PL Properties of (Ba, Ca)2( Si, P)O4: Eu Synthesized by Various Annealing and Cooling Process

2021 ◽  
Vol 1016 ◽  
pp. 231-235
Author(s):  
Shota Ando ◽  
Hiromi Nakano ◽  
Koichiro Fukuda
Keyword(s):  
Crystal Structure ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Slow Cooling ◽  
X Ray ◽  
Host Materials ◽  
Emission Color ◽  
Increasing Temperature ◽  
X Ray Absorption ◽  
Color Emission

We have been investigating the series of P doped Ca2SiO4 (C2S) using Eu2+ or Eu3+ as activator with various colors. The crystal structure of C2S is particularly easily controlled by heating because the established polymorphs of C2S are, in the order of increasing temperature, γ, β, α’L, α’H, and α. In order to control the crystal structure, the phosphors were synthesized and then annealed at temperatures 1473 K-1773 K. The crystal structures and PL properties were compared between slow cooling and quenching (cooled in water). We found unique phenomena when the phosphors were treated by quenching process. In the case of (Ba1-xCax)2(Si0.94P0.06)O4:Eu3+ ( 0.25 ≤ x ≤ 1), color emission changed from red to blue-white for the phosphor with a high concentration of Ba and quenched at 1773 K. In general, Eu3+ doped phosphors showed the red emission color in any host materials. However, Ba-included and quenched-treatment phosphors emitted a bright white color. The mechanism and relationship between the PL property and crystal structure were characterized carefully using X-ray diffraction, electron microscope and X-ray absorption fine structure.

scholarly journals Synthesis, Crystal Structure and Magnetic Properties of Bixbyite-type Vanadium Oxide Nitrides

2009 ◽  
Vol 64 (3) ◽  
pp. 281-286 ◽  
Author(s):  
Suliman Nakhal ◽  
Wilfried Hermes ◽  
Thorsten Ressler ◽  
Rainer Pöttgen ◽  
Martin Lerch
Keyword(s):  
Crystal Structure ◽  
Vanadium Oxide ◽  
Magnetic Ordering ◽  
Vanadium Oxides ◽  
Detectable Amount ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vanadium Sulfide ◽  
Structure Result ◽  
X Ray Absorption

Ammonolysis of vanadium sulfide leads to the formation of bixbyite-type vanadium oxide nitrides. Small amounts of nitrogen incorporated in the structure result in the stabilization of the bixbyite type not known for vanadium oxides. The crystal structure was investigated using X-ray diffraction and X-ray absorption spectroscopy. At temperatures above 550 °C the powders decompose to corundumtype V2O3 containing no detectable amount of nitrogen. Below 39 K magnetic ordering is observed.

Structural and phase equilibria studies in the system Pt-Fe-Cu and the occurrence of tulameenite (Pt2FeCu)

1985 ◽  
Vol 49 (353) ◽  
pp. 547-554 ◽  
Author(s):  
M. Shahmiri ◽  
S. Murphy ◽  
D. J. Vaughan
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Critical Temperature ◽  
Grain Boundary ◽  
Phase Region ◽  
X Ray Diffraction ◽  
Two Phase ◽  
Slow Cooling ◽  
X Ray ◽  
Diffraction Patterns

