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Author |
Morozov, V.A.; Belik, A.A.; Stefanovich, S.Y.; Grebenev, V.V.; Lebedev, O.I.; Van Tendeloo, G.; Lazoryak, B.I. |
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Title |
High-temperature phase transition in the whitlockite-type phosphate Ca9In(PO4)7 |
Type |
A1 Journal article |
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Year |
2002 |
Publication |
Journal of solid state chemistry |
Abbreviated Journal |
J Solid State Chem |
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Volume |
165 |
Issue |
2 |
Pages |
278-288 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
The double phosphate Ca9In(PO4)(7) was obtained by solid-state reaction and was studied by room and high-temperature Xray powder diffraction, electron diffraction, high-resolution electron microscopy, second-harmonic generation (SHG) technique, differential scanning calorimetry, dielectric and conductivity measurements. The beta-Ca9In(PO4)(7) room-temperature phase is related to the mineral whitlockite and is similar to beta-Ca-3(PO4)(2). It has space group R (3) over barc, with unit cell parameters: a = 10.4008(1) Angstrom, c = 37.272(1) Angstrom, Z = 6. The structure was refined by the Rietveld method (R-wp = 4.69, R-I = 1.81). A reversible first-order beta <----> beta' phase transition of the ferroelectric type with T-c = 902 K is revealed by SHG, differential scanning calorimetry and dielectric measurements. The centrosymmetric beta'-Ca9In(PO4)(7) (973 K) has space group R (3) over barc, a = 10.4611(2) Angstrom, c = 37.874 (1) Angstrom (R-wp = 4.27, R-I = 4.11). Compared to the low-temperature beta-Ca9In(PO4)(7) structure, beta'-Ca9In(PO4)(7) can be described as an orientational disordering of the P1O(4) tetrahedra together with a calcium disordering on the M3 site. (C) 2002 Elsevier Science (USA). |
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Place of Publication |
London |
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Wos |
000175916000010 |
Publication Date |
2002-10-06 |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0022-4596; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.299 |
Times cited |
57 |
Open Access |
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Notes |
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Approved |
Most recent IF: 2.299; 2002 IF: 1.671 |
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Call Number |
UA @ lucian @ c:irua:94926 |
Serial |
1467 |
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Permanent link to this record |
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Author |
Lazoryak, B.I.; Baryshnikova, O.V.; Stefanovich, S.Y.; Malakho, A.P.; Morozov, V.A.; Belik, A.A.; Leonidov, I.A.; Leonidova, O.N.; Van Tendeloo, G. |
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Title |
Ferroelectric and ionic-conductive properties of nonlinear-optical vanadate, Ca9Bi(VO4)7 |
Type |
A1 Journal article |
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Year |
2003 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
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Volume |
15 |
Issue |
15 |
Pages |
3003-3010 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
Structural, chemical, and physical properties of whitlockite-type Ca9Bi(VO4)(7) were studied by X-ray powder diffraction (XRD), electron diffraction (ED), second-harmonic generation (SHG), thermogravimetry, differential scanning calorimetry, dielectric, and electrical-conductivity measurements. A new phase-transition of the ferroelectric type was found in Ca9Bi(VO4)(7) with a transition temperature, T-c of 1053 +/- 3 K. The polar phase, beta-Ca9Bi(VO4)(7), is stable below T-c down to at least 160 K. The centrosymmetric beta'-phase is stable above T-c up to 1273 +/- 5 K. Above 1273 K, it decomposes to give BiVO4 and whitlockite-type solid solutions of Ca9+1.5xBi1-x(VO4)(7). The beta<---->beta' phase transition is reversible and of second order. Electrical conductivity of beta'-Ca9Bi(VO4)(7) is rather high (sigma = 0.6 x 10(-3) S/cm at 1200 K) and obeys the Arrhenius law with an activation energy of 1.0 eV. Structure parameters of Ca9Bi(VO4)(7) are refined by the Rietveld method from XRD data measured at room temperature (space group R3c; Z = 6; a = 10.8992(1) Angstrom, c = 38.1192(4) Angstrom, and V = 3921.6(1) Angstrom(3); R-wp = 3.06% and R-p = 2.36%). Bi3+ ions together with Ca2+ ions are statistically distributed among the M1, M2, M3, and M5 sites. Ca9Bi(VO4)(7) has a SHG efficiency of about 140 times that of quartz. Through the powder SHG measurements, we estimated the nonlinear optical susceptibility, Digital, at about 6.1-7.2 pm/V. This value for Ca9Bi(VO4)(7) is comparable with that for known nonlinear optical materials such as LiNbO3 and LiTaO3. |
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Place of Publication |
Washington, D.C. |
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Wos |
000184379900024 |
Publication Date |
2003-07-22 |
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Series Issue |
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Edition |
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ISSN |
0897-4756;1520-5002; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
9.466 |
Times cited |
51 |
Open Access |
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Notes |
Iup V-1; Dwtc |
Approved |
Most recent IF: 9.466; 2003 IF: 4.374 |
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Call Number |
UA @ lucian @ c:irua:103284 |
Serial |
1179 |
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Author |
Lazoryak, B.I.; Morozov, V.A.; Belik, A.A.; Stefanovich, S.Y.; Grebenev, V.V.; Leonidov, I.A.; Mitberg, E.B.; Davydov, S.A.; Lebedev, O.I.; Van Tendeloo, G. |
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Title |
Ferroelectric phase transition in the whitlockite-type Ca9Fe(PO4)7; crystal structure of the paraelectric phase at 923 K |
Type |
A1 Journal article |
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Year |
2004 |
Publication |
Solid state sciences |
Abbreviated Journal |
Solid State Sci |
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Volume |
6 |
Issue |
2 |
Pages |
185-195 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Place of Publication |
Amsterdam |
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Wos |
000220312700005 |
Publication Date |
2004-02-06 |
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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 |
1293-2558; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
1.811 |
Times cited |
41 |
Open Access |
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Notes |
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Approved |
