Luminescence, structure and antiferroelectric-type phase transition in Ca8ZnEu(PO4)7

Lazoryak, Bogdan I.; Zhukovskaya, Evgeniya S.; Baryshnikova, Oksana V.; Belik, Alexei А.; Леонидова, О. Н.; Deyneko, Dina V.; Савон, А.Е.; Dorbakov, Nikolai G.; Морозов, В.А.

doi:10.1016/j.materresbull.2018.03.052

Cited by 27 publications

(7 citation statements)

References 38 publications

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“…There are no changes in symmetry, but the effect on the curves becomes smaller and diffused. The sample with x = 1 belongs to the nonpolar structure , (with centrosymmetric SG R 3̅ c ), and the absolute absence of the maximum on tan δ was observed (Figure a). For x = 0.72, the most diffused transition was detected (see the inset in Figure a).…”

Section: Resultsmentioning

confidence: 99%

Role of the Eu³⁺ Distribution on the Properties of β-Ca₃(PO₄)₂ Phosphors: Structural, Luminescent, and ¹⁵¹Eu Mössbauer Spectroscopy Study of Ca_9.5–1.5xMgEu_x(PO₄)₇

et al. 2021

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The series of β-Ca3(PO4)2-type phosphors Ca9.5–1.5x MgEu x (PO4)7 were synthesized by a solid-state route. Observation of the proper Eu3+ ion distribution in the Ca9.5Mg(PO4)7 host matrix was made by a direct method using 151Eu Mössbauer spectroscopy in combination with X-ray analysis and dielectric and luminescent spectroscopy. The photoluminescence properties were studied in detail. The samples exhibit an exceptionally narrow-band red emission according to the dominant 5D0 → 7F2 transition and fulfill the industrial requirements for high-energy-efficiency red phosphors. The contribution of Eu3+ ions in different crystal sites to the luminescent properties is discussed in detail. The difference of the excitation of Eu3+ in the M1 and M2 sites was revealed by photoluminescence excitation spectra in accordance with structure refinement. The temperature dependence of the luminescence intensity was studied. Different tendencies in the thermal behavior of emission lines allow one to consider the studied compounds as phosphors suitable for luminescence thermometry. The measured quantum yield for Ca9.5–1.5x MgEu x (PO4)7 shows excellent results and reaches 63%.

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Section: Resultsmentioning

confidence: 99%

Role of the Eu³⁺ Distribution on the Properties of β-Ca₃(PO₄)₂ Phosphors: Structural, Luminescent, and ¹⁵¹Eu Mössbauer Spectroscopy Study of Ca_9.5–1.5xMgEu_x(PO₄)₇

et al. 2021

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“…The maximum luminescence was observed in Ca 8 ZnEu(PO 4 ) 7 and is associated with an increase in the polyhedral distortion degree. 41 Apparently, with a general structure symmetry increase, the local distortion of the Eu 3+ polyhedra increases. The predominant red luminescence band centered at 615 nm indicates that Eu 3+ occupies low-symmetry sites in the host lattice.…”

Section: Discussionmentioning

confidence: 99%

“…Upon a transition to region III, the luminescence intensity again increases sharply. The maximum luminescence was observed in Ca 8 ZnEu(PO 4 ) 7 and is associated with an increase in the polyhedral distortion degree . Apparently, with a general structure symmetry increase, the local distortion of the Eu 3+ polyhedra increases.…”

Section: Discussionmentioning

confidence: 99%

Symmetry Inhomogeneity of Ca_9–xZn_xEu(PO₄)₇ Phosphor Determined by Second-Harmonic Generation and Dielectric and Photoluminescence Spectroscopy

Deyneko

Aksenov

Nikiforov

et al. 2020

Crystal Growth & Design

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A series of Ca 9−x Zn x Eu(PO 4 ) 7 phosphates (0 ≤ x ≤ 1) with a β-Ca 3 (PO 4 ) 2 -type structure was successfully synthesized and studied. Three areas of compositions, I (0 ≤ x ≤ 0.5), II (0.5 < x ≤ 0.8), and III (0.8 < x ≤ 1), were distinguished. In these regions the unit cell parameters and the full width at half-maximum (FWHM) of reflexes in the X-ray diffraction patterns change monotonously. The fracture in these dependences was observed on the frontiers between regions I/II and II/III. The limits of these areas were determined by second-harmonic generation (SHG), dielectric, and photoluminescence spectroscopy methods. It was shown that in Ca 9−x Zn x Eu(PO 4 ) 7 the Eu 3+ cations occupy low-symmetry sites. With an increase in of Zn 2+ concentration, the structure symmetry changes from noncentrosymmetric (space group (SG) R3c) to centrosymmetric (SG R3̅ c). In this case, the distortion of europium polyhedra in the structure increases and, as a result, the luminescence intensity rises. It was found that in β-Ca 3 (PO 4 ) 2 -type solid solutions by replacing Ca 2+ with Zn 2+ the luminescence intensity can be finely tuned. Measured quantum yields (QY) reach 65%. It can be concluded that centrosymmetric phases show higher luminescence intensity. This method of property management may be common for β-Ca 3 (PO 4 ) 2 -type structure phosphors, since the host matrix is very sensitive to changes in composition.