AbstractThe crystal structure and compositional limits of the ternary compound Pt2FeCu (tulameenite), formed either by quenching from above the critical temperature of 1178°C or by slow cooling, have been investigated using X-ray diffraction, transmission electron microscopy, differential thermal analysis and electron probe microanalysis.The crystal structure of Pt2FeCu, established using electron density maps constructed from the measured and calculated intensities of X-ray diffraction patterns of powdered specimens, has the (000) and (½½0) lattice sites occupied by Pt atoms and the (½0½) and (0½½) sites occupied by either Cu or Fe atoms in a random manner. The resulting face-centred tetragonal structure undergoes a disordering transformation at the critical temperature to a postulated non-quenchable face-centred cubic structure. Stresses on quenching, arising from the ordering reaction, are relieved by twinning along {101} planes or by recrystallization along with deformation twinning; always involving grain boundary fracturing.Phase relations in the system Pt-Fe-Cu have been investigated through the construction of isothermal sections at 1000 and 600°C. At 1000°C there is an extensive single phase region of solid solution around Pt2FeCu and extending to the binary composition PtFe. At 600°C the composition Pt2FeCu lies just outside this now reduced area of solid solution in a two-phase field. Comparison of the experimental results with data for tulameenite suggests that some observed compositions may be metastably preserved. The occurrence of fine veinlets of silicate or other gangue minerals in tulameenite is suggested to result from grain boundary fracturing on cooling below the critical temperature of 1178°C and to be evidence of a magmatic origin.

Structural, morphological, and magnetic study of nanocrystalline cobalt-copper powders synthesized by the polyol process

1995 ◽  
Vol 10 (6) ◽  
pp. 1546-1554 ◽  
Author(s):  
G.M. Chow ◽  
L.K. Kurihara ◽  
K.M. Kemner ◽  
P.E. Schoen ◽  
W.T. Elam ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Copper Powders ◽  
Face Centered ◽  
Increasing Temperature ◽  
X Ray Absorption

Nanocrystalline CoxCu100−x (4 ⋚ x ⋚ 49 at. %) powders were prepared by the reduction of metal acetates in a polyol. The structure of powders was characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), extended x-ray absorption fine structure (EXAFS) spectroscopy, solid-state nuclear magnetic resonance (NMR) spectroscopy, and vibrating sample magnetometry (VSM). As-synthesized powders were composites consisting of nanoscale crystallites of face-centered cubic (fcc) Cu and metastable face-centered cubic (fcc) Co. Complementary results of XRD, HRTEM, EXAFS, NMR, and VSM confirmed that there was no metastable alloying between Co and Cu. The NMR data also revealed that there was some hexagonal-closed-packed (hcp) Co in the samples. The powders were agglomerated, and consisted of aggregates of nanoscale crystallites of Co and Cu. Upon annealing, the powders with low Co contents showed an increase in both saturation magnetization and coercivity with increasing temperature. The results suggested that during preparation the nucleation of Cu occurred first, and the Cu crystallites served as nuclei for the formation of Co.

The Structural Characterization of a Series of Uranium-containing Gadolinium Zirconates

2012 ◽  
Vol 1475 ◽  
Author(s):  
Daniel J. Gregg ◽  
Yingjie Zhang ◽  
Zhaoming Zhang ◽  
Inna Karatchevtseva ◽  
Mark G. Blackford ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Diffuse Reflectance ◽  
Charge Balance ◽  
X Ray Diffraction ◽  
Edge Structure ◽  
Gadolinium Zirconate ◽  
X Ray ◽  
Host Materials ◽  
X Ray Absorption

ABSTRACTA series of uranium-containing gadolinium zirconate samples have been fabricated at 1723 K in air. X-ray diffraction and Raman spectroscopy have confirmed pyrochlore or defect fluorite structures, while diffuse reflectance, X-ray absorption near edge structure and X-ray photoelectron spectroscopies indicate a predominantly U6+ oxidation state, even when Ca2+ was added to charge balance for U4+. The results demonstrate the potential of gadolinium zirconates as host materials for actinides.

scholarly journals Crystal structure of apatite type Ca2.49Nd7.51(SiO4)6O1.75

2016 ◽  
Vol 72 (2) ◽  
pp. 209-211 ◽  
Author(s):  
Thu Hoai Le ◽  
Neil R. Brooks ◽  
Koen Binnemans ◽  
Bart Blanpain ◽  
Muxing Guo ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Room Temperature ◽  
Solubility Limit ◽  
Temperature Data ◽  
X Ray Diffraction ◽  
Slow Cooling ◽  
X Ray ◽  
Natural Apatite ◽  
Apatite Type

