In our case, La substituted PZT (PLZT) ceramic powders were calcined at 800oC for 4 hours to transform the raw materials into the PLZT phase. This temperature is slightly lower than the phase formation temperature to reduce lead loss at high temperature. This process was done in the alumina crucible. Calcined powders were pressed into the shape of pellets, which were further densified by sintering at 1200oC for 4 hours. To prevent the lead loss particularly at high temperatures a small crucible with lead zirconate powders with 10 wt% excess PbO was placed with PLZT pellets in a double crucible configuration. The entire assembly consisted of a double sealed alumina crucible with lids sealed with alumina powder as cement.

thank you very much Ajeet Kumar

but in the calcination, do i need  pelletizing ? and is there any other type of crucible (beside alumina) i can use to calcinate my samples ?

In my opinion, no need for pelletization. 

Alumina crucibles are the best option due to low cost, high-temperature stability. Alumina will not react with most of the materials.

that's what i'm looking for

thank you so much  Ajeet Kumar

I suggest TG-SDTA studies for appropriate temperature-time profile for calcination. You need about 15-20mg of sample in powder form for the study. Further, you can carry out calcination in powder form. Calcination temperatures are about 1000°C depending upon composition and particle size. You don't need to convert powder into pellet form for calcination. Calcined powder can be analysed by XRD for perovskite phase formations. Calcined powder has to be milled to reduce particle size. Further, to convert it in to pellet form by adding suitable binder like PVA. For achieving superior piezoelectric properties, maintain green density of pellets around 4.8 g/cc. Sintering temperature can be estimated form dilatometric studies. Typically, sintering temperature for PZT lies between 1200°C-1290C° depending upon particle size of milled-calcined powder. Sintering has to be carried out in lead rich atmosphere to compensate/prevent lead loss from samples which takes place @886°C which is much lower than Sintering temperature.

ok, thank you so much Chandrashekhar Madhav Lonkar for your detailled answer.

I just want to ask you another question about sintering, especialy lead rich atmosphere, how to do sintering with less Pb-loss (if possible, i nead an answer join with figure)

Thanks advance

Best regards

Ahmed

Sintering of PZTs requires following-

1. Alumina plate and crucible of minimum appropriate size.

2. Separating powder- powder of same composition sintered @1290°C, crush in mortor and sieved to obtain particle size upto 450 um.

3. PbZrO3 powder in order to provide lead atmosphere

Preparation-

1. On alumina plate and on samples, spread separating powder by means of sieve.

2. Stack samples with separation of separating powder and place on plate.

3. At some distance from samples place PbZrO3 powder which would be in the form of ring.

4. Place crucible, inverted, on it.

5. You may seal the gap between crucible and plate. Place the assembly in furnace and sinter at desired temperature with heating rates varying 2-5 degC/min.

ok, Thank you so much Ph.D Chandrashekhar Madhav Lonkar for this valuable information, i really appreciate that and i wish you more success in the field of scientific research.

Best Regards

Ahmed

Dear Ahmad

I want to add a point, if you want to reduce the lead loss in pzt then you can do proper sealing of crucible or chose proper Furnace environment.