Samarium ( /səˈmɛəriəm/ sə-MAIR-ee-əm) is a chemical element with the symbol Sm,
atomic number 62 and atomic weight 150.36. It is a moderately hard
silvery metal which readily oxidizes in air. Being a typical member of
the lanthanide series, samarium usually assumes the oxidation state +3;
however, compounds of samarium(II) are also known, most notably monoxide
SmO, monochalcogenides SmS, SmSe and SmTe, as well as samarium(II)
iodide. The last compound is a common reducing agent in chemical
synthesis. Samarium has no significant biological role and is only
slightly toxic.
Samarium was discovered in 1879 by the French
chemist Paul Émile Lecoq de Boisbaudran and named after the mineral
samarskite where it was isolated from. The mineral itself was earlier
named after the Russian military engineer Vasili Samarsky-Bykhovets who
thereby became the first person to have a chemical element named after
him, albeit indirectly. Although classified as a rare earth element,
samarium is the 40th most abundant element in the Earth's crust and is
more common than such metals as tin. Samarium occurs with concentration
up to 2.8% in several minerals including cerite, gadolinite, samarskite,
monazite and bastnäsite, the last two being the most common commercial
sources of the element. These minerals are mostly found in China, the
USA, Brazil, India, Sri Lanka and Australia; China is by far the world
leader in samarium mining and production.
The major commercial
application of samarium is in samarium-cobalt magnets which have
permanent magnetization second only to neodymium magnets; however,
samarium compounds can withstand significantly higher temperatures,
above 700 °C, without losing their magnetic properties. Radioactive
isotope samarium-153 is the major component of the drug samarium (153Sm)
lexidronam (Quadramet) which kills cancer cells in the treatment of
lung cancer, prostate cancer, breast cancer and osteosarcoma. Another
isotope, samarium-149, is a strong neutron absorber and is therefore
added to the control rods of nuclear reactors. It is also formed as a
decay product during the reactor operation and is one of the important
factors considered in the reactor design and operation. Other
applications of samarium include catalysis of chemical reactions,
radioactive dating and an X-ray laser.
Contents
[hide]
- 1 Physical properties
- 2 Chemical properties
- 3 Compounds
- 3.1 Oxides
- 3.2 Chalcogenides
- 3.3 Halides
- 3.4 Borides
- 3.5 Other inorganic compounds
- 3.6 Organometallic compounds
- 4 Isotopes
- 5 History
- 6 Occurrence and production
- 7 Applications
- 7.1 Non-commercial and potential applications
- 8 Health issues
- 9 References
- 10 Bibliography
- 11 External links
[edit] Physical properties
Samarium
is a rare earth metal having the hardness and density similar to those
of zinc. With the boiling point of 1794 °C, samarium is the third most
volatile lanthanide after ytterbium and europium; this property
facilitates separation of samarium from the mineral ore. At ambient
conditions, samarium normally assumes a rhombohedral structure (α form).
Upon heating to 731 °C, its crystal symmetry changes into hexagonal
close-packed (hcp), however the transition temperature depends
on the metal purity. Further heating to 922 °C transforms the metal into
a body-centered cubic (bcc) phase. Heating to 300 °C combined with compression to 40 kbar results in a double-hexagonal close-packed structure (dhcp).
Applying higher pressure of the order hundreds or thousands kilobars
induces a series of phase transformations, in particular with a
tetragonal phase appearing at about 900 kbar.[2] In one study, the dhcp
phase could be produced without compression, using a nonequilibrium
annealing regime with a rapid temperature change between about 400 and
700 °C, confirming the transient character of this samarium phase. Also,
thin films of samarium obtained by vapor deposition may contain the hcp or dhcp phases at ambient conditions.[2]
Samarium
(and its sesquioxide) are paramagnetic at room temperature. Their
corresponding effective magnetic moments, below 2 µB, are the 3rd lowest
among the lanthanides (and their oxides) after lanthanum and lutetium.
