Are Cds made of dysprosium?
As dysprosium has alloys with useful magnetic properties I would think it is more likely to used in the CD player than the CD, but I'm quite willing to be corrected.
I doubt it. I would think it was too expensive for CD disks. The first reference below does NOT list the use of Dy in the manufacture of CD disks, but the other two list CD disks as a use for Dy. My best guess is that both of the latter came from the same source and there is no documentation here. You can get all kinds of information on the web. Some is good and some not so good. Personally, I still doubt it but that's just a peronal opinion. http://www.osta.org/technology/cdqa15.htm
But www.webelements lists that as one of its uses.
http://www.webelements.com/webelements/elements/text/Dy/uses.html
http://www.chemicool.com/elements/dysprosium.html
Based on the information you provided, it seems that there is some uncertainty about whether dysprosium is used in the production of CDs. While the first reference you mentioned does not list dysprosium as a material used in CD manufacturing, the other two references mention it as a possible use for dysprosium.
To get a definitive answer, it would be best to consult reliable sources specifically focused on CD manufacturing or materials science. One way to do this would be to search for scholarly articles or research papers that discuss the composition of CDs. Additionally, you can reach out to CD manufacturers or industry experts to inquire about the materials used in CD production.
Remember, it is always important to critically evaluate the information you find on the internet and consult multiple reliable sources to ensure accuracy.