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“…In general, the structures of Ca 9 R(PO 4 ) 7 are very labile. For example, the replacement of calcium cations with magnesium or zinc at the M5 position is accompanied by the formation of a centrosymmetric structure ( R 3̅ c ) with antiferroelectric properties , and noncentrosymmetric ( R 3 c ) . In the antiferroelectric phase, in half of columns A, the P1O 4 tetrahedra are oriented in one direction along the 3-fold axis, and in the other half of columns A in the other .…”

Section: Resultsmentioning

confidence: 99%

A Comprehensive Study of Ca₉Tb(PO₄)₇ and Ca₉Ho(PO₄)₇ Doped β-Tricalcium Phosphates: Ab initio Crystal Structure Solution, Rietveld Analysis, and Dielectric Properties

Rizzi

Capitelli

Lazoryak

et al. 2021

Crystal Growth & Design

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The scientific interest toward the structural, luminescence, and dielectric properties of tricalcium phosphate (TCP) materials, in particular, the doped TCP-based compounds, is mainly due to their biocompatibility and bioactivity behavior and the increasing number of their applications. In the literature, structural investigations of a doped β-TCP compound are usually carried out by powder diffraction data under the assumption that it has a centrosymmetric whitlockite structure. Recent studies have shown that this assumption is not always fulfilled. For this reason, it is necessary to use methods of nonlinear and dielectric spectroscopy to prove the true symmetry of whitlockite-like phases. This work provides a detailed and comprehensive study on the structural, dielectric, and nonlinear properties of the polycrystalline Tb-and Ho-doped tricalcium phosphates, chemically Ca 9 Tb(PO 4 ) 7 and Ca 9 Ho(PO 4 ) 7 . Their crystal structure was explored using powder X-ray diffraction, adopting an ab initio approach for the structure solution followed by the Rietveld refinement. For Ca 9 Tb(PO 4 ) 7 , the qualitative analysis of the experimental powder X-ray diffraction pattern revealed that the sample was not a single phase. Nevertheless, its crystal structure has been determined by Direct Methods. The presence of the dopant cation was omitted in the solution process by Direct Methods and considered in the successive Rietveld refinement step. The analysis of the occupancies has clarified the Tb 3+ cation distribution in its preferential sites. The same pathway has been followed for the Ca 9 Ho(PO 4 ) 7 sample, which corresponded to a single-phase structure. The dielectric properties of the two doped compounds (Tb 3+ and Ho 3+ ) were also examined, and reversible ferroelectric-paraelectric phase transitions were found at 862 and 872 K, respectively.

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Luminescence, structure and antiferroelectric-type phase transition in Ca8ZnEu(PO4)7

Cited by 27 publications

References 38 publications

Role of the Eu³⁺ Distribution on the Properties of β-Ca₃(PO₄)₂ Phosphors: Structural, Luminescent, and ¹⁵¹Eu Mössbauer Spectroscopy Study of Ca_9.5–1.5xMgEu_x(PO₄)₇

Role of the Eu³⁺ Distribution on the Properties of β-Ca₃(PO₄)₂ Phosphors: Structural, Luminescent, and ¹⁵¹Eu Mössbauer Spectroscopy Study of Ca_9.5–1.5xMgEu_x(PO₄)₇

Symmetry Inhomogeneity of Ca_9–xZn_xEu(PO₄)₇ Phosphor Determined by Second-Harmonic Generation and Dielectric and Photoluminescence Spectroscopy

A Comprehensive Study of Ca₉Tb(PO₄)₇ and Ca₉Ho(PO₄)₇ Doped β-Tricalcium Phosphates: Ab initio Crystal Structure Solution, Rietveld Analysis, and Dielectric Properties

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Luminescence, structure and antiferroelectric-type phase transition in Ca8ZnEu(PO4)7

Cited by 27 publications

References 38 publications

Role of the Eu3+ Distribution on the Properties of β-Ca3(PO4)2 Phosphors: Structural, Luminescent, and 151Eu Mössbauer Spectroscopy Study of Ca9.5–1.5xMgEux(PO4)7

Role of the Eu3+ Distribution on the Properties of β-Ca3(PO4)2 Phosphors: Structural, Luminescent, and 151Eu Mössbauer Spectroscopy Study of Ca9.5–1.5xMgEux(PO4)7

Symmetry Inhomogeneity of Ca9–xZnxEu(PO4)7 Phosphor Determined by Second-Harmonic Generation and Dielectric and Photoluminescence Spectroscopy

A Comprehensive Study of Ca9Tb(PO4)7 and Ca9Ho(PO4)7 Doped β-Tricalcium Phosphates: Ab initio Crystal Structure Solution, Rietveld Analysis, and Dielectric Properties

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Role of the Eu³⁺ Distribution on the Properties of β-Ca₃(PO₄)₂ Phosphors: Structural, Luminescent, and ¹⁵¹Eu Mössbauer Spectroscopy Study of Ca_9.5–1.5xMgEu_x(PO₄)₇

Role of the Eu³⁺ Distribution on the Properties of β-Ca₃(PO₄)₂ Phosphors: Structural, Luminescent, and ¹⁵¹Eu Mössbauer Spectroscopy Study of Ca_9.5–1.5xMgEu_x(PO₄)₇

Symmetry Inhomogeneity of Ca_9–xZn_xEu(PO₄)₇ Phosphor Determined by Second-Harmonic Generation and Dielectric and Photoluminescence Spectroscopy

A Comprehensive Study of Ca₉Tb(PO₄)₇ and Ca₉Ho(PO₄)₇ Doped β-Tricalcium Phosphates: Ab initio Crystal Structure Solution, Rietveld Analysis, and Dielectric Properties