Physical properties
Lead Borate is a white crystalline powder. The metaborate loses water of crystallization at 160 °C and melts at 500 °C. It is insoluble in water and alkalies, but readily soluble in nitric and hot acetic acid.
Uses
The main use of lead metaborate is in glazes on pottery, porcelain, and chinaware, as well as in enamels for cast iron. Other applications include as radiation-shielding plastics, as a gelatinous thermal insulator containing asbestos fibers for neutron shielding, and as an additive to improve the properties of semiconducting materials used in thermistors.
Production Methods
Lead metaborate may be produced by a fusion of boric acid with lead carbonate or litharge. It also may be formed as a precipitate when a concentrated solution of lead nitrate is mixed with an excess of borax. The oxides of lead and boron are miscible and form clear lead-borate glasses in the range of 21 to 73 mol% PbO.
