Probably you're preparing cross-sections, right? Alumina is hard, but using any kind of SiC papers (mine are from Struers, but it doesn't matter really) should do the job just fine. Are you using standard prep method (disc-grinder, dimpling etc)? The only "extended" time I noticed were with zirconia or tungsten samples... new SiC papers (even 500) should eat the single-crystal alumina substrate without any special problems...

I am not sure which kind of materials you were dealing with but if these were metals you shouldn't be surprised. I don't know how hard the titanate is but it should be clearly weaker than corundum. However, since corundum is also used for preparation (Mohs hardness 9, i.e. directly below diamond) and SiC is s far as I remember given by 9.5, it should be clear that the abrasive power of SiC on Al2O3 is unusually low. It simply need time ad a little bit experience. 

Dear Janez,

I am preparing cross section using tripod with silicon dummy to control thickness. This time I used SiC with grit 180 which I never use it for silicon based thin films. It took half an hour to reduce the thickness of the substrate, then I went for cross section preparation using two dummy silicon to protect substrate from both sides. If I don´t do it, then the mechanical polishing will damage the substrate until the film, actually by the end of polishing down to 10 microns thickness of silicon, you do not have initial substrate, it is full of damage and cracks.

Just add to answer of Gert, this procedure is harder in the case of SrTiO3, th difficulty for Al2O3 is less.

regards

Ok I understand.. I usually try to pre-format the samples as much as possible on wire-saw. I get the si-dummy as thickness reference, but to protect the thin film maybe it would be better to use alumina due to the big difference in hardness between perovskite and alumina which can easily result in strong relief (thinner si and perovskite as alumina protective slag). 180 sounds a bit rough, I try to avoid going under 500... 

Also... diamond laping papers (dlp) will go faster, but the price is a big turn-off :-)

Thank you Janez, seems interesting to put alumina instead of silicon, I will try it as you said. Yesterday on sapphire it was actually cool, I didn´t spend much time to reduce thickness of substrate. 

Dear Ali,

For this case the in-situ TEM lamella preparation with the Dual Beam System (combined FIB-SEM) will be the most appropriate. 

Regards, 

Anastasia 

Thank you Anastasia, you are right, but there is no FIB around, at least cheap. By the way I could do successful preparation on sapphire substrate total one hour to get less than 10 microns in thickness. regards. Ali