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Vajuu (Índia)

Scientists reveal the secret why natural stones can shine in the dark – all sides

Publicado em 12 agosto 2021

Nationalgeographic.co.id—In general, materials that “shine in the dark” are often used by people traveling on cruise ships or airplanes, where they serve as aids for self-igniting emergency exit signs.

The materials used today are actually synthetic materials. sustained luminescence (persistent luminescence / PeL) in the form of green light can be obtained from divalent europium doped to synthetic strontium aluminate. But researchers at the University of Turku have managed to find a natural mineral glow that gives white glow in the dark.

There are several natural minerals that can produce glow, one of which is hackmanit. How do researchers identify it?

Hackmanite is a member of the rare Sodalite sulfur chlorate sodium aluminum silicate family. This material crystallizes in mass, cubic and octahedral formations. It is one of the few minerals that tenebrescence (can change color when exposed to sunlight), as well as UV-reflecting.

This material can also be seen in a variety of colors such as gray, green, yellow, purple, pink and blue, but usually occurs in dusty white. Hackmanite was first discovered in Greenland by LH Borgstroem in 1901.

Borgstroem named the mineral after the famous Finnish geologist Victor Axel Hackman. Important hackmanite deposits are found in Afghanistan, Myanmar, Canada, Pakistan, Norway and Russia. But not all hacksaws can shine in the dark.

As reported by Techexplorist.com, Isabella Norrbo, a postdoctoral fellow who participated in the study, said: “We have done a lot of research with synthetic hackmanite and have been able to develop a material with a clear glow much longer than natural hackmanite.

He added, “But the conditions affecting luminescence are unclear so far.”

Isabella’s research results on hackmanite have been published in the journal ACS Publications on September 25, 2020 with the title ‘Hackmanite-The Natural Glow-in-the-Dark Material’. The research was carried out as a collaboration between researchers and international teams from different areas.

According to Sami Vuori, a doctoral student who also participated in the research, “nature has extensive experience in optimizing minerals, which is why we used natural hackmanite to study the glow effect.”

“Through this extensive collaboration, we were able to conclude that the most central elements behind the natural luster of hackmanite are sulfur, titanium, potassium and iron, and their proper balance,” says Mika Lastusaari. He is also a lecturer as head of photonics research in the research group for inorganic materials chemistry at the University of Turku.

Titan makes the hackmanite shine

To support this study, which was funded by Business Finland, the French National Research Academy ANR, the Pôle de Compétitivité from France, the São Paulo Research Foundation FAPESP and Ghent University, researchers linked experimental data and computational data. As in the end, they found that titanium shines in the nucleus of hackmanite, and the residues associated with the transfer of electrons in the conduction band.

In this regard, Lastusaari explains, “With these results, we gained valuable information about the conditions that affect hackmanit residues. Although nature in this respect has not been able to form fluorescence materials as efficiently as synthetic materials, nature has helped considerably in the development of increasingly efficient fluorescent materials. “

“Optimizing natural materials allows us to discover how hackmanite produces light most efficiently,” says another researcher, Cecilia Agamah.

Natural minerals often contain complex compositions and the differences in composition are quite large depending on the conditions under which they were formed. This natural mineral is of great help to researchers in developing fluorescent materials that can effectively glow in the dark.

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