Dear Mahesh Sir,

The temperature of the glow peak maximum is determined by two processes i) increase of released charge carriers with increasing temperature ii) the decrease of charge carriers due to depletion of the trap. For a low heating rate the sample will be held at a certain temperature for a longer time with implies that that the trap is earlier (lower temperature) emptied resulting in a lower glow peak temperature. Under Randall-Wilkings conditions the heating rate influences only the time at which the trapped charge is released but not the total light output. The total light output is determined by the trapped charged i.e. proportional to the absorbed dose.

and Also the with increased in the temperature crystalline nature of the sample get increases which attributes to the superior physico-chemical properties of the specimen.

Also

The shift of the maximum (Tm) with heating rate β is the following. Consider a first-order peak. The maximum condition is

βE/kTm^2=s*exp(-E/kTm).

This can be written as:

β=(ks/E)Tm^2*exp(-E/kTm).

The right-hand side is an always increasing function of Tm. When β increases, the right-hand side must increase so that the equality holds. However, since this is an increasing function of Tm, this implies that Tm must be larger. The extension to non-first-order situations is a bit more complicated, but in principle it is similar.

Note: Tm means thermoluminiscence

Thank You Respected Sachin Suryavanshi sir,

Thank you so much for your simple answer and excellent  to search new ideas from source (Research gate).

I know Dr. Adrie J.J. Bos (He is a great scientist in luminescence field) answer (Whatever you copied from his rply to Dr. Naresh Ravat on Jan 8, 2014) and also known the Dr. Reuven Chen (Professor Emeritus) answer (same rply to Dr. Ravat on Jan 13, 2014).

Whatever they explain, I totally/basically known. But i want to expect different kinds of explanation such as effect on trapping levels between C.B-V.B , effects on meta-stable state, effects on OTOR, effect on activation energy, effect on defects and their trapping parameter or related phenomena due to Contact with temperature (annealing effect).

I respect your answer and searching ability.

Thanks.

Dear Mahesh,....

I just tried to answer u r question based on..peoples discussion ...and their comment on Research gate..i hope this will help u to get the much more science..this is my little try...

Sachin

Dear Mr. Bhadane,

It is not just annealing and slow cooling but there could be different kind of heat treatment(s). For example, annealing and slow cooling, annealing and quenching to room temperature. There may be increase in the particle size on annealing if the material is in nanocrystalline form. There would also be increase in the crystallinity due to annealing out of the defects. There could be change in the TL sensitivity due these changes. However, it is not necessary that there would always be increase in the TL intensity on annealing. There could be decrease in the TL intensity as well due to several reasons. For example, there could be phase transitions in certain ranges of temperatures, there could be redox reactions that change the ionic state(s) of the impurity(ies). There could also be diffusion of oxygen on annealing in air or some other chemical effects on annealing in reactive atmosphere which may change the sensitivity of a TLD material. Not only that but there could be agglomeration and/or complex formation(s) on annealing and change the sensitivity of the material. On irradiation, there could be change in the ionic state(s) of the impurity(ies) which may not be completely on heating/annealing. Therefore, it is very important to know about the annealing temperature, its duration and the heat treatment history. Also, there won't always be increase in the TL intensity. Thus the question is not properly formulated for an expected answer. The answer given by Mr. Suryawanshi is also not very relevant in this regard.

Thank you,

--- P D Sahare 

Respected Dr. Sahare Sir,

Thank you so much for giving me your valuable time.

Yes Sir, I totally agree with your answer...!!! After annealing, it may be changes intensity or sensitivity dramatically due to several reason. So, by your suggestion I was corrected the above question.

I am so impress, after getting your valuable reply. It will very helpful for me.

But, if particle is almost less than 70 nm and there is no change in phase transition. It could be possible to erase defect level or increase defect levels due to annealing ??

Again waiting for your valuable reply...

Thank you so much sir.

-Mahesh Bhadane

Let me kindly ask you whether you refer to a specific material or, alternatively, you speak generally. For example, in the case of quartz, this phenomenon is under ongoing study.

