Structural investigations of YPO4, ScPO4, and LuPO4

Milligan, W. O.; Mullica, D. F.; Beall, Gary W.; Boatner, L. A.

doi:10.1016/s0020-1693(00)91148-4

Cited by 196 publications

(107 citation statements)

References 10 publications

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“…The phosphate group in each compound forms a distorted tetrahedron. 13 The differences between the two compounds in ionic radii, interatomic distances, and lattice parameters are listed in Table I.…”

Section: A Sample Preparationmentioning

confidence: 99%

Controlled electron and hole trapping inYPO4:Ce3+,Ln3+
Krumpel
¹
,
Bos
²
,
Bessière
³

et al. 2009
Phys. Rev. B
62
4
31
0
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A detailed and systematic electron trapping study was conducted in the scientifically important wide bandgap materials LuPO 4 and YPO 4 doubly doped with Ce 3+ and Ln 3+ ͑Ln= Sm, Dy, Ho, Er, Tm͒. By using vacuum-ultraviolet luminescence spectroscopy and detailed thermoluminescence spectroscopy it was possible to establish by two independent methods that the observed electron traps can be assigned to the Ln 3+ codoping ions. It is shown that the associated electron trap depths are determined by the energy separation between the Ln 2+ ground states and the bottom of the conduction band. Both methods reveal a systematic behavior of electron trap depths as a function of the type of Ln 3+ codoping ion that can be explained by recently developed empirical models. Small differences in trap depths obtained by the two methods are discussed in the context of charge-transfer induced relaxation processes and uncertainties in glow peak analysis. Our experiments provide valuable information on 4f n ↔ 4f n , 4f n → 4f n−1 5d, O 2− → Ln 3+ charge transfer and the lowest-energy PO 4 3− group transitions as well as electron trap depths. These transition energies allowed us to construct a complete energy-level diagram for LuPO 4 :Ln 3+/2+ and YPO 4 :Ln 3+/2+ .

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Section: A Sample Preparationmentioning

confidence: 99%

Controlled electron and hole trapping inYPO4:Ce3+,Ln3+
Krumpel
¹
,
Bos
²
,
Bessière
³

et al. 2009
Phys. Rev. B
62
4
31
0
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“…Figure 9 shows this relationship; for comparison, corresponding linear dependences are shown for the known zero field splittings of Gd 3+ in zircons [18,26] and scheelites [21]. The lattice constants were available in the literature (zircon structure silicates [28][29][30], germanates [31] and phosphates [32], scheelite structure germanates [31,33], molybdates [34,35] and tungstates [35,36]). …”

Section: Zero Field Splittingmentioning

confidence: 99%

EPR Studies of Tb⁴⁺ in Single Crystals of Zircon and Scheelite Structure Silicates and Germanates

Hansen

Mosel

Müller‐Warmuth

et al. 1996

Zeitschrift Für Naturforschung A

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In memoriam Professor Gerhard LehmannElectron paramagnetic resonance spectra of tetravalent terbium ions have been observed in host crystals of ZrSi0 4 , HfSi0 4 , ThSi0 4 , ThGe0 4 (zircon structure) and ZrGe0 4 , HfGe0 4 (scheelite structure) at X band and Q band and various temperatures. The spin Hamiltonian parameters have been determined from the rotational diagrams; the zero field splittings turned out to be extremely large, so that complex spectra far from the strong magnetic field limit had to be analyzed. In all the compounds Tb 4+ substitutes for the tetragonal metal lattice sites. The incorporation of terbium, the origin of the large second-order parameters and comparisons with the spectra of trivalent gadolinium in similar systems are discussed.

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“…Excitation is via the host at 150 nm. The spectra exhibit characteristic 5 18 We observe no systematic change in the ratio of these two peaks with Eu concentration. However, we do observe a slight increase in the red/orange ratio in the smaller crystallites.…”

Section: Resultsmentioning

confidence: 67%

“…Dorenbos previously referred to this as the "mobility gap", and suggested that mobile e-h pairs are created when the excitation energy is at least 8% greater than the absorption edge. 22 By way of an example calculation of transfer efficiency, consider the excitation and absorption data for YPO 4 18 The η t calculation was performed for host excitation at both 138 and 150 nm. As expected, η t increases with Ln 3+ concentration as trapping of an e-h pair becomes more likely.…”

Section: Resultsmentioning

confidence: 99%

VUV Optical Properties of Rare Earth Doped YPO₄ Prepared by Different Routes

Way

Wallace

Diaz

2017

ECS J. Solid State Sci. Technol.

