阅读说明：本技术 用于uv发射装置的磷光体组合物和利用该磷光体组合物的uv发生装置 (Phosphor composition for UV emitting device and UV generating device using the same ) 是由 M·萨尔弗莫瑟 M·布罗克斯特曼 T·尤斯特尔 于 2020-02-27 设计创作，主要内容包括：一种UV发射装置,具有至少一个第一磷光体,其吸收波长小于200nm的UV辐射并且发射波长在220nm和245nm之间的UV辐射,和至少一个第二磷光体,其吸收波长在220nm和245nm之间的UV辐射并发射波长在250nm和315nm之间的UV辐射。(A UV emitting device having at least one first phosphor that absorbs UV radiation having a wavelength of less than 200nm and emits UV radiation having a wavelength between 220nm and 245nm, and at least one second phosphor that absorbs UV radiation having a wavelength between 220nm and 245nm and emits UV radiation having a wavelength between 250nm and 315 nm.)

1. A UV emitting device having

-at least one first phosphor which absorbs UV radiation with a wavelength of less than 200nm and emits UV radiation with a wavelength between 220nm and 245nm, and

-at least one second phosphor that absorbs UV radiation having a wavelength between 220nm and 245nm and emits UV radiation having a wavelength between 250nm and 315 nm;

characterized in that the first phosphor and the second phosphor are applied in the form of layers, wherein the first phosphor is located between the discharge space and the second phosphor layer.

2. The UV emitting device of claim 1, wherein the VUV emitting gas discharge space is provided contained in a UV transparent container, the container having an inner surface and an outer surface, wherein:

-the first phosphor and the second phosphor are both applied to the inner surface of the container, or

-the first phosphor and the second phosphor are both applied to an outer surface of the container, or

-the first phosphor is applied to an inner surface of the container and the second phosphor is applied to an outer surface of the container.

3. UV-emitting device according to one of the preceding claims, characterized in that a coating is applied directly on the inner and/or outer surface of the container; wherein preferably the coating comprises Al₂O₃MgO and/or SiO₂And a layer comprising the phosphor is applied over the coating.

4. UV-emitting device according to one of the preceding claims, characterized in that the container is a quartz tube.

5. UV-emitting device according to one of the preceding claims, characterized in that the device is an excimer lamp.

6. UV emitting device according to one of the preceding claims, characterized in that the device is a xenon excimer UV lamp.

7. UV-emitting device according to one of the preceding claims, characterized in that the inner surface of the layer of the first phosphor is covered with a protective layer of MgO.

8. A phosphor composition for use in a UV-C and/or UV-B emitting device, characterized in that the composition comprises

-at least one first phosphor which absorbs UV radiation with a wavelength of less than 200nm and emits UV radiation with a wavelength between 220nm and 245nm, and

-at least one second phosphor which absorbs UV radiation with a wavelength between 220nm and 245nm and emits UV radiation with a wavelength between 250nm and 315 nm.

9. A phosphor composition according to claim 8, wherein the at least one first phosphor is one or more phosphors selected from the group comprising:

CaSO₄:Pr,Na

SrSO₄:Pr,Na

LaPO₄:Pr

CaSO₄:Pb

LiLaP₄O₁₂:Pr

Y₂(SO₄)₃:Pr

LuPO₄:Pr

YPO₄:Pr

GdPO₄:Pr

NaMgPO₄:Pr

KSrPO₄:Pr

LiCaPO₄:Pr

LUPO₄:Bi

YPO₄:Bi

YBP₂O₈:Pr

YAlO₃:Pr

LaMgAl₁₁O₁₉:Pr

Ca₅(PO₄)₃F:Pr,K。

10. a phosphor as claimed in claim 8 or 9, characterized in that the at least one second phosphor is one or more phosphors selected from the group comprising:

