# Ppm and doping

Tags:
1. Mar 6, 2016

### Fizica7

Hi. If a metal is very pure but still has other elements in it like this:
-1 or 2 at 500ppm, 1 at 150ppm, 2 or 3 at 20-30ppm, 1 or 2 at 3-5ppm. Which are manufacturing impurities and which are deliberate doping? Are the 500ppm doping?

2. Mar 6, 2016

### Staff: Mentor

What do you think? Is this for schoolwork?

3. Mar 6, 2016

### Fizica7

Finished highschool many years ago... so long ago that chemistry wasn't even invented :D
No... I'm just trying to establish the purpose of a certain metal and it's impurities.

4. Mar 30, 2016

### Fizica7

So I've got this little table from a magnesium sample which contains some other elements : 500ppm, 160ppm, 35ppm , 32ppm.
They appear to be intentional additions to the magnesium, right?
So does one just weigh the right amount of each and melt all together or what?
Is there any way to figure out our approximate the purpose or characteristics of the final product from knowing the impurities?

Last edited: Mar 30, 2016
5. Mar 31, 2016

### 256bits

Well you can look at iron and the doping with carbon to get steel.
Add some other elements to the mix for favourable properties.

A more familiar alloy might be bronze.
Mix copper with tin to get bronze.
Add some other doping elements to get favourable properties.
https://en.wikipedia.org/wiki/Bronze

or brass,
https://en.wikipedia.org/wiki/Brass

6. Mar 31, 2016

### Fizica7

I understand that various periodic elements have various preferred arrangements like cubic, hexagon, and other geometric shapes with complicated names... And that we can somehow infer what a set of dopants will achieve in a certain base element based on each elements "affinity" to the others and ability to place itself into a certain spot in the final lattice... sort of like the junctions in solar cells? They've very complicated crystalline (aka repeating?) structures where even one single element can break or make the desired property yet for all their complexity somehow someone knows how to predict the outcome... is it by amassed knowledge via trial and error or element/lattice maths?!?
If I knew the dopants going into magnesium, could someone guestimates the final product's properties?

7. Jun 17, 2016

### Fizica7

I understand that, I guess my question is what the minimum scientific or metallurgically accepted value to declare that one is doped and the other is not? 20ppm, 5ppm?
At which point natural impurities are ruled out and deliberate doping is declared?