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Saha, Surajit; Muthu, D. V. S.; Pascanut, C.; Dragoe, Nita; Suryanarayanan, R.; Dhalenne, G.; Revcolevschi, A.; Karmakar, S.; Sharma, Surinder M.; Sood, Anil K.

doi:10.1103/physrevb.74.064109

Cited by 80 publications

(75 citation statements)

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“…This is not surprising since in all the Raman-active modes, only the oxygen atoms are displaced. 57,58 Consequently, there is no obvious systematic variation of the phonon frequencies with the mass of the respective rare earth ions, as has been noted FIG. 2.…”

Section: A Magnetic Measurementsmentioning

confidence: 59%

“…Finally, there is some low intensity scattering at higher wave numbers, around 700 cm −1 ͑last two rows of Table II͒. This intensity has been observed before [58][59][60][61][62] and is ascribed to forbidden IR modes made active by slight local nonstoichiometry in the system.…”

Section: A Magnetic Measurementsmentioning

confidence: 61%

“…The assignment of the Raman-active modes to the observed peaks is indicated by the filled Lorentzian line shapes. 58 and Vandenborre et al 67 Earlier works either interchanged the mode assignment within this band 57,59 or ascribed the whole band to only one of these modes. 60,61 However, our temperature and angle dependent measurements confirm the assignment made by Saha et al 58 The last expected phonon, an F 2g mode, has been either not accounted for, 57 combined with the A 1g mode in one band, 58,62 or ascribed to low intensity peaks around 105, 60 450, 59 or 680 cm −1 ͑Ref.…”

Section: A Magnetic Measurementsmentioning

confidence: 99%

“…The figure depicts the room-temperature ͑RT͒ parallel polarization spectra of the rare earth titanates and the corresponding modes. The assignment of the mode symmetries is based on comparison with assignments in previous works on these [57][58][59][60][61][62] and related [62][63][64][65][66][67] compounds ͑see Table II͒, on aforementioned measurements ͑not shown͒ of the angular dependence of mode intensities and on the temperature dependence of the modes ͑vide infra͒.…”

Section: A Magnetic Measurementsmentioning

confidence: 99%

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Phonon and crystal field excitations in geometrically frustrated rare earth titanates

et al. 2008

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Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. are used for characterization, while Raman spectroscopy and terahertz time domain spectroscopy are employed to probe the excitations in the materials. The lattice excitations are found to be analogous across the compounds over the whole temperature range investigated ͑295-4 K͒. The resulting full phononic characterization of the R 2 Ti 2 O 7 pyrochlore structure is then used to identify crystal field excitations observed in the materials. Several crystal field excitations have been observed in Tb 2 Ti 2 O 7 in Raman spectroscopy, among which all of the previously reported excitations. The presence of additional crystal field excitations, however, suggests the presence of two inequivalent Tb 3+ sites in the low-temperature structure. Furthermore, the crystal field level at approximately 13 cm −1 is found to be both Raman and dipole active, indicating broken inversion symmetry in the system and thus undermining its current symmetry interpretation. In addition, evidence is found for a significant crystal field-phonon coupling in Tb 2 Ti 2 O 7 . The additional crystal field information on Tb 2 Ti 2 O 7 adds to the recent discussion on the low temperature symmetry of this system and may serve to improve its theoretical understanding.

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Section: A Magnetic Measurementsmentioning

confidence: 59%

Section: A Magnetic Measurementsmentioning

confidence: 61%

Section: A Magnetic Measurementsmentioning

confidence: 99%

Section: A Magnetic Measurementsmentioning

confidence: 99%

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Phonon and crystal field excitations in geometrically frustrated rare earth titanates

et al. 2008

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“…[21,22] (see Table- cm −1 (N7, E g ), 458 cm −1 (N8, F 2g ), 520 cm −1 (N9, F 2g ) and 609 cm −1 (N10, F 2g ). Some of the previous studies [23,24,25] labeled the mode M9(N9) as A 1g + F 2g , and overlooked the weak mode near 450 cm −1 . We and Lummen et al [16] have observed a mode near 450 cm −1 in several of the pyrochlore titanates.…”

