Dear Raju,

The method of grinding the powder (wt% ratio) for several hours to obtain the homogenous powder is the most common method for mixing of different powder materials to obtain a single phase. But this method is not feasible for all types of materials. For example we are working on the multiferroics materials RMn2O5 and we tried the same method but in addition to the RMn2O5 phase, we also obtained RMnO3 phase.

It all depends on the material you are using whether they can form single phase by grinding in agate mortar.

There are some materials which are obtained in single phase by single crystal growth only (like RMn2O5). So I will suggest to go through some literature survey for your materials before you start your process.

Dear Raju, in our lab we produce multiferroic materials, like LiNbO3, by using mechano activation with a spex8000 mill followed by a thermal treatment. After milling, we characterized by SEM our samples and with EDS we found our powders highly homogeneous. Our starting materials are carbonates, and after the thermal treatment we obtained the LiNbO3 without secondary phases.

Mixing powders is a difficult problem as soon as the density of the materials is very different. Mixing and shaking can induce, after some time, segregation in the system, with most grains of one phase being separated from those of the other phase. So there exists an optimum mixing time. I think that your method is OK, provided that you plan to use what is known as the "ceramic method". Otherwise, you can get homogeneity at the molecular scale by using soluble precursors previously mixed in a solvent, or by using the sol-gel method.

Alain

Hi,

what does the "ceramic method" consist of?

Ceramic method, unlike sol-gel method or precursor method for example, is the easiest and cheapest method in solid-state chemistry, as it just consists in heating finely divided ingredients at high temperature in order to make them react with each other. Ceramics are indeed most of times prepared this way.

Alain