Zinc oxide is an inorganic compound with the
formula ZnO. ZnO is a white powder that is
insoluble in water, and it is widely used
as an additive in numerous materials and products
including rubbers, plastics, ceramics, glass,
cement, lubricants, paints, ointments, adhesives,
sealants, pigments, foods, batteries, ferrites,
fire retardants, and first-aid tapes. It occurs
naturally as the mineral zincite, but most
zinc oxide is produced synthetically.
In materials science, ZnO is a wide-bandgap
semiconductor of the II-VI semiconductor group
of the periodic table and zinc, a transition
metal, as a member of the IIB, now 12th, group).
The native doping of the semiconductor is
n-type. This semiconductor has several favorable
properties, including good transparency, high
electron mobility, wide bandgap, and strong
room-temperature luminescence. Those properties
are used in emerging applications for transparent
electrodes in liquid crystal displays, in
energy-saving or heat-protecting windows,
and in electronics as thin-film transistors
and light-emitting diodes.
Chemical properties
ZnO occurs as a white powder. The mineral
zincite usually contains manganese and other
impurities that confer a yellow to red color.
Crystalline zinc oxide is thermochromic, changing
from white to yellow when heated and in air
reverting to white on cooling. This color
change is caused by a small loss of oxygen
to the environment at high temperatures to
form the non-stoichiometric Zn1+xO, where
at 800 °C, x = 0.00007.
Zinc oxide is an amphoteric oxide. It is nearly
insoluble in water, but it is soluble in most
acids, such as hydrochloric acid:
ZnO + 2 HCl → ZnCl2 + H2O
Bases also degrade the solid to give soluble
zincates:
ZnO + 2 NaOH + H2O → Na2[Zn(OH)4]
ZnO reacts slowly with fatty acids in oils
to produce the corresponding carboxylates,
such as oleate or stearate. ZnO forms cement-like
products when mixed with a strong aqueous
solution of zinc chloride and these are best
described as zinc hydroxy chlorides. This
cement was used in dentistry.
ZnO also forms cement-like material when treated
with phosphoric acid; related materials are
used in dentistry. A major component of zinc
phosphate cement produced by this reaction
is hopeite, Zn3(PO4)2·4H2O.
ZnO decomposes into zinc vapor and oxygen
at around 1975 °C with a standard oxygen
pressure. In a carbothermic reaction, heating
with carbon converts the oxide into zinc vapor
at a much lower temperature.
ZnO + C → Zn(Vapor) + CO
Zinc oxide can react violently with aluminium
and magnesium powders, with chlorinated rubber
and linseed oil on heating causing fire and
explosion hazard.
It reacts with hydrogen sulfide to give the
sulfide. This reaction is used commercially.
ZnO + H2S → ZnS + H2O
Physical properties
Structure
Zinc oxide crystallizes in two main forms,
hexagonal wurtzite and cubic zincblende. The
wurtzite structure is most stable at ambient
conditions and thus most common. The zincblende
form can be stabilized by growing ZnO on substrates
with cubic lattice structure. In both cases,
the zinc and oxide centers are tetrahedral,
the most characteristic geometry for Zn(II).
ZnO converts to the rocksalt motif at relatively
high pressures about 10 GPa.
Hexagonal and zincblende polymorphs have no
inversion symmetry. This and other lattice
symmetry properties result in piezoelectricity
of the hexagonal and zincblende ZnO, and pyroelectricity
of hexagonal ZnO.
The hexagonal structure has a point group
6 mm or C6v, and the space group is P63mc
or C6v4. The lattice constants are a = 3.25
Å and c = 5.2 Å; their ratio c/a ~ 1.60
is close to the ideal value for hexagonal
cell c/a = 1.633. As in most group II-VI materials,
the bonding in ZnO is largely ionic with the
corresponding radii of 0.074 nm for Zn2+
and 0.140 nm for O2–. This property accounts
for the preferential formation of wurtzite
rather than zinc blende structure, as well
as the strong piezoelectricity of ZnO. Because
of the polar Zn-O bonds, zinc and oxygen planes
are electrically charged. To maintain electrical
neutrality, those planes reconstruct at atomic
level in most relative materials, but not
in ZnO – its surfaces are atomically flat,
stable and exhibit no reconstruction. This
anomaly of ZnO is not fully explained yet.
