Magnetic and Optical Properties of Eu-doped GaN

2006 ◽  
Vol 955 ◽  
Author(s):  
Jennifer Hite ◽  
G T Thaler ◽  
J H Park ◽  
A J Steckl ◽  
C R Abernathy ◽  
...  
Keyword(s):  
Saturation Magnetization ◽  
Room Temperature Ferromagnetism ◽  
Inverse Correlation ◽  
Absolute Intensity ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
Cell Temperature ◽  
X Ray ◽  
Pl Intensity ◽  
The Eu

ABSTRACTGaN films were doped with Eu to a concentration of ∼0.12 at. % during growth at 800°C by molecular beam epitaxy, with the Eu cell temperature held constant at 470°C. All samples were post-annealed at 675°C. The films exhibited strong photoluminescence (PL) in the red (622 nm) whose absolute intensity was a function of the Ga flux during growth, which ranged from 3-5.4×10−7 Torr. The maximum PL intensity was obtained at a Ga flux of 3.6×10−7 Torr. The samples showed room temperature ferromagnetism with saturation magnetization of ∼0.1-0.45 emu/cm3, consistent with past reports where the Eu was found to be predominantly occupying substitutional Ga sites. There was an inverse correlation between the PL intensity and the saturation magnetization in the films. X-ray diffraction showed the presence of EuGa phases under all of our growth conditions but these cannot account for the observed magnetic properties.

Effects of Microstructure on Photoluminescence of SrS:Eu2+,SM3+ thin Films

1993 ◽  
Vol 301 ◽  
Author(s):  
Susan Z. Hua ◽  
L. Salamanca-Riba ◽  
M. Wuttig ◽  
P. K. Soltani
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Growth Rates ◽  
Growth Conditions ◽  
Photoluminescence Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Substrate Temperatures ◽  
The Eu

ABSTRACTThe microstructure and its effects on the photoluminescence properties of SrS:Eu2+,Sm3+ thin films grown with different conditions were studied by transmission electron microscopy, x-ray diffraction and photoluminescence techniques. The SrS:Eu2+,Sm3+ thin films were prepared by e-beam evaporation at different substrate temperatures and growth rates. Both of these growth conditions affect the crystallinity of the thin films. The Sm3+ emission is stronger in the films grown at higher growth rates and at an optimum substrate temperature. We believe that the stronger Sm3+ emission is due to the higher population of Sm trivalent charge states in the films. Further increase of the substrate temperature increases the grain size in the films, but has no significant effect on the PL emission properties. In contrast, the Eu2+ emission is less sensitive to growth conditions.

scholarly journals Investigations of M3Al8O15:Eu3+,Dy3+ (M = Ba, Ca, Mg) phosphors

2016 ◽  
Vol 34 (2) ◽  
pp. 412-417
Author(s):  
Esra Öztürk
Keyword(s):  
Electron Microscopy ◽  
Solid State Reaction Method ◽  
Morphological Characterization ◽  
X Ray Diffraction ◽  
Reaction Method ◽  
X Ray ◽  
Three Samples ◽  
Scanning Electron ◽  
The Eu

AbstractIn this work, aluminate type phosphorescence materials were synthesized via the solid state reaction method and the photoluminescence (PL) properties, including excitation and emission bands, were investigated considering the effect of trace amounts of activator (Eu3+) and co-activator (Dy3+). The estimated thermal behavior of the samples at certain temperatures (> 1000 °C) during heat treatment was characterized by differential thermal analysis (DTA) and thermogravimetry (TG). The possible phase formation was characterized by X-ray diffraction (XRD). The morphological characterization of the samples was performed by scanning electron microscopy (SEM). The PL analysis of three samples showed maximum emission bands at around 610 nm, and additionally near 589 nm, 648 nm and 695 nm. The bands were attributed to typical transitions of the Eu3+ ions.

