Transparent, ceramic, ferroelectric, lead free niobate - made by sintering fine precurson powder and used for optical commutators

摘要

A transparent, ceramic, ferroelectric, strontium sodium niobate plate of formula Sr5-x/2 Nax Nb10O30 where x = 5-7, is prepd. by forming the niobate by reaction from a mixt. of precursors; grinding and calcining, then moulding and sintering. The moulding is effected by compaction without a binder at =5 kb at ambient temp. and the sintering in a series of steps in a current of O2. The first heating step is 10 mins at 1300 degrees C at a pressure of 1 torr. with pumping to draw the O2 over the samples, the second 48-60 hrs. at 1375-1390 degrees C, and this is followed by a slow cooling over =12 hrs. both under the same conditions of oxygen pressure as the first step. Transparent ceramic bodies can be prepd. in larger and more readily controlled shapes.