Mechanical properties
ZnO is a relatively soft material with approximate
hardness of 4.5 on the Mohs scale. Its elastic
constants are smaller than those of relevant
III-V semiconductors, such as GaN. The high
heat capacity and heat conductivity, low thermal
expansion and high melting temperature of
ZnO are beneficial for ceramics. ZnO exhibits
a very long lived optical phonon E2(low) with
a lifetime as high as 133 ps at 10 K
Among the tetrahedrally bonded semiconductors,
it has been stated that ZnO has the highest
piezoelectric tensor, or at least one comparable
to that of GaN and AlN. This property makes
it a technologically important material for
many piezoelectrical applications, which require
a large electromechanical coupling.
Electrical properties
ZnO has a relatively large direct band gap
of ~3.3 eV at room temperature. Advantages
associated with a large band gap include higher
breakdown voltages, ability to sustain large
electric fields, lower electronic noise, and
high-temperature and high-power operation.
The bandgap of ZnO can further be tuned to
~3–4 eV by its alloying with magnesium
oxide or cadmium oxide.
Most ZnO has n-type character, even in the
absence of intentional doping. Nonstoichiometry
is typically the origin of n-type character,
but the subject remains controversial. An
alternative explanation has been proposed,
based on theoretical calculations, that unintentional
substitutional hydrogen impurities are responsible.
Controllable n-type doping is easily achieved
by substituting Zn with group-III elements
such as Al, Ga, In or by substituting oxygen
with group-VII elements chlorine or iodine.
Reliable p-type doping of ZnO remains difficult.
This problem originates from low solubility
of p-type dopants and their compensation by
abundant n-type impurities. This problem is
observed with GaN and ZnSe. Measurement of
p-type in "intrinsically" n-type material
is complicated by the inhomogeneity of samples.
Current limitations to p-doping does not limit
electronic and optoelectronic applications
of ZnO, which usually require junctions of
n-type and p-type material. Known p-type dopants
include group-I elements Li, Na, K; group-V
elements N, P and As; as well as copper and
silver. However, many of these form deep acceptors
and do not produce significant p-type conduction
at room temperature.
Electron mobility of ZnO strongly varies with
temperature and has a maximum of ~2000 cm2/(V·s)
at 80 K. Data on hole mobility are scarce
with values in the range 5–30 cm2/(V·s).
Production
For industrial use, ZnO is produced at levels
of 105 tons per year by three main processes:
Indirect process
In the indirect or French process, metallic
zinc is melted in a graphite crucible and
vaporized at temperatures above 907 °C.
Zinc vapor reacts with the oxygen in the air
to give ZnO, accompanied by a drop in its
temperature and bright luminescence. Zinc
oxide particles are transported into a cooling
duct and collected in a bag house. This indirect
method was popularized by LeClaire in 1844
and therefore is commonly known as the French
process. Its product normally consists of
agglomerated zinc oxide particles with an
average size of 0.1 to a few micrometers.
By weight, most of the world's zinc oxide
is manufactured via French process.
Direct process
The direct or American process starts with
diverse contaminated zinc composites, such
as zinc ores or smelter by-products. The zinc
precursors are reduced by heating with a source
of carbon such as anthracite to produce zinc
vapor, which is then oxidized as in the indirect
process. Because of the lower purity of the
source material, the final product is also
of lower quality in the direct process as
compared to the indirect one.
Wet chemical process
A small amount of industrial production involves
wet chemical processes, which start with aqueous
solutions of purified zinc salts, from which
zinc carbonate or zinc hydroxide is precipitated.
The precipitate is then filtered, washed,
dried and calcined at temperatures around
800 °C.
Laboratory synthesis
A large number of specialised methods exist
for producing ZnO for scientific studies and
niche applications. These methods can be classified
by the resulting ZnO form, temperature, process
type and other parameters.
Large single crystals can be grown by the
gas transport, hydrothermal synthesis, or
melt growth. However, because of high vapor
pressure of ZnO, growth from the melt is problematic.
Growth by gas transport is difficult to control,
leaving the hydrothermal method as a preference.
Thin films can be produced by chemical vapor
deposition, metalorganic vapour phase epitaxy,
electrodeposition, pulsed laser deposition,
sputtering, sol-gel synthesis, atomic layer
deposition, spray pyrolysis, etc.
Ordinary white powdered zinc oxide can be
produced in the laboratory by electrolyzing
a solution of sodium bicarbonate with a zinc
anode. Zinc hydroxide and hydrogen gas are
produced. The zinc hydroxide upon heating
decomposes to zinc oxide.
