WO2016200349A1 - LONG-LASTING YELLOWISH-GREEN EMITTING PHOSPHORESCENT PIGMENTS IN THE STRONTIUM ALUMINATE [SrAl2O4] SYSTEM - Google Patents
LONG-LASTING YELLOWISH-GREEN EMITTING PHOSPHORESCENT PIGMENTS IN THE STRONTIUM ALUMINATE [SrAl2O4] SYSTEM Download PDFInfo
- Publication number
- WO2016200349A1 WO2016200349A1 PCT/TR2015/050005 TR2015050005W WO2016200349A1 WO 2016200349 A1 WO2016200349 A1 WO 2016200349A1 TR 2015050005 W TR2015050005 W TR 2015050005W WO 2016200349 A1 WO2016200349 A1 WO 2016200349A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- long
- mentioned
- proper
- lasting
- yellowish
- Prior art date
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
- C09K11/7783—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals containing two or more rare earth metals one of which being europium
- C09K11/7792—Aluminates
Abstract
Long lasting yellowish-green emitting phosphorescent pigments in the strontium aluminate (SrAl2O4) system. This invention is about pigments with phosphorescence property, having long lasting luminescence of bluish-green colour in the dark and wide usage areas requesting optimum specifications in the product obtained.
Description
This invention is related with pigments, having
phosphorescence property, that can glow longterm in the
dark, glowing yellowish-green, having optimum
characteristics for optained product and production method
and having a wealth of usage areas.
Phosphorescence (or afterglow) refers to the light
emissionof an insulator that persists at room temperature
after stoppingexcitation (usually UV irradiation). This
delayed light
emission arises from the fact that charge carriers
(i.e.,electrons and/or holes) generated by the excitation
are trappedat certain defect sites, and their detrapping is
thermallyactivated. Phosphorescence event, besides
luminescence center, requires the presence of discrete
layers in forbidden bandgap related with chemical and
physical defects (contributions and gaps) in the main
lattice. Some electrons and gaps occuring with excitation
under UV emission are entrapped at these kind of layers.
According to these defects and dimensional split between
luminescence centers or more precisely direct re-combination
has low possibility in the lack of orbital overlaps. As a
result, the trapped charge carriers stay at metastable state
unless there is not enough energy to trigger of reunification.
Phosphorescent pigments that absorb a certain
wavelength of light emit to surrounding when the light
source is removed.
In recent years the strontium aluminate hosts such
as
Sr4Al14O25:Eu2+,Dy3+
and SrAl2O4: Eu2+,
Dy3+ had been studied intentionally as their
advantages of high quantum efficiency, long lasting
phosphorescence and stability.
SrAl2O4,
SrAl12O19,
Sr2Al6O11 and
Sr4Al14O25 phases in the
SrO-Al2O3 system are well known 4 main
crystals. The green emission from SrAl2O4
crystal phasethat Eu2+ and Dy3+
ions are used as co-dopants and obtained by re-cyrstallizing
of utilizing melting property of B2O3
is known as long-afterglow phosphor. The phosphorescence
characteristics of
SrAl2O4:Eu2+,
Dy3+ system are explained as a mechanism which
occurs with thermal emissions of charge carriers and traps
at room temperature where Dy3+ ion is functioned
as trappingcenter and Eu2+ ion is emission
center. It is also observed that B2O3
improved the long lasting luminescence of phosphor system.
B2O3 is used as high temperature
melter in reducing atmosphere to quicken the growth of
particles of strontium aluminate. This had increased the
penetration of trapping centers in ceramics. Improvement of
brightness and long term luminescence is provided by doping
the SrAl2O4:Eu2+,
Dy3+ lattice with univalent ions such as
K+ and Na+ or bivalent ions like
Mg2+ and Zn2+. This kind of balancing
decreases charge defects by taking place of trivalent rare
earth ions in alkaline earth ion areas inside aluminate. In
the studies performed by Han et al. the optimum
concentrations were set as 2, 4, 6 mole % of Eu2+
, Dy3+and B2O3
respectively for optimum phosphorescent properties in
SrAl2O4. Apart from this 4 moles %
Mg2+ ion doping had provided the improvement in
the luminescence. The improvement of photoluminescence and
long lasting luminescence properties with doping
B2O3had been based to liquid phase
sintering at 1350 oC. The presence of charge
stabilizer Mg2+ is for the decrease of the
defects of interstitial oxygen which lead to the reduction
in phosphorescence.
During studies performed,
SrAl2O4, CaAl2O4
and BaAl2O4 had been chosen as
different crystal stucture materials, dopped with rare earth
elements (Eu, Dy) as activator and sub-activator. Generally
MAl2O4: Dy (M: Ca, Sr, Ba) developed
phosphors are synthesized by traditional methods. Studies
have shown that prepared MAl2O4: Dy
(M: Ca, Sr, Ba) phosphors have not exhibited luminescence
behavior. This situation supports the approach that occurs
related to the 5d → transition of Eu2+ ions of
main emission peaks. Actually,
CaAl2O4, SrAl2O4
and BaAl2O4 main crystals have
tridimit form and main structure containing AlO4
5- tetrahedras and M2+
(Ca2+, Sr2+, Ba2+) ions
which support the charges in the holes. Emission spectrum
depends on the structure of main lattice and alkali ion
selection. If it is necessary to submit an example of
MAl12O19:Eu (M: Ca, Sr, Ba) phosphors,
the main emission peaks are 410, 395 and 443 nm.
