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The most stable oxide of samarium is the sesquioxide Sm 2 O 3. Like many samarium compounds, it exists in several crystalline phases. The trigonal form is obtained by slow cooling from the melt. The melting point of Sm 2 O 3 is high (2345 °C), so it is usually melted not by direct heating, but with induction heating, through a radio-frequency ...
Samarium-149 (149 Sm) is an observationally stable isotope of samarium (predicted to decay, but no decays have ever been observed, giving it a half-life at least several orders of magnitude longer than the age of the universe), and a product of the decay chain from the fission product 149 Nd (yield 1.0888%).
Some of the fission products generated during nuclear reactions have a high neutron absorption capacity, such as xenon-135 (microscopic cross-section σ = 2,000,000 barns (b); up to 3 million barns in reactor conditions) [3] and samarium-149 (σ = 74,500 b). Because these two fission product poisons remove neutrons from the reactor, they will ...
Samarium-149 is the second most important neutron poison in nuclear reactor physics. Samarium-151, produced at lower yields, is the third most abundant medium-lived fission product but emits only weak beta radiation. Both have high neutron absorption cross sections, so that much of them produced in a reactor are later destroyed there by neutron ...
Some fission products decay with the release of delayed neutrons, important to nuclear reactor control. Other fission products, such as xenon-135 and samarium-149, have a high neutron absorption cross section. Since a nuclear reactor must balance neutron production and absorption rates, fission products that absorb neutrons tend to "poison" or ...
149 Sm 13.8% stable 150 Sm 7.37% ... Main isotopes of samarium; Main isotopes [1] Decay; abundance ... Two neutrons ejected from nucleus simultaneously.
Conversely, of the 251 known stable nuclides, only five have both an odd number of protons and odd number of neutrons: hydrogen-2 , lithium-6, boron-10, nitrogen-14, and tantalum-180m. Also, only four naturally occurring, radioactive odd–odd nuclides have a half-life >10 9 years: potassium-40 , vanadium-50 , lanthanum-138 , and lutetium-176 .
Samarium has seven naturally occurring isotopes, and neodymium has seven. The two elements are joined in a parent–daughter relationship by the alpha decay of parent 147 Sm to radiogenic daughter 143 Nd with a half-life of 1.066(5) × 10 11 years and by the alpha decay of 146 Sm (an almost-extinct radionuclide with a half-life of 9.20(26) × 10 7 years [2] [a]) to produce 142 Nd.