Ca₉Lu(PO₄)₇:Pr

Ca₉Y(PO₄)₇:Pr

NaSrPO₄:Pr

NaCaPO₄:Pr

Sr₄Al₁₄O₂₅:Pr,Na

SrAl₁₂O₁₉:Pr,Na

CaLi₂SiO₄:Pr,Na

KCaPO₄:Pr

LuBO₃:Pr

YBO₃:Pr

Lu₂SiO₅:Pr

Y₂SiO₅:Pr

Lu₂Si₂O₇:Pr

CaZrO₃:Pr,Na

CaHfO₃:Pr,Na

Y₂Si₂O₇:Pr

Lu₃Al₅O₁₂:Bi,Sc

Lu₂SiO₅:Pr

Lu₃Al₃Ga₂O₁₂:Pr

Lu₃Al₄GaO₁₂:Pr

SrMgAl₁₀O₁₇:Ce,Na

Lu₃Al₅O₁₂:Pr

YBO₃:Gd

Lu₃Al₅O₁₂:Gd

Y₃Al₅O₁₂:Gd

LaMgAl₁₁O₁₉:Gd

LaAlO₃:Gd

YPO₄:Gd

GdPO₄:Nd

LaB₃O₆:Gd,Bi

SrAl₁₂O₁₉:Ce。

11. a phosphor composition according to claim 8, wherein the first phosphor is YPO₄Bi and the second phosphor is YBO₃:Pr。

Technical Field

The present disclosure relates to a phosphor composition for a UV emitting device and a UV generating device including the same.

Background

In this context, a phosphor is a chemical component that absorbs electromagnetic radiation of a particular energy and then re-emits electromagnetic radiation of a different energy. Such phosphors are well known, for example, from fluorescent lamps. The term "phosphor" is not to be understood as a chemical element phosphorus and the term "phosphor composition" is to be understood as a combination of at least two phosphors, which may be one or more layers. For example a mixture of two different phosphors or a multi-layer application of one phosphor over another.

UV-C emitting gas discharge lamps, such as low-or medium-pressure mercury discharge lamps, are widely used for disinfection purposes in water and wastewater applications, they can also be used in the so-called "advanced oxidation process", i.e. the cracking of highly persistent fluorinated or chlorinated carbon. Low-pressure mercury gas discharge lamps emit UV-C at a wavelength of mainly 254nm and radiate out through the wall materials of the lamp vessel and the protective sleeve, which are usually made of quartz. This portion of the radiation is effective in destroying DNA, such as bacteria and viruses. Such lamps are widely used in facilities such as municipal water supply and sewage treatment.

On the other hand, environmental problems have led to the need for mercury-free alternatives, and hence Xe excimer lamps have been developed which emit a large proportion of the radiation in the wavelength range of 172nm ± 8 nm. This portion of the electromagnetic spectrum is known as "vacuum ultraviolet" (VUV). A large part of this high-energy radiation is absorbed by the quartz body of the lamp and is therefore lost in the application.

The prior art documents disclose lamps for illumination purposes, in which a combination of two phosphors is used, for example documents DE 10129630 a1, DE 10324832 a1 and US 6,982,046B 2. In all these documents, a first phosphor is used to absorb VUV radiation and emit UV radiation of longer wavelength, e.g. UV-C. These lamps also provide a second phosphor to absorb UV-C radiation and emit radiation in the visible region of the electromagnetic spectrum. In this way, part of the radiant energy emitted by the VUV region can be converted into visible light, thereby increasing the energy efficiency of the lamp. However, visible light cannot be used for disinfection purposes.

Ultraviolet radiation disinfection requires lamps that emit in the UV-C portion of the spectrum. Several phosphors have been proposed which can convert radiation of wavelength 170nm to 185nm into radiation of longer wavelength around 250nm, for example documents US 6,734,631B 2, US 2005/0073239 a1, US 2009/0160341 a1, US 2012/0319011 a1, US 2008/0258601 a1, US 7,935,273B 2 and US 8,647,531B 2. US 2007/0247052 a1 discloses a lamp with two different UV-B phosphors, wherein the two different UV-B phosphors are applied in layers in the interior of the discharge vessel and optionally comprise MgO as an additive. However, the proposed phosphor does not contain bismuth (Bi). These documents are incorporated herein by reference, and the phosphors proposed in the prior art documents suffer from several drawbacks in the above-mentioned technical applications.