MAl2O4 main crystals consist of three
dimensional structures of AlO4 tetrahedras shared
from corners each one of oxygen is shared by two aluminium
ion and each one of tetrahedron has a negative charge. The
charge balance is completed by bivalent large cations
(Ca2+, Sr2+ and Ba2+) which
hold interstitial sites in the tetrahedral structure and
tetrahedral structure having tridymite structure. Therefore,
the emission spectrums are similar to each other.
According to XRD patterns of
MAl2O4: Eu, Dy (M: Ca, Sr, Ba)
phosphors, SrAl2O4 has two phases as
high temperature hexagonal (β-phase) and low temperature
monoclinic (α-phase) forms. Phase transition temperature is
650 ˚C. The crystal structure of
β-SrAl2O4 is very similar to that of
BaAl2O4. Because the ionic radius of
Ba2+ ion (0.135 nm) is almost the same with
Sr2+ (0.127 nm) and O2- (0.135 nm)
ions. Ba2+ and Sr2+ ions are
convenient for packing of O2- ions.
Ca2+ ion is quite small which results
deterioration in the structure. It’s a known fact that the
Eu2+ ions settle in M2+ locations in
MAl2O4main crystals. The radius of
Ba2+ and Sr2+ ions are almost the same
with that of Eu2+, but the radius of
Ca2+ ion (0.112 nm) is 85 % smaller than that of
Eu2+ ion (0.130). Therefore, the crystallographic
deteriorations will affect the crystal area in
Eu2+ location. As a function of crystal area
resistance (Δ), the schematic representation of the energy
level of Eu2+ ion in MAl2O4
main crystal is as shown in Figure 1.
This figure shows the change in emission peaks of
different crystal structures.
According to the research of Abbruscato, the
SrAl2O4: Eu phosphors photocariers
form with irregular UV irradiation and Halt effected
mesaurements have shown that holes are conductive while
under UV excitation. This situtation arises from two
different centers as emission center of Eu2+ and
Dy3+ traps. Therefore, phosphorescence mechanism
of phosphors system can be explained the excitation of UV,
4f→5d direct transition and production of many holes,
respectively. Some of the free holes thermally released to
valence band and at the same time are trapped by
Dy3+as being carried to valence band.
Eu1+ becomes metastable [(Eu1+)] when
excitation source is removed. The trapped holes release
thermally to valence band and combine with residual
electrons in metastable [(Eu1+)] location which
move together. Schematic representation of luminescence
mechanism is given in Figure 2.
As a result of studies performed, Dy3+
trap depths in MAl2O4: Eu, Dy
phosphors are listed in the order of
BaAl2O4 main crystal >
CaAl2O4 main crystal >
SrAl2O4 main crystal (Figure 3). In
this case, if releasing of trapped holes and occured traps
are deeper in the main crystal, it is more difficult for
them to reunite. The initial luminescence intensity and
persistent property of SrAl2O4: Eu, Dy
between these three phosphors in
MAl2O4: Eu, Dy system are much more
than others. The reasons can be more appropriate level of
Dy3+ trap depthsand location of Eu2+
ion in SrAl2O4 main crystal.
Phosphorescence observations are done for
monoclinic phase of SrAl2O4:
Eu2+ phosphors prepared in thin layers or in
crystallized form by solid-state reactions (sintering for
couple of hours at 1300 ˚C), sol-gel methods (at 1150 ˚C),
microwave method and combustion method. It goes in to
europium as Eu3+ (Eu2O3)
which is in the form of oxidizing and phosphorescence
observed after this reduction process is performed. The
luminescence mesaurements showed that europium is mainly
reduced (Eu2+) after this reduction process. But
according to Mössbauer measurements, approximately 5-10 mole
% of Eu3+ took place in the system (residual
Eu3+). The Dy3+ co-dopant is
stabilized for XANES measurements.
There are identical coordination numbers (as 6+1)
of Sr2+, two different crystallographic locations
which have similar average Sr – O internal (2.695 Å and
2.667 Å) and each one of them has similar average Sr – O
internal (Wyckoff 2a position). This two media are seperated
from each other only by a little distortion of square
planes. Size of Sr2+ and Eu2+ ions are
very similar to one another (1.20 and 1,21 Å respectively).
Apart from this, when crystallographic location of
Sr2+ is occupied by Eu2+ ions, it will
have a very similar local distortion. Therefore,
Eu2+ ions settled in two different Sr2+locations.