The metal transforms to an antiferromagnetic state upon cooling to 14.8
K.[3][4] Individual samarium atoms can be isolated by encapsulating them
into fullerene molecules.[5] They can also be doped between the C60
molecules in the fullerene solid, rendering it superconductive at
temperatures below 8 K.[6] Samarium doping of iron-based superconductors
– the most recent class of high-temperature superconductors – allows to
enhance their transition temperature to 56 K, which is the highest
value achieved so far in this series.[7]
[edit] Chemical properties
Freshly
prepared samarium has a silvery luster. In air, it slowly oxidizes at
room temperature and spontaneously ignites at 150 °C.[8][9] Even when
stored under mineral oil, samarium gradually oxidizes and develops a
grayish-yellow powder of the oxide-hydroxide mixture at the surface. The
metallic appearance of a sample can be preserved by sealing it under an
inert gas such as argon.
Samarium is quite electropositive and
reacts slowly with cold water and quite quickly with hot water to form
samarium hydroxide:[10]
2 Sm (s) + 6 H2O (l) → 2 Sm(OH)3 (aq) + 3 H2 (g)
Samarium
dissolves readily in dilute sulfuric acid to form solutions containing
the yellow[11] to pale green Sm(III) ions, which exist as a [Sm(OH2)9]3+
complexes:[10]
2 Sm (s) + 3 H2SO4 (aq) → 2 Sm3+ (aq) + 3 SO2−
4 (aq) + 3 H2 (g)
Samarium is one of the few lanthanides that exhibit the oxidation state +2. The Sm2+ ions are blood-red in solutions.[12]
[edit] Compounds
See also: Category:Samarium compounds
[show]Formula color symmetry space group No Pearson symbol a (pm) b (pm) c (pm) Z density,
g/cm3
Sm silvery rhombohedral[2] R3m 166 hR9 362.9 362.9 2621.3 9 7.52
Sm silvery hexagonal[2] P63/mmc 194 hP4 362 362 1168 4 7.54
Sm silvery tetragonal[13] I4/mmm 139 tI2 240.2 240.2 423.1 2 20.46
SmO golden cubic[14] Fm3m 225 cF8 494.3 494.3 494.3 4 9.15
Sm2O3 trigonal[15] P3m1 164 hP5 377.8 377.8 594 1 7.89
Sm2O3 monoclinic[15] C2/m 12 mS30 1418 362.4 885.5 6 7.76
Sm2O3 cubic[16] Ia3 206 cI80 1093 1093 1093 16 7.1
SmH2 cubic[17] Fm3m 225 cF12 537.73 537.73 537.73 4 6.51
SmH3 cubic[18] P3c1 165 hP24 377.1 377.1 667.2 6
Sm2B5 gray monoclinic[19] P21/c 14 mP28 717.9 718 720.5 4 6.49
SmB2 hexagonal[20] P6/mmm 191 hP3 331 331 401.9 1 7.49
SmB4 tetragonal[21] P4/mbm 127 tP20 717.9 717.9 406.7 4 6.14
SmB6 cubic[22] Pm3m 221 cP7 413.4 413.4 413.4 1 5.06
SmB66 cubic[23] Fm3c 226 cF1936 2348.7 2348.7 2348.7 24 2.66
Sm2C3 cubic[24] I43d 220 cI40 839.89 839.89 839.89 8 7.55
SmC2 tetragonal[24] I4/mmm 139 tI6 377 377 633.1 2 6.44
SmF2 cubic[25] Fm3m 225 cF12 587.1 587.1 587.1 4 6.18
SmF3 orthorhombic[25] Pnma 62 oP16 667.22 705.85 440.43 4 6.64
SmCl2 orthorhombic[26] Pnma 62 oP12 756.28 450.77 901.09 4 4.79
SmCl3 hexagonal[25] P63/m 176 hP8 737.33 737.33 416.84 2 4.35
SmBr2 orthorhombic[27] Pnma 62 oP12 797.7 475.4 950.6 4 5.72
SmBr3 orthorhombic[28] Cmcm 63 oS16 404 1265 908 2 5.58
SmI2 monoclinic P21/c 14 mP12
SmI3 trigonal[29] R3 63 hR24 749 749 2080 6 5.24
SmN cubic[30] Fm3m 225 cF8 357 357 357 4 8.48
SmP cubic[31] Fm3m 225 cF8 576 576 576 4 6.3
SmAs cubic[32] Fm3m 225 cF8 591.5 591.5 591.5 4 7.23
[edit] Oxides
The
most stable oxide of samarium is sesquioxide Sm2O3. As most other
samarium compounds, it exists in several crystalline phases. The
trigonal form is obtained by slow cooling from the melt. The melting
point of Sm2O3 is rather high (2345 °C) and therefore melting is usually
achieved not by direct heating, but with induction heating, through a
radio-frequency coil. The Sm2O3 crystals of monoclinic symmetry can be
grown by the flame fusion method (Verneuil process) from the Sm2O3
powder, that yields cylindrical boules up to several centimeters long
and about one centimeter in diameter. The boules are transparent when
