Dysprosium is a chemical element with
the symbol Dy and atomic number 66. It
is a rare earth element with a metallic
silver luster. Dysprosium is never found
in nature as a free element, though it
is found in various minerals, such as
xenotime. Naturally occurring dysprosium
is composed of seven isotopes, the most
abundant of which is 164Dy.
Dysprosium was first identified in 1886
by Paul Émile Lecoq de Boisbaudran, but
was not isolated in pure form until the
development of ion exchange techniques
in the 1950s. Dysprosium is used for its
high thermal neutron absorption
cross-section in making control rods in
nuclear reactors, for its high magnetic
susceptibility in data storage
applications, and as a component of
Terfenol-D. Soluble dysprosium salts are
mildly toxic, while the insoluble salts
are considered non-toxic.
Characteristics 
= Physical properties =
Dysprosium is a rare earth element that
has a metallic, bright silver luster. It
is soft enough to be cut with a knife,
and can be machined without sparking if
overheating is avoided. Dysprosium's
physical characteristics can be greatly
affected, even by small amounts of
impurities.
Dysprosium and holmium have the highest
magnetic strengths of the elements,
especially at low temperatures.
Dysprosium has a simple ferromagnetic
ordering at temperatures below 85 K.
Above 85 K, it turns into an helical
antiferromagnetic state in which all of
the atomic moments in a particular basal
plane layer are parallel, and oriented
at a fixed angle to the moments of
adjacent layers. This unusual
antiferromagnetism transforms into a
disordered state at 179 K.
= Chemical properties =
Dysprosium metal tarnishes slowly in air
and burns readily to form
dysprosium(III) oxide:
4 Dy + 3 O2 → 2 Dy2O3
Dysprosium is quite electropositive and
reacts slowly with cold water to form
dysprosium hydroxide:
2 Dy + 6 H2O → 2 Dy(OH)3 + 3 H2
Dysprosium metal vigorously reacts with
all the halogens at above 200 °C:
2 Dy + 3 F2 → 2 DyF3 [green]
2 Dy + 3 Cl2 → 2 DyCl3 [white]
2 Dy + 3 Br2 → 2 DyBr3 [white]
2 Dy + 3 I2 → 2 DyI3 [green]
Dysprosium dissolves readily in dilute
sulfuric acid to form solutions
containing the yellow Dy(III) ions,
which exist as a [Dy(OH2)9]3+ complex:
2 Dy + 3 H2SO4 → 2 Dy3+ + 3 SO2−
4 + 3 H2
The resulting compound, dysprosium(III)
sulfate, is noticeably paramagnetic.
= Compounds =
Dysprosium halides, such as DyF3 and
DyBr3, tend to take on a yellow color.
Dysprosium oxide, also known as
dysprosia, is a white powder that is
highly magnetic, more so than iron
oxide.
Dysprosium combines with various
non-metals at high temperatures to form
binary compounds with varying
composition and oxidation states +3 and
sometimes +2, such as DyN, DyP, DyH2 and
DyH3; DyS, DyS2, Dy2S3 and Dy5S7; DyB2,
DyB4, DyB6 and DyB12, as well as Dy3C
and Dy2C3.
Dysprosium carbonate, Dy2(CO3)3, and
dysprosium sulfate, Dy2(SO4)3, result
from similar reactions. Most dysprosium
compounds are soluble in water, though
dysprosium carbonate tetrahydrate3·4H2O)
and dysprosium oxalate
decahydrate3·10H2O) are both insoluble
in water. Two of the most abundant
dysprosium carbonates,
tengerite-(Dy)3·2–3H2O) and
kozoite-(Dy)) are known to form via a
poorly ordered precursor phase with a
formula of Dy2(CO3)3·4H2O. This
amorphous precursor consists of highly
hydrated spherical nanoparticles of
10–20 nm diameter that are exceptionally
stable under dry treatment at ambient
and high temperatures.
= Isotopes =
Naturally occurring dysprosium is
composed of seven isotopes: 156Dy,
158Dy, 160Dy, 161Dy, 162Dy, 163Dy, and
164Dy. These are all considered stable,
although 156Dy decays by alpha decay
with a half-life of over 1×1018 years.
