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TL;DR f-f transitions in lanthanide ions give rise to the colours of the ions. The electronic states can be derived from quantum mechanics, and their energies vary from ion to ion, which give rise to different colours.. The colours are pale because these transitions are Laporte-forbidden and therefore weak. These absorption bands do indeed arise from ...


6

Exactly. In your example, it is related to oxygen vacancy (oxygen deficiency) in the crystal lattice. It can affect the physical properties of the ceramic material. Take the example of this piezoelectric ceramic material:$\ce{Eu_{0.5}Ba_{0.5}TiO_{3-\delta}} $ Oxygen-vacancy induces antiferromagnetism to ferromagnetism transformation. In general, $\delta$ ...


5

I have a few silicon nitride balls in my drawer. They look pretty cool, that's why I keep them and touch them all of the time. It is a very hard, glasslike material. It won't be easy to crack. There is nothing coming off the surface, ball bearings have extremely smooth surfaces (nm roughness), if anything would rub off, they would not be usable as ball ...


5

One candidate for reaction with the rubidium is silica, $\ce{SiO2}$. Reference [1] reports that black powders are formed when alkali metals are contacted with silica. Such powders are more stable in dry air than ordinary alkali metals. The reference suggests that electrons are imparted from the alkali metals into the silica forming an electride complex. ...


4

However, would there be any damage to its optical properties? It is almost guaranteed. Corundum is incredibly sensitive to thermal shock and unless you can do this in a furnace that heats very slowly, it will fracture/crack. As far as any other properties, your ruby should not see any change in other optical properties for such a short duration, but for ...


4

The commonly used method of obtaining ionic radii for higher coordination numbers (C.N.) is to extrapolate values from the Shannon's scale [1] using the relationship between ionic radius and coordination number proposed by Zachariasen [2]: ... the bond lengths $D(N_1)$ and $D(N_2)$ for cation coordination numbers $N_1$ and $N_2$ were related as follows ...


3

Assuming the iron oxide is just mixed and has not been fused with the other oxides you could use a magnet to pull it from the other oxides. If it is fused with the other oxides, you could smelt the iron out with carbon. This will also smelt out the tin, which mixes with iron quite well. If you re-oxidized the iron in a furnace with air the iron will ...


3

There is a near continuum (and thus a potential infinitude) of relative concentrations of the different components of ceramics and their means of fabrication, but US Patent US7879449 B2 (PDF) gives a thorough description of their own non-stick ceramic invention as well as descriptions and references to others. Below are several excerpts from the cited ...


3

What is the crystal structure of bismuth oxyhydroxyphosphate (BOHP)? Not exactly sure what an answer looks like so here is everything. First off looking at the diffraction pattern from the paper, bismuth oxyhydroxyphosphate matches that of petitjeanite so that is definately the prototype structure. Using the information about diffraction, from the ICDD ...


2

I once was using a silver nitrate and had collected a small amount of silver chloride. At the time, we were operating a lab muffle furnace (for a related reason), so I decided to reduce the $\ce{AgCl2}$ to $\ce{Ag}$. I needed some graphite crucibles and it took 48 - 72 hours of high heat. I collected an amount of silver equal in mass to maybe two quarters (...


2

This is known to be because the $\ce{Ba^2+}$ ion sits off center in the middle of the tetragonal crystal structure First of all this is not correct. It is the $\ce{Ti^4+}$ ion that sits in a tetragonal off center configuration (black atom in perovskite structure below). Also this hold for any material with perovskite structure with the $\ce{ABC3}$ general ...


2

I have done a minimal amount of research to try and help you understand this material. The credibility of this research is very debatable, as it basically involves me typing in silicon nitride into YouTube. That being said, understand that silicon nitride is first of all extremely strong, inert, according to that link, and being considered as a contemporary '...


1

Zirconium dioxide is not soluble in organic solvents like isopropyl alcohol. Of more concern would be any plastic component of the knife, like a handle that could be damaged by isopropyl alcohol or other solvents.


1

There are ways, of course. Smelting, for one (reducing the oxides in a high temperature furnace), and leaching for another (flowing a solvent through the crushed media). Oxides and silicates are rather stable, however, and the temperatures, reagents and solvents that attack them are not tabletop-friendly. If the scrap was well-sorted, or valuable, or ...


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