 Dear Mahesh,

It is a good question. Quite often prior to irradiation, the annealing treatment is given without understanding the reason behind it. 

As George S. Polmeris has stated it is pertinent to refer this issue on a particular phosphor as the mechanisms differ considerably with the phosphor material. Also I believe that you mean by annealing temperature the annealing treatment given to the phosphor after preparation (this is usually referred to as sintering temperature) prior to its irradiation and not to the post-irradiation readout temperature during TL measurement. 

Let us take the case of CaSO4:Dy. Its TL sensitivity increases by 30% with sintering temperature in the range 300 - 750 deg C accompanied by a 10% dip at 400 deg C (J.Phys.D: Appl. Phys. 35, 386, 2002). The  increase in TL sensitivity  is attributed to increased crystallinity and increased stabilization of defects (including Dy at Ca sites and anion interstitials as well as anion vacancies) causing TL with sintering temperature. The decline in TL at 400 deg C is attributed to the destabilization (thermally induced migration)  of anion interstitials towards anion vacancies (J. Lumin. 142, 212, 2013)

Annealing treatment involved in LiF:Mg,Ti is more complex. . The usual annealing treatment is 400 deg C 1h quench to RT followed by 80 deg C 24 hr or 100 deg C 2h.  The TL sensitivity increases by more than a factor of 2 when the cooling rate after 400 deg C anneal  was increased from 1 to 1000 deg c /min. The fast cooling is believed to disperse the Mg2+ ions as free ions and dipoles in LiF lattice which are responsible for the 200 deg C main TL peak.  The 80 deg C anneal is given to reduce the contribution of low temperature TL peaks (J. Phys.D:appl. Phys15, 2053, 1982). LiF:Mg,Cu,P is much more complex

.   

Dear Mahesh,

I do not know whether "annealing" was meant for post irradiation heat treatment. Generally, "annealing" is used for the heat treatments give to the material before pre-irradiation (heating at a constant temperature and suddenly quenching to room temperature) and it is also very important. "Sintering" (heating at a constant temperature and cooling slowly) is generally used during the preparation for densifying the material. 

Now, more specific to your question, "

"If particle is almost less than 70 nm and there is no change in phase transition. It could be possible to erase defect level or increase defect levels due to annealing ??"

Again the answer is not very easy. As mentioned earlier, it is important to know the temperature at which you are annealing; whether it is preirradiation or post-irradiation. During annealing there again could be change in the particle size. But even in post irradiation annealing treatment it is very complicated and not easy to predict. It has been seen in many cases that the luminescence intensity increases with the particle size and if there is increase in the particle size on annealing it may increase. However, it may decrease also for other reasons. So, it would depend on what kind of changes are taking place inside the material on annealing and also depending on in what atmosphere it has been annealed. For example, there could be some redox reactions and diffusion of oxygen/nitrogen or other impurities (may be from due to contamination from the container) and generate other kinds of defects. Not only that but if the material is codoped with more than one other impurity(ies) there could be very prominent effect of one impurity on the others complicating the whole system. For example, in LiF:Mg,Ti or LiF:Mg,Cu,P on annealing above 250 degrees centigrade several changes could take place and the materials loose their reusability. Similar is the case with CaF2:Mn (You may refer to some of my recent papers on these systems). Thus, it is not possible to generalize it and studies on defects is the integral part of phosphor development process and no 'good' phosphor could be developed without doing such studies in details.

Thank you,

--- P D Sahare 

Thank You so much Prof. Sahare Sir.

Your answer is very helpful for me, now and for future too.

Thanks again.

Also thanks to Dr. Arunachalam Lakshmananfor giving me valuable or motivated reply.

Respected Dr. George S. Polymeris,

Now at that stage, i am talking about specific insulator type material.

Ok. which one?

I think it will be good to share with us your results. Maybe we can be helpful

Respected and Dear all,

Thank you so much for your valuable replays, answer and Suggestions. I got lot of information from you.