Locations of dopants and co-dopants of
SrAl2O4 are determined according to
ionic radius. Eu2+ (1.20 Å), Eu3+
(1.01 Å) and Dy3+ (0.97 Å) ions can be easly
substituted Sr2+ (1.21 Å) ions. Two different
locations of Sr2+ are different from each other
in crystallograpy. Therefore, it is expected from
Eu2+ ions to be available in both locations. EPR
measurements have supported this expectation. Also, it is a
known fact that it is possible to show the ionic radius of
Sr2+ and Eu2+ ions which are very
close to each other when the reduction of Eu3+
ions as Eu2+ in Sr2+ locations.
Moreover, the B3+ co-dopant ions (0.11 Å) occupy
locations of Al3+ ions and this was supported by
IR and NMR measurements. But, due to the difference between
ionic radius, replacement of B3+ ions with
Al3+ ions will cause strong local stresses. Later
on, these stresses needs a partial release by occurence of
triangular planar BO3 units according to IR and
NMR measurements.
So far, different mechanisms have been proposed to
explain the phosphorescence of co-doped
SrAl2O4:Eu2+. One of them
studied by Matsuzawa et al. developed for
SrAl2O4: Eu2+system depends
on photoconductivity works of powder samples in the
SrAl2O4: Eu2+ system. This
event shows that UV irradiation causes photoconductivity in
hole type, so establishes the presence of hole trap (or
held) (Figure 4).
Excitation and emission spectrums are related with
Eu2+ ion;
[Chem. 1]
Eu 2 + (4f 7 ) + hv Eu 2 + * (4f 6 5d 1 )
[Chem. 2]
Eu 2 + * (4f 6 5d 1 ) Eu 2 + (4f 7 ) hv’
transformations indicates this event.
[Chem. 1]
Eu 2 + (4f 7 ) + hv Eu 2 + * (4f 6 5d 1 )
[Chem. 2]
Eu 2 + * (4f 6 5d 1 ) Eu 2 + (4f 7 ) hv’
transformations indicates this event.
According to Matsuzawa et al. origin of the holes
is capturing of electrons from the valence band by the
Eu2+* ions, and the co-dopants Dy3+
trap these holes.
[Chem. 3]
Dy 3 + (4f 9 ) + h + Dy 4 + (4f 8 )
[Chem. 3]
Dy 3 + (4f 9 ) + h + Dy 4 + (4f 8 )
The transformation above depicts the best way and
the return of trapped holes for the distorted emission to Eu
location is started by the supports of electrons thermally
applied to Dy4+ from highest valence band. It is
also mentioned by other researches that trapped holes are
created by cationic holes. Matsuzawa et. al submitted two
important assumptions on their mechanisms; top or bottom
level of 4f7 arrangements of Eu2+ is
in a similar energy to valence band (0.06 eV) and
Eu2+ ion excited by irradiation transform to
Eu1+ by catching an electron;
[Chem. 4]
Eu 2 + (4f 6 5d 1 ) + e - Eu + (4f 7 5d 1 )
[Chem. 4]
Eu 2 + (4f 6 5d 1 ) + e - Eu + (4f 7 5d 1 )
It is observed that mechanism of Matsuzawa et. al
and all phosphorescence mechanisms mentioned in the
literature are not compatible with each other according to
the experimental and theoric observations.A new
phophorescence mechanism development became significant
being consistent with each other by experimental and theoric
observations for the SrAl2O4 system,
with or without adding Dy3+ and/or B3+
co-dopants. The Eu2+concentration reduces under
UV excitation in the new mechanism seen in Figure 5.This
mechanism depends on the arguments that phosphorescence
samples consist of Eu3+ ion and it is infact d
orbitals of Eu2+ settles on near the bottom
conduction band of SrAl2O4 as
imposibility of reduction of all Eu3+ ions to
Eu2+ in synthetic conditions.
Electrons under UV irradiation take position from
occupied level to empty 5d level of Eu2+ ion and
from top valence band to unoccupied level of remained
Eu3+.While holes created in valence band can trap
in VSr or VAl level, the electrons are
risen to level 5d can trap in VO defects which
settle arround Eu3+ cations. Remained
Eu3+ ion is reduced to Eu2+ while
Eu2+ is oxidizing to Eu3+ during this
trapping process, thermal energy causes release of trapped
electrons to 5d level of Eu3+ ions.By this way,
green phosphorescence occurs by transition of
4f65d1 4f7
(8S7/2). The blue emission in 450 nm
wavelength which only observed at low temperature (less than
150 K) possibly occurs because of the charge transfer to
valence band from main level of 4f7 arrangements
of Eu2+ and related to hole releasing mechanism.
The luminescence mechanisms to explain long
persistent phosphorescence of SrAl2O4:
Eu2+, Dy3+ system and others are
not able to provide some experimental and teoric
observation. The basic reality is; the Eu2+ ion
occurs as a result of its d orbitals to settle near the
bottom of conducting band, reducing of Eu2+
concentration under UV excitation.Trace quantity of
Eu3+ always remains in these
compounds.Phosphorescence mechanism iscreated by oxidizing
Eu2+ ions to Eu3+.Reunification of
electrons which trapped in photoproductive Eu3+
locations with 520 nm emission of phosphorescence occurs and
electrons trap in oxygen holes around photoproductive
Eu3+. One of the other emission of
SrAl2O4: Eu2+,
Dy3+ system at low temperature at 450 nm is a
fact related to UV irradiation, occuring during charge
transfer to Eu3+ ion from oxygen and hole trap in
holes of Sr2+. These studies showed that it is an
important fact to phosphorescence mechanismthat
Dy3+ the co-dopant increases the number of
electron traps and depth around Eu3+ ion.