pure and defect-free and are orange otherwise. Heating the metastable
trigonal Sm2O3 to 1900 °C converts it to the more stable monoclinic
phase.[15] Cubic Sm2O3 has also been described.[16]
Samarium is
one of the few lanthanides that form a monoxide, SmO. This lustrous
golden-yellow compound was obtained by reducing Sm2O3 with samarium
metal at elevated temperature (1000 °C) and pressure above 50 kbar;
lowering the pressure resulted in an incomplete reaction. SmO has the
cubic rock-salt lattice structure.[33][14]
[edit] Chalcogenides
See also: Samarium monochalcogenides
Samarium
forms trivalent sulfide, selenide and telluride. Divalent
chalcogenides SmS, SmSe and SmTe with cubic rock-salt crystal structure
are also known. They are remarkable by converting from semiconducting
to metallic state at room temperature upon application of pressure.
Whereas the transition is continuous and occurs at about 20–30 kbar in
SmSe and SmTe, it is abrupt in SmS and requires only 6.5 kbar. This
effect results in spectacular color change in SmS from black to golden
yellow when its crystals of films are scratched or polished. The
transition does not change the lattice symmetry, but there is a sharp
decrease (~15%) in the crystal volume.[34] It shows hysteresis, that is
when the pressure is released, SmS returns to the semiconducting state
at much lower pressure of about 0.4 kbar.[8][35]
[edit] Halides
Color of samarium halides[36]
Oxidation
state F Cl Br I
+3 SmF3
white SmCl3
yellow SmBr3
yellow SmI3
orange
+2 SmF2
purple SmCl2
brown SmBr2
brown SmI2
green
Samarium metal reacts with all the halogens X = F, Cl, Br or I, forming trihalides:[37]
2 Sm (s) + 3 X2 (g) → 2 SmX3 (s)
Their
further reduction with samarium, lithium or sodium metals at elevated
temperatures (about 700–900 °C) yields dihalides.[26] The diiodide can
also be prepared by heating SmI3, or by reacting the metal with
1,2-diiodoethane in anhydrous tetrahydrofuran at room temperature:[38]
Sm (s) + ICH2=CH2I → SmI2 + CH2=CH2
In
addition to dihalides, the reduction also produces numerous
non-stoichiometric samarium halides with a well-defined crystal
structure, such as Sm3F7, Sm14F33, Sm27F64,[25] Sm11Br24, Sm5Br11 and
Sm6Br13[39]
As reflected in the table above, samarium halides
change their crystal structures when one type of halide atoms is
substituted for another, which is an uncommon behavior for most
elements (e. g. actinides). Many halides have two major crystal phases
for one composition, one being significantly more stable and another
being metastable. The latter is formed upon compression or heating,
followed by quenching to ambient conditions. For example, compressing
the usual monoclinic samarium diiodide and releasing the pressure
results in a PbCl2-type orthorhombic structure (Pearson symbol oP12,
space group Pnma, No. 62, a = 889.3 pm, b = 457.5 pm, c
= 1118.4 pm, Z = 4, 5.90 g/cm3),[40] and similar treatment results in a
new phase of samarium triiodide (Pearson symbol oS16, space group Cmcm,
No. 63, a = 423.6 pm, b = 1400 pm, c = 996.9 pm, Z = 4, 5.97 g/cm3).[41]
[edit] Borides
Sintering
powders of samarium oxide and boron, in vacuum, yields a powder
containing several samarium boride phases, and their volume ratio can be
controlled through the mixing proportion.[42] The powder can be
converted into larger crystals of a certain samarium boride using arc
melting or zone melting techniques, relying on the different
melting/crystallization temperature of SmB6 (2580 °C), SmB4 (about 2300
°C) and SmB66 (2150 °C). All these materials are hard, brittle,
dark-gray solids with the hardness increasing with the boron
content.[22] Samarium diboride is too volatile to be produced with
these methods and requires high pressure (about 65 kbar) and low
temperatures between 1140 and 1240 °C to stabilize its growth.