Of the naturally occurring isotopes,
164Dy is the most abundant at 28%,
followed by 162Dy at 26%. The least
abundant is 156Dy at 0.06%.
Twenty-nine radioisotopes have also been
synthesized, ranging in atomic mass from
138 to 173. The most stable of these is
154Dy, with a half-life of approximately
3×106 years, followed by 159Dym with a
half-life of 144.4 days. The least
stable is 138Dy, with a half-life of 200
ms. As a general rule, isotopes that are
lighter than the stable isotopes tend to
decay primarily by β+ decay, while those
that are heavier tend to decay by β−
decay. However, 154Dy decays primarily
by alpha decay, and 152Dy and 159Dy
decay primarily by electron capture.
Dysprosium also has at least 11
metastable isomers, ranging in atomic
mass from 140 to 165. The most stable of
these is 165mDy, which has a half-life
of 1.257 minutes. 149Dy has two
metastable isomers, the second of which,
149m2Dy, has a half-life of 28 ns.
History 
In 1878, erbium ores were found to
contain the oxides of holmium and
thulium. French chemist Paul Émile Lecoq
de Boisbaudran, while working with
holmium oxide, separated dysprosium
oxide from it in Paris in 1886. His
procedure for isolating the dysprosium
involved dissolving dysprosium oxide in
acid, then adding ammonia to precipitate
the hydroxide. He was only able to
isolate dysprosium from its oxide after
more than 30 attempts at his procedure.
On succeeding, he named the element
dysprosium from the Greek dysprositos,
meaning "hard to get". However, the
element was not isolated in relatively
pure form until after the development of
ion exchange techniques by Frank
Spedding at Iowa State University in the
early 1950s.
In 1950, Glenn T. Seaborg, Albert
Ghiorso, and Stanley G. Thompson
bombarded 241Am with helium ions, which
produced atoms with an atomic number of
97 and which closely resembled the
neighboring lanthanide terbium. Because
terbium was named after Ytterby, the
city in which it and several other
elements were discovered, this new
element was named berkelium for the city
in which it was synthesized. However,
when the research team synthesized
element 98, they could not think of a
good analogy for dysprosium, and instead
named the element californium in honor
of the state in which it was
synthesized, California. The research
team went on to "point out that, in
recognition of the fact that dysprosium
is named on the basis of a Greek word
meaning 'difficult to get at,' that the
searchers for another element a century
ago found it difficult to get to
California".
Occurrence 
While Dysprosium is never encountered as
a free element, it is found in many
minerals, including xenotime,
fergusonite, gadolinite, euxenite,
polycrase, blomstrandine, monazite and
bastnäsite; often with erbium and
holmium or other rare earth elements.
Currently, most dysprosium is being
obtained from the ion-adsorption clay
ores of southern China, and future
sources will include the Halls Creek
region in Western Australia. In the
high-yttrium version of these,
dysprosium happens to be the most
abundant of the heavy lanthanides,
comprising up to 7–8% of the
concentrate. The concentration of Dy in
the Earth crust is about 5.2 mg/kg and
in sea water 0.9 ng/L.
Production 
Dysprosium is obtained primarily from
monazite sand, a mixture of various
phosphates. The metal is obtained as a
by-product in the commercial extraction
of yttrium. In isolating dysprosium,
most of the unwanted metals can be
removed magnetically or by a flotation
process. Dysprosium can then be
separated from other rare earth metals
by an ion exchange displacement process.
The resulting dysprosium ions can then
react with either fluorine or chlorine
to form dysprosium fluoride, DyF3, or
dysprosium chloride, DyCl3. These
compounds can be reduced using either
calcium or lithium metals in the
following reactions:
3 Ca + 2 DyF3 → 2 Dy + 3 CaF2
3 Li + DyCl3 → Dy + 3 LiCl
The components are placed in a tantalum
crucible and fired in a helium
atmosphere. As the reaction progresses,
the resulting halide compounds and
molten dysprosium separate due to
differences in density. When the mixture
cools, the dysprosium can be cut away
from the impurities.
About 100 tonnes of dysprosium are
produced worldwide each year, with 99%
of that total produced in China.
