Thanks Lipeng.

Can you specify a bit more the issues? What Nb source? What do you mean by "the quality of target"?

Hey! What are you using as a starting material? Niobium ethoxide?

Can you supply the articles you are using for your research?

If you search for sol-gel, in organic phase, you'll find the typical problems associated with it.

As soon as you answer, I'll attempt to help as much as possible!

(I'm also interested in niobium materials :) )

Thanks David.

Is there any other Nb precursor that might be used in sol-gel?

I do have some experience with Ta ethoxide, and I know it is difficult to handle and stabilize to be air-stable. Is the problem similar with Nb?

There is!

Basically, any salt should be a source for a sol-gel process.

Here are some other examples for Nb:

Niobium Chloride (in Ethanol, since it decomposes in water) - DOI: 10.1016/j.optlastec.2013.11.014

Since you are using K, you can use the oxide itself Nb2O5 mixed with KOH (I would bet on this one, since the precursor is the already oxidized metal and you, obviously, won't face oxidations issues) - DOI: 10.1134/S1087659614010064

Or even the hydroxide Nb(OH)5 - DOI: 10.1080/10584587.2014.904166

This is all based on article research. I have no experience with Nb sol-gels, except with silica ones, nor with physical vapor deposition.

Hope it helps!

In case of KNN-based thin film, deficiency of K and Na content in final thin film is main problem. K and Na ions are easily volatilized at high temperature during heat treatments. Therefor, you should add a excess K and Na precursor in KNN-based sol-gel solution and ceramics target. Please refer below.

Ref 1) doi:10.1088/0022-3727/42/21/215304

Ref 2) doi:10.1143/JJAP.49.095801

Ref 3) DOI: 10.1063/1.3095500

In addition, Mn-doping is useful method for enhance the ferroelectric and piezoelectric properties of KNN-based thin film.

REf 4) doi:10.1016/j.cap.2011.03.050