[0001] The present invention relates to a composite material in which electro-magnetic radiation
is generated by applying an electric field across said material and whereby said material
contains at least an electrically conductive component, as well as a component that
generates radiation under the influence of an electric field applied to it, and a
component acting as a lens on the generated radiation. The said composite material
is thereby characterised by the fact that trivalent ytterbium or a compound of trivalent
ytterbium is another component that is present in the composite material and acts
as an amplifier for the radiation that is generated in the material.
[0002] Numerous solid state semiconductor materials that generate electro-magnetic radiation
when an electric field is applied to them are known from prior art. These materials
are nowadays commonly used in devices in many science and technology fields like telecommunications,
laser technology etc. It seems however that the performance of said materials in terms
of, for instance, energy efficiency, depends on the position of their output wavelength
range in the electro-magnetic spectrum.
[0003] The electro-magnetic spectrum for non- (or very limited) ionising radiation is divided
into several wavelength 'windows', for instance radio, optical and infrared. For all
of these wavelength windows the basic devices that are required for efficient application
are radiation sources and detectors. Every device utilising radiation from said wavelength
windows is based on either a radiation source or a radiation detector or both. So
it is obvious that a major part of the research efforts in this field is devoted to
designing and producing reliable and (energy)efficient sources and detectors, and
miniaturising such devices so that they can be integrated in microelectronic circuits.
For most of the wavelength windows much progression in science and technology has
been made in the recent years. For the infrared window however the scientifical and
technological developments have not been as extensive as for the other windows. One
of the main reasons for this is that, although there are nowadays many relevant applications
of infrared radiation, for instance in telecommunications, medicine and materials
science, there is still a lack of reliable and (energy)efficient infrared radiation
sources and detectors. This is especially the case for the far-infrared (FIR) wavelength
range (6000-10,000 nm.). The main drawback for the infrared wavelength window is that
there presently is no semiconductive material that can be used in, for instance, solid
state infrared radiation source devices, that offers the possibility to be 'tuned'
to a specific narrow wavelength range and to have a predetermined radiation intensity,
by varying only the weight percentage of a limited number of components in the material.
Although there is a strong need for such material for use in the infrared wavelength
window, it would also remedy many drawbacks of prior art technology for the other
wavelength windows for non- (or very limited) ionising radiation.
[0004] It is therefore the object of the present invention to propose a composite material
in which electro-magnetic radiation is generated by applying an electric field across
said material and whereby said material contains at least an electrically conductive
component, as well as a component that generates radiation under the influence of
an electric field applied to it, and a component acting as a lens on the generated
radiation, whereby the composite material is characterised by the fact that trivalent
ytterbium or a compound of trivalent ytterbium is another component that is present
in the composite material and acts as an amplifier for the radiation that is generated
in the material. The component that acts as a lens on the generated electro-magnetic
radiation, enables to tune the output wavelength to a specific wavelength range. The
output radiation is emitted in the form of photons. In the patent
FR 2 683 919 of the same applicant silicates were used as amplifying component. The trivalent
Ytterbium that is used according to the present invention enables a larger amplification
of the output radiation and increases the photon production.
[0005] In a preferred embodiment of said composite material the intensity of said radiation
that is generated in the material, can be varied by varying the amount of trivalent
ytterbium between 5 and 38 weight parts for every 100 weight parts of said component
acting as a lens. Experiments have shown that this relation between the weight percentages
of the amplifying and the lens component provides the most stable result.
[0006] In a further preferred embodiment the said composite material according to the present
invention may be advantageously characterised by the fact that the wavelength of said
radiation that is generated in the material, can be varied between 250 and 10.000
nanometres if the said radiation generating component of the composite material contains
at least the following active compounds: CU
2O
3, Si
2O
3, Al
2O
3, CuSO
4, Li
2O and Cr
2O
3 and whereby the amounts of Cu
2O
3 and Si
2O
3 are respectively 10 and 30 weight parts for every 100 weight parts of said component
acting as a lens. The specified wavelength range in this case covers the infrared
part of the electro-magnetic spectrum. The wavelength and intensity of the output
radiation can now be further tuned by varying the weight percentages of the amplifying
and lens components.
[0007] In another preferred embodiment of the composite material according to the present
invention, said component acting as a lens consists of a carborundum, silicon or zirconium
compound or a mixture of said compounds, whereby, in a mixture the zirconium amounts
to 50 to 70 weight parts per 100 weight parts of the total amount of the component
acting as a lens.
[0008] The composite material according to the present invention may further be advantageously
characterised by the fact that said zirconium compounds are present in the material
in the form of grains with a diameter between 200 and 250 micrometres. Experiments
have shown that this diameter range provides the best results for the lens function.