Document WO 2018/106168 a1 discloses a UV lamp with a single phosphor layer comprising one or more phosphors. Since the phosphor is mixed in a single layer, the Quantum Efficiency (QE) of the lamp is not optimal.

First, many phosphors contain rare and expensive elements, which make their use in large scale devices prohibitively expensive. Furthermore, some prior art compounds do not exhibit the desired long term stability, which is necessary in e.g. municipal facilities. More importantly, these phosphors do not emit significantly in the wavelength range between 255nm and 265nm, and in particular the quantum efficiency describing the ratio between the absorption of VUV photons and the emission of UV-C photons is not satisfactory to obtain a good overall lamp efficiency.

Disclosure of Invention

It is therefore an object of the present invention to provide a novel UV-C and/or UV-B emitting device which is energy efficient and stable over time, with an improved UV-C and/or UV-B emission spectrum to meet specific applications, such as disinfection or photochemical applications.

It is another object of the present invention to provide a novel phosphor composition, in particular for mercury-free UV emitting devices, to ameliorate the above disadvantages. It is also an object of the present invention to provide a UV generating device comprising such a phosphor.

This object is achieved by a UV generating device having the features of claim 1 and a phosphor composition having the features of claim 10.

A UV emitting device having

-at least one first phosphor which absorbs UV radiation with a wavelength of less than 200nm and emits UV radiation with a wavelength between 220nm and 245nm, and

-at least one second phosphor which absorbs UV radiation in the wavelength range between 220nm and 245nm and emits UV radiation in the wavelength range between 250nm and 315 nm;

the UV emitting device is capable of absorbing VUV photons in the first phosphor and re-emitting UV-C photons, absorbing UV-C photons in the second phosphor and re-emitting UV-C and/or UV-B photons of longer wavelengths, such as 255nm to 265nm for disinfection purposes, or other UV-C or UV-B wavelengths for photochemical reactions, such as 280nm to 315 nm. Wherein the first phosphor and the second phosphor are applied in layers, the first phosphor being located between the VUV emitting gas discharge space (volume) and the second phosphor, which improves the uniformity and the required reflection of the coating and the overall quantum efficiency.

Preferably, a gas discharge space is provided which in operation emits VUV radiation, which is contained in a UV transparent container having an inner surface and an outer surface, wherein the first phosphor and said second phosphor are both applied to the inner surface or the outer surface of the container, or the first phosphor is applied to the inner surface of the container and said second phosphor is applied to the outer surface of the container.

There are generally three options to choose from, depending on the requirements of the application.

If both layers of phosphor are applied to the inner surface of the container, they may be protected from adverse environmental effects. Since the VUV radiation is converted to longer wavelengths within the vessel, ordinary UV transparent quartz can be used, which is readily available and cost-effective.

If both layers of phosphor are applied to the exterior surface of the container, these phosphor layers are sealed off from the interior of the container, which in some embodiments may contain chemicals or elements, such as mercury, that may degrade some of the phosphor upon contact with the phosphor. In these cases, it is preferred that both phosphors are applied to the outer surface of the container. However, since the VUV radiation must pass through the container before reaching the first layer of phosphor, the container material must be VUV transparent, which requires the use of special materials such as synthetic quartz.

A third option is to apply the first layer of phosphor to the inner surface of the container and the second layer of phosphor to the outer surface of the container. In this case, only the first layer of phosphor is in contact with the internal medium, while the second layer of phosphor is not affected by the internal medium. On the other hand, the first layer of phosphor is not affected by the environment, while the second layer of phosphor is affected by the environment. In this embodiment, as in the first embodiment, the VUV radiation has been converted to longer wavelength UV inside the container, so that ordinary quartz or other UV transparent material can be used to make the container.

