at this temperature the carbonate will not suffer decomposition process, for it you have to heat at high temperature (> 900 °C)and the final product will be the CaO.

You can decompose CaCO3 in bit lower temperatures by roasting CaCO3 powder in vacuum, e.g. in a platinum boat. You can obserrve the start of decomposition by encrease the pressure (CO2 production) in the system around 600oC.

You should be aware that calcium oxide will extract carbon dioxide from the atmosphere, reverting ultimately to calcium carbonate.  The very high surface area of finely divided CaO will tend to facilitate this reaction.

CaO (also known as burnt lime and as quicklime) is very alkaline and will produce chemical burns on skin or other tissue it contacts.  Inhaling the fine powder would damage the lungs.

Thanks a lot for your valuable comments, respectable gentlemen. I now, finally have got the idea of manipulating CaO. Thanks again.

I want to know the decomposition time of CaCO3 to CaO and CO2

I don’t know time required for full decompsodition

I have sent private message to you

Calcium oxide is usually made by the thermal decomposition of materials [...] that contain calcium carbonate (CaCO3; mineral calcite) in a lime kiln. This is accomplished by heating the material to above 825 °C (1,517 °F),[6] a process called calcination or lime-burning, to liberate a molecule of carbon dioxide (CO2), leaving quicklime.

CaCO3(s) → CaO(s) + CO2(g)

Source: https://en.wikipedia.org/wiki/Calcium_oxide

is there any chemical reaction to produce CaO from CaCO3?

Ratnakar A. Joanna J. Sokołowska Mohammed Alzuhairi Matthew Hulbert Stan Halas

In case you are dealing with CaO powder; you may consider to pelletize the powder: https://www.researchgate.net/post/which_binder_can_be_used_for_making_pellets_of_snail_shell_based_CaO_powder_and_what_will_b_ethe_method_of_it

Dr Pradip Kumar , it is a physical process caused by temperature and te reaction is as previously said:

CaCO3(solid) ---heat→ CaO(solid) + CO2(gas)