Zn + 2 H2O → Zn(OH)2 + H2
Zn(OH)2 → ZnO + H2O
ZnO nanostructures
Nanostructures of ZnO can be synthesized into
a variety of morphologies including nanowires,
nanorods, tetrapods, nanobelts, nanoflowers,
nanoparticles etc. Nanostructures can be obtained
with most above-mentioned techniques, at certain
conditions, and also with the vapor-liquid-solid
method.
Rodlike nanostructures of ZnO can be produced
via aqueous methods, which are attractive
for the following reasons: They are low cost,
less hazardous, and thus capable of easy scaling
up; the growth occurs at a relatively low
temperature, compatible with flexible organic
substrates; there is no need for the use of
metal catalysts, and thus it can be integrated
with well-developed silicon technologies.
In addition, there are a variety of parameters
that can be tuned to effectively control the
morphology and properties of the final product.
Wet chemical methods have been demonstrated
as a very powerful and versatile technique
for growing one-dimensional ZnO nanostructures.
The synthesis is typically carried out at
temperatures of about 90 °C, in an equimolar
aqueous solution of zinc nitrate and hexamine,
the latter providing the basic environment.
Certain additives, such as polyethylene glycol
or polyethylenimine, can improve the aspect
ratio of the ZnO nanowires. Doping of the
ZnO nanowires has been achieved by adding
other metal nitrates to the growth solution.
The morphology of the resulting nanostructures
can be tuned by changing the parameters relating
to the precursor composition or to the thermal
treatment.
Aligned ZnO nanowires on pre-seeded silicon,
glass and gallium nitride substrates have
been grown in aqueous solutions using aqueous
zinc salts such as Zinc nitrate and Zinc acetate
in basic environments. Pre-seeding substrates
with ZnO creates sites for homogeneous nucleation
of ZnO crystal during the synthesis. Common
pre-seeding methods include in-situ thermal
decomposition of zinc acetate crystallites,
spincoating of ZnO nanoparticles and the use
of physical vapor deposition methods to deposit
ZnO thin films. Pre-seeding can be performed
in conjunction with top down patterning methods
such as electron beam lithography and nanosphere
lithography to designate nucleation sites
prior to growth. Aligned ZnO nanowires can
be used in dye-sensitized solar cells and
field emission devices.
History
Zinc compounds were probably used by early
humans, in processed and unprocessed forms,
as a paint or medicinal ointment, but their
composition is uncertain. The use of pushpanjan,
probably zinc oxide, as a salve for eyes and
open wounds, is mentioned in the Indian medical
text the Charaka Samhita, thought to date
from 500 BC or before. Zinc oxide ointment
is also mentioned by the Greek physician Dioscorides
Avicenna mentions zinc oxide in The Canon
of Medicine, which mentioned it as a preferred
treatment for a variety of skin conditions,
including skin cancer. Though it is no longer
used for treating skin cancer, it is still
widely used to treat a variety of other skin
conditions, in products such as baby powder
and creams against diaper rashes, calamine
cream, anti-dandruff shampoos, and antiseptic
ointments.
The Romans produced considerable quantities
of brass as early as 200 BC by a cementation
process where copper was reacted with zinc
oxide. The zinc oxide is thought to have been
produced by heating zinc ore in a shaft furnace.
This liberated metallic zinc as a vapor, which
then ascended the flue and condensed as the
oxide. This process was described by Dioscorides
in the 1st century AD. Zinc oxide has also
been recovered from zinc mines at Zawar in
India, dating from the second half of the
first millennium BC. This was presumably also
made in the same way and used to produce brass.
From the 12th to the 16th century zinc and
zinc oxide were recognized and produced in
India using a primitive form of the direct
synthesis process. From India, zinc manufacture
moved to China in the 17th century. In 1743,
the first European zinc smelter was established
in Bristol, United Kingdom.
The main usage of zinc oxide was in paints
and as an additive to ointments. Zinc white
was accepted as a pigment in oil paintings
by 1834 but it did not mix well with oil.
This problem was quickly solved by optimizing
the synthesis of ZnO. In 1845, LeClaire in
Paris was producing the oil paint on a large
scale, and by 1850, zinc white was being manufactured
throughout Europe. The success of zinc white
paint was due to its advantages over the traditional
white lead: zinc white is essentially permanent
in sunlight, it is not blackened by sulfur-bearing
air, it is non-toxic and more economical.