Dy3+ application in phosphorescence
process causes lots of trap levels occurance in the
structure. As it is seen in Figure 6; Eu2+ ions
excite by UV irradiation and electron hole pairs occur.
Thus, electron transforms to excitation state (Transition
1). Later on, the electron relaxes to metastable state
fastly (Transition 2). Apart from this, Transition 4
constitution which causes reduction of phosphorescence
strength might occur. It is being thought that
Eu2+ Eu1+ transformation also occurs
in Transition 3. As a result, it occurs by release of
visible light hole and re-unification with electrons
(Transition 5).
The studies indicated that, as Dy3+ the
co-dopant increases electron trap amount in Eu3+
neighborhood and deepths and it is an important fact in
phosphorescence progress.
The researches on phosphorescence development
process by attraction of Eu2+ and Dy3+
added SrAl2O4 and
Sr4Al14O25 phosphors
emphasized on various addition effects, molar rates of
components and preparation methods. During these studies it
was found out that shape and size of phosphor particles
affect phosphorescence specifications. New properties are
invented as emission intensity transforms to blue when
particle size reaches nano level. Phosphor particles are
expected to create high density compact as a result of
orientation and better light absorbtion when the particles
are well shaped and in a plate-like structure. This
situation provides an obtain of higher luminescence
strength. Particle size and shape of phosphorescent powders
can be depend on the type of consisted crystal, particle
size of begining materials and so preparation process.
Long lasting luminescence of phosphor with small
particle size can be explained by 4f-5d transition of
excited Eu2+ from after exciting by light source
and creation of large amount of space near valence band.
Some of the free-state holes are thermally released to
valence band, immigrate towards valence band and trapped by
Dy3+-borate complex. The trapped spaces are
released to valence band thermally, immigrate towards
excited Eu2+ and at the end reunification which
provides long persistent luminescence occurs (Figure 7). It
is being understood that long persistent luminescence
depends on the number of held holes which depend on the
concentration of Dy-borate complexes and trap depths. As
long as the particle size reduces, transformation to blue
appears by trap depths, and this provides improvement of
persistent luminescence.
Until a few years ago, the only practically known
phosphorescence compound was copper and cobalt-doped zinc
sulfate (ZnS: Cu+, Co2+).
Phosphorescence applications remained limited due to the
large number of defects. There are two undesired properties
in the ZnS: Cu+, Co2+ material; short
decay time (nearly 1 hour) and sensitivity to humidity.
These two properties have brought limitation seriously. But,
this material is still used in watches and wall clocks to
show the time in the dark. Tens of years ago, radioactive
materials such as promethium, mezotorium and trithium were
attached to the main lattice which consists of ZnS to
eliminate the loss of luminescence intensity in a short
time. On those days, Swiss producers managed to isolate
microtubes consisting of a very little amount of gas tritium
in glass. Inner wall of microtube was coated with ZnS which
diffuses green light, doped and undoped. The tritium amount
used was as little as it can be neglected and radioactive
beta particles were not able to go out from the glass they
locked in.
The figures to support the phosphorescence
pigments which have luminescence in yellowish-green colour
description are given below:
In the yellowish-green phosphorescence system, four different recipes (Y-01, Y-03, Y-05, Y-07) are examined when spectroscopic specifications of Y2O3 in 0.001-0.007 molar rate by changing the molar amount in yttrium:
XRD graphs are given in Figure 8.
Emission graphichs (excitation wavelength ~255 nm) which belong to yellowish-green phosphorescent pigments consisting of different Y2O3 amounts are exhibited in Figure 9.
Graphics belonging to the mesaurement of afterglow property for powders are given in Figure 10.
In the yellowish-green phosphorescence system, four different recipes (Y-01, Y-03, Y-05, Y-07) are examined when spectroscopic specifications of Y2O3 in 0.001-0.007 molar rate by changing the molar amount in yttrium:
XRD graphs are given in Figure 8.
Emission graphichs (excitation wavelength ~255 nm) which belong to yellowish-green phosphorescent pigments consisting of different Y2O3 amounts are exhibited in Figure 9.
Graphics belonging to the mesaurement of afterglow property for powders are given in Figure 10.
