Ce,Pr-Coactivated Calcium Pyrophosphate Phosphor for 185 nm UV Utilization
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Solution Overview
Problem
Cerium-activated calcium pyrophosphate phosphors used in ultraviolet applications are inefficient in utilizing the full spectrum of radiation emitted by low-pressure mercury discharge lamps, particularly under 185 nm excitation, leading to suboptimal performance in suntan lamps and other applications.
Innovation Solution
Incorporating a praseodymium coactivator into the cerium-activated calcium pyrophosphate phosphor to enhance UV emission under 185 nm radiation while maintaining sensitivity to 254 nm radiation, represented by the formula Ca2P2O7:Ce,Pr, with sodium for charge balance, and optimizing the formulation to increase overall brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If cerium-activated calcium pyrophosphate phosphor is used for UV emission, then 254 nm radiation sensitivity is maintained, but 185 nm radiation utilization is insufficient
Solution Approach 1:
The patent applies composite materials by combining cerium and praseodymium activators within the calcium pyrophosphate host lattice to create a dual-activator phosphor system. This composite approach enables the phosphor to respond to both 254 nm and 185 nm radiation wavelengths simultaneously, resolving the contradiction between maintaining 254 nm sensitivity and improving 185 nm utilization.
Solution Approach 2:
The patent employs parameter changes by systematically varying the molar ratios of cerium and praseodymium activators, as well as adjusting the stoichiometric factors in the phosphor formulation. By optimizing these compositional parameters, the phosphor achieves enhanced 185 nm response while preserving 254 nm sensitivity, thus resolving the technical contradiction.
2Productivity
If low-pressure mercury discharge is used for excitation, then 254 nm radiation is generated, but only limited 185 nm radiation is available
Solution Approach 1:
The patent applies universality by designing a phosphor that performs multiple functions: it responds to both 254 nm and 185 nm radiation from the mercury discharge lamp. The dual-activator system makes the phosphor universally responsive to different wavelengths, maximizing utilization of the available excitation spectrum and improving overall UV emission efficiency.
Solution Approach 2:
The patent uses parameter changes by optimizing the activator concentration ratios and host lattice composition to enhance absorption efficiency at 185 nm while maintaining 254 nm response. This compositional optimization increases the productivity of UV emission by better utilizing the limited 185 nm radiation available from the mercury discharge source.
3Illumination intensity
If praseodymium coactivator is added to enhance 185 nm response, then UV emission under 185 nm excitation increases, but phosphor formulation complexity increases
Solution Approach 1:
The patent applies composite materials by integrating praseodymium as a coactivator with cerium in the calcium pyrophosphate matrix. This composite phosphor formulation achieves enhanced UV emission intensity under 185 nm excitation while managing the increased formulation complexity through systematic compositional design and optimization.
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 Ce,Pr-coactivated phosphor significantly increases UV emission under 185 nm excitation with minimal impact on 254 nm sensitivity, resulting in improved brightness and efficiency when used in low-pressure mercury discharge lamps.
Implementation Method 1
The phosphor emits ultraviolet radiation at about 334 nm in response to stimulation by 254 nm and 185 nm radiation
Data Source
AI summary
A UV-emitting, Ce,Pr-coactivated calcium pyrophosphate phosphor is provided wherein the Pr activator increases the phosphor's sensitivity to excitation by 185 nm radiation. The improved sensitivity to the 185 nm radiation allows the phosphor to make better use of the approximate 10% of the UV radiation that is emitted at 185 nm by a low pressure mercury discharge.