Increasing the temperature results in the preferential formations of
Sm6.[20]
Samarium hexaboride is a typical intermediate-valence
compound where samarium is present both as Sm2+ and Sm3+ ions at the
ratio 3:7.[42] It belongs to a class of Kondo insulators, that is at
high temperatures (above 50 K), its properties are typical of a Kondo
metal, with metallic electrical conductivity characterized by strong
electron scattering, whereas at low temperatures, it behaves as a
non-magnetic insulator with a narrow band gap of about 4–14 meV.[43] The
cooling-induced metal-insulator transition in SmB6 is accompanied by a
sharp increase in the thermal conductivity, peaking at about 15 K. This
increase is explained as follows: electrons themselves do not
contribute to the thermal conductivity at low temperatures, which is
dominated by phonons. However, the decrease in electron concentration
reduced the rate of electron-phonon scattering.[44]
[edit] Other inorganic compounds
Samarium
carbides are prepared by melting a graphite-metal mixture in an inert
atmosphere. After the synthesis, they are unstable in air and are
studied also under inert atmosphere.[24] Samarium monophosphide SmP is a
semiconductor with the bandgap of 1.10 eV, the same as in silicon, and
high electrical conductivity of n-type. It can be prepared by annealing
at 1100 °C an evacuated quartz ampoule containing mixed powders of
phosphorus and samarium. Phosphorus is highly volatile at high
temperatures and may explode, thus the heating rate has to be kept well
below 1 °C/min.[31] Similar procedure is adopted for the monarsenide
SmAs, but the synthesis temperature is higher at 1800 °C.[32]
A
large number of crystalline binary compounds are known for samarium and
one of the non-metallic group-4, 5 or 6 element X, where X is Si, Ge,
Sn, Pb, Sb or Te, and metallic alloys of samarium form another large
group. They are all prepared by annealing mixed powders of the
corresponding elements. Many of the resulting compounds are
non-stoichiometric and have nominal compositions SmaXb, where the b/a
ratio varies between 0.5 and 3.[45][46][47]
[edit] Organometallic compounds
Samarium
forms a cyclopentadienide Sm(C5H5)3 and its chloroderivatives
Sm(C5H5)2Cl and Sm(C5H5)Cl2. They are prepared by reacting samarium
trichloride with NaC5H5 in tetrahydrofuran. Contrary to
cyclopentadienides of most other lanthanides, in Sm(C5H5)3 some C5H5
rings bridge each other by forming ring vertexes η1 or edges η2 toward
another neighboring samarium atom, thereby creating polymeric
chains.[12] The chloroderivative Sm(C5H5)2Cl has a dimer structure which
is more accurately expressed as (η5-C5H5)2Sm(µ-Cl)2(η5-C5H5)2. There,
the chlorine bridges can be replaced, for instance, by iodine, hydrogen
or nitrogen atoms or by CN groups.[48]
The (C5H5)– ion in samarium
cyclopentadienides can be replaced by the indenide (C9H7)– or
cyclooctatetraenide (C8H8)2– ring, resulting in Sm(C9H7)3 or
KSm(η8-C8H8)2. The latter compound has a similar structure to that of
uranocene. There is also a cyclopentadienide of divalent samarium,
Sm(C5H5)2 – a solid which sublimates at about 85 °C. Contrary to
ferrocene, the C5H5 rings in Sm(C5H5)2 are not parallel but are tilted
by 40°.[49][48]
Alkyls and aryls of samarium are obtained through a metathesis reaction in tetrahydrofuran or ether:[48]
SmCl3 + 3 LiR → SmR3 + 3 LiClSm(OR)Cl3 + 3 LiCH(SiMe3)2 → Sm{CH(SiMe3)2}3 + 3 LiOR
Here R is a hydrocarbon group and Me stands for methyl.