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The optical properties of nanocrystalline YPO 4 :Ln 3+ (Ln = Eu, Sm, Tb) prepared via co-precipitation are compared to larger crystallites of YPO 4 :Ln 3+ prepared via traditional solid state reaction. In larger crystals (∼330 nm) a distinct peak is observed at 150 nm in the excitation spectra, the intensity of which decreases markedly in smaller crystals (∼20 nm). Using excitation and reflectance spectroscopy, host-to-activator energy transfer efficiencies were calculated for Y 1-x PO 4 :Ln x 3+ (0.01 ≤ x ≤ 0.10). From the transfer efficiency data, we estimate that trapping by Eu 3+ and Sm 3+ is at least five times more efficient than trapping by Tb 3+ for excitation at the band edge. The fraction of energy lost to the surface or grain boundaries for excitation at 150 nm and 138 nm is also estimated. We propose that in the samples prepared via co-precipitation, an amorphous phase forms at grain boundaries that is responsible for the loss of efficiency under 150 nm excitation. Rare-earth doped YPO 4 has been studied extensively, both for potential technological applications and in more fundamental investigations of electron transport and trapping processes.1-4 Nakazawa reported on the vacuum ultraviolet (VUV) spectroscopy of Ln 3+ doped microcrystalline YPO 4 , 4 and assigned excitations due to host, 4f -5d, and charge transfer transitions for all of the lanthanides (except Pm and Lu). Additional studies of YPO 4 include one by Lai et al. that described a precipitation route to ∼20 nm YPO 4 :Eu 3+ , but only the UV optical properties are discussed.5 Di et al. have compared the VUV optical properties of YPO 4 :Tb 3+ prepared via solid state reaction and co-precipitation. 6 However, unlike in the work presented here, the high calcination temperatures applied to the co-precipitated samples led to materials that were similar in size to solid state samples but with improved morphology. Van Pieterson et al. obtained high-resolution excitation spectra of YPO 4 doped with both light 7 and heavy 8 lanthanides at 6 K. They assigned spectral features and compared the experimentally observed spectra with energy level calculations for the 4f n-1 5d 1 states. Makhov et al. investigated the optical properties of YPO 4 :Nd 3+ under VUV synchrotron radiation over a temperature range of 9-300 K. Their work included the assignment of various hostsensitized excitation mechanisms that will be discussed more later. 9Several groups have also reported on the optical properties of doubledoped YPO 4 .10-12 Much of that work was interpreted in the context of the lanthanide energy level scheme for YPO 4 reported by Bos et al. 13 and Dorenbos and Bos, 14 in which the Ln 2+ and Ln 3+ ground state energies are placed relative to the host valence and conduction bands. Of interest to the current study is the observation that the excitation spectra of some lanthanides (particularly Sm, Eu, Gd and Tm) contain a distinct, intense peak for excitation right at the band edge of YPO 4 (∼150 nm). Since the focus of prior work was on assigning peaks in ...

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Structural investigations of YPO4, ScPO4, and LuPO4

Cited by 196 publications

References 10 publications

Controlled electron and hole trapping inYPO4:Ce3+,Ln3+
Krumpel
¹
,
Bos
²
,
Bessière
³

et al. 2009
Phys. Rev. B
62
4
31
0
View full text Add to dashboard Cite

Controlled electron and hole trapping inYPO4:Ce3+,Ln3+
Krumpel
¹
,
Bos
²
,
Bessière
³

et al. 2009
Phys. Rev. B
62
4
31
0
View full text Add to dashboard Cite

EPR Studies of Tb⁴⁺ in Single Crystals of Zircon and Scheelite Structure Silicates and Germanates

VUV Optical Properties of Rare Earth Doped YPO₄ Prepared by Different Routes

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Structural investigations of YPO4, ScPO4, and LuPO4

Cited by 196 publications

References 10 publications

Controlled electron and hole trapping inYPO4:Ce3+,Ln3+Krumpel1, Bos2, Bessière3 et al. 2009Phys. Rev. B624310View full textAdd to dashboardCite

Controlled electron and hole trapping inYPO4:Ce3+,Ln3+Krumpel1, Bos2, Bessière3 et al. 2009Phys. Rev. B624310View full textAdd to dashboardCite

EPR Studies of Tb 4+ in Single Crystals of Zircon and Scheelite Structure Silicates and Germanates

VUV Optical Properties of Rare Earth Doped YPO4 Prepared by Different Routes

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Controlled electron and hole trapping inYPO4:Ce3+,Ln3+
Krumpel
¹
,
Bos
²
,
Bessière
³

et al. 2009
Phys. Rev. B
62
4
31
0
View full text Add to dashboard Cite

Controlled electron and hole trapping inYPO4:Ce3+,Ln3+
Krumpel
¹
,
Bos
²
,
Bessière
³

et al. 2009
Phys. Rev. B
62
4
31
0
View full text Add to dashboard Cite

EPR Studies of Tb⁴⁺ in Single Crystals of Zircon and Scheelite Structure Silicates and Germanates

VUV Optical Properties of Rare Earth Doped YPO₄ Prepared by Different Routes