Improvements in or relating to piezoelectric devices

摘要

Zinc oxide crystals are grown from a vapour phase by causing zinc vapour and oxygen to combine in a furnace at 1250-1300 DEG C. The furnace comprises concentric inner and outer tubes of aluminium oxide, the smaller tube being open-ended. Zinc powder is placed near the end of the smaller tube and air is blown through until equilibrium is reached at the above temperature, after which a carrier gas mixture of nitrogen and a minor amount of wet hydrogen is passed over the zinc oxide powder. Reduced zinc vapour is carried out of the inner tube into the central region of the furnace where it reacts with the oxygen of the air to produce crystalline zinc oxide growth in the vicinity of the end of the inner concentric chamber. The crystalline mass is withdrawn with the inner tube. Specification 959,294 is referred to.