Einsteinium(III) oxide is an

oxide An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the E ...

of the

synthetic Synthetic things are composed of multiple parts, often with the implication that they are artificial. In particular, 'synthetic' may refer to: Science * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic o ...

actinide The actinide () or actinoid () series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium. The actinide series derives its name from the first element in the series, actinium. The inform ...

einsteinium which has the molecular formula Es₂O₃. It is a colourless solid. Three modifications are known. The body-centered cubic form has

lattice parameter A lattice constant or lattice parameter is one of the physical dimensions and angles that determine the geometry of the unit cells in a crystal lattice, and is proportional to the distance between atoms in the crystal. A simple cubic crystal has o ...

''a'' = 1076.6 ± 0.6 pm; this allows the ionic radius of the Es³⁺

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

to be calculated as 92.8 pm. The other two forms are

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...

and

hexagonal In geometry, a hexagon (from Greek , , meaning "six", and , , meaning "corner, angle") is a six-sided polygon. The total of the internal angles of any simple (non-self-intersecting) hexagon is 720°. Regular hexagon A '' regular hexagon'' has ...

: the hexagonal form has the

lanthanum(III) oxide Lanthanum(III) oxide, also known as lanthana, chemical formula , is an inorganic compound containing the rare earth element lanthanum and oxygen. It is used in some ferroelectric materials, as a component of optical materials, and is a feedstock ...

structure.R. G. Haire, L. Eyring, in: ''Handbook on the Physics and Chemistry of Rare Earths'', Vol. 18 ''Lanthanoids and Actinides Chemistry'' (hrsg. von K. A. Gscheidner, Jr., L. Eyring, G. R. Choppin, G. H. Lander), North-Holland, New York 1994, S. 414–505. Einsteinium(III) oxide can be obtained by annealing

einsteinium(III) nitrate Einsteinium is a synthetic element with the symbol Es and atomic number 99. Einsteinium is a member of the actinide series and it is the seventh transuranium element. It was named in honor of Albert Einstein. Einsteinium was discovered as a com ...

in sub- microgram quantities.R. G. Haire, R. D. Baybarz: "Identification and Analysis of Einsteinium Sesquioxide by Electron Diffraction", in: '' Journal of Inorganic and Nuclear Chemistry'', 1973, ''35'' (2), S. 489–496; .

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Further reading