The yellowish-green phosphorescence pigment recipe
in SrAl2O4:Eu, Dy, Y system are studied with 4 different
Y2O3 molar rates:
Recipes | SrCO 3 (g) | H 3 AlO 3 (g) | Dy 2 O 3 (g) | Eu 2 O 3 (g) | Nd 2 O 3 (g) | H 3 BO 3 (g) |
Recipe 10.001 mole Y2O3 | 4.82 | 4.83 | 0.18 | 0.1 | 0.02 | 0.19 |
Recipe 20.003 mole Y2O3 | 4.80 | 4.80 | 0.15 | 0.07 | 0.05 | 0.17 |
Recipe 30.005 mole Y2O3 | 4.75 | 4.72 | 0.12 | 0.04 | 0.1 | 0.12 |
Recipe 40.007 mole Y2O3 | 4.70 | 4.65 | 0.10 | 0.01 | 0.15 | 0.1 |
According to XRD analysis results (Figure 8), it
can be seen that different Y2O3
amounts do not affect consisted main phase of structure and,
SrAl2O4 occurs as a main crystal in 4
different recipes consistingY2O3. In
the prepared recipes SrAl4O7 phase
begin to disappear by increasing Y2O3,
in compounds of Y-05 and above it disappeared completely.
It can be clearly seen from the emission graphs
(Figure 9) belonging to yellowish-green phosphorescence
pigments consisting different amount of
Y2O3, each one of all the prepared
pigments diffuses in green wavelength rate. Some amounts of
Y2O3 are added to structure of
aluminate crystal and the rest to structure of secondary
phase. It can be thought that the yttrium contributes the
support of creation of carrier traps or stability-enhancing
carrier traps meaning, directly increases brightness of
phosphorescence, and second phase has a role in stabilizing
carrier traps by arranging aluminate crystal. As a result
brightness of phosphorescent pigments can be increased and
even excitation time to reduce half the way.
Afterglow timegraphics of phosphorescent powders
are given in Figure 10. When results are examined, it is
seen that the emission and decay of Y-03 and Y-05 coded
phosphorescence pigments are longer comparing to the others.
Earth alkaline aluminate systems activated with
rare earth elements are phosphorescence pigments with
luminescence ability. The most important feature of these
systems are strong light absorbtion by courtesy of their
crystal structure, ability for storageand dissemination and
as a result showing long-lasting phosphorescence with high
brightness. According to the light source (generally room
light) which they are under influence, they provide emission
for more than 12 hours after the light source was removed.
Their brightness and delay time are ten times more than that
of very known zinc sulphate. Earth alkaline aluminate
systems do not show any harmfull effects to health as they
do not contain radioactive contribution. Apart from this,
they are stable and resistant to atmospheric effects unlike
zinc sulphate system. Light excitation and emission drive continuously.
In this invention, the yellowish-green colour
emitting phosphorescent pigments from strontium aluminates (
SrAl2O4: Eu, Dy, Y) which are most
common and accomplished in the earth alkaline aluminate
systems were developed under the lights of previous studies
reported in the literature.
1. When we characterize the long lasting
yellowish-green color emitting phosphorescent pigments
MAl2O4: R x, y, z, t, k, l, m, r, a,
b, c, d is valid:
M: Strontium (Sr) element
R: Europium (Eu) as emission center, one or more from Dysprosium (Dy), Yttrium (Y) or Neodymium (Nd) Yttrium (Y), Praseodymium (Pr), Ytterbium (Yb), Erbium (Er), Gadolinium (Gd), Cerium (Ce), Samarium (Sm), Hafnium (Hf), Thulium (Tm) occur as co-dopant in the structure.
M: Strontium (Sr) element
R: Europium (Eu) as emission center, one or more from Dysprosium (Dy), Yttrium (Y) or Neodymium (Nd) Yttrium (Y), Praseodymium (Pr), Ytterbium (Yb), Erbium (Er), Gadolinium (Gd), Cerium (Ce), Samarium (Sm), Hafnium (Hf), Thulium (Tm) occur as co-dopant in the structure.
2. In the phosphorescent pigments havinglong
lasting bluish-green emission mentioned in the claim 1 the
molar ranges of rare earth elements; Eux, Dyy, Ndz, Yt, Prk,
Ybl, Erm, Gdr, Cea, Smb, Hfc, Tmd which can be added to
SrAl2O4, the main phase are as follows:
SrAl 2 O 4 : Eu x , Dy y , Nd z , Y t , Pr k , Yb l , Er m , Gd r , Ce a , Sm b , Hf c , Tm d , B e | 0.0001≤ x, y, z, t, k, l, m, r, a, b, c, d ≤0.1 |
3. The phosphorescent pigments withlong lasting
yellowish-green emission mentioned in the claim 1-2 have
been characterized by synthesizing via solid-state reaction
method under reductive nitrogen (N2) – hydrogen
(H2) gas atmosphere.
4. Claim 3 indicates the synthesizing method and
its specification consists of the relevant steps as
follows:
- Mentioned gas atmosphere is nitrogen (N2) – hydrogen (H2) mixture. 90-98.5 % N2 and 1.5-10 H2 % is used.
- Appropriate raw materials are chosen for solid-state reaction method of the phosphorescence pigment (in oxide, carbonate, hydroxide etc. forms). The determined raw materials are selected with the proper purities (>99.5 %).
