Hydrothermal synthesis and characterization of LaPO4 for bio-imaging phosphors

Byrappa, K.; Devaraju, Murukanahally Kempaiah; Paramesh, J. R.; Basavalingu, B.; Soga, Kohei

doi:10.1007/s10853-007-2337-8

Cited by 36 publications

(23 citation statements)

References 10 publications

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“…A similar result has been also reported, for Nd-doped LaPO 4 [50]. Therefore, our luminescence results are perfectly compatible with the above mentioned arguments and the fact that in LaPO 4 it is possible to remove very efficiently remaining impurities by calcination.…”

Section: 2-optical Characterizationsupporting

confidence: 92%

“…Particularly OH -radicals are known to be efficient Er 3+ -luminescence quenchers [45][46][47][48][49][50][51][52][53][54][55][56], because of its vibration energy and that only 2 phonons are needed to match the energy gap of the 1.5 m emission. In fact, it has been demostrated in phosphate glasses that there is a direct releationship between OH -content and the reduction of the observed luminescence lifetime [55].…”

Section: 2-optical Characterizationmentioning

confidence: 99%

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LaPO4:Er microspheres with high NIR luminescent quantum yield

García‐Sevillano

Cantelar

Justo

et al. 2013

Materials Chemistry and Physics

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Er-doped LaPO 4 micro-spheres have been synthesized by spray pyrolysis and the near infrared (NIR) properties have been characterized. It has been found that, following an adequate post-annealing treatment, the emission properties are remarkably improved. The NIR luminescence intensity is highly enhanced and its decay time increases to a value almost coincident with the reported radiative lifetime, which implies that the quantum yield approaches   100%. This improvement in luminescence characteristics is probably related to the suppression of residual OH -radicals, that otherwise act as NIR luminescence quenchers, and to the increase in material's crystallinity. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 2 *Manuscript Click here to view linked References 1.-INTRODUCTIONLanthanide phosphate (LaPO 4 ) and, in particular, its monoclinic polymorph (monazite), has been widely used as a host for the preparation of lanthanide-based phosphors. In fact, doped with Ce and Tb constitutes one of the classical phosphors used in high-quality fluorescent lighting due to its high quantum yield and stability at high temperature [1][2][3][4]. By varying the dopants (Pr, Nd, Eu, …) the optical properties can be tuned over a wide spectral range, with emerging applications in different fields such as biomedicine [5][6], photonic band gap materials or optical amplification [7][8]. In particular, for optical amplifiers and lasers, Er becomes the most interesting dopant because of its characteristic emission, at around 1.5 m, coincident with the transparency window of optical fibers [8][9]. Along this line, there has been a considerable effort along the last years in order to prepare Er doped phosphate particles incorporated into polymer-based components, in order to improve luminescence characteristics and trying to achieve long lifetimes and high quantum efficiencies [10][11][12][13][14][15][16][17]. The data reported in the literature for the 1.5 m emission lifetime vary within a very large range (60 s [14] to 3.7 ms [17]), reflecting possibly the large variety of dopants concentration, particle size and fabrication processes; affecting material's properties such as crystallinity or impurities content [10][11][12][13][14][15][16][17].Spray pyrolysis is a well known technique for the synthesis of powdered materials, whose main advantages are simplicity and continuous character, which, along with its suitability to control particle size (micrometric) and shape (spherical), make it very attractive for industrial purposes [18][19]. Recently, this method has been used to prepare LaPO 4 spheres doped with Ce and Tb ions, which showed a high luminescence efficiency after a post heating treatment at >1300ºC [20][21]. However, up to our knowledge, this synthesis method has never been applied to the synthesis of Er-doped LaPO ...

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Section: 2-optical Characterizationsupporting

confidence: 92%

Section: 2-optical Characterizationmentioning

confidence: 99%

LaPO4:Er microspheres with high NIR luminescent quantum yield

García‐Sevillano

Cantelar

Justo

et al. 2013

Materials Chemistry and Physics

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“…Because of this, there have been many studies which report on the fluorescence properties of doped monazite materials [e.g. [17][18][19][20][21]. Few studies, however, report the fluorescence of these materials to a level that is useful for determining detailed structural information.…”

Section: Introductionmentioning

confidence: 99%

Site-selective time resolved laser fluorescence spectroscopy of Eu and Cm doped LaPO₄

Holliday¹,

Babelot

Walther

et al. 2011

Radiochimica Acta

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Samples of LaPO 4 doped with Eu 3+ or Cm 3+ were synthesized by a hydrothermal process which resulted in a solid solution at temperatures less than conventional processing. Time resolved laser fluorescence spectroscopy was used to probe the incorporated Eu 3+ or Cm 3+ in order to gain structural information on its local environment. This revealed that Eu 3+ and Cm 3+ incorporate on the La site as expected. The emission spectrum of Eu 3+ resolves the fully degenerate 5-fold splitting of the peaks in the F 2 transition due to the low symmetry of the site, confirming previous calculations. A minor site in the Eu 3+ doped sample is identified as coordinated with hydroxide contamination. Direct excitation of Cm 3+ doped samples show the presence of "satellite" species. Although these spectral features have been observed in Cm 3+ doped LuPO 4 and YPO 4 , this is the first time that these satellites are resolved into their individual species. These are hypothesized to be due to a disturbance in the ideal structure which creates a break in the equivalence of the four lanthanum sites within a unit cell. The 4-fold ground state splitting of all species is identical, although slightly shifted, indicating similar environments. The fluorescence lifetimes were long (1.2 ms for Cm and 3.6 ms for Eu) indicating an absence of water in the immediate coordination sphere due to the incorporation of the doping ion.

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“…3). The luminescence spectra of Nd 3 þ ions well investigated in the literature LaPO 4 matrix have been already published [12][13][14].…”

Section: Resultsmentioning

confidence: 99%