A far-red-emitting ZnAl1.95Cr0.05O4 phosphor for plant growth LED applications.
I Elhamdi1, F Mselmi1, S Kammoun1
1Applied Physics Laboratory, Faculty of Sciences, University of Sfax, 3000-Sfax, Tunisia. imen.elhamdi.etud@fss.usf.tn.
Dalton Transactions (Cambridge, England : 2003)
|June 22, 2023
Summary
This study synthesized a novel far-red phosphor, ZnAl1.95Cr0.05O4, using solid-state reactions. Its properties show excellent thermal stability and emission matching plant photoreceptors, making it ideal for plant growth applications.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Photophysics
Background:
- The development of efficient phosphors is crucial for advanced lighting applications.
- Understanding the luminescence properties of transition metal-doped oxides is key to designing new materials.
- Far-red light plays a significant role in plant photomorphogenesis.
Purpose of the Study:
- To synthesize and characterize the far-red phosphor ZnAl1.95Cr0.05O4.
- To investigate the Cr3+ ion's behavior and luminescence properties within the ZnAl2O4 host lattice.
- To evaluate the suitability of this phosphor for plant growth applications by analyzing its emission spectrum and thermal stability.
Main Methods:
- High-temperature solid-state reaction for sample synthesis.
- Photoluminescence (PL) and excitation (PLE) spectroscopy to study emission and absorption.
- Electron Paramagnetic Resonance (EPR) measurements to determine Cr3+ site symmetry.
- Temperature-dependent luminescence measurements to assess thermal stability.
- Analysis of CIE chromaticity coordinates for color purity.
Main Results:
- ZnAl1.95Cr0.05O4 exhibits bright far-red emission around 687 nm upon excitation at 390 nm and 530 nm, attributed to Cr3+ 2Eg → 4A2(4F) transitions.
- Cr3+ ions substitute Al3+ ions in the ZnAl2O4 host with D3d symmetry, leading to split R1 and R2 emission lines.
- The phosphor demonstrates nearly zero-thermal-quenching behavior, with minimal intensity decrease from 300 K to 440 K.
- High color purity was observed, and the emission spectrum aligns well with the absorption of phytochromes in plants.
Conclusions:
- ZnAl1.95Cr0.05O4 is a promising far-red emitting phosphor with excellent thermal stability.
- Its emission characteristics are well-suited for stimulating plant growth, particularly when paired with UV LED chips.
- This material represents a significant advancement for horticultural lighting and plant science research.
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