page_title: Einsteinium
section_title: Physical
hierarchical_section_title: Einsteinium / Characteristics / Physical
caption_attribution_description: English: Self‐luminescence arising from the intense radiation from ~300 µg of 253Es solid in a quartz cone (9 mm diameter). The heat and radiation accompanying decay often generate detrimental effects in studies of Es.
context_page_description: Einsteinium is a synthetic element with the symbol Es and atomic number 99. As a member of the actinide series, it is the seventh transuranic element.
  Einsteinium was discovered as a component of the debris of the first hydrogen bomb explosion in 1952, and named after Albert Einstein. Its most common isotope einsteinium-253 is produced artificially from decay of californium-253 in a few dedicated high-power nuclear reactors with a total yield on the order of one milligram per year. The reactor synthesis is followed by a complex process of separating einsteinium-253 from other actinides and products of their decay. Other isotopes are synthesized in various laboratories, but in much smaller amounts, by bombarding heavy actinide elements with light ions. Owing to the small amounts of produced einsteinium and the short half-life of its most easily produced isotope, there are currently almost no practical applications for it outside basic scientific research. In particular, einsteinium was used to synthesize, for the first time, 17 atoms of the new element mendelevium in 1955.
  Einsteinium is a soft, silvery, paramagnetic metal.
context_section_description: Einsteinium is a synthetic, silvery-white, radioactive metal. In the periodic table, it is located to the right of the actinide californium, to the left of the actinide fermium and below the lanthanide holmium with which it shares many similarities in physical and chemical properties. Its density of 8.84 g/cm³ is lower than that of californium (15.1 g/cm³) and is nearly the same as that of holmium (8.79 g/cm³), despite atomic einsteinium being much heavier than holmium. The melting point of einsteinium (860 °C) is also relatively low – below californium (900 °C), fermium (1527 °C) and holmium (1461 °C). Einsteinium is a soft metal, with the bulk modulus of only 15 GPa, which value is one of the lowest among non-alkali metals.
  Contrary to the lighter actinides californium, berkelium, curium and americium which crystallize in a double hexagonal structure at ambient conditions, einsteinium is believed to have a face-centered cubic (fcc) symmetry with the space group Fm3m and the lattice constant a = 575 pm. However, there is a report of room-temperature hexagonal einsteinium metal with a = 398 pm and c = 650 pm, which converted to the fcc phase upon heating to 300 °C.
  The self-damage induced by the radioactivity of einsteinium is so strong that it rapidly destroys the crystal lattice, and the energy release during this process, 1000 watts per gram of ²⁵³Es, induces a visible glow. These processes may contribute to the relatively low density and melting point of einsteinium. Further, owing to the small size of the available samples, the melting point of einsteinium was often deduced by observing the sample being heated inside an electron microscope. Thus the surface effects in small samples could reduce the melting point value.
  The metal is divalent and has a noticeably high volatility. In order to reduce the self-radiation damage, most measurements of solid einsteinium and its compounds are performed right after thermal annealing. Also, some compounds are studied under the atmosphere of the reductant gas, for example H₂O+HCl for EsOCl so that the sample is partly regrown during its decomposition.
  Apart from the self-destruction of solid einsteinium and its compounds, other intrinsic difficulties in studying this element include scarcity – the most common ²⁵³Es isotope is available only once or twice a year in sub-milligram amounts – and self-contamination due to rapid conversion of einsteinium to berkelium and then to californium at a rate of about 3.3% per day:
  Thus, most einsteinium samples are contaminated, and their intrinsic properties are often deduced by extrapolating back experimental data accumulated over time. Other experimental techniques to circumvent the contamination problem include selective optical excitation of einsteinium ions by a tunable laser, such as in studying its luminescence properties.
  Magnetic properties have been studied for einsteinium metal, its oxide and fluoride. All three materials showed Curie–Weiss paramagnetic behavior from liquid helium to room temperature. The effective magnetic moments were deduced as 10.4±0.3 µB for Es₂O₃ and 11.4±0.3 µB for the EsF₃, which are the highest values among actinides, and the corresponding Curie temperatures are 53 and 37 K.
caption: Glow due to the intense radiation from ~300 µg of 253Es.[24]
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