- To get long-afterglow phosphorescent pigment by the synthesizing method mentioned wet milling is applied for appropriate time by planetary mill (30 minutes – 6 hours).
- In the wet milling process mentioned the proper wet medium (ethanol, propanol-2 pure water, etc.), appropriate milling and mixing media, aluminum and zirconuim oxide balls in the diameter of 1mm-, and their jars are provided.
A) In the synthesizing method mentioned to get long-afterglow phosphorescent pigment a proper gas flow rate (0.1-0.50 lt/min) is set in the sintering furnace.
B) In the synthesizing method mentioned to obtain Sr4Al14O25 phase, a proper sintering temperature (1250-1600 oC) and time (30 minutes-6 hours) are set in the furnace.
- In the synthesizing method mentioned the wet-milled and then dried batch is loaded in proper crucibles. The conditions indicated in A and B are followed:
- In the synthesizing method mentioned to get long-afterglow phosphorescent pigment dry milling to the bulk phosphor is performed under proper conditions for certain time to obtain particle sizes previously determined depending on the application field of the pigment.
- Mentioned gas atmosphere is nitrogen (N2) – hydrogen (H2) mixture. 90-98.5 % N2 and 1.5-10 H2 % is used.
- Appropriate raw materials are chosen for solid-state reaction method of the phosphorescence pigment (in oxide, carbonate, hydroxide etc. forms). The determined raw materials are selected with the proper purities (>99.5 %).
- To get long-afterglow phosphorescent pigment by the synthesizing method mentioned wet milling is applied for appropriate time by planetary mill (30 minutes – 6 hours).
- In the wet milling process mentioned the proper wet medium (ethanol, propanol-2 pure water, etc.), appropriate milling and mixing media, aluminum and zirconuim oxide balls in the diameter of 1mm-, and their jars are provided.
A) In the synthesizing method mentioned to get long-afterglow phosphorescent pigment a proper gas flow rate (0.1-0.50 lt/min) is set in the sintering furnace.
B) In the synthesizing method mentioned to obtain Sr4Al14O25 phase, a proper sintering temperature (1250-1600 oC) and time (30 minutes-6 hours) are set in the furnace.
- In the synthesizing method mentioned the wet-milled and then dried batch is loaded in proper crucibles. The conditions indicated in A and B are followed:
- In the synthesizing method mentioned to get long-afterglow phosphorescent pigment dry milling to the bulk phosphor is performed under proper conditions for certain time to obtain particle sizes previously determined depending on the application field of the pigment.
Phosphorescent pigments are used in coating of
products surfaces and can also be mixed with plastic,
elastic, polyvinyl chloride (PVC), other synthetic resins
and glass.
They find themselves a wide usage area in traffic
safety signs, traffic control gloves, reflection plates of
vehicles, reflection flags, highway signs, tyres, shoes,
trench coats, telephone keypad overlays, watches, stair
edges, emergency exit signs, the surface of the fire
extinguisher cylinder, toys, writing tools. Apart from
these, ceramic glazes doped with phosphorescence pigment
have potential usage in apartments, especially as skirting
(ceramic production used in area where the wall and ground
intersect). It can be a practical solution in the case of
sudden electric cut, afterwards in emergency when the
phosphorescent signs are placed beside stairs. Ceramic and
glass products with phosphorescence pigment can be used as
decor. As a border, glow stone, overlays in kitchen,
bathroom or pool, ceramics with phosphorescent pigments
containing glazes also provide visual richness which could
be of ceramic artists interest.
Claims (4)
- When we characterize the long lasting yellowish-green color emitting phosphorescent pigments MAl2O4: R x, y, z, t, k, l, m, r, a, b, c, d is valid:
M: Strontium (Sr) element
R: Europium (Eu) as emission center, one or more from Dysprosium (Dy), Yttrium (Y) or Neodymium (Nd) Yttrium (Y), Praseodymium (Pr), Ytterbium (Yb), Erbium (Er), Gadolinium (Gd), Cerium (Ce), Samarium (Sm), Hafnium (Hf), Thulium (Tm) occur as co-dopant in the structure. - In the phosphorescent pigments havinglong lasting bluish-green emission mentioned in the claim 1 the molar ranges of rare earth elements; Eux, Dyy, Ndz, Yt, Prk, Ybl, Erm, Gdr, Cea, Smb, Hfc, Tmd which can be added to SrAl2O4, the main phase are as follows:
Reference---Table 2 - The phosphorescent pigments withlong lasting yellowish-green emission mentioned in the claim 1-2 have been characterized by synthesizing via solid-state reaction method under reductive nitrogen (N2) – hydrogen (H2) gas atmosphere.
- Claim 3 indicates the synthesizing method and its specification consists of the relevant steps as follows:
- Mentioned gas atmosphere is nitrogen (N2) – hydrogen (H2) mixture. 90-98.5 % N2 and 1.5-10 H2 % is used
- Appropriate raw materials are chosen for solid-state reaction method of the phosphorescence pigment (in oxide, carbonate, hydroxide etc. forms). The determined raw materials are selected with the proper purities (>99.5 %).
