EPR Study of Gd 3+ local structure in ScF 3 crystal with negative thermal expansion coefficient

Sivaramaiah²,

et al. 2019

Bull Mater Sci

A BaAl 2 O 4 :Gd 3+ phosphor was successfully prepared using a combustion technique. An X-ray diffraction pattern was used to characterize the resultant phosphor, and the photoluminescence (PL) of the prepared BaAl 2 O 4 :Gd 3+ was studied. Under a 273-nm excitation, the main emission peak of the phosphor is located at 314 nm, and this is attributed to the 6 P 7/2 → 8 S 7/2 transition of Gd 3+. Electron paramagnetic resonance (EPR) spectrum appears to be U-shaped, and lines are evident at g eff ∼ 2.14, 4.56 and 6.75. The PL and EPR analyses indicate the presence of Gd as Gd 3+ in this sample.

Section: Epr Studiesmentioning

confidence: 99%

Ultraviolet B emission from a $$\hbox {Gd}^{3+}$$ Gd 3 + -doped $$\hbox {BaAl}_{2}\hbox {O}_{4}$$

Sivaramaiah²,

et al. 2019

Bull Mater Sci

“…[31,32] S-state ions with [Xe]4f 7 electron configuration (Gd 3+ , Eu 2+ ) are known to produce EPR spectra with fine structure centered at g = 1.99 in cubic crystals of CaF2, SrF2, BaF2 and ScF3. [33][34][35][36][37][38][39][40] Zero field splitting (ZFS) of the ground state leads to an EPR spectrum consisting of seven major fine-structure lines. Hyperfine structure interaction with nuclear spin I = 5/2 of europium isotopes 151 Eu and 153 Eu results in further splitting of fine structure components.…”

Section: Epr Measurementsmentioning

confidence: 99%

Electron paramagnetic resonance and photoluminescence investigation of europium local structure in oxyfluoride glass ceramics containing SrF2 nanocrystals

et al. 2017

Different compositions of europium doped aluminosilicate oxyfluoride glass ceramics prepared in air atmosphere have been studied by electron paramagnetic resonance (EPR) and optical spectroscopy methods. X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements show presence of homogenously distributed SrF2 nanocrystals after the heat treatment of the precursor glass. Efficient Eu 3+ incorporation in the high symmetry environment of glass ceramics is observed from the photoluminescence spectra. EPR spectra indicate Eu 3+ → Eu 2+ reduction upon precipitation of crystalline phases in the glass matrix. For composition abundant with Eu 2+ in the glassy state such behaviour is not detected. Local structure around europium ions is discussed based on differences in chemical compositions.

Low Temperature Physics

“…Absorption and luminescence spectra, on the other hand, can indicate changes in the local environment around the luminescence centres, however, structure sensitive magnetic resonance spectroscopy techniques should be employed to reveal the detailed nature of defects in glass ceramics. Electron paramagnetic resonance (EPR) is one of the most convenient and informative methods for the study of point defects in crystals and glasses [1][2][3][4][5][6][7][8][9][10][11], however, there has been only a limited number of applications to glass ceramics [12][13][14][15][16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Crystalline phase detection in glass ceramics by EPR spectroscopy

Antuzevičš

Rogulis

Fedotovs

et al. 2018

The advances of EPR spectroscopy for the detection of activators as well as determining their local structure in the crystalline phase of glass ceramics is considered. The feasibility of d-element (Mn 2+ , Cu 2+ ) and f-element (Gd 3+ , Eu 2+ ) ion probes for the investigation of glass ceramics is discussed. In the case of Mn 2+ , the information is obtained from the EPR spectrum superhyperfine structure, for Gd 3+ and Eu 2+ probes -from the EPR spectrum fine structure, whereas for Cu 2+ ions the changes in the EPR spectrum shape could be useful. The examples of EPR spectra of the above-mentioned probes in oxyfluoride glass ceramics are illustrated. PACS: 76.30.-v Electron paramagnetic resonance and relaxation; 61.72.Hh Indirect evidence of dislocations and other defects.