[edit] Isotopes
Main article: Isotopes of samarium
Naturally
occurring samarium has a radioactivity of 128 Bq/g. It is composed of
four stable isotopes: 144Sm, 150Sm, 152Sm and 154Sm, and three extremely
long-lived radioisotopes, 147Sm (half-life t½ = 1.06×1011 years), 148Sm
(7×1015 years) and 149Sm (>2×1015 years), with 152Sm being the most
abundant (natural abundance 26.75%).[50]
The half-lives of 151Sm
and 145Sm are 90 years and 340 days, respectively. All of the remaining
radioisotopes have half-lives that are less than 2 days, and the
majority of these have half-lives that are less than 48 seconds.
Samarium also has five nuclear isomers with the most stable being 141mSm
(half-life 22.6 minutes), 143m1Sm (t½ = 66 seconds) and 139mSm (t½ =
10.7 seconds).[50]
The long-lived isotopes,146Sm, 147Sm, and 148Sm
primarily decay by emission of alpha particles to isotopes of
neodymium. Lighter unstable isotopes of samarium primarily decay by
electron capture to isotopes of promethium, while heavier ones convert
through beta decay to isotopes of europium.[50]
[edit] History
Paul Émile Lecoq de Boisbaudran – the discoverer of samarium.
Detection
of samarium and related elements was announced by several scientists
in the second half of the 19th century; however, most sources give the
priority to the French chemist Paul Émile Lecoq de Boisbaudran.[51][52]
Boisbaudran isolated samarium oxide and/or hydroxide in Paris in 1879
from the mineral samarskite ((Y,Ce,U,Fe)3(Nb,Ta,Ti)5O16) and identified a
new element in it via sharp optical absorption lines.[9] The Swiss
chemist Marc Delafontaine announced a new element decipium (from Latin: decipiens
meaning "deceptive, misleading") in 1878,[53][54] but later in
1880–1881 demonstrated that it was a mixture of several elements, one
being identical to the Boisbaudran's samarium.[55][56] Although
samarskite was first found in the remote Russian region of Urals, by
the late 1870s its deposits had been located in other places making the
mineral available to many researchers. In particular, it was found
that the samarium isolated by Boisbaudran was also impure and contained
europium. Reasonably pure element was produced only in 1901 by
Eugène-Anatole Demarçay.[57]
Boisbaudran named his element samaria
after the mineral samarskite, which in turn honored Vasili
Samarsky-Bykhovets (1803–1870). Samarsky-Bykhovets was the Chief of
Staff of the Russian Corps of Mining Engineers who granted access for
the German mineralogists, brothers Gustav Rose and Heinrich Rose, to
study the mineral samples from the Urals.[58][59][60] In this sense
samarium was the first chemical element to be named after a
person.[57][61] Later Boisbaudran's samaria was transformed into samarium,
to conform with other element names, and samaria nowadays is sometimes
used to refer to samarium oxide, by analogy with yttria, zirconia,
alumina, ceria, holmia, etc. The symbol Sm was suggested for samarium; however an alternative Sa was frequently used instead until the 1920s.[62][57]
Prior
to the advent of ion-exchange separation technology in the 1950s,
samarium had no commercial uses in pure form. However, a by-product of
the fractional crystallization purification of neodymium was a mixture
of samarium and gadolinium that acquired the name of "Lindsay Mix"
after the company that made it. This material is thought to have been
used for nuclear control rods in some of the early nuclear reactors.
