Samarium-147

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title: "Samarium-147" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["isotopes-of-samarium", "radionuclides-used-in-radiometric-dating"] description: "Isotope of samarium" topic_path: "general/isotopes-of-samarium" source: "https://en.wikipedia.org/wiki/Samarium-147" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Isotope of samarium ::

::data[format=table title="Infobox isotope"]

Field	Value
name	Samarium-147
mass_number	147
symbol	Sm
num_neutrons	85
num_protons	62
abundance	15.00%
halflife	1.066 years
decay_product	Neodymium-143
decay_mass	143
decay_symbol	Nd
parent	Promethium-147
parent_mass	147
parent_symbol	Pm
parent_decay	β−
parent2	Gadolinium-151
parent2_mass	151
parent2_symbol	Gd
parent2_decay	α
mass	146.914898
spin	7/2−
decay_mode1	α
decay_energy1	2.311
::

| name = Samarium-147 | image = | image_caption = | alternate_names = | mass_number = 147 | symbol = Sm | num_neutrons = 85 | num_protons = 62 | abundance = 15.00% | halflife = 1.066 years | decay_product = Neodymium-143 | decay_mass = 143 | decay_symbol = Nd | parent = Promethium-147 | parent_mass = 147 | parent_symbol = Pm | parent_decay = β− | parent2 = Gadolinium-151 | parent2_mass = 151 | parent2_symbol = Gd | parent2_decay = α | parent3 = | parent3_mass = | parent3_symbol = | parent3_decay = | mass = 146.914898 | spin = 7/2− | excess_energy = | binding_energy = | decay_mode1 = α | decay_energy1 = 2.311 | decay_mode2 = | decay_energy2 = | decay_mode3 = | decay_energy3 = | decay_mode4 = | decay_energy4 = Samarium-147 (147Sm or Sm-147) is an isotope of samarium, making up 15% of natural samarium. It is an extremely long-lived radioisotope, with a half-life of years, and an alpha emitter, the only significant one outside the heavy decay chains from thorium and uranium.

Uses

Main article: Samarium–neodymium dating

Samarium-147 is used in samarium–neodymium dating. The method of isochron dating is used to find the date at which a rock (or group of rocks) are formed. The Sm-Nd isochron plots the ratio of radiogenic 143Nd to non-radiogenic 144Nd against the ratio of the parent isotope 147Sm to the non-radiogenic isotope 144Nd. 144Nd is used to normalize the radiogenic isotope in the isochron because it is a slightly radioactive and relatively abundant neodymium isotope.

The Sm-Nd isochron is defined by the following equation:

: \left(\frac\right){\mathrm{present}} = \left(\frac\right){\mathrm{initial}} + \left(\frac\right) \cdot (e^{\lambda t}-1),

where:

: t is the age of the sample, : λ is the decay constant of 147Sm, : (eλt−1) is the slope of the isochron which defines the age of the system.

Alternatively, one can assume that the material formed from mantle material which was following the same path of evolution of these ratios as chondrites, and then again the time of formation can be calculated (see Samarium–neodymium dating#The CHUR model).

References

|element=samarium |lighter=samarium-146 |heavier=samarium-148 |before=gadolinium-151 (α) promethium-147 (β−) |after=neodymium-143 (α)

References

1. {{NUBASE2020
2. {{AME2020 II
3. {{NNDC
4. (1976). "Nd isotopic variations and petrogenetic models". Geophysical Research Letters.
5. (1978). "Sm-Nd and Rb-Sr Chronology of Continental Crust Formation". Science.

::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::