Barium ferrite these species include BaFeO, BaFeO, and BaFeO. A one-step hydrothermal process can be used to form crystals of barium ferrite, by mixing barium chloride, ferrous chloride, potassium nitrate, and sodium hydroxide with a hydroxide to chloride concentration ratio of 2:1. Nanoparticles are prepared from ferric nitrate, barium chloride, sodium citrate, and sodium hydroxide. The typical preparation, however, is by calcining barium carbonate with iron(III) oxide: Barium ferrite has been considered for long term data storage. The material has proven to be resistant to a number of different environmental stresses, including humidity and corrosion. Because ferrites are already oxidized it can
Native metal brass, bronze, pewter, German silver, osmiridium, electrum, white gold, and silver-mercury and gold-mercury amalgam. Only gold, silver, copper and the platinum metals occur in nature in large amounts. Over geological time scales, very few metals can resist natural weathering processes like oxidation, which is why generally only the less reactive metals such as gold and platinum are found as native metals. The others usually occur as isolated pockets where a natural chemical process reduces a common compound or ore of the metal, leaving the pure metal behind as small flakes or inclusions. Non-metallic elements occurring in the native state include