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This is a comment on: H. Sun, A. Hosokawa, Y. Miwa, F. Shimaoka, M. Fujii, M. Mizuhata, S. Hayashi, S. Deki Strong Ultra-Broadband Near-Infrared Photoluminescence from Bismuth-Embedded Zeolites and Their Derivatives Advanced Materials (deerfield Beach, Fla.) 2009 page 1-5 volume 21  DOI: 10.1002/adma.200900573

"Strong Ultra-Broadband Near-Infrared Photoluminescence from Bismuth-Embedded Zeolites and Their Derivatives" AMORPHOUS STUFF   published on Monday, 22-Jun-09 09:48:30 CEST by FrankMiller

Amorphous Stuff It is known for many, many years, that heating a zeolite at elevated temperatures (called calcination) leads above a certain temperature to an amorphous or dense crystalline product. Often the dense crystalline material is formed out of the amorphous "intermediate state". Therefore -in my eyes - it is absolutely not astonishing, that heating a FAU type Zeolite to 1000°C leads to an amorphous Silica/Alumina compound with -in this case- incorporated Bismut. Thus, a known method for producing amorphous compounds does its job and produces a material which has similar properties as already exsisting amorphous compounds (Bi-Glas). Ok, I might not get the point of this paper, especially as "Advanced Materials" is a high quality journal, but what’s new and remarkable? I have some more nitpicker remarks and questions: -How the hack can the proposed Bi+ be formed? What is reducing Bi3+ in a Zeolite in Ar Atmosphere at 900°C ? The Zeolite itself? The Argon? Did I miss something? -As Zeolites are less dense than the formed dense materials at elevated temperatures, it is certainly true, that if you compare the luminescence spectra of samples of _same_ volume, with the denser material you have more solid matter (and in this case especially more luminescating species) in your sample holder. Has anyone taken care of this effect? I could not figure this out from the experimental part, but I assume that the authors took care. Regards Frank

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