In addition to the conventional solid state synthesis methods (e.g. arc melting) we are particularly interested in microwave heating. It is important to note that the reactions do not take place in liquid medium (as often found in organic syntheses) but in the solid state. We have gathered a lot of experience with the solid state preparation of inorganic compounds by microwave heating and found that many phases are accessible.
Microwave heating is a complex process and fundamentally different from conventional heating mechanisms. The microwave radiation interacts directly with the reactants depending on their dielectric properties and physical state (powder, bulk,..). In order to reach high temperatures that are necessary for the solid state reactions, we can rely on the strong coupling of either the reactants themselves, one of the reactants or an external susceptor. Typical susceptor materials that couple strongly to the electromagnetic microwave radiation are for example graphite and silicon carbide.
For reactions inside a commercial microwave oven a maximum of 1000 W is accessible whereas our laboratory microwave oven can reach power levels of up to 1800 W. The latter also allows for simultaneous temperature monitoring using an optical pyrometer.
Conventional synthesis methods
Of course we also employ conventional solid state methods. For high temperature syntheses arc melters, induction furnaces as well as box furnaces are available. Reactions under inert atmosphere are performed using a glovebox and evacuated quartz ampoules for example.
