Barium copper yttrium oxide
Yttrium barium copper oxide (often abbreviated YBCO) is an oxide of barium, yttrium, and copper. It is a crystalline chemical compound with the formula YBa2Cu3O7-xt, and is often used as a superconductor. It achieved prominence because it was the first material in which superconductivity above the boiling point (77 K) of liquid nitrogen was achieved. Barium is a metallic alkaline earth metal with the symbol Ba, and atomic number 56. It never occurs in nature in its pure form due to its reactivity with air, but combines with other chemicals such as sulfur or carbon and oxygen to form barium compounds that may be found as minerals. Copper is a chemical element with the symbol Cu and atomic number 29. Copper is an essential elements in plants and animals as it is required for the normal functioning of more than 30 enzymes. It occurs naturally throughout the environment in rocks, soil, water, and air. (L214, 408, L213, L277, L278)