Synchrotron white beam x-ray topography (SWBXT) and high resolution triple axis diffraction studies on AlN layers grown on 4H- and 6H-SiC seeds

2004 ◽  
Vol 831 ◽  
Author(s):  
Balaji Raghothamachar ◽  
Michael Dudley ◽  
Rafael Dalmau ◽  
Raoul Schlesser ◽  
Zlatko Sitar
Keyword(s):  
High Resolution ◽  
Single Crystal ◽  
Large Diameter ◽  
Laser Diodes ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
White Beam ◽  
Strain Data ◽  
Growth Experiments

ABSTRACTFor nitride based devices such as LEDs, high power FETs and laser diodes, single crystal substrates of AlN are highly desirable. While the sublimation technique is suitable for growing bulk AlN crystals, appropriate seeds are also necessary for growing large diameter oriented boules. 4H- and 6H-SiC substrates which are readily available commercially can potentially be implemented as seeds for bulk AlN growth. However, issues regarding SiC decomposition at high temperatures, thermal expansion mismatch, single crystal growth, etc. need to be addressed. Towards this end, a series of growth experiments have been carried out in a resistively heated reactor using on and off-axis 4H- and 6H-SiC substrates as seeds for AlN growth from the vapor phase. Several hundred microns thick AlN layers have been grown under different growth conditions. Synchrotron white beam x-ray topography (SWBXT) has been used to map the defect distribution in the grown layers and high resolution triple axis x-ray diffraction (HRTXD) experiments were carried out to record reciprocal space maps from which tilt, mismatch and strain data can be obtained. These results are analyzed with respect to the growth conditions in order to gain a better understanding of this growth process.

X-ray diffraction patterns for BaR2PdO5 (R=Nd, Sm, Eu, and Gd)

1996 ◽  
Vol 11 (1) ◽  
pp. 9-12
Author(s):  
W. Wong-Ng
Keyword(s):  
Materials Characterization ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Diffraction Patterns ◽  
The Eu

Calculated patterns for the BaR2PdO5 series, in which X is Pd and R=Nd, Sm, Eu, or Gd, have been prepared for materials characterization until experimental patterns can be determined. These compounds are isostructural to the superconductor related “brown phases” BaLa2CuO5 and BaNd2CuO5, which are tetragonal with space group P4/mbm, Z=4. The cell parameters of the Eu and Gd compounds were derived from the La and Nd analogs. The calculated patterns of these four compounds compared well to an experimental pattern of BaNd2CuO5.

Luminescent and magnetic bifunctional coordination complex based on a chiral tartaric acid derivative and europium

2019 ◽  
Vol 75 (9) ◽  
pp. 1220-1227 ◽  
Author(s):  
Mei-rong Han ◽  
Shao-dong Li ◽  
Ling Ma ◽  
Bang Yao ◽  
Si-Si Feng ◽  
...  
Keyword(s):  
Tartaric Acid ◽  
Complex I ◽  
Coupling Parameter ◽  
Chain Structure ◽  
Magnetic Behaviour ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Carboxylate Groups ◽  
The Eu