Because zinc white is so "clean" it is very
valuable for making tints with other colors;
however, it makes a rather brittle dry film
when unmixed with other colors. For example,
during the late 1890s and early 1900s, some
artists used zinc white as a ground for their
oil paintings. All those paintings developed
cracks over the years.
In the recent times, most zinc oxide was used
in the rubber industry. In the 1970s, the
second largest application of ZnO was photocopying.
High-quality ZnO produced by the "French process"
was added into the photocopying paper as a
filler. This application was however soon
displaced.
Applications
The applications of zinc oxide powder are
numerous, and the principal ones are summarized
below. Most applications exploit the reactivity
of the oxide as a precursor to other zinc
compounds. For material science applications,
zinc oxide has high refractive index, high
thermal conductivity, binding, antibacterial
and UV-protection properties. Consequently,
it is added into materials and products including
plastics, ceramics, glass, cement, rubber,
lubricants, paints, ointments, adhesive, sealants,
concrete manufacturing, pigments, foods, batteries,
ferrites, fire retardants, etc.
Rubber manufacture
Between 50% and 60% of ZnO use is in the rubber
industry. Zinc oxide along with stearic acid
is used in the vulcanization of rubber ZnO
additive also protect rubber from fungi and
UV light.
Ceramic industry
Ceramic industry consumes a significant amount
of zinc oxide, in particular in ceramic glaze
and frit compositions. The relatively high
heat capacity, thermal conductivity and high
temperature stability of ZnO coupled with
a comparatively low coefﬁcient of expansion
are desirable properties in the production
of ceramics. ZnO affects the melting point
and optical properties of the glazes, enamels,
and ceramic formulations. Zinc oxide as a
low expansion, secondary ﬂux improves the
elasticity of glazes by reducing the change
in viscosity as a function of temperature
and helps prevent crazing and shivering. By
substituting ZnO for BaO and PbO, the heat
capacity is decreased and the thermal conductivity
is increased. Zinc in small amounts improves
the development of glossy and brilliant surfaces.
However in moderate to high amounts, it produces
matte and crystalline surfaces. With regard
to color, zinc has a complicated inﬂuence.
Medicine
Zinc oxide as a mixture with about 0.5% iron(III)
oxide is called calamine and is used in calamine
lotion. Two minerals, zincite and hemimorphite,
have been historically called calamine. When
mixed with eugenol, a ligand, zinc oxide eugenol
is formed, which has applications as a restorative
and prosthodontic in dentistry.
Reflecting the basic properties of ZnO, fine
particles of the oxide have deodorizing and
antibacterial properties and for that reason
are added into materials including cotton
fabric, rubber, oral care products, and food
packaging. Enhanced antibacterial action of
fine particles compared to bulk material is
not exclusive to ZnO and is observed for other
materials, such as silver. This property is
due to the increased surface area of the fine
particles.
Zinc oxide is widely used to treat a variety
of other skin conditions, in products such
as baby powder and barrier creams to treat
diaper rashes, calamine cream, anti-dandruff
shampoos, and antiseptic ointments. It is
also a component in tape used by athletes
as a bandage to prevent soft tissue damage
during workouts.
Zinc oxide can be used in ointments, creams,
and lotions to protect against sunburn and
other damage to the skin caused by ultraviolet
light. It is the broadest spectrum UVA and
UVB reflector that is approved for use as
a sunscreen by the FDA, and is completely
photostable. When used as an ingredient in
sunscreen, zinc oxide blocks both UVA and
UVB rays of ultraviolet light. Zinc oxide
and the other most common physical sunscreen,
titanium dioxide, are considered to be nonirritating,
nonallergenic, and non-comedogenic. Zinc from
zinc oxide is, however, slightly absorbed
into the skin
Many sunscreens use nanoparticles of zinc
oxide because such small particles do not
scatter light and therefore do not appear
white. There has been concern that they might
be absorbed into the skin, a study published
in 2010 found a 0.23% to 1.31% of blood zinc
levels in venous blood samples could be traced
to zinc from ZnO nanoparticles applied to
human skin for 5 days, and traces were also
found in urine samples. In contrast, a comprehensive
review of the medical literature from 2011
says that no evidence of systemic absorption
can be found in the literature.