Nowadays, a similar commodity product has the name
"samarium-europium-gadolinium" (SEG) concentrate.[61] It is prepared by
solvent extraction from the mixed lanthanides isolated from bastnäsite
(or monazite). Since the heavier lanthanides have the greater affinity
for the solvent used, they are easily extracted from the bulk using
relatively small proportions of solvent. Not all rare earth producers
who process bastnäsite do so on large enough scale to continue onward
with the separation of the components of SEG, which typically makes up
only one or two percent of the original ore. Such producers will
therefore be making SEG with a view to marketing it to the specialized
processors. In this manner, the valuable europium content of the ore is
rescued for use in phosphor manufacture. Samarium purification follows
the removal of the europium. Currently, being in oversupply, samarium
oxide is less expensive on a commercial scale than its relative
abundance in the ore might suggest.[63]
[edit] Occurrence and production
Samarskite
With
the average concentration of about 8 parts per million (ppm), samarium
is the 40th most abundant element in the Earth's crust. It is the
fifth most abundant lanthanide and is more common than such element as
tin. Samarium concentration in soils varies between 2 and 23 ppm, and
oceans contain about 0.5–0.8 parts per trillion.[8] Distribution of
samarium in soils strongly depends on its chemical state and is very
inhomogeneous: in sandy soils, samarium concentration is about 200
times higher at the surface of soil particles than in the water trapped
between them, and this ratio can exceed 1,000 in clays.[64]
Samarium
is not found free in nature, but, like other rare earth elements, is
contained in many minerals, including monazite, bastnäsite, cerite,
gadolinite and samarskite; monazite (in which samarium occurs at
concentrations of up to 2.8%)[9] and bastnäsite are mostly used as
commercial sources. World resources of samarium are estimated at two
million tonnes; they are mostly located in China, US, Brazil, India, Sri
Lanka and Australia, and the annual production is about 700 tonnes.[8]
Country production reports are usually given for all rare-earth metals
combined. By far, China has the largest production with 120,000 tonnes
mined per year; it is followed by the US (about 5,000 tonnes)[64] and
India (2,700 tonnes).[65] Samarium is usually sold as oxide, which at
the price of about 30 USD/kg is one of the cheapest lanthanide
oxides.[63] Whereas mischmetal – a mixture of rare earth metals
containing about 1% of samarium – has long been used, it was not until
recent years that relatively pure samarium has been isolated through
ion exchange processes, solvent extraction techniques, and
electrochemical deposition. The metal is often prepared by electrolysis
of a molten mixture of samarium(III) chloride with sodium chloride or
calcium chloride. Samarium can also be obtained by reducing its oxide
with lanthanum. The product is then distilled to separate samarium
(boiling point 1794 °C) and lanthanum (b. p. 3464 °C).[52]
Samarium-151
is produced in nuclear fission of uranium with the yield of about 0.4%
of the total number of fission events. It is also synthesized upon
neutron capture by samarium-149, which is added to the control rods of
nuclear reactors. Consequently, samarium-151 is present in spent nuclear
fuel and radioactive waste.[64]
[edit] Applications
Barbier reaction using SmI2
One
of the most important applications of samarium is in samarium-cobalt
magnets, which have a nominal composition of SmCo5 or Sm2Co17. They have
high permanent magnetization, which is about 10,000 times that of iron
and is second only to that of neodymium magnets. However,
samarium-based magnets have higher resistance to demagnetization, as
they are stable to temperatures above 700 °C (cf. 300–400 °C for
neodymium magnets). These magnets are found in small motors,
headphones, high-end magnetic pickups for guitars and related musical
instruments.[8] For example, they are used in the motors of a
solar-powered electric aircraft Solar Challenger and in the Samarium
Cobalt Noiseless electric guitar and bass pickups.
Another
important application of samarium and its compounds is as catalyst and
chemical reagent. Samarium catalysts assist decomposition of plastics,
dechlorination of pollutants such as polychlorinated biphenyls (PCBs),
as well as the dehydration and dehydrogenation of ethanol.[9]
Samarium(III) triflate (Sm(OTf)3, that is Sm(CF3SO3)3) is one of the
most efficient Lewis acid catalysts for a halogen-promoted
Friedel–Crafts reaction with alkenes.[66] Samarium(II) iodide is a very
common reducing and coupling agent in organic synthesis, for example in