A new mononuclear europium complex incorporating the (+)-di-p-toluoyl-D-tartaric acid (D-H2DTTA) ligand, namely, catena-poly[tris{μ2-3-carboxy-2,3-bis[(4-methylphenyl)carbonyloxy]propanoato}tris(methanol)europium(III)], [Eu(C20H17O8)3(CH3OH)3] n , (I), has been synthesized and characterized by IR spectroscopy, elemental analysis, powder X-ray diffraction and single-crystal X-ray diffraction analysis. The structure analysis indicates that complex (I) crystallizes in the trigonal space group R3 and exhibits an infinite one-dimensional chain structure, in which the Eu3+ ion is surrounded by six O atoms from six D-HDTTA− ligands and three O atoms from three coordinated methanol molecules, thus forming a tricapped trigonal prism geometry. The D-H2DTTA ligand is partially deprotonated and adopts a μ1,6-coordination mode via two carboxylate groups to link adjacent Eu3+ ions, affording an infinite one-dimensional propeller-shaped coordination polymer chain along the c axis, with an Eu...Eu distance of 7.622 (1) Å. Moreover, C—H...π interactions lead to the formation of helical chains running along the c axis and the whole structure displays a snowflake pattern in the ab plane. The circular dichroism spectrum confirms the chirality of complex (I). The solid-state photoluminescence properties were also investigated at room temperature and (I) exhibits characteristic red emission bands derived from the Eu3+ ion (CIE 0.63, 0.32), with a reasonably long lifetime of 0.394 ms, indicating effective energy transfer from the ligand to the metal centre. In addition, a magnetic investigation reveals single-ion magnetic behaviour. The spin-orbit coupling parameter (λ) between the ground and excited states is fitted to be 360 (2) cm−1 through Zeeman perturbation. Therefore, complex (I) may be regarded as a chiral optical-magneto bifunctional material.

THE GIANT MAGNETOSTRICTION OF [Fe/Tb/Fe/Dy]n MULTILAYER FILMS UNDER DIFFERENT ANNEALING TEMPERATURE

2009 ◽  
Vol 16 (01) ◽  
pp. 123-126 ◽  
Author(s):  
X. D. LI ◽  
Z. J. ZHAO ◽  
T. FENG ◽  
L. K. PAN ◽  
S. M. HUANG ◽  
...  
Keyword(s):  
Saturation Magnetization ◽  
Annealing Temperature ◽  
Multilayer Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Low Field ◽  
Giant Magnetostriction

The effect of annealing temperature on the magnetic and giant magnetostriction (GMS) of [ Fe / Tb / Fe / Dy ]n multilayer films were investigated. X-ray diffraction showed that the multilayer films' microstructures were still in amorphous at annealing temperature 300°C. The multilayer films began to crystalline at annealing temperature 400°C. The saturation magnetization of multilayer films increased by the increasing annealed temperature. The coercivity first decreased at annealing temperature 300°C and then increased when the annealing temperature was higher than 400°C. The multilayer films had good low-field GMS, and the magnetostriction of the multilayer films increased by the increasing annealing temperature.

scholarly journals Photocatalytic Activity and Optical Properties of Blue Persistent Phosphors under UV and Solar Irradiation

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
C. R. García ◽  
L. A. Diaz-Torres ◽  
J. Oliva ◽  
M. T. Romero ◽  
P. Salas
Keyword(s):  
Photocatalytic Activity ◽  
Annealing Temperature ◽  
Uv Light ◽  
Solar Irradiation ◽  
Photoluminescence Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Water Cleaning ◽  
Different Temperatures ◽  
The Eu

Blue phosphorescent strontium aluminosilicate powders were prepared by combustion synthesis route and a postannealing treatments at different temperatures. X-ray diffraction analysis showed that phosphors are composed of two main hexagonal phases: SrAl2O4and Sr3Al32O51. The morphology of the phosphors changed from micrograins (1000°C) to a mixture of bars and hexagons (1200°C) and finally to only hexagons (1300°C) as the annealing temperature is increased. Photoluminescence spectra showed a strong blue-green phosphorescent emission centered atλem=455 nm, which is associated with4f65d1→4f6  (8S7/2)transition of the Eu2+. The sample annealed at 1200°C presents the highest luminance value (40 Cd/m2) with CIE coordinates (0.1589, 0.1972). Also, the photocatalytic degradation of methylene blue (MB) under UV light (at 365 nm) was monitored. Samples annealed at 1000°C and 1300°C presented the highest percentage of degradation (32% and 38.5%, resp.) after 360 min. In the case of photocatalytic activity under solar irradiation, the samples annealed at 1000°C, 1150°C, and 1200°C produced total degradation of MB after only 300 min. Hence, the results obtained with solar photocatalysis suggest that our powders could be useful for water cleaning in water treatment plants.

