Kinetic study of the collisional quenching of electronically excited phosphorus atoms, P 3 2 D J , 3 2 P J , by polyatomic molecules. You have access to this article. Please wait while we load your content Something went wrong.
Try again? Cited by. Back to tab navigation Download options Please wait Article type: Paper. DOI: Download Citation: J. Kinetic study of the collisional quenching of electronically excited phosphorus atoms, P 3 2 D J , 3 2 P J , by polyatomic molecules A. Acuna and D. Husain, J. Search articles by author A. Ulyses Acuna. David Husain. Back to tab navigation Fetching data from CrossRef. Since, bulk amorphous alloys retain their fluidity, they do not accumulate significant stress when cooled from their casting temperatures down to below the glass transition temperature, and as such dimensional distortions from thermal stress gradients can be minimized.
Accordingly, intricate structures with large surface area and small thickness can be produced cost-effectively.
Differential Scanning Calorimetry measurements at typical heating rates e. Moreover, the time and temperature of the heating and shaping operation is selected such that the elastic strain limit of the amorphous alloy is substantially preserved to be not less than 1. In the context of the embodiments herein, temperatures around glass transition means the forming temperatures can be below glass transition, at or around glass transition, and above glass transition. This value is known to be proportional to the cube of the atomic number Z, of the element doing the blocking.
The table below gives estimates of the blocking power of several example BMG alloys. None of the materials cited have a stopping power as high as Lead for gamma-rays, but are much more environmentally and biologically friendly, and can be used in bio-applications where lead is entirely inappropriate. Other high-Z alloys are also feasible.
For non-ionizing radiation, the shielding properties of the material are determined by its conductivity, permeability, and thickness. This is a rough approximation due to the amorphous nature of BMG materials, but gives an initial estimate where empirical data is lacking. The complete.compmimanpicon.tk
EP2761047A1 - Radiation shielding structures - Google Patents
A combination of higher conductivity and permeability in a BMG alloys reduces the skin depth of the material, and therefore reduces the necessary thickness of a shield made from that material, consequently reducing cost, weight, and volume. The first reason is that with the different alloy compositions that one can make from the different atomic weight materials and the different amounts of each atomic weight material, one can come up with different conductivities for the BMG materials.
So one can actually tune the conductivity of the materials to have a specific shielding property, and that would be especially useful for radio frequency in the kilohertz and megahertz regime. One is not limited to a single density of the material like of copper or steel or lead, but one can generate different materials with different densities. This shows that one can have different compositions of BMG materials that fall on the density scale in different places, and select a specific composition that would be suitable for a specific application.
In this case, the magnetic field in the material is strengthened by the induced magnetization. As a result, the magnetic field in the material is weakened by the induced magnetization. Generally, non-magnetic materials are said para- or diamagnetic because they do not possess permanent magnetization without external magnetic field. Ferromagnetic, ferrimagnetic, or antiferromagnetic materials, have high positive susceptibility, and possess permanent magnetization even without external magnetic field.
Magnetic materials having different susceptibilities could be beneficial in different applications. Bulk metallic glasses would allow one to choose the material that has just the right amount of magnetization for a particular application. Even in an aqueous environment where there are ions that would eventually deteriorate other metals, or in an organic environment that is corrosive to the metal or any sort of harsh environmental conditions, BMGs tend to have good corrosion resistance. It is very easy to make a continuous shield without seems or without welding even for a complex shape that would shield whatever one wanted to put inside or outside.
That is due to the forming processes that are available for thermoplastic forming the bulk metallic glasses. The thermoplastic forming processes could be hot forming or blow molding or extruding; they can produce different shapes fairly easily with the bulk metallic glasses. One can shield radiation from the inside out from a radiating source by enclosing the radiation source, for example, or shield from the outside in by enclosing the body that should be protected from radiation. One can have a wall that shields against particles or radiation so that one puts whatever one is trying to shield on one side of the wall and the radiation emitter would be on the other.