[0009] In a preferred embodiment, the composite material according to the present invention
contains a lens amplifying component which at least contains one or more compounds
of trivalent neodymium, erbium or holmium. This lens amplifying component further
amplifies the radiation that has been 'selected' by the lens component and improves
the photon emission.
[0010] The composite material according to the present invention may be advantageously characterised
by the fact that the amount of the said trivalent neodymium, erbium or holmium in
the lens amplifying component is between 5 and 15 weight parts per 100 weight parts
of the said component acting as a lens.
[0011] It is a further objective of the present invention to propose a device for heating
by means of infra red radiation, characterised by the fact that the part of the device
where the said infra red radiation is generated, is comprised of a layered structure
of materials, of which the composite material according to the invention, is present
in the form of one or more layers.
[0012] The device for heating by means of infra red radiation according to the present invention
can be advantageously characterised by the fact that said layered structure consists
of a succession of one or more layers containing a precious metal and one or more
layers containing a metal oxide, in addition to the said one or more layers of the
composite material according to the invention. The layers containing a precious metal
are functioning as a reflector for the infrared radiation photons generated by the
layer of composite material according to the present invention. The metal oxide layers
are mainly meant to provide a good basis for depositing the precious metal layer(s)
on a carrier material like glass and to shield the precious metal layer(s) from radiation
and temperature conditions. The reflected photons are reflected back into the composite
material and increase the overall energy efficiency of the device.
[0013] The device for heating by means of infra red radiation according to the invention
may further be characterised by the fact that said precious metal is gold, copper,
rhodium or palladium.
[0014] The device for heating by means of infra red radiation according to the invention
may additionally be characterised by the fact that said metal oxide is indium oxide
or tin oxide.
[0015] In a preferred embodiment of the device for heating by means of infra red radiation
according to the present invention, the said layered structure contains a carrier
layer that is transparent for the electro-magnetic radiation which is generated by
said radiation generating component in said composite material according to the invention.
[0016] The device for heating by means of infra red radiation according to the present invention
may furthermore be characterised by the fact that said carrier layer contains an oxide
or an alkoxide of an element from group IV-B of the Periodical System of Elements,
whereby the concentration of said oxide or alkoxide is between 18 and 45 weight parts
per 100 weight parts of the carrier material.
[0017] In a preferred embodiment the device for heating by means of infra red radiation
according to the present invention is characterised by the fact that said carrier
material consists of KaBaSi-glass or LiMgAIS-glass. These kinds of glass are best
suited for applications in the infrared wavelength window, because they contain the
least impurities that prohibit the transmittance of infrared radiation photons emitted
by the said layer of composite material.
[0018] In a further preferred embodiment the device for heating by means of infra red radiation
according to the present invention is characterised by the fact that the device is
attached to a wall or ceiling and forms part of an infra red central heating system.
In the following a preferred embodiment of a device for heating by means of infrared
radiation comprising the composite material according to the present invention will
be described. The following description and the attached drawing will show to the
reader in more detail how the invention remedies the aforementioned disadvantages
associated with the prior art. However, the reader should observe that description
and drawings are merely meant to illustrate application of the invention and should
in no way be regarded as limiting the scope of the present invention.
[0019] Figure 1 is a schematical view of a specific embodiment of the device for heating
by means of infrared radiation, whereby the device is attached to a wall and forms
part of an infra red central heating system.
[0020] Devices for heating by means of infrared radiation are known from prior art. Devices
that use a solid state semiconductive material for generating infrared radiation in
the far infrared wavelength (around 10,000 nm.) range, that have an energy efficiency
that is close to unity and can have a surface temperature that is acceptable for use
in a domestic environment, are however not commonly known. With the composite material
and the device according to the present invention it is possible to provide an infrared
heating device with such characteristics that can easily be used as part of a domestic
infrared central heating system. The device shown in figure 1 consists of a plate
(1) of KaBaSi-glass or LiMgAlS-glass that serves as a carrier material for a layer
of composite material according to the present invention. Said layer of composite
material may for instance have been deposited on the glass carrier material by industrial
silk-screen printing. On the other side of the layer of composite material, opposite
to the side where it is attached to the glass carrier, there may be a layer of precious
metal present, for instance a very thin layer of gold, for reflecting photons that
are emitted towards the back-side of the device in the direction of the wall. Normally
these photons would only increase the temperature in the interior of the device and
constitute an energy loss. Now they are reflected back into the layer of composite
material where they can again play a role in the photon generation process. The back-side
of the layer of precious metal is for instance covered by a layer of indium oxide.
