Solid-State Single Crystal Scintillator Growth via Seed Orientation
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Solution Overview
Problem
Conventional methods for producing single crystal scintillators are expensive and time-consuming due to the need for high-temperature processes and liquid solubility limitations, which restrict activator ion concentration and distribution, making them unsuitable for cost-effective applications like CT and PET imaging.
Innovation Solution
A method for solid-state conversion of polycrystalline materials to single crystals without melting, using heat-treatment and seed crystals to grow grains along a predetermined plane, allowing for higher activator ion concentrations and homogeneous distribution, and employing anisotropic materials like lutetium silicate and lutetium iodide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional melt-based methods are used to grow single crystal scintillators, then single crystal transparency is achieved, but the process becomes expensive and time-consuming due to high temperatures and complex equipment requirements
Solution Approach 1:
The patent changes the fundamental parameter of crystal growth from liquid-phase melt growth to solid-state diffusion growth. This parameter change eliminates the need for high-temperature melting equipment and complex seed crystal arrangements, thereby reducing manufacturing cost and complexity while still achieving single crystal transparency through controlled solid-state diffusion processes
Solution Approach 2:
The patent utilizes solid-state phase transitions and diffusion processes instead of liquid-phase melting. By employing solid-state conversion where polycrystalline material transforms to single crystal through thermal diffusion without melting, the process avoids expensive melt-growth equipment while maintaining crystal quality
2Reliability
If liquid melt methods are used for crystal growth, then single crystals can be formed, but activator ion concentration is limited by liquid state solubility
Solution Approach 1:
The patent changes the physical state parameter from liquid to solid, enabling activator ion concentrations to exceed liquid solubility limits. In the solid-state diffusion process, activator ions can be incorporated at much higher concentrations through direct diffusion into the crystal lattice,不受限于 liquid phase solubility constraints
Solution Approach 2:
Instead of dissolving activator ions in liquid melt and then crystallizing, the patent inverts the process by using solid-state diffusion where activator ions are introduced directly into solid polycrystalline material which then converts to single crystal. This inversion allows bypassing of liquid solubility limitations
3Reliability
If liquid melt methods are used, then crystals can grow from melt, but activator ions are not homogeneously distributed in the liquid melt or resulting crystal
Solution Approach 1:
The patent changes the growth medium from liquid to solid state. In solid-state diffusion, activator ions diffuse through the crystal lattice in a controlled manner, ensuring homogeneous distribution. The solid matrix provides fixed diffusion paths and prevents the segregation and convection issues present in liquid melts, achieving uniform activator ion distribution throughout the single crystal
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the production of cost-effective, high-transparency single crystal scintillators with improved light output and decay times, suitable for medical imaging applications like CT and PET, by overcoming solubility and distribution limitations of conventional methods.
Implementation Method 1
growing at least one of a plurality of grains of the polycrystalline composition along a predetermined plane
Implementation Method 2
the polycrystalline material having the seed crystal may be subjected to heat-treating, where the heat-treating does not include melting the polycrystalline material
Implementation Method 3
heat-treating the polycrystalline composition to a temperature sufficient to reduce a porosity of the polycrystalline composition
Implementation Method 4
scintillators are generally used to convert gamma rays, X-rays or visible light into optical photons
Data Source
AI summary
A method of making a single crystal material is provided. The method includes providing a polycrystalline material having a plurality of grains. The method further includes adding a seed crystal to the polycrystalline material to define a plane of growth for the polycrystalline material. Further, the polycrystalline material having the seed crystal may be subjected to heat-treating, where the heat-treating does not include melting the polycrystalline material.