the desulfonylation reactions; annulation; Danishefsky, Kuwajima,
Mukaiyama and Holton Taxol total syntheses; strychnine total synthesis;
Barbier reaction and other reductions with samarium(II) iodide.[67]
In
its usual oxidized form, samarium is added to ceramics and glasses
where it increases absorption of infrared light. As a (minor) part of
mischmetal, samarium is found in "flint" ignition device of many
lighters and torches.[8][9]
Chemical structure of Sm-EDTMP
Radioactive
samarium-153 is beta emitter with a half-life of 46.3 hours. It is used
to kill cancer cells in the treatment of lung cancer, prostate cancer,
breast cancer and osteosarcoma. For this purpose, samarium-153 is
chelated with ethylene diamine tetramethylene phosphonate (EDTMP) and
injected intravenously. The chelation prevents accumulation of
radioactive samarium in the body that would result in excessive
irradiation and generation of new cancer cells.[8] The corresponding
drug has several names including samarium (153Sm) lexidronam and its
trade name is Quadramet.[68][69][70]
Samarium-149 has high
cross-section for neutron capture (41,000 barns) and is therefore used
in the control rods of nuclear reactors. Its advantage compared to
competing materials, such as boron and cadmium, is stability of
absorption – most of the fusion and decay products of samarium-149 are
other isotopes of samarium which are also good neutron absorbers. For
example, the cross sections of samarium-151 is 15,000 barns, it is on
the order of hundred barns for samarium-150, 152, 153, and is 6,800
barns for natural (mixed-isotope) samarium.[71][64][9] Among the decay
products in a nuclear reactor, samarium-149 is regarded as the second
most important for the reactor design and operation after
xenon-135.[72]
[edit] Non-commercial and potential applications
Samarium-doped
calcium fluoride crystals were used as an active medium in one of the
first solid-state lasers designed and constructed by Peter Sorokin
(co-inventor of the dye laser) and Mirek Stevenson at IBM research labs
in early 1961. This samarium laser emitted pulses of red light at
708.5 nm. It had to be cooled by liquid helium and thus did not find
practical applications.[73][74]
Another samarium-based laser
became the first saturated X-ray laser operating at wavelengths shorter
than 10 nanometers. It provided 50-picosecond pulses at 7.3 and 6.8 nm
suitable for applications in holography, high-resolution microscopy of
biological specimens, deflectometry, interferometry and radiography of
dense plasmas related to confinement fusion and astrophysics. Saturated
operation meant that the maximum possible power was extracted from the
lasing medium, resulting in the high peak energy of 0.3 millijoule.
The active medium was samarium plasma produced by irradiating
samarium-coated glass with a pulsed Nd-glass laser (wavelength of 1.05
microns).[75]
The change in electrical resistivity in samarium
monochalcogenides can be used in a pressure sensor or in a memory
device triggered between a low-resistance and high-resistance state by
external pressure,[76] and such devices are being developed
commercially.[77] Samarium monosulfide also generates electric voltage
upon moderate heating to about 150 °C that can be applied in
thermoelectric power converters.[78]
The analysis of relative
concentrations of samarium and neodymium isotopes 146Sm, 144Nd and 143Nd
allows the determination of the age and origin of rocks and meteorites
in samarium-neodymium dating. Both elements are lanthanides and have
very similar physical and chemical properties. Therefore, Sm-Nd dating
is either insensitive to partitioning of the marker elements during
various geological processes, or such partitioning can well be
understood and modeled from the ionic radii of the involved
elements.[79]
[edit] Health issues
Samarium
metal has no biological role in human body. Its salts stimulate
metabolism, but it is unclear whether this is the effect of samarium or
other lanthanides present with it. The total amount of samarium in
adults is about 50 micrograms, mostly in liver and kidneys and with
about 8 micrograms per liter being dissolved in the blood. Samarium is
not absorbed by plants to a measurable concentration and therefore is
normally not a part of human diet. However, a few plants and vegetables
may contain up to 1 part per million of samarium. Insoluble salts of
samarium are non-toxic and the soluble ones are only slightly toxic.[8]
When
ingested, only about 0.05% of samarium salts is absorbed into the
bloodstream and the remainder is excreted. From the blood, about 45%
goes to the liver and 45% is deposited on the surface of the bones
where it remains for about 10 years; the balance 10% is excreted.[64]
引用出處：