- To get long-afterglow phosphorescent pigment by the synthesizing method mentioned wet milling is applied for appropriate time by planetary mill (30 minutes – 6 hours).
- In the wet milling process mentioned the proper wet medium (ethanol, propanol-2 pure water, etc.), appropriate milling and mixing media, aluminum and zirconuim oxide balls in the diameter of 1mm-, and their jars are provided.
C) In the synthesizing method mentioned to get long-afterglow phosphorescent pigment a proper gas flow rate (0.1-0.50 lt/min) is set in the sintering furnace.
D) In the synthesizing method mentioned to obtain Sr4Al14O25 phase a proper sintering temperature (1250-1600 oC) and time (30 minutes-6 hours) are set in the furnace.
- In the synthesizing method mentioned the wet-milled and then dried batch is loaded in proper crucibles. The conditions indicated in A and B are followed:
In the synthesizing method mentioned to get long-afterglow phosphorescent pigment dry milling to the bulk phosphor is performed under proper conditions for certain time to obtain particle sizes previously determined depending on the application field of the pigment.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/TR2015/050005 WO2016200349A1 (en) | 2015-06-10 | 2015-06-10 | LONG-LASTING YELLOWISH-GREEN EMITTING PHOSPHORESCENT PIGMENTS IN THE STRONTIUM ALUMINATE [SrAl2O4] SYSTEM |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/TR2015/050005 WO2016200349A1 (en) | 2015-06-10 | 2015-06-10 | LONG-LASTING YELLOWISH-GREEN EMITTING PHOSPHORESCENT PIGMENTS IN THE STRONTIUM ALUMINATE [SrAl2O4] SYSTEM |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2016200349A1 true WO2016200349A1 (en) | 2016-12-15 |
Family
ID=53514385
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/TR2015/050005 WO2016200349A1 (en) | 2015-06-10 | 2015-06-10 | LONG-LASTING YELLOWISH-GREEN EMITTING PHOSPHORESCENT PIGMENTS IN THE STRONTIUM ALUMINATE [SrAl2O4] SYSTEM |
Country Status (1)
Country | Link |
---|---|
WO (1) | WO2016200349A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN112251224A (en) * | 2020-10-26 | 2021-01-22 | 陕西科技大学 | Long afterglow luminescent material surface loaded CsPbX3Preparation method of (1) |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2010114403A1 (en) * | 2009-04-03 | 2010-10-07 | Universidade De Aveiro | LUMINESCENT BERYLLIUM, MAGNESIUM, CALCIUM, STRONTIUM OR BARIUM ALUMINATE NANOTUBES DOPED WITH CERIUM (III) AND CO-DOPED WITH OTHER LANTHANIDE IONS M(1-x-y)N2O4: Cex, Lny |
-
2015
- 2015-06-10 WO PCT/TR2015/050005 patent/WO2016200349A1/en active Application Filing
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2010114403A1 (en) * | 2009-04-03 | 2010-10-07 | Universidade De Aveiro | LUMINESCENT BERYLLIUM, MAGNESIUM, CALCIUM, STRONTIUM OR BARIUM ALUMINATE NANOTUBES DOPED WITH CERIUM (III) AND CO-DOPED WITH OTHER LANTHANIDE IONS M(1-x-y)N2O4: Cex, Lny |
Non-Patent Citations (6)
Title |
---|
HOLSA J ET AL: "Persistent luminescence of Eu<2+> doped alkaline earth aluminates, MAl2O4:Eu<2+>", JOURNAL OF ALLOYS AND COMPOUNDS, ELSEVIER SEQUOIA, LAUSANNE, CH, vol. 323-324, 12 July 2001 (2001-07-12), pages 326 - 330, XP027389893, ISSN: 0925-8388, [retrieved on 20010712] * |
NAKAZAWA EIICHIRO ET AL: "Mechanism of the persistent phosphorescence in Sr4Al14O25:Eu and SrAl2O4:Eu codoped with rare earth ions", JOURNAL OF APPLIED PHYSICS, AMERICAN INSTITUTE OF PHYSICS, US, vol. 100, no. 11, 7 December 2006 (2006-12-07), pages 113113 - 113113, XP012089066, ISSN: 0021-8979, DOI: 10.1063/1.2397284 * |
QIU ET AL: "Combustion synthesis of long-persistent luminescent MAl2O4: Eu<2+>, R<3+> (M=Sr, Ba, Ca, R=Dy, Nd and La) nanoparticles and luminescence mechanism research", ACTA MATERIALIA, ELSEVIER, OXFORD, GB, vol. 55, no. 8, 6 April 2007 (2007-04-06), pages 2615 - 2620, XP022023964, ISSN: 1359-6454, DOI: 10.1016/J.ACTAMAT.2006.12.018 * |
SELVIN YEILAY KAYA ET AL: "Effect of Al/Sr ratio on the luminescence properties of SrAlO:Eu, Dyphosphors", CERAMICS INTERNATIONAL, ELSEVIER, AMSTERDAM, NL, vol. 38, no. 5, 4 January 2012 (2012-01-04), pages 3701 - 3706, XP028409701, ISSN: 0272-8842, [retrieved on 20120121], DOI: 10.1016/J.CERAMINT.2012.01.013 * |
