| Records |
| Author |
Belik, A.A.; Morozov, V.A.; Deyneko, D.V.; Savon, A.E.; Baryshnikova, O.V.; Zhukovskaya, E.S.; Dorbakov, N.G.; Katsuya, Y.; Tanaka, M.; Stefanovich, S.Y.; Hadermann, J.; Lazoryak, B.I. |
| Title |
Antiferroelectric properties and site occupations ofR3+ cations in Ca8MgR(PO4)7 luminescent host materials |
Type |
A1 Journal article |
Year  |
2017 |
Publication |
Journal of alloys and compounds |
Abbreviated Journal |
|
| Volume |
699 |
Issue |
|
Pages |
928-937 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
| Abstract |
Ca8MgR(PO4)(7) = La, Pr, Nd, Sm-Lu, and Y) phosphates with a beta-Ca-3(PO4)(2) related structure were prepared by a standard solid-state method in air. Second-harmonic generation, differential scanning calorimetry, and dielectric measurements led to the conclusion that all Ca8MgR(PO4)(7) are centrosymmetric and go to another centrosymmetric phase in the course of a first-order antiferroelectric phase transition well above room temperature (RT). High-temperature electron diffraction showed that the symmetry changes from R (3) over barc to R (3) over barm during the phase transition. Structures of Ca8MgR(PO4)(7) at RT were refined by the Rietveld method in centrosymmetric space group R (3) over barc. Mg2+ cations occupy the M5 site; the occupancy of the M1 site by R3+ cations increases monotonically from 0.0389 for R = La to 0.1667 for R = Er-Lu, whereas the occupancy of the M3 site by R3+ cations decreases monotonically from 0.1278 for R = La to 0 for R = Er-Lu. In the case of R = Er-Lu, the M3 site is occupied only by Ca2+ cations. P1O(4) tetrahedra and cations at the M3 site are disordered in the R (3) over barc structure of Ca8MgEu(PO4)(7). Using synchrotron X-ray powder diffraction, we found that annealing conditions do not significantly affect the distribution of Ca2+ and Eu3+ cations between the structure positions of Ca8MgEu(PO4)(7). Luminescent properties of CasMgEu(PO4)(7) powder samples were investigated under near-ultraviolet (n-UV) light. Excitation spectra of CasMgEu(PO4)(7) show the strongest absorption at about 395 nm that matches with commercially available n-UV-emitting GaN-based LED chips. Emission spectra show an intense red emission due to the D-5(0) -> F-7(2) transition of Eu3+. (C) 2016 Elsevier B.V. All rights reserved. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
|
| Language |
|
Wos |
000393727500129 |
Publication Date |
2016-12-24 |
| Series Editor |
|
Series Title |
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Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0925-8388 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
|
Times cited |
|
Open Access |
|
| Notes |
|
Approved |
no |
| Call Number |
UA @ admin @ c:irua:152665 |
Serial |
7464 |
| Permanent link to this record |
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| |
| Author |
Deyneko, D.V.; Morozov, V.A.; Hadermann, J.; Savon, A.E.; Spassky, D.A.; Stefanovich, S.Y.; Belik, A.A.; Lazoryak, B.I. |
| Title |
A novel red Ca8.5Pb0.5Eu(PO4)7 phosphor for light emitting diodes application |
Type |
A1 Journal article |
| Year |
2015 |
Publication |
Journal of alloys and compounds |
Abbreviated Journal |
J Alloy Compd |
| Volume |
647 |
Issue |
647 |
Pages |
965-972 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
| Abstract |
Ca9-xPbxEu(PO4)(7) (0 <= x <= 1) solid solutions with a whitlockite-type (or beta-Ca-3(PO4)(2)-type) structure (sp.gr. R3c) were prepared by a standard solid-state method in air. Their luminescent properties under near-ultraviolet (n-UV) light were investigated. Excitation spectra of Ca9-xPbxEu(PO4)(7) showed the strongest absorption at about 395 nm, which matches well with commercially available n-UV-emitting GaN-based LED chips. Emission spectra indicated an intense red emission due to the D-5(0) -> F-7(2) transition of Eu3+, with a maximum in the intensity for Ca8.5Pb0.5Eu(PO4)(7). The emission intensity of Ca8.5Pb0.5Eu(PO4)(7) was about 1.8 times higher than that of a Ca9Eu(PO4)(7) phosphor. We suggest that the introduction of Pb2+ is an efficient approach to enhance luminescence properties of such phosphors. We clarified the influence of the Ca2+/Pb2+ substitution on intensities of three bands for the D-5(0) -> F-7(0) transition in excitation spectra of Ca9-xPbxEu(PO4)(7). In addition, we found a reversible first-order phase transition from R3c to R (3) over barc symmetry by second-harmonic generation in the range from 753 K (x = 1) to 846 K (x = 0). (C) 2015 Elsevier B.V. All rights reserved. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
Amsterdam |
Editor |
|
| Language |
|
Wos |
000361156400135 |
Publication Date |
2015-06-18 |
| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0925-8388 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.133 |
Times cited |
18 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 3.133; 2015 IF: 2.999 |
| Call Number |
UA @ lucian @ c:irua:128720 |
Serial |
4215 |
| Permanent link to this record |