Most recent IF: 1.811; 2004 IF: 1.598 |
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Call Number |
UA @ lucian @ c:irua:54699 |
Serial |
1180 |
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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. |
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Title |
A novel red Ca8.5Pb0.5Eu(PO4)7 phosphor for light emitting diodes application |
Type |
A1 Journal article |
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Year |
2015 |
Publication |
Journal of alloys and compounds |
Abbreviated Journal |
J Alloy Compd |
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Volume |
647 |
Issue |
647 |
Pages |
965-972 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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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. |
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Place of Publication |
Amsterdam |
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Wos |
000361156400135 |
Publication Date |
2015-06-18 |
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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 |
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Impact Factor |
3.133 |
Times cited |
18 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.133; 2015 IF: 2.999 |
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Call Number |
UA @ lucian @ c:irua:128720 |
Serial |
4215 |
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Author |
Stefanovich, S.Y.; Belik, A.A.; Azuma, M.; Takano, M.; Baryshnikova, O.V.; Morozov, V.A.; Lazoryak, B.I.; Lebedev, O.I.; Van Tendeloo, G. |
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Title |
Antiferroelectric phase transition in Sr9In(PO4)7 |
Type |
A1 Journal article |
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Year |
2004 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
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Volume |
70 |
Issue |
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Pages |
172103,1-4 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Place of Publication |
Lancaster, Pa |
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Wos |
000225477000003 |
Publication Date |
2004-11-12 |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
17 |
Open Access |
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Notes |
Iuap P5/01 |
Approved |
Most recent IF: 3.836; 2004 IF: 3.075 |
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Call Number |
UA @ lucian @ c:irua:54744 |
Serial |
135 |
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Author |
Savina, A.A.; Morozov, V.A.; Buzlukov, A.L.; Arapova, I.Y.; Stefanovich, S.Y.; Baklanova, Y.V.; Denisova, T.A.; Medvedeva, N.I.; Bardet, M.; Hadermann, J.; Lazoryak, B.I.; Khaikina, E.G. |
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Title |
New solid electrolyte Na9Al(MoO4)6 : structure and Na+ ion conductivity |
Type |
A1 Journal article |
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Year |
2017 |
Publication |
Chemistry of materials |
Abbreviated Journal |
Chem Mater |
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Volume |
29 |
Issue |
20 |
Pages |
8901-8913 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Abstract |
<script type='text/javascript'>document.write(unpmarked('Solid electrolytes are important materials with a wide range of technological applications. This work reports the crystal structure and electrical properties of a new solid electrolyte Na9Al(MoO4)(6). The monoclinic Na9Al(MoO4)(6) consists of isolated polyhedral, [Al(MoO4)(6)](9-) clusters composed of a central AlO6 octahedron sharing vertices with six MoO4 tetrahedra to form a three-dimensional framework. The AlO6 octahedron also shares edges with one NalO(6) octahedron and two Na2O(6) octahedra. Na3-Na5 atoms are located in the framework cavities. The structure is related to that of sodium ion conductor II-Na3Fe2(AsO4)(3). High-temperature conductivity measurements revealed that the conductivity (sigma) of Na9Al(MoO4)(6) at 803 K equals 1.63 X 10(-2) S cm(-1). The temperature behavior of the Na-23 and Al-27 nuclear magnetic resonance spectra and the spin-lattice relaxation rates of the Na-23 nuclei indicate the presence of fast Na+ ion diffusion in the studied compound. At T\u003C490 K, diffusion occurs by means of Na+ ion jumps exclusively through the sublattice of Na3-Na5 positions, whereas Na1 and Na2 become involved in the diffusion processes (through chemical exchange with the Na3-Na5 sublattice) only at higher temperatures.')); |
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Publisher |
American Chemical Society |
Place of Publication |
Washington, D.C |
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Wos |
000413884900037 |
Publication Date |
2017-09-26 |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0897-4756 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
9.466 |
Times cited |
13 |
Open Access |
OpenAccess |
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Notes |
; The research was performed within the state assignment of FASO of Russia (Themes 01201463330, A16-116122810214-9, and 0339-2016-0007), supported in part by the Russian Foundation for Basic Research (Projects 16-03-00510, 16-03-00164, and 17-03-00333). ; |
Approved |
Most recent IF: 9.466 |
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Call Number |
UA @ lucian @ c:irua:147432 |
Serial |
4886 |
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Permanent link to this record |
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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. |
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Title |
Antiferroelectric properties and site occupations ofR3+ cations in Ca8MgR(PO4)7 luminescent host materials |
Type |
A1 Journal article |
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Year |
2017 |
Publication |
Journal of alloys and compounds |
Abbreviated Journal |
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Volume |
699 |
Issue |
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Pages |
928-937 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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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. |
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Wos |
000393727500129 |
Publication Date |
2016-12-24 |
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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 |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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no |
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Call Number |
UA @ admin @ c:irua:152665 |
Serial |
7464 |
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