Dear Ratnakar,

From my point of view this is a two part question.

First part: Annealing is the processes of holding a material at an elevated temperature so as to obtain (positive) changes in the micro-structure.

Calcination is heating of the material at elevated temperatures high enough to allow feasible ionic movement. This leads to crystal growth and is often used for solid oxide reaction techniques to form new compounds.

Sintering is the process of heating the material to a high enough temperature so as to allow densification and compaction.

Quenching is when you cool the material at a rapid rate so as to bypass the crystallization kinetics.

Second part:

If the powders are amorphous to begin with, heating them to a temperature of 400oC in air for two hours should give you anatase phase. For a more detailed analysis kindly refer to the attached publications.

I hope this helps. 

http://www.sciencedirect.com/science/article/pii/S0254058412004427

Dear Ratnakar,

From my point of view this is a two part question.

First part: Annealing is the processes of holding a material at an elevated temperature so as to obtain (positive) changes in the micro-structure.

Calcination is heating of the material at elevated temperatures high enough to allow feasible ionic movement. This leads to crystal growth and is often used for solid oxide reaction techniques to form new compounds.

Sintering is the process of heating the material to a high enough temperature so as to allow densification and compaction.

Quenching is when you cool the material at a rapid rate so as to bypass the crystallization kinetics.

Second part:

If the powders are amorphous to begin with, heating them to a temperature of 400oC in air for two hours should give you anatase phase. For a more detailed analysis kindly refer to the attached publications.

I hope this helps. 

http://www.sciencedirect.com/science/article/pii/S0254058412004427

The definitions may vary and the terms are sometimes misused but, if trying to separate these notions from each other, I would add a few words to otherwise very exhaustive reply of Aditya Chauhan. One can emphasize the difference between the calcination and annealing as follows: when a heat treatment leads to a change in the chemical composition, crystallization of amorphous phases or transphormation of existing crystalline phases, it is more appropriate to talk about calcination. Annealing should refer to a treatment where neither the chemical nor the phase composition  significanly change.

Dear Dr. Ratnakar:

Really, same terms can be applied in several ways depending on the case and context. This feature occurs due different areas and consolidation of the term application as  a function of time.

As an example, calcination in the Chemistry area represents a thermal process, in which oxidation and/or reduction take place. In Materials science, calcination represents a thermal process in a very broad sense. In specific way, a raw material type oxide can be calcined for that vapor or a gas phase adsorbed is desorbed. Also, calcination can be carried out to attain further grain growth. Yet, a mixture of binary oxides can undergo calcination to reach the formation of new polycation oxide. Another process as pyrolysis of polymeric precursor can be calcined to synthesis of an oxide. Well, changing of crystalline symmetry can be reach by proper selection of time and temperature of calcination. Here is interesting to comment that typically calcination idea is connected with powder.

Sintering idea is connect with compact body that after thermal process can be dense exhibiting a density close to the theoretical density or a compact with large number of pores with density far from of the theoretical one. In the first case, densifying mechanism is operational with efficient action via one or more mass transport mechanism. In the second case, non-densifying mechanism, as an example grain growth, preponderate. The development of sintering at powders lead to heterogeneous powder with large grain size distribution, agglomerate and aggregate development.

Quenching is a very fast process of cooling of a sample, which is directed to investigation of thermal properties as thermal shock resistance, but used to avoid phase transformation (crystalline symmetry) or grain growth during conventional cooling rate. In this sense, the major objective is preserve at room temperature the crystalline structure exhibited by powder at high temperature. A priori, the process of quenching can be used to control crystallization in some materials, also. Quenching can be applied at materials with low resistance to the thermal shock giving to an extensive fragmentation of this body.

Annealing or thermal annealing can represent several function but most common uses is correlated to a process, in which chemical transformation is not involved as highlighted previously, as an example release of stress/strain in a sample type glass, ceramic ... 

If the powder prepared by chemical synthesis was sintered or calcined at high temperature will occurs a fast grain growth, aggregate formation, agglomerate formation, particle coalescence… seems that mixture of phases will be formed.

 Best regards

Marcos Nobre

thermal treatment of  nanopowder is termed as calcination process. In case of thin film form, which would be named as annealing process. Suppose heat treatment of pellet samples is named as sintering process.

Mostly quenching means that the sudden cooling for thin film deposited onto glass substrate

Thanks a lot for all you replies; Aditya Chauhan, Roman Kubrin, Marcos Augusto Lima Nobre and Thiruramanathan Pandirengan. And my special thanks to Marcos Augusto Lima Nobre. The answers gave me a lot of confidence. As a beginner scholar, we face a lot of challenges and many a times, the superiors put our default library (our brains) to test. So needed a clarification and it helped. 

Thanks a lot again

https://www.researchgate.net/post/What_is_the_difference_between_annealing_sintering_and_calcination#view=58904155615e27192e3d0e46

Those interested on this discussion may possibly want to check ― on quenching:

https://www.researchgate.net/post/Is_quenching_process_change_the_internal_structure_of_material

https://www.researchgate.net/post/when_to_do_quenching