# metal oxide analysis

I am looking in to analytical techniques for a future project. I may have a mixture of metals, i.e. an alloy, which I am thinking XRF spectroscopy would be the best quantitative technique. I could even purchase a handheld XRF analyser.

However, I believe that the XRF technology does not detect light elements such as oxygen. Therefore, if I have a mixture of metal oxides in a sample; what is the best quantitative analytical technique for me to identify each oxide?

I have had a look at XPS but I am confused about how I can work out which oxide I have in my sample. For example, if my sample contains Lead oxide and Copper oxide. How do I know whether it is Cu(II) oxide or Cu(I) oxide?

• XRF is good for metals but samples must be "homogeneous," at least to a reasonable degree. X-ray Diffraction (XRD) can identify specific oxides, but it isn't a good quantitative technique. I've not done any XRF work since the a handheld XRF analyzers became commercially available. However I double they have the resolution to analyze a Cr/Fe/Ni alloy quantitatively. If you're willing to supply more information on the matrix perhaps we can provide more help. – MaxW Feb 15 '17 at 14:25

If the oxides are separate grains or compounds (a mixture, not a solid solution), you can find this with SEM microprobe (a geology technique). For tricky new mixtures, may be better than powder x-ray diffraction (find small amounts of new compound, than resolve stoichiometry and do XRD on phase pure samples. It will not give you the oxidation level though.

You could just do visual examination. $\ce{PbO}$ is yellow and $\ce{PbO2}$ is black-brown. $\ce{CuO}$ is black and $\ce{Cu2O}$ is red. You can use a metallography microscope (high powered optical) to look at individual grains. [May also be able to see the crystal habit.]

In general, people working with oxides know the expected oxidation state of the materials they have processed given the conditions. E.g. cerium will always be $+4$, not $+2$ under atmospheric ceramic processing conditions. Not always possible, but often the case.

If you could narrow down a little more what you are trying to do, might be easier to answer. What substances, processing conditions and what info do you need on the end result (and why, really)?

ICP or AA are techniques helpful for trace metal analysis but you won't get oxidation state.