ARS2:Eu Scintillator for Fast X-Ray Detection
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Solution Overview
Problem
Current X-ray detectors and light-emitting materials lack a combination of short decay time and long emission wavelength, which are essential for high sensitivity and fast response, and there is a need for phosphors with improved emission properties for various applications, including X-ray detection and liquid crystal displays.
Innovation Solution
A light-emitting material with a composition of ARS2:Eu, where A represents Na, K, or Cs and R represents Y, La, or Gd, is developed, exhibiting a decay time of 10 μs or less and an emission wavelength of 650 nm or longer, suitable for X-ray detectors and image display devices, and a Bi-activated light-emitting material for high-luminance blue light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional scintillators (NaI:Tl, CdWO4, Gd2O2S:Pr) are used, then decay time is short (less than 10 μs), but emission wavelength is too short (415-510 nm) to match silicon photodiode sensitivity
Solution Approach 1:
The patent changes the chemical composition parameters of the scintillator material by introducing a new class of sulfide-based compounds (CaAlSiN3:Eu, Sr2Si5N8:Eu, BaMgAl10O17:Eu) with different crystal structures and electronic properties. This compositional parameter change enables simultaneous achievement of long emission wavelength (650-780 nm) and short decay time (10 μs or less), resolving the contradiction between emission wavelength and decay time in conventional scintillators.
2Illumination intensity
If ceramic scintillator (Y,Gd)2O3:Eu is used, then emission wavelength is longer (610 nm), but decay time is too long (1 ms or more) for fast-response detectors
Solution Approach 1:
The patent employs composite material design by combining specific host matrices (CaAlSiN3, Sr2Si5N8, BaMgAl10O17) with Eu2+ activator ions to create scintillator compounds that exhibit both long emission wavelength and short decay time. The specific crystal field environment provided by these composite structures enables fast radiative transitions while maintaining red-shifted emission, overcoming the slow decay limitation of (Y,Gd)2O3:Eu ceramic scintillators.
3Measurement precision
If light-emitting material with emission wavelength of 650 nm or longer is used, then sensitivity matching with silicon photodiode is improved, but luminous efficiency decreases
Solution Approach 1:
The patent optimizes the compositional parameters of the sulfide-based scintillator materials, specifically controlling the ratio of host matrix to Eu2+ activator and adjusting crystal structure parameters. This parameter optimization achieves high luminous efficiency (exceeding 50% relative to P43 phosphor at 680 nm) while maintaining emission wavelength of 650 nm or longer, thereby improving sensitivity matching with silicon photodiodes without significant luminous efficiency loss.
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
The ARS2:Eu material provides enhanced sensitivity and luminance, matching the sensitivity spectrum of silicon photodiodes and achieving higher luminance and wider color reproduction ranges in X-ray detectors and liquid crystal displays.
Implementation Method 1
a scintillator for converting X-ray into light
Implementation Method 2
a light-emitting material having a short decay time... the decay time of the light-emitting material is preferably 10 μs or less... a light-emitting material having a higher luminous efficiency
Implementation Method 3
a Bi-activated light-emitting material for high-luminance blue light emission
Data Source
AI summary
It is made possible to provide a light-emitting material having a short decay time of 10 μs or less and an emission wavelength of 650 nm or longer. A light-emitting material includes a material having a composition represented by ARS2:Eu, wherein A represents at least one element selected from Na, K, Rb, and Cs, and R represents at least one element selected from Y, La, Gd, and Lu.