SONG ET AL: "Synthesis of SrAl2O4: Eu<2+>, Dy<3+>, Gd<3+> phosphor by combustion method and its phosphorescence properties", DISPLAYS DEVICES, DEMPA PUBLICATIONS, TOKYO, JP, vol. 29, no. 1, 22 November 2007 (2007-11-22), pages 41 - 44, XP022357331, ISSN: 0141-9382, DOI: 10.1016/J.DISPLA.2007.08.004 * |
WEI XIE ET AL: "The long Afterglow and Thermoluminescence Properties of MAl<sub>2</sub>O<sub>4</sub> Eu<sup>2+</sup>, Dy<sup>3+</sup>(M=Ca, Sr and Ba) Phosphors Syntheized by Combustion Technique", ADVANCED MATERIALS RESEARCH, vol. 197-198, 1 February 2011 (2011-02-01), pages 318 - 322, XP055224621, DOI: 10.4028/www.scientific.net/AMR.197-198.318 * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN112251224A (en) * | 2020-10-26 | 2021-01-22 | 陕西科技大学 | Long afterglow luminescent material surface loaded CsPbX3Preparation method of (1) |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
KR100858269B1 (en) | Method of producing aluminate fluorescent substance, a fluorescent substance and a device containing a fluorescent substance | |
KR100700952B1 (en) | A process for producing aluminate-based phosphor | |
Ren et al. | Water triggered interfacial synthesis of highly luminescent CsPbX 3: Mn 2+ quantum dots from nonluminescent quantum dots | |
Ma et al. | KSr4 (BO3) 3: Pr3+: a new red-emitting phosphor for blue-pumped white light-emitting diodes | |
DE112006002452T5 (en) | Fluorescent substance | |
Yousif et al. | Ultra-broadband luminescent from a Bi doped CaO matrix | |
Singh et al. | Surface and spectral studies of Sm3+ doped Li4Ca (BO3) 2 phosphors for white light emitting diodes | |
Wang et al. | Luminescent properties of a reddish orange long afterglow phosphor SrSnO3: Sm3+ | |
JP6465417B2 (en) | Luminescent phosphor and method for producing the same | |
EP2009077A1 (en) | Manganese-doped metal-silicon-nitrides phosphors | |
Singh et al. | UV emitting Pb2+ doped SrZrO3 phosphors prepared by sol-gel procedure | |
Swati et al. | Novel flux-assisted synthesis for enhanced afterglow properties of (Ca, Zn) TiO3: Pr3+ phosphor | |
Jiayue et al. | Luminescence properties of SrB4O7: Sm2+ for light conversion agent | |
DE102009030205A1 (en) | Luminescent substance with europium-doped silicate luminophore, useful in LED, comprises alkaline-, rare-earth metal orthosilicate, and solid solution in form of mixed phases arranged between alkaline- and rare-earth metal oxyorthosilicate | |
KR101339102B1 (en) | Sr-Al-O BASED LONG-AFTERGLOW PHOSPHORS AND METHOD FOR MANUFACTURING THE SAME | |
WO2016200349A1 (en) | LONG-LASTING YELLOWISH-GREEN EMITTING PHOSPHORESCENT PIGMENTS IN THE STRONTIUM ALUMINATE [SrAl2O4] SYSTEM | |
JP3826210B2 (en) | Rare earth complex oxide phosphor | |
EP2540799A1 (en) | Green luminescent material of terbiuim doped gadolinium borate and preparing method thereof | |
El Kazazz et al. | Production of violet-blue emitting phosphors via solid state reaction and their uses in outdoor glass fountain | |
WO2016200348A1 (en) | Long lasting bluish-green emitting phosphorescent pigments in the strontium aluminate (sr4al14o25) system | |
Revankar et al. | Luminescent Materials Based on Aluminates: A Review | |
Mishra et al. | Urea assisted self combustion synthesis of CaAl 2 O 4: Eu phosphor and its mechanoluminescence characterization | |
KR100724293B1 (en) | Preparation of long persistent green emitting phosphor | |
EL KAZAZZ et al. | PRODUCTION OF Pr6O11-DOPED SrAl2O4: Eu2+, Dy3+, Y3+ YELLOWISH-GREEN PHOSPHORS AND THEIR USAGE IN ARTISTIC GLASSES | |
RU2470982C2 (en) | Complex calcium metasilicate of europium and yttrium, red luminescent material based thereon for ultraviolet light-emitting diodes and method of producing said material |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 15734482 Country of ref document: EP Kind code of ref document: A1 |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
32PN | Ep: public notification in the ep bulletin as address of the adressee cannot be established |
Free format text: NOTING OF LOSS OF RIGHTS PURSUANT TO RULE 112(1)EPC DATED 03.04.2018 (EPO FORM 1205A). |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 15734482 Country of ref document: EP Kind code of ref document: A1 |