http://en.wikipedia.org/wiki/Samarium
歡迎來到Bewise Inc.的世界，首先恭喜您來到這接受新的資訊讓產業更有競爭力，我們是提供專業刀具製造商，應對客戶高品質的刀具需求，我們可以協助客戶滿足您對產業的不同要求，我們有能力達到非常卓越的客戶需求品質，這是現有相關技術無法比擬的，我們成功的滿足了各行各業的要求，包括：精密HSS DIN切削刀具、協助客戶設計刀具流程、DIN or JIS 鎢鋼切削刀具設計、NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計、超高硬度的切削刀具、醫療配件刀具設計、複合式再研磨機、PCD地板專用企口鑽石組合刀具、粉末造粒成型機、主機版專用頂級電桿、PCBN刀具、PCD刀具、單晶刀具、PCD V-Cut刀、捨棄式圓鋸片組、粉末成型機、航空機械鉸刀、主機版專用頂級電感、’汽車業刀具設計、電子產業鑽石刀具、木工產業鑽石刀具、銑刀與切斷複合再研磨機、銑刀與鑽頭複合再研磨機、銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計；從微細刀具到大型刀具；從小型生產到大型量產；全自動整合；我們的技術可提供您連續生產的效能，我們整體的服務及卓越的技術，恭迎您親自體驗！！
BW Bewise Inc. Willy Chen willy@tool-tool.com bw@tool-tool.com www.tool-tool.com
skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office
No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com/
/ FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North
Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao
City,Chiayi Hsien,Taiwan
Welcome to BW
tool world! We are an experienced tool maker specialized in cutting
tools. We focus on what you need and endeavor to research the best
cutter to satisfy users’ demand. Our
customers involve wide range of industries, like mold & die,
aerospace, electronic, machinery, etc. We are professional expert in
cutting field. We would like to solve every problem from you. Please
feel free to contact us, its our pleasure to serve for you. BW product including: cutting tool、aerospace tool .HSS DIN Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、NAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end mill、disc milling cutter,Aerospace cutting tool、hss drill’Фрезеры’Carbide drill、High speed steel、Compound Sharpener’Milling cutter、INDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) ’Core drill、Tapered end mills、CVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden Finger’PCD V-Cutter’PCD Wood tools’PCD Cutting tools’PCD Circular Saw Blade’PVDD End Mills’diamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE ‘Single Crystal Diamond ‘Metric end mills、Miniature end mills、Специальные режущие инструменты ‘Пустотелое сверло ‘Pilot reamer、Fraises’Fresas con mango’ PCD (Polycrystalline diamond) ‘Frese’POWDER FORMING MACHINE’Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、Staple Cutter’PCD diamond cutter specialized in grooving floors’V-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert’ PCD Diamond Tool’ Saw Blade with Indexable Insert’NAS tool、DIN or JIS tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills’end mill grinder’drill grinder’sharpener、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angel carbide end mills、Carbide torus cutters、Carbide ball-nosed slot drills、Mould cutter、Tool manufacturer.
Bewise Inc. www.tool-tool.com
ようこそＢｅｗｉｓｅ Ｉｎｃ.の世界へお越し下さいませ、先ず御目出度たいのは新たな
情報を受け取って頂き、もっと各産業に競争力プラス展開。
弊社は専門なエンド・ミルの製造メーカーで、客先に色んな分野のニーズ、
豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。
弊社は各領域に供給できる内容は：
（１）精密ＨＳＳエンド・ミルのＲ＆Ｄ
（２）Carbide Cutting tools設計
（３）鎢鋼エンド・ミル設計
（４）航空エンド・ミル設計
（５）超高硬度エンド・ミル
（６）ダイヤモンド・エンド・ミル
（７）医療用品エンド・ミル設計
（８）自動車部品＆材料加工向けエンド・ミル設計
弊社の製品の供給調達機能は：
（１）生活産業～ハイテク工業までのエンド・ミル設計
（２）ミクロ・エンド・ミル～大型エンド・ミル供給
（３）小Ｌｏｔ生産～大量発注対応供給
（４）オートメーション整備調達
（５）スポット対応～流れ生産対応
弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。
Bewise
Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z)
talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır.
Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini
Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik
Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel
Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.
BW специализируется
в научных исследованиях и разработках, и снабжаем самым
высокотехнологичным карбидовым материалом для поставки режущих /
фрезеровочных инструментов для почвы, воздушного пространства и
электронной индустрии. В нашу основную продукцию входит твердый карбид /
быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC
картонорезальные машины, фрезы для гравирования, режущие пилы,
фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм
для шлицевого вала / звездочки роликовой цепи, и специальные нано
инструменты. Пожалуйста, посетите сайт www.tool-tool.com для получения большей информации.
BW
is specialized in R&D and sourcing the most advanced carbide
material with high-tech coating to supply cutting / milling tool for
mould & die, aero space and electronic industry. Our main products
include solid carbide / HSS end mills, micro electronic drill, IC card
cutter, engraving cutter, shell end mills, cutting saw, reamer, thread
reamer, leading drill, involute gear cutter for spur wheel, rack and
worm milling cutter, thread milling cutter, form cutters for spline
shaft/roller chain sprocket, and special tool, with nano grade. Please
visit our web www.tool-tool.com for more info.
