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Color‐Changing Sparks from Rare Earth Metal Powders
Author(s) -
Lederle Felix,
Koch Jannis,
Schade Wolfgang,
Hübner Eike G.
Publication year - 2020
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201900300
Subject(s) - boiling point , combustion , boiling , metal , rare earth element , light emission , rare earth , materials science , analytical chemistry (journal) , chemistry , mineralogy , optoelectronics , metallurgy , organic chemistry , chromatography
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).