Examples of SEM-CL in combination with EDX, for use in phosphor research. From phosphor evaluation at the microscopic scale to single particle analysis
Behavioral Disorder: Schizophrenia & it's Case Study.pdf
SEM-CL presentation at ICOM 2015 - Budva Montenegro
1. Cathodoluminescence in electron microscopy:
from phosphor evaluation to single particle analysis
Philippe F. Smet, Lisa I.D.J. Martin, Jeroen Wattez, Filip Strubbe, Jonas J. Joos, Jonas
Botterman, Katleen Korthout, Sofie Abé, Heleen Sijbom, Dirk Poelman
http://LumiLab.UGent.be
http://tiny.cc/amazingCL
philippe.smet@ugent.be
@pfsmet
ICOM 2015 – Budva/Montenegro – September 1 2015
2. ‘Cold light’: generation of light in a non-thermal way
• Photoluminescence (PL)
• Cathodoluminescence (CL)
• Electroluminescence (EL)
• Chemoluminescence
• Bioluminescence
• Radioluminescence (RL)
• Triboluminescence
• Sonoluminescence
• Thermoluminescence (TL) (?)
CL: a brief introduction
3. Focused electron beam
(1 to 30 keV)
Heat
Light (CL)
White x-rays
Characteristic x-rays
Auger e-
Secondary e-
Backscattered e-
Transmitted e-
Diffracted e-
Sample
CL: a brief introduction
4. CL: a brief introduction
Cathode ray tube (CRT)
Field emission display (FED/SED)
12. Saturated green emission, but...
• Severe thermal quenching
• Short lifetime
• Low quantum efficiency (<20%)
Origin of green luminescence?
Case 1: ZnGa2S4:Eu
13. EDX: chemical composition
at the microscopic scale
Zn in green, Eu in red
J.J. Joos et al, Optical Materials Express 3 (2013) 1338
Case 1: ZnGa2S4:Eu
14. Zn in green, Eu in red
Formation of EuGa2S4 percipitates
J.J. Joos et al, Optical Materials Express 3 (2013) 1338
Case 1: ZnGa2S4:Eu
CL mapping EDX mapping
Optical behaviour Chemical composition
24. 2.5µm
Total CL intensity (-20°C)
CL (100°C)/CL (-20°C)
60%
100%
80%
EDX Eu-L signal
Total CL intensity (100°C)
Case 3: Thermal quenching in Sr0.9Eu0.1Ga2S4
25. Recording CL maps at different temperatures
Aligning all maps by appropriate shifting/skewing
5µm
Temperature (K)
Local variations in Eu concentration
affect global thermal quenching
Case 3: Thermal quenching in Sr0.9Eu0.1Ga2S4
26. Case 4: Lifetimes in SEM-CL
D. den Engelsen et al., Ultramicroscopy 2015
http://dx.doi.org/10.1016/j.ultramic.2015.05.009
29. 3 points are sufficient to calculate t - saves time!
Case 4: Luminescence lifetime in (Ca,Eu)2SiS4
D. Poelman and P.F. Smet, Physica B 439 (2014) 35-40
42. Conclusions
• ‘Standard’ photoluminescence research at microscale
• Discriminates between bulk and local behaviour
• Interesting add-on in phosphor research
• Standalone for single-particle analysis
CL in electron microscopy
43. Acknowledgments
Thank you for your attention!
http://LumiLab.UGent.be
http://tiny.cc/amazingCL
philippe.smet@ugent.be
@pfsmet