Is it possible to generalize chemical stability of group of materials versus the others? For instance, can we arrange oxides, fluorides and haloids in an order from most to least chemically stable ?
The term "Chemically stable" sounds confusing too. When we say a material is chemically stable, are we including factors such as Temperature, Pressure, pH of medium, etc all at the same time ? I'm asking this question because I saw in a reference that they said Oxides are more chemically stable than Fluorides. While, in another paper the exact opposite claim was mentioned without any condition explanation.
Hello,
You are generally right. The oxide are more stable than flourides. There are some papers that describe the dissolution of flourides.
1. PLOHL, Olivija, KRAFT, Marco, KOVAČ, Janez, BELEC, Blaž, PONIKVAR-SVET, Maja, WÜRTH, Christian, LISJAK, Darja, RESCH-GENGER, Ute. Optically detected degradation of NaYF4:Yb,TmNaYF4:Yb,Tm-based upconversion nanoparticles in phosphate buffered saline solution. Langmuir, ISSN 0743-7463, 2017, vol. 33, no. 2, str. 553-560, doi: 10.1021/acs.langmuir.6b03907.
2. LISJAK, Darja, PLOHL, Olivija, PONIKVAR-SVET, Maja, MAJARON, Boris. Dissolution of upconverting fluoride nanoparticles in aqueous suspensions. RSC advances, ISSN 2046-2069, 2015, vol. 5, no. 35, str. 27393-27397
3. LiSJAK, Darja, PLOHL, Olivija, VIDMAR, Janja, MAJARON, Boris, PONIKVAR-SVET, Maja. Dissolution mechanism of upconverting AYF4:Yb,TmAYF4:Yb,Tm (A = Na or K) nanoparticles in aqueous media. Langmuir, ISSN 0743-7463, 2016, vol. 32, no. 32, str. 8222-8229,
We need also to be careful what do we mean by oxide and fluoride. Inorganic, organic? tetrafluoropolyethylene is very stable. Its oxygen analog does not exist.
Oxides are more stable compared to Fluorides and Iodides. Iodides are very sensitive to moisture.
Hydrogen floride etches oxides such as silicon dioxide and. So, most oxides are not stable against HF.
Best wishes.
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