It would not have to be a plate like that drawn in Figure 3. It could be any shape but the goal there is to shield whatever is inside or plate an object that contains radiation to keep the radiation from going out. Please note that the plating or the substrate of Item 3, or the foil of Item 2, can all be patterned to give one specific patterns of transmission or reception of radiation and can also be used to tune reception or transmission or radiation in the case radio frequency waves or for whatever reason one wanted to pattern them.
Item 5 is a sealed container made by a hot forming process that can be used to form bulk metallic glasses. By a hot forming process, the two bulk metallic glass components can be sealed together to form a seal that would be the equivalent of a metal weld or a polymer bond, for example, using an epoxy or glue.
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The benefit of a hot formed seal is that the weld line would have the same shielding properties as the rest of the container so that there would be uniform shielding all the way around container. Depending on the mesh size one could shield something from different frequencies of radiation.
The structure of Item 6 could be a matrix of bulk metallic glass wires, and that can be in any shape.
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- resonance radiation;
The mesh form shield could be woven into a plate or it could be kind of a spherical shape or any cage that surrounds some kind of device or object or person that needed to be protected. One can either guide the waves to a specific region for use or one can guide them away from a specific region to protect oneself. A RF guide works due to these micro structures that happen to interact with certain wavelengths so one can tune it to a certain frequency.
One can do this in the radio frequency regime, and potentially in the optical regime as well for certain materials. Left handed and right handed in the figure are referred to, left handed and right handed indexes of refraction. One can actually create left handed and negative index of refraction materials using this method of micro patterning conductive metals.
While the figure shows RF flux being guided through the RF guide, i. The reason that bulk metallic glasses could be use to make RF guides is because they are easily patterned, easily molded into the complex shapes and would not have to be manufactured by complex machining or etching or laser ablation or any other expensive method.
For medical implants, one would prefer using something with a lower magnetic susceptibility, which means that it is going to have less of a magnetic response when it is put in an external magnetic field. So if one compares that magnetic susceptibility of the zirconium based bulk metallic glass compared with that of copper, one would choose the zirconium based bulk metallic glass because the latter has a lower magnetic susceptibility.
For MRI imaging, if one would have a zirconium based bulk metallic glass inside somebody's body that is being imaged, one would get less artifacts from that piece of metal than from copper. So, if somebody has a pacemaker and it has got a piece that is made of a bulk metallic glass such as zirconium based bulk metallic glass, one would expect to see less interference due to that bulk metallic glass material in the MRI image than one would if one made it out of a material that had a higher magnetic susceptibility.
These components could be shielded by a bulk metallic glass, foil, or deposited layer, or a bulk piece of material that was molded around a component.
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So applications could be to protect components against, for example, radio frequency or even higher frequency radiation, such as gamma rays or cosmic rays. One can also protect electronics on the board level, meaning the PCB printed circuit board level. One could design with foil or with bulk molding techniques designed shielding that goes around board level electronics so that the components are protected again against radio frequency, interference or even X-rays and gamma rays.
Figure 5 shows a PCB entirely enclosed by a BMG coating or layer, for example, where the whole device would be encased by a bulk metallic glass shield.
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For example, the component could be for phones or other electronic equipment that is sensitive to electromagnetic radiation, such as microphones or motors or anything that transmits or receives, such as a speaker or transducer or something along those lines. This means when added thicknesses are used, the shielding multiplies. For example, a practical shield in a fallout shelter is ten halving-thicknesses of packed dirt, which is 90 cm 3 ft of dirt.
The effectiveness of a shielding material in general increases with its density. As explained above, the density of bulk- solidifying amorphous alloys can be tailored as desired, thereby allowing one to make radiation shielding structures having different radiation shielding effectiveness. It could be used to in satellite-based particle detectors, offering several benefits: protection from radiation damage; reduction of background noise for detectors; and lower mass compared to single-material shielding.
Sometimes even lighter materials such as polypropylene or boron carbide could be used. It also absorbs gamma rays, which produces X-ray fluorescence. Each subsequent layers absorbs the X-ray fluorescence of the previous material, eventually reducing the energy to a suitable level. Each decrease in energy produces bremsstrahlung and Auger electrons, which are below the detector's energy threshold.