In a preferred embodiment, the coating is applied directly to the inner and/or outer surface of the container, wherein preferably the coating comprises Al₂O₃MgO and/or SiO₂And applying a layer comprising phosphor onto the coating. Such a coating and the application of the phosphor to the coating improve the adhesion of the phosphor and thus the mechanical stability of the phosphor layer. In case the first phosphor is applied inside the discharge vessel, it is also an advantage that an inner protective layer of MgO is provided, which directly contacts the discharge space and shields the discharge of the first phosphor.

If the container is a quartz tube, manufacturing is facilitated.

Preferably, the device is an excimer lamp, more preferably a Xe excimer UV lamp. These lamps have a suitable spectrum, a long service life and a good initial start-up behavior.

Due to environmental factors, the device is preferably an excimer gas discharge lamp having a gas filling which is substantially free of mercury.

This problem is also solved by a phosphor composition for use in a UV-C emitting device, wherein the composition comprises

-at least one first phosphor which absorbs UV radiation with a wavelength of less than 200nm and emits UV radiation with a wavelength between 220nm and 245nm, and

-at least one second phosphor which absorbs UV radiation with a wavelength between 220nm and 245nm and emits UV radiation with a wavelength between 250nm and 315 nm. The results show that the quantum efficiency of this composition is higher than that of other phosphors, which convert VUV photons directly to longer wavelength photons with wavelengths between 250nm and 315 nm. Furthermore, the first and second phosphors may be of a more cost-effective and long-term stable variety.

Preferably, the at least one first phosphor is selected from one or more phosphors of the group comprising:

CaSO₄:Pr,Na

SrSO₄:Pr,Na

LaPO₄:Pr

CaSO₄:Pb

LiLaP₄O₁₂:Pr

Y₂(SO₄)₃:Pr

LuPO₄:Pr

YPO₄:Pr

GdPO₄:Pr

NaMgPO₄:Pr

KSrPO₄:Pr

LiCaPO₄:Pr

LUPO₄:Bi

YPO₄:Bi

YBP₂O₈:Pr

YAlO₃:Pr

LaMgAl₁₁O₁₉:Pr

Ca₅(PO₄)₃F:Pr,K。

furthermore, the at least one second phosphor is selected from one or more phosphors of the group comprising:

Ca₉Lu(PO₄)₇:Pr

Ca₉Y(PO₄)₇:Pr

NaSrPO₄:Pr

NaCaPO₄:Pr

Sr₄Al₁₄O₂₅:Pr,Na

SrAl₁₂O₁₉:Pr,Na

CaLi₂SiO₄:Pr,Na

KCaPO₄:Pr

LuBO₃:Pr

YBO₃:Pr

Lu₂SiO₅:Pr

Y₂SiO₅:Pr

Lu₂Si₂O₇:Pr

CaZrO₃:Pr,Na

CaHfO₃:Pr,Na

Y₂Si₂O₇:Pr

Lu₃Al₅O₁₂:Bi,Sc

Lu₂SiO₅:Pr

Lu₃Al₃Ga₂O₁₂:Pr

Lu₃Al₄GaO₁₂:Pr

SrMgAl₁₀O₁₇:Ce,Na

Lu₃Al₅O₁₂:Pr

YBO₃:Gd

Lu₃Al₅O₁₂:Gd

Y₃Al₅O₁₂:Gd

LaMgAl₁₁O₁₉:Gd

LaAlO₃:Gd

YPO₄:Gd

GdPO₄:Nd

LaB₃O₆:Gd,Bi

SrAl₁₂O₁₉:Ce。

in a preferred embodiment, the first phosphor is YPO₄Bi and the second phosphor is YBO₃:Pr。

UV generating devices having a UV radiation source comprising the above described phosphor composition also solve the problems of the present invention, since the UV-C and/or UV-B source has a cost-effective phosphor composition with good VUV to UV-C and/or UV-B conversion efficiency at the desired target wavelength and long-term stability.

Preferably, the UV radiation source is a gas discharge lamp, in particular an excimer gas discharge lamp, and preferably the UV radiation source is an excimer gas discharge lamp having a gas filling which predominantly emits a second xenon excimer continuum at a VUV wavelength of about 172 nm. The gas filling may preferably comprise more than 50% by volume xenon.

