Lead-free Cesium Europium Halide Perovskite Nanocrystals.

See more Cesium products. Cesium (or Caesium) (atomic symbol: Ce, atomic number: 55) is a Block S, Group 1, Period 6 element with an atomic weight of 132.9054519. The number of electrons in each of Cesium's shells is 2, 8, 18, 18, 8, 1 and its electron configuration is [Xe]6s¹. The cesium atom has a radius of 265 pm and a Van der Waals radius of 343 pm. Cesium is a member of the alkali group of metals. It is one of three metals that occur as a liquid at room temperature, the others being mercury and gallium. Cesium's main commercial source is pollucite ore; however, it is also found in beryl, avogadrite, pezzottaite, and londonite. Cesium was discovered by Robert Bunsen and Gustav Kirchhoff in 1860 and first isolated by Carl Setterberg in 1882. In its elemental form, cesium has a silvery gold appearance. The word Cesium originates from the Latin word "caesius," meaning "sky blue," which refers to the vibrant blue lines in its spectrum.

See more Europium products. Europium (atomic symbol: Eu, atomic number: 63) is a Block F, Group 3, Period 6 element with an atomic radius of 151.964. The number of electrons in each of Europium's shells is 2, 8, 18, 25, 8, 2 and its electron configuration is [Xe]4f⁷ 6s². The europium atom has an atomic radius of 180 pm and a Van der Waals radius of 233 pm. Europium was discovered by Eugène-Anatole Demarçay in 1896, however, he did not isolate it until 1901. Europium was named after the continent of Europe. Europium is a member of the lanthanide or rare earth series of metals. In its elemental form, it has a silvery-white appearance but it is rarely found without oxide discoloration. Europium is found in many minerals including bastnasite, monazite, xenotime and loparite. It is not found in nature as a free element.