Zinc oxide nanoparticles can enhance the antibacterial
activity of Ciprofloxacin. It has been shown
that nano ZnO which has the average size between
20 nm and 45 nm can enhance the antibacterial
activity of Ciprofloxacin against Staphylococcus
aureus and Escherichia coli in Vitro. The
enhancing effect of this nanomaterial is concentration-dependent
against all test strains. This effect may
be due to two reasons. First, Zinc Oxide nanoparticles
can interfere with NorA protein. NorA is a
protein which is developed for conferring
resistance in bacteria and has pumping activity
that mediate the effluxing of hydrophilic
fluroquinolones from a cell. Second, Zinc
Oxide nanoparticles can interfere with Omf
protein. Omf is a membrane protein that is
responsible for the permeation of quinolones
into the cell.
Cigarette filters
Zinc oxide is a constituent of cigarette filters.
A filter consisting of charcoal impregnated
with zinc oxide and iron oxide removes significant
amounts of HCN and H2S from tobacco smoke
without affecting its flavor.
Food additive
Zinc oxide is added to many food products,
including breakfast cereals, as a source of
zinc, a necessary nutrient. Some prepackaged
foods also include trace amounts of ZnO even
if it is not intended as a nutrient.
Zinc oxide was linked to dioxin contamination
in pork exports in the 2008 Chilean pork crisis.
The contamination was found to be due to dioxin
contaminated zinc oxide used in pig feed.
Pigment
Zinc white is used as a pigment in paints
and is more opaque than lithopone, but less
opaque than titanium dioxide. It is also used
in coatings for paper. Chinese white is a
special grade of zinc white used in artists'
pigments. It is also a main ingredient of
mineral makeup.
UV absorber
Micronized and nano-scale zinc oxide and titanium
dioxide provide strong protection against
UVA ultraviolet radiation, and are used in
suntan lotion, and also in UV-blocking sunglasses
for use in space and for protection when welding,
following research by scientists at JPL.
Coatings
Paints containing zinc oxide powder have long
been utilized as anticorrosive coatings for
metals. They are especially effective for
galvanized iron. Iron is difficult to protect
because its reactivity with organic coatings
leads to brittleness and lack of adhesion.
Zinc oxide paints retain their flexibility
and adherence on such surfaces for many years.
ZnO highly n-type doped with Al, Ga, or In
is transparent and conductive. ZnO:Al coatings
are used for energy-saving or heat-protecting
windows. The coating lets the visible part
of the spectrum in but either reflects the
infrared radiation back into the room or does
not let the IR radiation into the room, depending
on which side of the window has the coating.
Plastics, such as polyethylene naphthalate,
can be protected by applying zinc oxide coating.
The coating reduces the diffusion of oxygen
with PEN. Zinc oxide layers can also be used
on polycarbonate in outdoor applications.
The coating protects PC from solar radiation
and decreases the oxidation rate and photo-yellowing
of PC.
Corrosion prevention in nuclear reactors
Zinc oxide depleted in the zinc isotope with
the atomic mass 64 is used in corrosion prevention
in nuclear pressurized water reactors. The
depletion is necessary, because 64Zn is transformed
into radioactive 65Zn under irradiation by
the reactor neutrons.
Methane reforming
Zinc oxide is used as a pretreatment step
to remove hydrogen sulfide from natural gas
following hydrogenation of any sulfur compounds
prior to a methane reformer, which can poison
the catalyst. At temperatures between about
230–430 °C, H2S is converted to water
by the following reaction:
H2S + ZnO → H2O + ZnS
The zinc sulfide is replaced with fresh zinc
oxide when the zinc oxide has been consumed.
Potential applications
Electronics
ZnO has wide direct band gap. Therefore, its
most common potential applications are in
laser diodes and light emitting diodes. Some
optoelectronic applications of ZnO overlap
with that of GaN, which has a similar bandgap.
Compared to GaN, ZnO has a larger exciton
binding energy, which results in bright room-temperature
emission from ZnO. ZnO can be combined with
GaN for LED-applications. For instance as
TCO layer and ZnO nanostructures provide better
light outcoupling. Other properties of ZnO
favorable for electronic applications include
its stability to high-energy radiation and
to wet chemical etching. Radiation resistance
makes ZnO a suitable candidate for space applications.
ZnO is the most promising candidate in the
field of random lasers to produce an electronically
pumped UV laser source.
The pointed tips of ZnO nanorods result in
a strong enhancement of an electric field.
Therefore, they can be used as field emitters.
Aluminium-doped ZnO layers are used as a transparent
electrodes. The constituents Zn and Al are
much cheaper and less toxic compared to the
generally used indium tin oxide. One application
which has begun to be commercially available
is the use of ZnO as the front contact for
solar cells or of liquid crystal displays.
