Calcination before Sintering plays a very important role. Calcination is done at a temperature lower than the temperature at which you are going to sinter your sample, this is done to remove volatile impurities present in the sample and gases formed during the reaction and most importantly if the sample is not calcined and kept directly at high temperature, there are chances of spilling out of sample from crucible.

refer to A.R.West for more details

Dear Richa Tomar,

thanks for your answer,here i would like to know the impotence of oxygen ?

Dear Kumar Raja

Importance of Oxygen in what respect, inside the system or its arrangement..... Please elaborate little bit.

Dear Kumar,

For Ceramic materials, calcination is an important step in sample preparation. Calcination is generally used for solid state synthesis route. By calcination all the volatile matters are removed. Decomposition of carbonates takes place and a reaction between all the reactants happens at calcination step. For example if you want to prepare BaTiO3 then the reaction will be:

                                    BaCO3 + TiO2 === BaTiO3

This reaction take place in calcination step.

After calcination the  powder is pressed to make samples (pellets).  The sample  at this stage is called green sample. After that we sinter it at higher temperature than calcination. In sintering, diffusion takes place and particles get fuses into each other and densification takes place. Sintering can be a solid state or liquid state depending upon the requirement of density of samples.