The synergy effect of rare earth cations on local structure and PL emission in a Ce3+:REPO4(RE = La, Gd, Lu, Y) system

2017 ◽  
Vol 46 (24) ◽  
pp. 7888-7896 ◽  
Author(s):  
Congting Sun ◽  
Dongfeng Xue
Keyword(s):  
Phase Transition ◽  
Rare Earth ◽  
Local Structure ◽  
Site Symmetry ◽  
Synergy Effect ◽  
System P ◽  
Pl Emission ◽  
Lower Site

The activation of P−O bonding that promotes the phase transition and enhances the PL emission of REPO4under the synergy effect of rare earth cations is studied. Anion groups with lower site symmetry coordinated with rare earth cations favor 5d → 4f emission of Ce3+.

Internal Friction Study of the Rare Earth Ion Substituted Fast Oxide-Ion Conductors (La1-ΧreΧ)2Mo2O9 (Re=Nd, Gd)

2012 ◽  
Vol 184 ◽  
pp. 110-115
Author(s):  
X.P. Wang ◽  
J. Hu ◽  
Zhong Zhuang ◽  
Tao Zhang ◽  
Qian Feng Fang
Keyword(s):  
Phase Transition ◽  
Rare Earth ◽  
Internal Friction ◽  
Diffusion Processes ◽  
Rare Earth Ion ◽  
Disorder Transition ◽  
Oxide Ion Conductors ◽  
Oxide Ion ◽  
The Rare Earth ◽  
Ion Conductors

The relaxation and phase transition behaviors of rare-earth ion substituted fast oxide-ion conductors (La1-xRex)2Mo2O9 (Re=Nd, Gd) were investigated by internal friction (IF) measurement in the temperature range 300 K - 950 K. Three different IF peaks (labeled as PL, PH, and PG, respectively) were observed in the rare-earth ion doped La2Mo2O9 samples. Peak PL corresponds to short diffusion processes of oxygen ions among different oxygen vacancy sites. Peak PH is associated with the static/dynamic disorder transition in oxygen ion distribution. Peak PG is a newly discovered peak embodying phase transition-like characteristics and is suggested to be related to order-disorder transition associated with the rearrangement of La/ Re sub-lattice.

Internal rotation of a light symmetric top relative to a heavy planar framework: theoretical calculations of vibration/internal-rotation spectra including effects of rotational barriers and non-degeneracy of perpendicular symmetric top vibrations

1969 ◽  
Vol 313 (1513) ◽  
pp. 149-167 ◽  
Keyword(s):  
Fine Structure ◽  
Internal Rotation ◽  
Theoretical Calculations ◽  
Site Symmetry ◽  
Frequency Range ◽  
Electronic Effects ◽  
Angular Variation ◽  
Band Contour ◽  
Lower Site ◽  
Fine Structure Lines

Model theoretical calculations have been made of the fine structure associated with the perpendicular vibrations of a ‘light’ symmetric top group (such as CH 3 , SiH 3 , etc.) resulting from its internal rotation with respect to an infinitely heavy planar framework. Investigations have been made of the effects on the internal rotational fine structure of the removal of the degeneracy of the perpendicular vibrations as required by the lower site symmetry. Separate calculations have been made for the cases where the removal of degeneracy is caused ( a ) by electronic effects which result in an angular variation of the appropriate force constant, or ( b ) by interaction with another vibration in the framework part of the molecule. It is found that no fine structure lines occur between the non-degenerate frequencies, but that the effect of internal rotation is to generate rotational wings outside this frequency range. The effects of a finite sixfold barrier to internal rotation on the vibrational/internal-rotational absorption band have been calculated for the degenerate and non-degenerate cases. It is shown that certain lines are split by amounts comparable to the barrier height, V 6 , which should therefore be experimentally obtainable from this type of spectrum in favourable cases. The effect of an increasing barrier is to cause more of the intensity within the overall band contour to occur in the vicinity of the vibrational frequency or frequencies, and less in the internal rotational wings, as expected on physical grounds.

Extended X-ray Absorption Fine Structure Studies of GaN Epilayers Doped in situ with Er and Eu During Molecular Beam Epitaxy

2003 ◽  
Vol 798 ◽  
Author(s):  
V. Katchkanov ◽  
J. F. W. Mosselmans ◽  
S. Dalmasso ◽  
K. P. O'Donnell ◽  
R. W. Martin ◽  
...  
Keyword(s):  
Fine Structure ◽  
Rare Earth ◽  
Molecular Beam Epitaxy ◽  
Local Structure ◽  
Molecular Beam ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption ◽  
The Eu

ABSTRACTThe local structure around Er and Eu atoms introduced into GaN epilayers was studied by means of Extended X-ray Absorption Fine Structure above the appropriate rare-earth X-ray absorption edge. The samples were doped in situ during growth by Molecular Beam Epitaxy. The formation of ErN clusters was found in samples with high average Er concentrations of 32±6% and 12.4±0.8%, estimated by Wavelength Dispersive X-ray analysis. When the average Er concentration is decreased to 6.0±0.2%, 1.6±0.2% and 0.17±0.02%, Er is found in localised clusters of ErGaN phase with high local Er content. Similar behaviour is observed for Eu-doped samples. For an average Eu concentration of 30.5±0.5% clusters of pure EuN occur. Decreasing the Eu concentration to 10.4±0.5% leads to EuGaN clusters with high local Eu content. However, for a sample with an Eu concentration of 14.2±0.5% clustering of Eu was not observed.

Sign in / Sign up

Export Citation Format

Share Document