The hackmanite developed by the researchers. Credit: University of Turku
A synthetic material has been developed by researchers at the University of Turku based on the natural hackmanite mineral which generates broad spectrum white light in lamps. The hackmanite developed by the Inorganic Materials Chemistry research group is a cost-effective material emitting luminescence closer to sunlight than that of the presently used lanthanides.
The hackmanite is made up of only non-toxic and highly abundant elements. Thus, hackmanite does not produce harmful waste or contain health risks and has low production costs.
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
Docent Mika Lastusaari, University of Turku.
He assumes that hackmanite is also capable of having applications in point-of-care diagnostics as it is excitable with sunlight.
Lamps that generate white light imitating sunlight are employed in lighting applications. LEDs and fluorescent lamps currently produce white light with luminescent materials that are made up of lanthanides.
The use of lanthanides is considered to be problematic. They are expensive and their price can experience a significant change. Another problem is that lanthanides do not produce the same broad spectrum that is produced by the Sun. White light is developed with lanthanides by merging three narrow spectrum primary colors, i.e. blue, green and red, and thus things appear to be different in their light than in the sunshine.
Hackmanite Produces Effective Afterglow
Persistent luminescence, also known as afterglow, is used in applications 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. Until now, there have been no materials that produce good white persistent luminescence.
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 materials have exceptional stability in water and the research group has proved that it has photoluminescence that can be effortlessly detected even in nanomolar concentrations.
We have also tested the material's application in diagnostics: we demonstrated that the material's persistent luminescence 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.
Additionally, the persistent luminescence mechanism of the materials was analyzed in colaboration with the University's Department of Physics, the Instrumentation and Instrument Centre of the Department of Chemistry, and the Laboratory of Electron Microscopy. Furthermore, the Ångström Laboratory at the Uppsala University and the University of São Paulo provided increased assistance in the research.
The Academy of Finland, Nordic Energy Research, Turku University Foundation, Swedish Energy Agency, Knut and Alice Wallenberg Foundation, Brazilian funding agency CNPq, and University of Turku Graduate School funded this research.
An article on this research was published in the journal Advanced Functional Materials.