Abstract: A thin porous piezoelectric Pb(Zr,Ti)O.sub.3 ceramic sheet having a thickness of 0.05 to 2 mm which is favorably employable for manufacturing a piezoelectric transducer has small pores essentially all of which have a size of less than 25 .mu.m in which pores having a size of 5 to 25 .mu.m have a mean pore size of 1/10 to 1/1,000 based on the thickness of the ceramic sheet, and which shows a ratio of apparent density to true density in the range of 5/10 to 9/10.

Abstract: A process for the production of an octyltin chloride of the formula,(n-C.sub.8 H.sub.17).sub.m SnCl.sub.4.sub.-mWherein m is an integer of 1 to 3, which comprises reacting n-octyl chloride with metallic tin in an organic solvent in the presence of (1) either a mixture of a phosphorus compound with an amine, or a phosphorus compound having a nitrogen atom in the molecule, and (2) at least one of bromine, a bromine compound, iodine and an iodine compound. The octyltin chlorides are useful for the production of stabilizers for polyvinyl chloride.