Section: Resultsmentioning

confidence: 99%

Temperature-dependent Raman and x-ray studies of the spin-ice pyrochloreDy2Ti2O7and nonmagnetic pyrochlore

et al. 2008

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We present here temperature-dependent Raman, x-ray diffraction and specific heat studies between room temperature and 12 K on single crystals of spin-ice pyrochlore compound Dy 2 T i 2 O 7 and its non-magnetic analogue Lu 2 T i 2 O 7 . Raman data show a "new" band not predicted by factor group analysis of Raman-active modes for the pyrochlore structure in Dy 2 T i 2 O 7 , appearing below a temperature of T c =110 K with a concomitant contraction of the cubic unit cell volume as determined from the powder x-ray diffraction analysis. Low temperature Raman experiments on O 18 -isotope substituted Dy 2 T i 2 O 7 confirm the phonon origin of the "new" mode. These findings, absent in Lu 2 T i 2 O 7 , suggest that the room temperature cubic lattice of the pyrochlore Dy 2 T i 2 O 7 undergoes a "subtle" structural transformation near T c . We find anomalous red-shift of some of the phonon modes in both the Dy 2 T i 2 O 7 and the Lu 2 T i 2 O 7 as the temperature decreases, which is attributed to strong phonon-phonon anharmonic interactions.

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Abnormal Pressure‐Induced Photoluminescence Enhancement and Phase Decomposition in Pyrochlore La₂Sn₂O₇

Zhao

et al. 2017

Advanced Materials

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La Sn O is a transparent conducting oxide (TCO) material and shows a strong near-infrared fluorescent at ambient pressure and room temperature. By in situ high-pressure research, pressure-induced visible photoluminescence (PL) above 2 GPa near 2 eV is observed. The emergence of unusual visible PL behavior is associated with the seriously trigonal lattice distortion of the SnO octehedra, under which the Sn-O1-Sn exchange angle θ is decreased below 22.1 GPa, thus enhancing the PL quantum yield leading to Sn P → S photons transition. Besides, bandgap closing followed by bandgap opening and the visible PL appearing at the point of the gap reversal, which is consistent with high-pressure phase decomposition, are discovered. The high-pressure PL results demonstrate a well-defined pressure window (7-17 GPa) with flat maximum PL yielding and sharp edges at both ends, which may provide a great calibration tool for pressure sensors for operation in the deep sea or at extreme conditions.

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High-pressure Raman and x-ray study of the spin-frustrated pyrochloreGd2Ti2O7

Cited by 80 publications

References 17 publications

Phonon and crystal field excitations in geometrically frustrated rare earth titanates

Phonon and crystal field excitations in geometrically frustrated rare earth titanates

Temperature-dependent Raman and x-ray studies of the spin-ice pyrochloreDy2Ti2O7and nonmagnetic pyrochlore

Abnormal Pressure‐Induced Photoluminescence Enhancement and Phase Decomposition in Pyrochlore La₂Sn₂O₇

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High-pressure Raman and x-ray study of the spin-frustrated pyrochloreGd2Ti2O7

Cited by 80 publications

References 17 publications

Phonon and crystal field excitations in geometrically frustrated rare earth titanates

Phonon and crystal field excitations in geometrically frustrated rare earth titanates

Temperature-dependent Raman and x-ray studies of the spin-ice pyrochloreDy2Ti2O7and nonmagnetic pyrochlore

Abnormal Pressure‐Induced Photoluminescence Enhancement and Phase Decomposition in Pyrochlore La2Sn2O7

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Product

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Abnormal Pressure‐Induced Photoluminescence Enhancement and Phase Decomposition in Pyrochlore La₂Sn₂O₇