It is well known how to produce phosphors of a given formulation using wet chemistry. In general, the compounds are dosed in portions in the form of the oxides or phosphates in the desired molar ratio, these are added to distilled water and H is added with stirring₃PO₄And the suspension is stirred at ambient temperature for several hours; the suspension was concentrated and dried in an evaporator and the solid residue was ground in a mortar; exposing the powder to air for high temperature calcination, e.g. at up to 1000 ℃ for 2-4 hours, and cooling to room temperature to obtain a solid phosphor; the phosphor was washed with distilled water, filtered and dried to obtain a pure white powder.

The coating with the phosphors can be applied to the lamp body by wet or dry deposition methods. These methods are known in the prior art.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows.

Drawings

In the following, embodiments of the invention are described in more detail, with reference to the accompanying drawings, in which:

FIG. 1 shows the left side where the Xe excimer emission spectrum (solid line) and the photoluminescence excitation spectrum (dotted line) are superimposed, and the right side where YPO is₄Photoluminescence emission spectrum of Bi;

FIG. 2 is a schematic diagram of a YPO₄Bi and YBO₃Emission spectrum of Pr bilayer coated Xe excimer discharge lamp;

fig. 3 is a preferred embodiment of a layered structure with two phosphors outside a quartz vessel.

Detailed Description

An excimer discharge lamp comprising a bilayer coating is disclosed wherein the first layer comprises YPO₄Bi (maximum emission 241nm) and the second layer comprises YBO₃Pr (maximum emission 265 nm).

A Xe excimer discharge lamp body made of high-quality synthetic quartz is treated in a coating procedure which comprises four spraying steps of nano-sized Al on the surface of the lamp body₂O₃A first pre-coating of particles; UV-C emitting phosphor YPO₄A second capping layer of Bi (λ (Em.)) max of 241 nm; UV-C/B emitting phosphor YBO₃A third coating layer of Pr (λ (Em.)) max 265nm, and SiO₂And (4) a final protective layer.

With nano-sized Al₂O₃The granules were made into a primer layer and uniformly dispersed in 7.5 wt% of isopropyl alcohol by spraying gamma-Al₂O₃The dispersion (trade name "AluC", supplied by Evonik Industries AG, elson, germany) applies the base coat to the lamp tube. The coating was then applied in a spray gun spray procedure involving continuous rotation of the lamp body along its longitudinal axis, and the coated lamp body was dried at room temperature for 20 minutes and then further dried in an oven at 80 ℃ for 1 hour.

Treating Al in another spraying step₂O₃Coated excimer lamp body, the spraying step comprising a spray paint based on n-butyl acetate as dispersant, whichContains 3 wt.% of nitrocellulose (type H7, available from Hagedorn-NC GmbH of Oersubuick, Germany), 1 wt.% of Al₂O₃(AluC,Evonik)，20wt.％YPO₄Bi (all wt.% values relative to the mass of n-butyl acetate). To increase homogeneity, Al is added before the homogeneous solution of nitrocellulose is dispersed in isopropanol₂O₃、YPO₄Bi and Al relative to₂O₃And YPO₄5 wt.% of the total weight of Bi of an organic dispersing additive (Dysperbyk 110, supplied by Wessel BYK-Chemie GmbH, Germany) were homogeneously mixed. The prepared dispersion was stirred on a roller belt for at least 2 hours in a polyethylene bottle to achieve homogeneity and then the coating was applied in a spray gun spray procedure with the lamp body continuously rotating about its longitudinal axis.

The lamp body thus coated was dried at room temperature for 1 hour and then calcined at 500 ℃ after drying (holding time 30 minutes) to bake a lamp body made of YPO₄Any organic component provided by the Bi phosphor coating.

