Suomeksi
 
 
Group of Rare Earth Chemistry

LUMINESCENT MATERIALS

 

 

The luminescent materials research in our group focuses on solid polycrystalline materials mostly containing rare earth elements (lanthanides). Both synthetic materials and minerals are studied.

Currently, the main topics are Persistent Luminescence and  Up-Conversion Luminescence

 

 

 

Persistent Luminescence

Persistent luminescence is visible light emission for several hours after the removal of the excitation/irradiation source. 

•Storage of energy from visible light, UV and higher energy radiation to lattice defects.

•Release of energy by thermal stimulation (available at room temperature) as light.

The current uses of persistent luminescence include emergency signage, watches and clocks, traffic signs, toys, medical diagnostics, solar cells, etc. Our aim is to elucidate the mechanism of persistent luminescence and develop new more efficient materials.

 

 

Up-Conversion Luminescence

 

Up-converting materials convert lower energy radiation (e.g. NIR) to higher energy radiation (e.g. visible). For example, in the case of Yb3+,Er3+ doped nanomaterials 

•Absorption of two or more low energy photons (Yb3+).

•Emission of a higher energy photon (Er3+).

The current uses for up-conversion luminescence include: lasers, displays, inks for security printing, medical diagnostics, etc. Our aim is to produce optimized up-converting nanoparticles for point-of-care diagnostic applications

 

NANOMATERIALS

 Our group also specializes in the synthesis and characterization of materials with nanoscale crystallites. These can be used in various applications, including as luminescent materials.

MINERALS

 Together with synthetic materials, our group also specializes in studying the properties of minerals. Examples of studied materials include vermiculite and the Bologna Stone, which was history’s first persistent luminescence material.

 

CERAMICS


 

Along with powders, our group specializes in the research of ceramic materials.

 

PIGMENTS


 

Our group studies inorganic rare earth based pigments aimed to replace the conventional materials containing heavy metals.

OTHER ACTIVITIES


 

Crystal structure determination by powder diffraction

  • X-ray, neutron and electron powder diffraction.

  • Rietveld method.

  • Lattice defects and stacking faults.

  • High temperature X-ray powder diffraction.

 

High resolution spectroscopy of lanthanides in solids.

  • UV-vis-NIR absorption and luminescence.

  • Inelastic neutron scattering.

 

 Energy level schemes of lanthanides: wave functions (EPR, specific heat,…), VUV range.

Magnetic susceptibility of lanthanides.

  • Experimental and simulation of temperature dependency.

  • High temperature thermogravimetry and DSC.    

  • Thermoluminescence.

  • EPR (defects, rare earths).

 

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People


 

 

 Adj. professor  Mika Lastusaari

 

Ph.D. Student

Laura Pihlgren

 

Ph.D. Student
Tero Laihinen

 



 Post doc researcher
Karol Lemański

 

Post doc researcher
Paweł Głuchowski

 
Visiting PhD researcher
Ana Ungureanu
 


Hellen Santos

 
        Professor emeritus            Jorma Hölsä
 

 

 Recent Publications


 

 FEOFILOV, S. P., KULINKIN, A. B., ZAKHARCHENYA, R. I., HÖLSÄ, J. & MALKAMÄKI, M. 2013. Temperature quenching of Ce3+ impurity ion fluorescence in Y2O2S: Spatial confinement effect in multiphonon relaxation. Physica Status Solidi (B) Basic Research, 250, 249-253.

  

ANTAL, T., HARJU, E., PIHLGREN, L., LASTUSAARI, M., TYYSTJÄRVI, T., HÖLSÄ, J. & TYYSTJÄRVI, E. 2012. Use of near-infrared radiation for oxygenic photosynthesis via photon up-conversion. International Journal of Hydrogen Energy, 37, 8859-8863.

 

BRITO, H. F., FELINTO, M. C. F. C., HÖLSÄ, J., LAAMANEN, T., LASTUSAARI, M., MALKAMÄKI, M., NOVÁK, P., RODRIGUES, L. C. V. & STEFAN, R. 2012a. DFT and synchrotron radiation study of Eu 2+ doped BaAl 2O 4. Optical Materials Express, 2, 420-431.

 

BRITO, H. F., HÖLSÄ, J., JUNGNER, H., LAAMANEN, T., LASTUSAARI, M., MALKAMÄKI, M. & RODRIGUES, L. C. 2012b. Persistent luminescence fading in Sr 2MgSi 2O 7: Eu 2+, R 3+ materials: A thermoluminescence study. Optical Materials Express, 2, 287-293.

 

CARVALHO, J. M., RODRIGUES, L. C. V., HÖLSÄ, J., LASTUSAARI, M., NUNES, L. A. O., FELINTO, M. C. F. C., MALTA, O. L. & BRITO, H. F. 2012. Influence of titanium and lutetium on the persistent luminescence of ZrO 2. Optical Materials Express, 2, 331-340.

  

LASTUSAARI, M., LAAMANEN, T., MALKAMÄKI, M., ESKOLA, K. O., KOTLOV, A., CARLSON, S., WELTER, E., BRITO, H. F., BETTINELLI, M., JUNGNER, H. & HÖLSÄ, J. 2012. The Bologna Stone: History's first persistent luminescent material. European Journal of Mineralogy, 24, 885-890.

 

All Publications 

 

Dissertations


 

Taneli Laamanen 2011,                 "Defects in Persistent Luminescence Materials"  Link