Dysprosium prices have climbed nearly
twentyfold, from $7 per pound in 2003,
to $130 a pound in late 2010. According
to the United States Department of
Energy, the wide range of its current
and projected uses, together with the
lack of any immediately suitable
replacement, makes dysprosium the single
most critical element for emerging clean
energy technologies - even their most
conservative projections predict a
shortfall of dysprosium before 2015. As
of late 2015, there is a nascent rare
earth extraction industry in Australia.
Applications 
There are not many applications unique
to dysprosium. Theodore Gray wrote in
his book The Elements: A Visual
Exploration of Every Known Atom in the
Universe "Look up dysprosium, and you
have to go to the fourth page of results
before finding anything that isn't a
periodic table website's entry for
dysprosium, usually an obligatory 'It's
an element, so we have to have a page
about it' sort of page."
Dysprosium is used, in conjunction with
vanadium and other elements, in making
laser materials and commercial lighting.
Because of dysprosium's high
thermal-neutron absorption
cross-section, dysprosium-oxide–nickel
cermets are used in neutron-absorbing
control rods in nuclear reactors.
Dysprosium–cadmium chalcogenides are
sources of infrared radiation, which is
useful for studying chemical reactions.
Because dysprosium and its compounds are
highly susceptible to magnetization,
they are employed in various
data-storage applications, such as in
hard disks.
Neodymium–iron–boron magnets can have up
to 6% of the neodymium substituted by
dysprosium to raise the coercivity for
demanding applications, such as drive
motors for electric vehicles. This
substitution would require up to 100
grams of dysprosium per car produced.
Based on Toyota's projected 2 million
units per year, the use of dysprosium in
applications such as this would quickly
exhaust its available supply. The
dysprosium substitution may also be
useful in other applications, because it
improves the corrosion resistance of the
magnets.
Dysprosium is one of the components of
Terfenol-D, along with iron and terbium.
Terfenol-D has the highest
room-temperature magnetostriction of any
known material; which is employed in
transducers, wide-band mechanical
resonators, and high-precision
liquid-fuel injectors.
Dysprosium is used in dosimeters for
measuring ionizing radiation. Crystals
of calcium sulfate or calcium fluoride
are doped with dysprosium. When these
crystals are exposed to radiation, the
dysprosium atoms become excited and
luminescent. The luminescence can be
measured to determine the degree of
exposure to which the dosimeter has been
subjected.
Nanofibers of dysprosium compounds have
high strength and a large surface area.
Therefore, they can be used to reinforce
other materials and act as a catalyst.
Fibers of dysprosium oxide fluoride can
be produced by heating an aqueous
solution of DyBr3 and NaF to 450 °C at
450 bar for 17 hours. This material is
remarkably robust, surviving over 100
hours in various aqueous solutions at
temperatures exceeding 400 °C without
redissolving or aggregating.
Dysprosium iodide and dysprosium bromide
are used in high-intensity metal-halide
lamps. These compounds dissociate near
the hot center of the lamp, releasing
isolated dysprosium atoms. The latter
re-emit light in the green and red part
of the spectrum, thereby effectively
producing bright light.
Several paramagnetic crystal salts of
dysprosium are used in adiabatic
demagnetization refrigerators.
Precautions 
Like many powders, dysprosium powder may
present an explosion hazard when mixed
with air and when an ignition source is
present. Thin foils of the substance can
also be ignited by sparks or by static
electricity. Dysprosium fires cannot be
put out by water. It can react with
water to produce flammable hydrogen gas.
Dysprosium chloride fires, however, can
be extinguished with water, while
dysprosium fluoride and dysprosium oxide
are non-flammable. Dysprosium nitrate,
Dy(NO3)3, is a strong oxidizing agent
and will readily ignite on contact with
organic substances.
Soluble dysprosium salts, such as
dysprosium chloride and dysprosium
nitrate, are mildly toxic when ingested.
The insoluble salts, however, are
non-toxic. Based on the toxicity of
dysprosium chloride to mice, it is
estimated that the ingestion of 500
grams or more could be fatal to a human.
See also 
Lanthanide
References 
External links 
WebElements.com – Dysprosium
It's Elemental – Dysprosium