Al₂O₃Precoating and YPO₄The Bi-coated excimer lamp body is further treated in a further spray coating comprising a lacquer based on n-butyl acetate as a dispersant, which contains 3wt. -% nitrocellulose (H7 type, Hagedorn), 1wt. -% Al₂O₃(AluC，Evonik)，20wt.-％YBO₃Pr (all wt. -% values relate to the mass of n-butyl acetate). To increase homogeneity, Al is added before the homogeneous solution of nitrocellulose is dispersed in isopropanol₂O₃、YBO₃Pr and Al relative to₂O₃And YBO₃5wt. -% of the total weight of Pr of organic dispersing additives (Dysperbyk 110, Byk) are homogeneously mixed. The prepared dispersion was stirred on a roller belt for at least 2 hours in a polyethylene bottle to achieve homogeneity and then the coating was applied in a spray gun spray procedure with the lamp body continuously rotating about its longitudinal axis. The coated lamp body was dried at room temperature for 1 hour. After drying, calcination was carried out at 500 ℃ (holding time 30 minutes) to bake the YBO₃Any organic component provided by the Pr phosphor coating. By using 1:1:0.25 ethanol in another final spray gun spray procedure,Tetraethoxysilane and other mixture coated SiO₂The cover layer, the lamp body, is continuously rotated along its longitudinal axis, thereby completing the lamp coating process. The coated lamp body was dried at room temperature for 1 hour and then subjected to final calcination at 500 c (holding time 30 minutes).

A xenon excimer lamp is produced in a known manner using the quartz tube thus coated as a tubular discharge vessel containing a xenon filling as discharge volume, the emission spectrum of the xenon excimer lamp with such a coating being shown in fig. 2.

Fig. 3 is a main cross section of a preferred embodiment lamp. As shown, fig. 3 is radially symmetric, including the following features from the center outward:

the centre comprises a centre electrode 1 in the form of a line electrode, the electrode 1 being surrounded and centred by a gas space 2, which gas space 2 is filled with xenon at low pressure. The gas space 2 is contained in a discharge vessel 3, in which case the discharge vessel 3 is made of synthetic quartz, which is transparent to VUV radiation. The outer surface of the discharge vessel 3 comprises a first layer 4 made of a first phosphor which absorbs UV radiation with a wavelength of less than 200nm and emits UV radiation with a wavelength between 220nm and 245 nm. The second layer 5 is arranged radially outside the first layer 4 and comprises a second phosphor which absorbs UV radiation with a wavelength between 220nm and 245nm and emits UV radiation with a wavelength between 250nm and 315 nm. The phosphor layers 4 and 5 are surrounded by a transparent tube 6 made of conventional quartz transparent to wavelengths between 250nm and 315nm (and above).

The discharge space 2 provided by the arrangement is contained in a synthetic quartz discharge vessel 3 which is transparent to VUV emissions at wavelengths of less than 200nm on the one hand and which can sustain a discharge without physical or chemical deterioration due to internal discharges on the other hand. The first layer 4 can receive all the VUV radiation generated by the discharge. The first layer 4 is a pure VUV phosphor, the photon conversion efficiency of which is very high, about 80%. The first layer 4 subsequently generates UV radiation with a wavelength between 220nm and 245nm, which is absorbed by the second layer 5. The second layer 5 converts said radiation to longer wavelengths of 250nm to 315nm, which is the desired output of the UV lamp. The outer tube 6 is transparent for this output wavelength and protects the discharge vessel and the phosphor layer from external influences.

Since the layered structure of the phosphors ensures that the initial VUV radiation is received only by the first layer, and not by the phosphor mixture, the phosphor mixture is not efficient at converting incident VUV radiation less than 200nm to longer wavelengths of 220nm to 245nm, thereby making the overall quantum efficiency very good, which in turn hits the pure second phosphor layer with the same advantages.

Other embodiments, not shown, provide that a first layer is provided inside the discharge vessel, which first layer will be coated with a layer of MgO on its inner surface to protect the first layer from the chemical and physical effects of the discharge. The second layer may be arranged outside the first layer, between the first layer and the discharge vessel, or outside the discharge vessel. These embodiments allow the discharge vessel to be made of conventional quartz instead of synthetic quartz, since the VUV radiation has been converted to longer wavelengths within the discharge vessel by the first layer of VUV phosphor.