Barium chlorate in some sodium contamination, which is undesirable for pyrotechnic purposes, where the strong yellow of sodium can easily overpower the green of barium. Sodium-free barium chlorate can be produced directly through electrolysis: It can also be produced by the reaction of barium carbonate with boiling ammonium chlorate solution: The reaction initially produces barium chlorate and ammonium carbonate; boiling the solution decomposes the ammonium carbonate and drives off the resulting ammonia and carbon dioxide, leaving only barium chlorate in solution. When exposed to heat, barium chlorate alone will decompose to barium chloride and oxygen: Barium chlorate is used to produce chloric
Barium borate 1 GW/cm at 1064 nm and 500 MW/cm at 355 nm. Beta barium borate, β-BaBO, is a nonlinear optical material transparent in the range ~190–3300 nm. It can be used for spontaneous parametric down-conversion. Its Mohs hardness is also 4.5. Barium borate has strong negative uniaxial birefringence and can be phase-matched for type I ("ooe") second-harmonic generation from 409.6 to 3500 nm. The temperature sensitivity of the indices of refraction is low, leading to an unusually large (55 °C) temperature phase-matching bandwidth. Barium borate can be prepared by reaction of an aqueous solution of boric acid with barium hydroxide. The