy vs. toxic arguments
2021-01-26
DALLAS (SMU) - A new study suggests children on the autism spectrum may be more likely to misinterpret healthy arguments between their parents as being negative, compared to children who aren't on the autism spectrum.
That means they may be missing out on an opportunity to learn from their parents how to handle conflict constructively, researchers Naomi Ekas and Chrystyna Kouros said.
"Children can learn how to best handle conflict from watching their parents," said Kouros, associate professor of psychology at SMU (Southern Methodist University). "Seeing parents ...
A benchmark for single-electron circuits
2021-01-26
Manipulating individual electrons with the goal of employing quantum effects offers new possibilities and greater precision in electronics. However, these single-electron circuits are governed by the laws of quantum mechanics, meaning that deviations from error-free operation still occur - albeit (in the best possible scenario) only very rarely. Thus, insights into both the physical origin the and metrological aspects of this fundamental uncertainty are crucial for the further development of quantum circuitry. To this end, scientists from PTB and the University of Latvia have collaborated to develop a statistical testing methodology. Their results have been published in the journal Nature Communications.
Single-electron circuits are already used as electric-current quantum standards and ...