Hexagonal Zinc Oxide Particles with Ti-Fe Solid Solution
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Solution Overview
Problem
Current ultraviolet shielding agents, such as zinc oxide and titanium oxide, are inadequate in effectively shielding UV-A radiation, which contributes to photoaging, and there is a need for improved UV-A and UV-B radiation shielding performance without compromising the direct transition properties of zinc oxide particles.
Innovation Solution
Development of hexagonal prism-shaped zinc oxide particles with a solid solution of Ti and/or Fe elements, forming a layer on the surface, specifically Zn2TiO4 or ZnFe2O4, to enhance ultraviolet shielding ratio at wavelengths of 400 nm or less, achieved through a method involving the addition of titanium and/or iron salts to a zinc oxide slurry followed by baking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional zinc oxide and titanium oxide are used as ultraviolet shielding agents, then the scattering effect is achieved, but the absorption effect for UV-A radiation is insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of zinc oxide particles by incorporating iron and titanium elements to form solid solutions (Zn1-x-yFexTiyO). This modifies the band gap energy and electronic structure of the particles, enabling them to absorb UV-A radiation through direct electronic transitions while maintaining their scattering properties. The specific composition ranges (0 < x ≤ 0.5, 0 < y ≤ 0.5, x + y < 1) are optimized to achieve both UV-A absorption and UV-B shielding effects simultaneously.
Solution Approach 2:
The patent creates composite zinc oxide particles containing multiple elements (Zn, Fe, Ti) in a solid solution structure. This composite approach combines the scattering effect of zinc oxide with the UV-A absorption capabilities of iron and titanium, achieving multi-functional ultraviolet protection. The solid solution structure ensures homogeneous distribution of elements and synergistic optical properties.
2Object-affected harmful factors
If iron oxide is added to increase UV absorption, then the wavelength range expands, but the direct transition properties of zinc oxide are impaired
Solution Approach 1:
The patent precisely controls the concentration parameters of iron and titanium elements within specific ranges (0 < x ≤ 0.5, 0 < y ≤ 0.5 for Zn1-x-yFexTiyO) to maintain the direct transition properties of zinc oxide. By limiting the doping levels, the fundamental electronic structure of zinc oxide is preserved, ensuring direct band gap transitions remain dominant for effective UV absorption, while still expanding the absorption range to include UV-A wavelengths.
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 resulting zinc oxide particles exhibit significantly improved ultraviolet shielding ratios for both UV-A and UV-B radiation while maintaining direct transition properties, providing enhanced protection against photoaging.
Implementation Method 1
the absorption effect depends on the band gap energy (Eg) of the powder particle. The Eg of zinc oxide is 3.2 eV and electronic excitation thereof is direct transition so that zinc oxide can absorb effectively the light at the wavelength of 388 nm or less
Implementation Method 2
The scattering effect depends on the reflection factor of the particle and the particle size
Data Source
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AI summary
It is one of the objects of the present disclosure to provide hexagonal prism-shaped zinc oxide particles having improved ultraviolet shielding ratio at the wavelength of 400 nm or less without impairing the direct transition properties of electronic excitation thereof and having remarkably improved ultraviolet shielding ratio for UV-B radiation and UV-A radiation. A zinc oxide particle containing a solid solution of a Ti element and/or a Fe element and a Zn element in at least a portion thereof, and having a hexagonal prism shape.