This metal oxide layer shields the layer of precious metal from temperature and radiation
conditions that would cause rapid deterioration of the metal. The glass carrier material
with the layered structure thereon is provided with integrated electrodes which enable
to apply an electric field to the said composite layer. The glass plate is mounted
in a frame (2) of, for instance, aluminum and attached to a wall (3) of, for instance
a living room in an appartment. The device may be part of a complete central heating
system consisting of one or more similar devices in every room of the appartment and
appropriate control systems and thermostates to control the room temperatures. Under
the influence of the electric field applied to it, the said layer of composite material
according to the present invention generates infrared radiation, for instance with
a wavelength around 10,000 nm., in the form of photons. The said zirkonium compounds
in the composite material scatters the photons (4) over an angle of about 170 degrees.
Now every photon that impacts on, for instance, a piece of furniture in the room,
the walls or the skin of person that is present, serves as a micro source of heat.
So the room is heated very evenly and gradually, with very little convection, because
air is not required as a medium, as is the case with traditional central heating.
Research has shown that people experience infrared radiation with a wavelength close
to 10,000 nm. as very agreeable, and that it may even be beneficial to the human health.
The layer of composite material according to the present invention and the application
of said material in a device for infrared heating according to the present invention
make it possible to achieve an energy efficiency that is close to unity (100%). The
said composite material and the device can be manufactured with commonly available
materials and commonly known manufacturing methods.
1. Composite material in which electro-magnetic radiation is generated by applying an
electric field across said material and whereby said material contains at least an
electrically conductive component, as well as a component that generates radiation
under the influence of an electric field applied to it, and a component acting as
a lens on the generated radiation,
characterised by the fact that trivalent ytterbium or a compound of trivalent ytterbium is another
component that is present in the composite material and acts as an amplifier for the
radiation that is generated in the material.
2. Composite material according to claim 1, characterised by the fact that the intensity of said radiation that is generated in the material,
can be varied by varying the amount of trivalent ytterbium between 5 and 38 weight
parts for every 100 weight parts of said component acting as a lens.
3. Composite material according to claim 1, characterised by the fact that the wavelength of said radiation that is generated in the material,
can be varied between 250 and 10.000 nanometres if the said radiation generating component
of the composite material contains at least the following active compounds: Cu2O3, Si2O3, Al2O3, CuSO4, Li2O and Cr2O3 and whereby the amounts of Cu2O3 and Si2O3 are respectively 10 and 30 weight parts for every 100 weight parts of said component
acting as a lens.
4. Composite material according to claim 1, characterised by the fact that said component acting as a lens consists of a carborundum, silicon
or zirconium compound or a mixture of said compounds, and that in a mixture the zirconium
amounts to 50 to 70 weight parts per 100 weight parts of the total amount of the component
acting as a lens.
5. Composite material according to claim 4, characterised by the fact that said zirconium compounds are present in the material in the form of
grains with a diameter between 200 and 250 micrometres.
6. Composite material according to claim 1, characterised by the fact that said material contains a lens amplifying component which at least contains
one or more compounds of trivalent neodymium, erbium or holmium.
7. Composite material according to claim 6, characterised by the fact that the amount of the said trivalent neodymium, erbium or holmium in the
lens amplifying component is between 5 and 15 weight parts per 100 weight parts of
the said component acting as a lens.
8. Device for heating by means of infra red radiation, characterised by the fact that the part of the device where the said infra red radiation is generated,
is comprised of a layered structure of materials, of which the composite material,
mentioned in the previous claims, is present in the form of one or more layers.
9. Device for heating by means of infra red radiation according to claim 8, characterised by the fact that said layered structure consists of a succession of one or more layers
containing a precious metal and one or more layers containing a metal oxide in addition
to the said one or more layers of the composite material according to the invention.
10. Device for heating by means of infra red radiation according to claim 9, characterised by the fact that said precious metal is gold, copper, rhodium or palladium.
11. Device for heating by means of infra red radiation according to claim 8, characterised by the fact that said metal oxide is indium oxide or tin oxide.
12. Device for heating by means of infra red radiation according to claim 8, characterised by the fact that said layered structure contains a carrier layer that is transparent
to the electro-magnetic radiation which is generated by said radiation generating
component in said composite material.
13. Device for heating by means of infra red radiation according to claim 12, characterised by the fact that said carrier layer contains an oxide or an alkoxide of an element from
group IV-B of the Periodical System of Elements, whereby the concentration of said
oxide or alkoxide is between 18 and 45 weight parts per 100 weight parts of the carrier
material.
14. Device for heating by means of infra red radiation according to claim 12, characterised by the fact that said carrier material consists of KaBaSi-glass or LiMgAIS-glass.
15. Device for heating by means of infra red radiation according to one of the preceding
claims 8 to 14, characterised by the fact that the device is attached to a wall or ceiling and forms part of an infra
red central heating system.