Europium(II) Heptaphosphide EuP7 [1] Europium(II)heptaphosphid EuP7 [1]

1980 ◽  
Vol 35 (7) ◽  
pp. 824-831 ◽  
Author(s):  
Hans Georg von Schnering ◽  
Manfred Wittmann
Keyword(s):  
Chair Conformation ◽  
Monoclinic Space Group ◽  
The Novel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Divalent Europium ◽  
Salt Melts ◽  
Tetrahedral Environment ◽  
Mineral Acids ◽  
The Eu

The novel polyphosphide EuP7 was prepared under controlled conditions by the reaction of the elements in salt melts at 750-800 K. EuP7 forms black prismatic crystals not attacked by diluted mineral acids and bases. The thermal decomposition yields EuP3 at 700 K and in further steps EuP2, Eu3P4 and EuP, respectively. According to the crystal structure as well as the electrical, optical and magnetic properties EuP7 is a semiconductor (EG = 0.9 eV; EG (vert) = 1.1 eV) with divalent europium (μ = 7.55 B.M.). The compound crystallizes in the monoclinic space group P21/n with a = 1148.8(7) pm, b = 570.0(3) pm, c = 1061.0(6) pm, and β= 106.08°(5); (X-ray diffraction data; 1479 hkl, R = 0.031). The P-atoms are connected (P-P) = 218.0-223.5 pm) to a 2-dimensional infinite polyanionic structure with homonuclear 3-bonded and 2-bonded P-atoms in the ratio 5:2. The polyanionic network contains P6-rings (chair conformation) as well as P8-rings and P10-rings. The Eu-atoms are bonded to 9 P-atoms (1,4,4-polyhedra) with bond distances ranging from 306.6 to 326.6 pm. The Eu-atoms complete the tetrahedral environment of the P-atoms

Synthesis of Glycolic and Oxalic Acid Europium: [Eu (C3 H6O9)] ·2(H2O)

2012 ◽  
Vol 554-556 ◽  
pp. 792-795
Author(s):  
Hai Xing Liu ◽  
Jing Wang ◽  
Fang Fang Jian ◽  
Hui Juan Yue ◽  
Guang Zeng ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Oxalic Acid ◽  
Single Crystal ◽  
Hydrothermal Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrogen Bonding Interactions ◽  
The Eu

A new Eu complex [Eu (C3O9H6)] ·2(H2O) has been synthesized from a hydrothermal reaction and the crystal structure has been determined by means of single-crystal X-ray diffraction. The Eu atom is coordinated by eight O atoms. The molecular is antisymmetric structure by the C3-C3 axis. It is striking that the structure of the complex exhibits extensive O-H…O hydrogen-bonding interactions.

Crystalline phase transformation of colloidal cadmium sulfide nanocrystals

2017 ◽  
Vol 31 (06) ◽  
pp. 1750037
Author(s):  
M. Ghali ◽  
A. M. Eissa ◽  
M. M. Mosaad
Keyword(s):  
Phase Transformation ◽  
Optical Absorption ◽  
Crystalline Phase ◽  
Growth Conditions ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Solution Ph ◽  
X Ray ◽  
Ph Values ◽  
Transmission Electron

In this paper, we give a microscopic view concerning influence of the growth conditions on the physical properties of nanocrystals (NCs) thin films made of CdS, prepared using chemical bath deposition CBD technique. We show a crystalline phase transformation of CdS NCs from hexagonal wurtzite (W) structure to cubic zincblende (ZB) when the growth conditions change, particularly the solution pH values. This effect was confirmed using X-ray diffraction (XRD), transmission electron microscopy (TEM), optical absorption and photoluminescence (PL) measurements. The optical absorption spectra allow calculation of the bandgap value, [Formula: see text], where significant increase [Formula: see text]200 meV in the CdS bandgap when transforming from Hexagonal to Cubic phase was found.

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