Author(s)

Bommareddi Rami Reddy^*, Kristopher Liggins, Vernessa M. Edwards

Department of Physics, Alabama A & M University, Normal, AL, USA.

Phosphor coated diodes are critical to the lighting industry. Rare-earth doped fluoride phosphors are characterized in this work. Spectroscopy and lifetime measurements of CaF₂: Dy³⁺, LaF₃: Eu³⁺ and Tb³⁺-doped LaF₃ and CaF₂ crystals were performed by irradiating the samples with 405 and 375 nm diode lasers. Chromaticity diagrams are developed from spectral measurements. Dy³⁺-doped CaF₂ revealed bright white light emission having peaks at 492, 570 and 654 nm. The measured color coordinates are x = 0.322 and y = 0.340 for Dy³⁺-doped CaF₂ and these values are close to those of sunlight and the coordinated color temperature is 6147 K, under 405 m laser excitation. Eu³⁺-doped LaF₃ revealed twenty emission peaks in the visible wavelength region. The color coordinates measured for LaF₃: Eu³⁺ are x = 0.283 and y = 0.293 under 405 nm diode laser excitation and the color temperature is 9557 K. Eu³⁺-doped LaF₃ provides cool white-light, under 405 nm diode laser excitation. Tb³⁺-doped fluoride crystals revealed bright white light under low power diode laser excitation. The measured color coordinates for Tb³⁺-doped CaF₂ are x = 0.329 and y = 0.558 and the color temperature is 7713 K. The color coordinates for LaF₃: Tb³⁺ are x = 0.342 and y = 0.365 and the coordinated color temperature is 5370 K. These values are close to those of sunlight.

Rare-Earth Spectroscopy, White-Light Emission, Color Coordinates, Coordinated Color Temperature, Fluoride Materials, Laser Induced Fluorescence, Europium, Terbium, Dysprosium Ions

Reddy, B. , Liggins, K. and Edwards, V. (2018) Characterization of Fluoride Phosphors for Diode Pumped Solid-State Lighting Applications. Optics and Photonics Journal, 8, 288-300. doi: 10.4236/opj.2018.88024.