Crystal growth, structure and optical properties of Pr³⁺-doped yttria-stabilized zirconia single crystals*

Abstract

The development of blue semiconductor light-emitting diodes (LEDs) has produced potential applications for Pr-doped materials that can absorb blue light, especially crystals, and we now report structure and optical properties for high-quality Pr-doped single crystals of yttria-stabilized zirconia (YSZ) grown by the optical floating zone (FZ) method. X-ray diffraction (XRD) and Raman spectroscopy showed that all of the single crystal samples were in the cubic phase, whereas the corresponding ceramic samples contained a mixture of monoclinic and cubic phases. X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) spectroscopy showed that Pr was present as the Pr3+ ion in ceramic rods and single crystals after heating to high temperatures. The absorption and photoluminescence excitation (PLE) spectra of the Pr-doped YSZ crystals measured at room temperature showed strong absorption of blue light, while their photoluminescence (PL) spectra showed five emission peaks at 565 nm, 588 nm, 614 nm, 638 nm, and 716 nm under 450 nm excitation. The optimum luminescence properties were obtained with the crystal prepared using 0.15 mol% Pr6O11, and those with higher concentrations showed evidence of quenching of the luminescence properties. In addition, the color purity of Pr-doped YSZ single crystal reached 98.9% in the orange–red region.

Probing High Oxygen Activity in YSZ Electrolyte

“…On the one side, YSZ-5Pr samples show smaller luminescence intensity than YSZ-1Pr, as well as a change in the shape of the spectra. Savoini et al 30 observed a faster decay monitoring the 1 D 2 to 3 H 4 luminescence in YSZ doped with 6.3 at% Pr, ascribed to concentration quenching by cross-relaxation, 44 which explains the strong decrease of the luminescence intensity, as also recently observed by Wang et al 45 for YSZ doped with Pr at concentrations above 1 at% Pr. This luminescence band also overlaps the rather intense low energy feature of the absorption corresponding to the transition 3 H 4 to 1 D 2 .…”

Effect of Pr doping on structure and luminescence properties of ZrO2 nanoparticles

“…If the lattice constant value is close to 5.42 Å indicating that the Pr in the sample is a mixture of Pr 3+ and Pr 4+ . In the present work, the lattice constant determined for the cubic peak is 5.102 Å, suggesting that Pr is in the Pr 3+ state [28].…”

Upconversion Visible Light Emission in Yb/Pr Co-Doped Yttria-Stabilized Zirconia (YSZ) Single Crystals

“…Using these coordinates, the color purity of the 2.5 mol% Yb 2 O 3 sample was calculated as 69.9%. The strong long wavelength red and short wavelength green components of the upconversion emission in the Yb/Pr: YSZ crystal samples are different from those observed with YSZ single crystal samples, where the spectral color coordinates are located in the red and orange region under blue light excitation [18]. Thus the addition of Yb 3+ to Pr-doped YSZ single crystals alters the populations of the Pr 3+ excited states, and enhances the green light emission.…”

“…Single doped Pr crystal samples were grown by the optical floating zone method using YSZ as the matrix material. X-ray photoelectron spectroscopy (XPS) analysis shows that Pr only exists in the form of Pr 3+ in the YSZ crystal, and its downconversion emission peaks are located at 564, 587, 614, 639, and 716 nm under the excitation of 450 nm [18]. However, absorptions of Pr 3+ in the infrared to near-infrared range have a low intensity, and it is necessary to incorporate appropriate sensitizers in the YSZ matrix in order to improve the intensity of these transitions for practical uses [10].…”

“…In the present paper, we report the preparation of large, high-quality Pr/Yb co-doped YSZ single crystals by the optical floating zone (FZ) method. These samples were all prepared with 0.15 mol% Pr 6 O 11 , which was shown in previous work to produce the maximum Pr 3+ luminescence intensity [18], and the influence of different concentrations of Yb 2 O 3 on the upconversion emission in the visible region was investigated following stimulation by a 980 nm laser.…”