Transparent thin-film transistors can be produced
with ZnO. As field-effect transistors, they
even may not need a p–n junction, thus avoiding
the p-type doping problem of ZnO. Some of
the field-effect transistors even use ZnO
nanorods as conducting channels.
Zinc oxide nanorod sensor
Zinc oxide nanorod sensors are devices detecting
changes in electrical current passing through
zinc oxide nanowires due to adsorption of
gas molecules. Selectivity to hydrogen gas
was achieved by sputtering Pd clusters on
the nanorod surface. The addition of Pd appears
to be effective in the catalytic dissociation
of hydrogen molecules into atomic hydrogen,
increasing the sensitivity of the sensor device.
The sensor detects hydrogen concentrations
down to 10 parts per million at room temperature,
whereas there is no response to oxygen.
Spintronics
ZnO has also been considered for spintronics
applications: if doped with 1–10% of magnetic
ions, ZnO could become ferromagnetic, even
at room temperature. Such room temperature
ferromagnetism in ZnO:Mn has been observed,
but it is not clear yet whether it originates
from the matrix itself or from secondary oxide
phases.
Piezoelectricity
The piezoelectricity in textile fibers coated
in ZnO have been shown capable of fabricating
"self-powered nanosystems" with everyday mechanical
stress from wind or body movements.
In 2008 the Center for Nanostructure Characterization
at the Georgia Institute of Technology reported
producing an electricity generating device
delivering alternating current by stretching
and releasing zinc oxide nanowires. This mini-generator
creates an oscillating voltage up to 45 millivolts,
converting close to seven percent of the applied
mechanical energy into electricity. Researchers
used wires with lengths of 0.2–0.3 mm and
diameters of three to five micrometers, but
the device could be scaled down to smaller
size.
Safety
As a food additive, zinc oxide is on the U.S.
FDA's list of generally recognized as safe,
or GRAS, substances.
Zinc oxide itself is non-toxic; however it
is hazardous to inhale zinc oxide fumes, as
generated when zinc or zinc alloys are melted
and oxidized at high temperature. This problem
occurs while melting brass because the melting
point of brass is close to the boiling point
of zinc. Exposure to zinc oxide in the air,
which also occurs while welding galvanized
steel, can result in a nervous malady called
metal fume fever. For this reason, typically
galvanized steel is not welded, or the zinc
is removed first.
See also
References
Reviews
U. Ozgur et al. "A comprehensive review of
ZnO materials and devices" J. Appl. Phys.
98 041301 doi:10.1063/1.1992666
A. Bakin and A. Waag "ZnO Epitaxial Growth"
Chapter in “Comprehensive Semiconductor
Science and Technology“ 6 Volume Encyclopaedia,
ELSEVIER, edited by Pallab Bhattacharya, Roberto
Fornari and Hiroshi Kamimura, ISBN 978-0-444-53143-8
S. Baruah and J. Dutta "Hydrothermal growth
of ZnO nanostructures" Sci. Technol. Adv.
Mater. 10 013001 doi:10.108810013001
R. Janisch et al. "Transition metal-doped
TiO2 and ZnO—present status of the field"
J. Phys.: Condens. Matter 17 R657 doi:10.108817R01
Y.W. Heo et al. "ZnO nanowire growth and devices"
Mater. Sci. Eng. R 47 1 doi:10.1016/j.mser.2004.09.001
C. Klingshirn "ZnO: From basics towards applications"
Phys. Stat. Solidi 244 3027 doi:10.1002/pssb.200743072
C. Klingshirn "ZnO: Material, Physics and
Applications" ChemPhysChem 8 782 doi:10.1002/cphc.200700002
J. G. Lu et al. "Quasi-one-dimensional metal
oxide materials—Synthesis, properties and
applications" Mater. Sci. Eng. R 52 49 doi:10.1016/j.mser.2006.04.002
S. Xu and Z. L. Wang "One-dimensional ZnO
nanostructures: Solution growth and functional
properties" Nano Res. 4 1013 doi:10.1007/s12274-011-0160-7
S. Xu and Z. L. Wang "Oxide nanowire arrays
for light-emitting diodes and piezoelectric
energy harvesters" Pure Appl. Chem. 83 2171
doi:10.1351/PAC-CON-11-08-17
External links
Zincite properties
International Chemical Safety Card 0208.
NIOSH Pocket Guide to Chemical Hazards.
Pesticide Properties DataBase record for Zinc
oxide
