Oxide Phosphor Surface Coating for Broad Near-Infrared Emission
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Solution Overview
Problem
Existing light emitting devices lack a near-infrared phosphor with a wide full width at half maximum and a light emission peak wavelength in a longer range, suitable for applications such as non-destructive measurement of food and agricultural products, plant growth, and safe visualization inside living bodies.
Innovation Solution
An oxide phosphor is produced by heat-treating a raw material mixture containing Ga and Cr with a flux containing Group 4, 5, or 14 elements, resulting in phosphor particles with adhered first compound particles, enhancing light emission intensity and particle size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional phosphor is used, then the light emitting device can be manufactured with standard materials, but the light emission intensity in the near-infrared range is insufficient
Solution Approach 1:
The patent employs a composite phosphor system consisting of a host crystal (β-Ga2O3) doped with activating elements (Cr, Mn, Fe, Co, or Ni) and surface-coated oxide particles (TiO2, ZrO2, HfO2, Nb2O5, Ta2O5, SiO2, GeO2, SnO2, PbO2, P2O5, As2O3, Sb2O3, or Bi2O3). This composite structure enables enhanced near-infrared light emission intensity while maintaining manufacturability through established ceramic processing techniques.
2Adaptability or versatility
If a phosphor with longer peak wavelength is used, then the suitability for non-destructive measurement and visualization applications is improved, but the full width at half maximum becomes narrower
Solution Approach 1:
The patent achieves a broad emission spectrum with extended near-infrared coverage by carefully controlling the composition ratios of multiple activating elements (Cr: 0.01-5 wt%, Mn: 0.01-5 wt%, Fe: 0.01-5 wt%, Co: 0.01-5 wt%, Ni: 0.01-5 wt%) in the β-Ga2O3 host crystal. This compositional parameter optimization results in a phosphor with both long peak wavelength and wide full width at half maximum, satisfying both application suitability and spectral breadth requirements.
3Illumination intensity
If the phosphor particle size is increased, then the light emission intensity is enhanced, but the particle aggregation and handling difficulty increase
Solution Approach 1:
The patent applies oxide particle coatings (TiO2, ZrO2, HfO2, Nb2O5, Ta2O5, SiO2, GeO2, SnO2, PbO2, P2O5, As2O3, Sb2O3, or Bi2O3) on the surface of the phosphor particles. This surface modification enhances the mechanical strength and dispersibility of large particles (10-50 μm diameter), preventing aggregation while maintaining high light emission intensity. The coated surface provides better handling characteristics despite the increased particle size.
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 oxide phosphor achieves high light emission intensity and a wide full width at half maximum, enabling effective non-destructive measurement and safe visualization in the near-infrared range.
Implementation Method 1
a light emitting element configured to emit light having a light emission peak wavelength of 365 nm or more and 650 nm or less
Implementation Method 2
an oxide phosphor... containing a host crystal containing Ga and oxygen and an activating element
Data Source
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AI summary
An oxide phosphor includes phosphor particles containing a host crystal containing Ga and oxygen and an activating element, and a first compound particle disposed on at a surface(s) of the phosphor particles, the at least one first compound particle containing an oxide particle containing a first element selected from the group consisting of Group 4 elements, Group 5 elements, Group 14 elements, and Group 15 elements.