The title compound, Ca2+xNd8–x(SiO4)6O2–0.5x(x= 0.49), was synthesized at 1873 K and rapidly quenched to room temperature. Its structure has been determined using single-crystal X-ray diffraction and compared with results reported using neutron and X-ray powder diffraction from samples prepared by slow cooling. The single-crystal structure from room temperature data was found to belong to the space groupP63/mand has the composition Ca2.49Nd7.51(SiO4)6O1.75[dicalcium octaneodymium hexakis(orthosilicate) dioxide], being isotypic with natural apatite and the previously reported Ca2Nd8(SiO4)6O2and Ca2.2Nd7.8(SiO4)6O1.9. The solubility limit of calcium in the equilibrium state at 1873 K was found to occur at a composition of Ca2+xNd8–x(SiO4)6O2–0.5x, wherex= 0.49.

Structural Diversity of Hydrogen-Bonded Networks of [Co(NH3)6]3+ Complex Cations and Acetylenedicarboxylic Acid Anions

2014 ◽  
Vol 69 (3) ◽  
pp. 277-288 ◽  
Author(s):  
Rüdiger W. Seidel ◽  
Richard Goddard ◽  
Verena Gramm ◽  
Uwe Ruschewitz
Keyword(s):  
Crystal Structure ◽  
Room Temperature ◽  
Structural Diversity ◽  
Crystalline Material ◽  
X Ray Diffraction ◽  
Slow Cooling ◽  
Unknown Compound ◽  
X Ray ◽  
Acetylenedicarboxylic Acid

2011The crystal structure of [Co(NH3)6](ADC)(HADC) · 2H2O (1) (ADC2- =acetylenedicarboxylate) (P21=n, Z = 4) was mistakenly described as containing the [Co(H2O)6]3+ ion [I. Stein, U. Ruschewitz, Z. Naturforsch. , 66b, 471 - 478]. A revision is reported. While attempting to reproduce 1, we isolated phase-pure crystalline material of [Co(NH3)6]Cl2(HADC) · H2O (2), the crystal structure of which was also reported in the article above. Upon standing in the aqueous mother liquor at room temperature for several days, the needle-shaped crystals of 2disappear, while blockshaped crystals of the formerly unknown compound [Co(NH3)6](ADC)(HADC) (3) grow. Satellite peaks in the X-ray diffraction frames indicate that the crystal structure is incommensurately modulated. Dissolving crystals of 3 in water at elevated temperature leads to plate-shaped crystals of the new compound [Co(NH3)6]2(ADC)3 · 3H2O (4) upon slow cooling to room temperature. Compounds 2- 4 were investigated by elemental analysis, powder X-ray diffraction and infrared spectroscopy. Structural characterization of 4 by single-crystal X-ray analysis was also achieved (P1̅ , Z = 2). Complex 1, however, could not be reproduced

scholarly journals Упругие и пьезоэлектрические параметры кристаллов гистидинфосфита L-Hist·H-=SUB=-3-=/SUB=-РО-=SUB=-3-=/SUB=-, полученные методом электромеханического резонанса

2018 ◽  
Vol 44 (3) ◽  
pp. 69
Author(s):  
Е.В. Балашова ◽  
Б.Б. Кричевцов ◽  
С.Н. Попов ◽  
П.Н. Брунков ◽  
Г.А. Панкова ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Elastic Moduli ◽  
Electromechanical Coupling ◽  
Elastic Compliance ◽  
X Ray Diffraction ◽  
Slow Cooling ◽  
X Ray ◽  
Cooling Method ◽  
Stretching Vibrations ◽  
Electromechanical Resonance

