New low-cost material for lighting and diagnostics produces white light imitating sunlight

June 7, 2017
The hackmanite developed by the researchers. Credit: University of Turku

Researchers at the University of Turku, Finland, have developed a synthetic material based on the natural hackmanite mineral, which produces broad spectrum white light in lamps. The low-cost hackmanite-based material created by the Inorganic Materials Chemistry research group emits luminescence closer to sunlight than currently used lanthanides.

The material contains only highly abundant and nontoxic elements, and therefore has low production costs and does not produce hazardous waste or contain health risks.

"The lower cost of the material is also a great asset in applications for diagnostics, as the lanthanides that are currently in use are expensive. Because of its persistent luminescence, hackmanite does not require expensive time-resolved spectrometers to measure luminescence," says Docent Mika Lastusaari from the University of Turku.

He believes that hackmanite has possible applications in point-of-care diagnostics because it is excitable with sunlight.

Lamps that produce imitating sunlight are used in lighting applications. Current fluorescent lamps and LEDs produce white with luminescent materials that contain lanthanides, which is problematic. On the one hand, they are expensive and their price can vary a great deal and, on the other, they do not produce the same as sunlight. White light is produced with lanthanides by mixing three narrow-spectrum primary colours, red, green and blue, and therefore produce reflected light that does not meet the quality of reflected .

Hackmanite Produces Effective Afterglow

- "Persistent luminescence, also known as afterglow, is used in that glow in the dark, such as exit signs and watches. Our hackmanite material can produce observable white persistent luminescence for seven hours in the dark. With a spectrometer, the luminescence can be detected for more than 100 hours." says Lastusaari.

Until now, there have been no materials that produce good white persistent luminescence. Lastusaari says, "The hackmanite we have developed can be used in ordinary lamps as a single component phosphor to produce natural white light. As a bonus, hackmanite lamps continue to glow even after a power failure, thus being suitable for exit and emergency signs."

Hackmanite have excellent stability in water and the research group has shown that it has easily detectable photoluminescence even in nanomolar concentrations.

"We have also tested the material's application in diagnostics: we demonstrated that the material's persistent can be used in authenticating spices and testing for counterfeit foods. The tests were conducted together with the Detection Technology Group of the Department of Chemistry," Lastusaari says.

Explore further: LEDs: Better red makes brighter white

More information: Isabella Norrbo et al, Lanthanide and Heavy Metal Free Long White Persistent Luminescence from Ti Doped Li-Hackmanite: A Versatile, Low-Cost Material, Advanced Functional Materials (2017). DOI: 10.1002/adfm.201606547

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dirk_bruere
not rated yet Jun 07, 2017
If only we knew what hackmanite is made of...
antialias_physorg
not rated yet Jun 07, 2017
...or you could just click on the link at the bottom of the article.
Eikka
not rated yet Jun 07, 2017
If only we knew what hackmanite is made of...


Lithium, Sodium, Aluminium, Silicon, Oxygen, Chlorine, Sulfur, Titanium.

Question is, if you make an ordinary lightbulb out of it, would it glow for hours after you switch it off? That would be somewhat annoying.
antialias_physorg
not rated yet Jun 07, 2017
That's why they say it's for medical diagnostics and emergency signs/exit lighting'. No do they claim taht this is suitable for common light fixtures.

Read what's there, people.
nkalanaga
not rated yet Jun 07, 2017
Persistent lighting would be fine for living areas, such as living rooms, kitchens, bathrooms, etc. I doubt that the persistent luminescence is nearly as bright as the light produced when the bulb is on.

In bedrooms it wouldn't be such a good idea, but that's why we have different types of lighting.
dnatwork
1 / 5 (1) Jun 07, 2017
If it glows because it is still carrying a charge, perhaps you could make it stop glowing by grounding it, reversing polarity, or otherwise draining charge, the instead of just turning it off.
Eikka
not rated yet Jun 07, 2017
No do they claim taht this is suitable for common light fixtures.

Read what's there, people.


It says:

"The hackmanite we have developed can be used in ordinary lamps as a single component phosphor to produce natural white light.


Practice what you preach, AA.

In bedrooms it wouldn't be such a good idea, but that's why we have different types of lighting.


I wish. It's getting more and more difficult to find 100+W equivalent standard incandecent bulbs because the bans are starting to affect even halogen lights. The irony is that high wattage incandecent bulbs are the most efficient.

Instant on/off, dimmable, perfect light quality, reasonable lifespan, cheap. It's the perfect light, so of course it has to be banned in favor of flaky and expensive LED/CFL bulbs with poor light spectrum. Too bad for anyone who likes painting, photography, etc. because there are literally no good alternatives.
EmceeSquared
1 / 5 (1) Jun 08, 2017
What's important about these hackmanite "phosphors" is not so much that they glow so long, though they do. It's that they glow in a full solar spectrum, better and cheaper than the current materials:

"luminescence closer to sunlight than currently used lanthanides.

The material contains only highly abundant and nontoxic elements, and therefore has low production costs and does not produce hazardous waste or contain health risks.
[...] for diagnostics, as the lanthanides that are currently in use are expensive. Because of its persistent luminescence, hackmanite does not require expensive time-resolved spectrometers to measure luminescence,"

So it's much cheaper to get solar white light for diagnostics, and also for regular illumination. Hackmanite phosphors provide a steadier light than the flickering light stimulating them. Which along with the nontoxic materials all makes even room lighting cheaper and higher quality.
nkalanaga
not rated yet Jun 08, 2017
dnatwork: Most phosphors continue to glow after exposure to radiation due to chemically-stored energy. This is useful, because they'll work for a while without energy input, but also means they can't be turned off on demand. It's like the "glow in the dark" numerals on some analog clocks, and the glowing exit signs that used to be popular, before battery-powered ones took over.
dnatwork
1 / 5 (1) Jun 12, 2017
@nkalanga:
dnatwork: Most phosphors continue to glow after exposure to radiation due to chemically-stored energy. This is useful, because they'll work for a while without energy input, but also means they can't be turned off on demand.


Chemically-stored energy sounds like a battery to me, which is why I wondered if it could be drained somehow. It is glowing as it dissipates that energy. If the substance had an easier path for the energy to take, some circuit that was open when you want it to glow but closed when you turned it off, wouldn't it stop glowing faster?

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