Dear Santanu

With increasing annealing temperature the sharpening of the peaks indicate a growth of the crystallite size, could also be related to a relaxation of strain introduced broadening to some extend. In the small angular window you have shown it is likely impossible to distinguish between both (though size broadening is more likely the major effect here). The splitting you observe is the Cu Kalpha 1,2 splitting. At lower annealing temperatures the splitting is "masked" by the size/strain broadening. The apparent shift of the peak positions is likely related to sample preparation. I would recommend blending your sample with a lattice parameter standard to correct the apparentshift and measuring a broader angular window for size / strain separation.

Regards

Dominique 

Hi Dominique,

happy new Year

as per your suggestion now i am attaching the Cu Kalpha 1,2 splitting details of my used instrument.

2 theta difference of Cu Kalpha 1,2 splitting in std corundum=0.09 deg

in the 900 deg annealed sample this =0.45 deg,

which is two large to be neglacted......please have a look at the attachment...

regards

santanu

You are right the splitting of the first peak cannot be Ka 2. I suggest measuring a larger range to identify or exclude a secondary phase. 

It appears that Ce4+ can be reduced during heating. Forming CeO(2-x); That might explain the secondary peak. You will have to dig deeper in literature e.g. http://dx.doi.org/10.1016/0022-1902(55)80067-X

Yes i have now got the TGA-DSC profile of the same, which has an endotherm with representative weight loss near about 800 deg C (Oxygen release)

signifying secondary phase transformation, i am attaching it for your observation and comment.

also thanks for a good paper link...

have a nice day

santanu