AbstractSingle crystals of L -histidine phosphite ( L -Hist · H_3РО_3) have been grown from aqueous solution by slow cooling method. The results of elemental analysis, of X-ray-diffraction studies of the crystal structure, and the habitus of the obtained crystals are given. The elastic and piezoelectric coefficients have been measured on the plates with the (010) natural faces by the method of electromechanical resonance for stretching vibrations in the temperature range 295–340 K. Elastic compliance values s _33 and s _22 and the corresponding elastic-moduli values, piezoelectric coefficients d _23 and d _22, coefficients of electromechanical coupling, and temperature coefficient of the resonance frequency are obtained. A comparison is given with other crystals, which are compounds of amino acids with phosphorous or phosphoric acid.

scholarly journals Promising solid electrolyte material for an IT-SOFC: crystal structure of the cerium gadolinium holmium oxide Ce0.8Gd0.1Ho0.1O1.9 between 295 and 1023 K

2018 ◽  
Vol 74 (2) ◽  
pp. 236-239 ◽  
Author(s):  
Sri Rahayu ◽  
Jennifer S. Forrester ◽  
Girish M. Kale ◽  
Mojtaba Ghadiri
Keyword(s):  
Crystal Structure ◽  
Solid Oxide Fuel Cells ◽  
Solid Electrolyte ◽  
Sol Gel ◽  
Fluorite Structure ◽  
Sodium Ion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Increasing Temperature ◽  
Co Doped

The crystal structure of Ce0.8Gd0.1Ho0.1O1.9 (cerium gadolinium holmium oxide) has been determined from powder X-ray diffraction data. This is a promising material for application as a solid electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Nanoparticles were prepared using a novel sodium alginate sol-gel method, where the sodium ion was exchanged with ions of interest and, after washing, the gel was calcined at 723 K in air. The crystallographic features of Gd and Ho co-doped cerium oxide were investigated around the desired operating temperatures of IT-SOFCs, i.e. 573 ≤ T ≤ 1023 K. We find that the crystal structure is a stable fluorite structure with the space group Fm\overline{3}m in the entire temperature range. In addition, the trend in lattice parameters shows that there is a monotonic increase with increasing temperature.

Crystal structure of adamite at high temperature

2016 ◽  
Vol 80 (5) ◽  
pp. 901-914 ◽  
Author(s):  
M. Zema ◽  
S. C. Tarantino ◽  
M. Boiocchi ◽  
A. M. Callegari
Keyword(s):  
Crystal Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Maximum Expansion ◽  
Cell Parameters ◽  
Temperature Range ◽  
Linear Evolution ◽  
Thermal Expansion Coefficients ◽  
Different Temperatures ◽  
Increasing Temperature

AbstractStructural modifications with temperature of adamite, Zn2(AsO4)(OH), were determined by single-crystal X-ray diffraction up to dehydration and collapse of the crystal structure. In the temperature range 25–400°C, adamite shows positive and linear expansion. Axial thermal expansion coefficients, determined over this temperature range, are αa = 1.06(2) × 10–5 K–1, αb = 1.99(2) × 10–5 K–1, αc = 3.7(1) × 10–6 K–1 and αV = 3.43(3) × 10–5 K–1. Axial expansion is then strongly anisotropic with αa:αb:αc = 2.86: 5.38 : 1. Structure refinements of X-ray diffraction data collected at different temperatures allowed us to characterize the mechanisms by which the adamite structure accommodates variations in temperature. Expansion is limited mainly by edge sharing Zn(2) dimers along a and by edge sharing Zn(1) octahedra chains along c; on the other hand, connections of polyhedra along b, the direction of maximum expansion, is governed by corner sharing. Increasing temperature induces mainly an axial expansion of Zn(1) octahedron, which becomes more elongated, and no significant variations of the Zn(2) trigonal bipyramids and As tetrahedra. Starting from 400°C, deviation from a linear evolution of unit-cell parameters is observed, associated with some deterioration of the crystal, a sign of incipient dehydration. The process leads to the formation of Zn4(AsO4)2O.

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