Single crystal and nanocrystalline Pr3+ doped LuPO4: Synthesis, structural characterization, photo- and cathodoluminescence
Graphical abstract
Introduction
Lanthanide doped LnPO4 (Ln = La, Y, Gd, Lu) materials are interesting for many technological applications, as scintillators and phosphors and also for bio-labelling applications [1], [2], [3], [4], [5]. They have good chemical and physical properties: high chemical stability and transparency in the near-UV and visible regions; relatively high emission intensities of the luminescent lanthanide ions. Lanthanide doped LuPO4 and other orthophosphates with the xenotime structure are being considered as phosphors that can find applications in the development of sensors to be used in space [6]. The suitability of these materials has been investigated by photoluminescence and cathodoluminescence spectroscopy in the case of the Eu3+, Er3+ and Nd3+ dopants [7]. We have found it interesting to extend these investigations to LuPO4 activated with Pr3+ and to compare the photoluminescence and the cathodoluminescence spectra of this material in the form of single crystals and of nanopowders.
Section snippets
Experimental
A concentration of 1 mol% of the Pr3+ dopant ion was chosen for this investigation, as it is of the order normally used for phosphor and scintillator applications. Single crystals of LuPO4 doped with 1 mol% of Pr3+ were obtained with a flux growth method as described by Feigelson [8]. Pb2P2O7 was used as a high temperature molten salt flux, and high purity Lu2O3, Pr6O11 (both 4 N), (NH4)2HPO4 and PbO were employed as starting materials in appropriate amounts. The melt was heated in a platinum
Structural and morphological properties of nanosized LuPO4:Pr3+
Powder X-ray diffraction shows that the LuPO4:Pr3+ nanopowders are single phase with the xenotime structure (Fig. 1). The Rietveld refinement with MAUD software [10] shows that the nanocrystalline powders have an average coherent diffraction length of about 20 nm. These results are confirmed by TEM images (Fig. 2) showing aggregated crystallites with individual sizes of about 10–30 nm.
In addition, as expected, the refined cell volume of the Pr3+ doped sample is larger than the one of the undoped
Conclusion
In this study we have presented a new synthetic approach to the synthesis of LuPO4:Pr3+ nanopowders, and their structural and morphological characterization using X-ray diffraction and transmission electron microscopy. We have shown that LuPO4 both as a single crystal and as a nanopowder, gives rise to efficient cathodoluminescence in the visible region, due to emission from the 3P0 and 1D2 levels. In addition, LuPO4:Pr3+ single crystals show also 5d–4f cathodoluminescence located in the UV
Acknowledgement
Erica Viviani (Univ. Verona) is gratefully acknowledged for expert technical assistance.
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Spectroscopic studies on Pr<sup>3+</sup> doped YPO<inf>4</inf> and LuPO<inf>4</inf> upon vacuum ultraviolet (VUV) and synchrotron radiation excitation
2022, Chemical PhysicsCitation Excerpt :Luminescence and scintillation properties of Pr3+ doped micro-YPO4 were studied in several papers, as e.g., in [3–6]. However, only a few papers were published with regard to the mechanism of UV emission of Pr3+ doped micro- and nano-LuPO4 [7–9]. Pr3+ doped YPO4 and LuPO4 show very efficient UV-C emission between 230 and 290 nm caused by interconfigurational [Xe]5d14f1 → [Xe]4f2 (thereafter referred as 5d14f1 → 4f2) transitions [10].
On the energy transfer from Pr<sup>3+</sup> to Gd<sup>3+</sup> in nanosized LuPO<inf>4</inf> particles
2021, Journal of LuminescenceCitation Excerpt :Considering the general requirements for nanoscintillators, Lutetium orthophosphate doped with Pr3+ and/or Gd3+ is of tremendous interest. Pr3+ as an activator give rise to fast and efficient interconfigurational [Xe]4f15d1→[Xe]4f2 transitions located in the UV range (230–285 nm) and interconfigurational transitions [Xe]4f2→[Xe]4f2 transitions mainly located in the visible range [6]. Moreover, host lattices that support the Pr3+ [Xe]4f15d1→[Xe]4f2 interconfigurational emission transitions can lead to the development of scintillators which are two or three times faster than presently used scintillators, based on the Ce3+ [Xe]4f05d1→[Xe]4f1 emission [7–11].
Photoluminescence properties of nano-sized (Lu<inf>1-x</inf>Y<inf>x</inf>)PO<inf>4</inf>:Pr<sup>3+</sup> (x = 10, 20, 30, 40, 50 at. %) phosphor powders
2020, Optical MaterialsCitation Excerpt :The obtained measurements results were shown in Fig. 4a–c and Fig. 6a,b. The emission spectra of nanopowders under λex = 230 nm are dominated by three large bands observed in region between 240 and 285 nm which are mainly assigned to interconfigurational transitions of Pr3+ from the lowest 415d1 level to lowest 4f2 levels namely: 4f15d1→3H5 (at 245 nm), 4f15 d1→3H6 (at 263 nm), 4f15d1→3F2 (at 272 nm),these emission bands has been observed and confirmed recently by A. Leto and al, S. Espinoza and al [4,6] in LuPO4 system and as well as in our previously works on YPO4 system [14,17]. Furthermore, an large emission bands with weak intensity can be observed at 368 nm attributed to 4f15 d1→3Pj,I6 (j = 0,1,2) transitions as it presented on Fig. 4a and another large emission band has been observed between 590 and 635 nm assigned to 1D2→3H4 transitions as it presented on Fig. 4c.The coexistence of 415d1→3Pj,I6 and 1D2→3H4 transitions indicate the existence of down-conversion (UV-conversion) phenomenon.
Intra- and inter-configurational luminescence spectroscopy of Pr<sup>3+</sup> -doped YPO<inf>4</inf> nanophosphors
2018, Current Applied PhysicsCitation Excerpt :The common geometrical structure of lanthanide orthophosphates LnPO4, namely the tetragonal phase with xenotime structure and the monoclinic phase with monazite structure, made them suitable candidates for a matrix where a substitutional doping with rare-earth element does not change the geometrical phase. The most important of these matrixes YPO4 [3–7] which used for many applications such as: scintillation, display devices, biological labeling [4–10]. YPO4 is known crystallize in the tetragonal zircon structure with space group I41/amd [5] and Pr3+ ion substitutes Y3+ in a site of D2d symmetry [6–8].
Photo and thermoluminescence of Pr<sup>3+</sup> ions activated SrZr<inf>4</inf>(PO<inf>4</inf>)<inf>6</inf> nanophosphors: plant growth LED and dosimetry applications
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