Color‐Changing Sparks from Rare Earth Metal Powders

Commonly, sparks emit light according to the well‐known black (gray) body radiation. Recently, we reported on color‐changing sparks based on erbium powder, which switch their light emission between black body emission (surface combustion) and element‐specific emission (vapor phase combustion). Herei...

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Published inZeitschrift für anorganische und allgemeine Chemie (1950) Vol. 646; no. 2; pp. 37 - 46
Main Authors Lederle, Felix, Koch, Jannis, Schade, Wolfgang, Hübner, Eike G.
Format Journal Article
LanguageEnglish
Published Weinheim Wiley Subscription Services, Inc 31.01.2020
Subjects
Blackbody
Boiling points
Color
Combustion
Emission analysis
Erbium
Lanthanides
Light emission
Metal powders
Pyrotechnics
Rare earth elements
Rare earths
Sparks
Vapor phases
Ytterbium
Yttrium
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Summary:Commonly, sparks emit light according to the well‐known black (gray) body radiation. Recently, we reported on color‐changing sparks based on erbium powder, which switch their light emission between black body emission (surface combustion) and element‐specific emission (vapor phase combustion). Herein, we investigated the spark formation from the adjacent rare‐earth elements. The corresponding boiling points are significantly below (Yb, Sm, Tm) or above (Y, Lu) the boiling point of Er. While Yb and Sm evaporate too fast to form longer sparks, Y, Lu and Tm form color‐changing sparks with varying length of the element‐specific emission phase. The sparks were investigated by time‐resolved emission spectroscopy, long‐time exposures, and NIR/MIR imaging. The same basic pyrotechnic formulation containing one of these metal powders reveals a strongly differing burning behavior depending on the boiling point of the metal. The burning characteristics change from a green strobe (Yb) to intense colorful crackling (Tm) and finally a sparkling fountain with long‐flying sparks (Lu, Y, Er).
ISSN:0044-2313
1521-3749
DOI:10.1002/zaac.201900300