The Effect of Substituting Ga for Alon Crystal Structure of Phosphors MAl 2Si2O8: Eu2+ (M= Ca, Sr, Ba)

2022 ◽  
Vol 905 ◽  
pp. 91-95
Author(s):  
Fei Wang ◽  
Hui Hui Chen ◽  
Shi Wei Zhang
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Cell Volume ◽  
Solid Solutions ◽  
Solid State Reaction ◽  
Unit Cell Volume ◽  
Lattice Parameter ◽  
Unit Cell ◽  
Lattice Parameters ◽  
Reductive Atmosphere

A series of luminescence phosphors M0.955Al2 –xGaxSi2O8∶Eu2+ (M=Ca, Sr, Ba, x = 0~1.0) were prepared via solid-state reaction in weak reductive atmosphere. The lattice positions were discussed. It was found that when Ga3+ entered MAl2Si2O8 lattice and substituted Al3+, complete solid solutions formed. The lattice parameters (a, b, c) and unit cell volume of phosphors M 0.955Al2 –xGaxSi2O8: Eu2+ (M=Ca, Sr, Ba, x = 0~1.0) increased linearly, the lattice parameters (α, β,γ) of Ca0.955Al2–xGaxSi2O8∶Eu2+(CAS) decreased linearly and the lattice parameter β of Sr0.955Al2–xGaxSi2O8∶Eu2+(SAS) and Ba0.955Al2–xGaxSi2O8∶Eu2+(BAS) increased linearly as Ga3+ content increased.

scholarly journals 1,1′,3,3′-Tetramesitylquinobis(imidazole)-2,2′-dithione

IUCrData ◽  
2019 ◽  
Vol 4 (9) ◽  
Author(s):  
Jayaraman Selvakumar ◽  
Kuppuswamy Arumugam
Keyword(s):  
Crystal Structure ◽  
Molecular Weight ◽  
Solid State ◽  
Structural Analysis ◽  
Hydrogen Bonds ◽  
Cell Volume ◽  
Title Compound ◽  
Unit Cell Volume ◽  
Density Peaks ◽  
Solvent Molecules

The solid-state structural analysis of the title compound [systematic name: 5,11-disulfanylidene-4,6,10,12-tetrakis(2,4,6-trimethylphenyl)-4,6,10,12-tetraazatricyclo[7.3.0.03,7]dodeca-1(9),3(7)-diene-2,8-dione], C44H44N4O2S2 [+solvent], reveals that the molecule crystallizes in a highly symmetric cubic space group so that one quarter of the molecule is crystallographically unique, the molecule lying on special positions (two mirror planes, two twofold axes and a center of inversion). The crystal structure exhibits large cavities of 193 Å3 accounting for 7.3% of the total unit-cell volume. These cavities contain residual density peaks but it was not possible to unambiguously identify the solvent therein. The contribution of the disordered solvent molecules to the scattering was removed using a solvent mask and is not included in the reported molecular weight. No classical hydrogen bonds are observed between the main molecules.

Method of High Active Preparation and Electrical Properties of CuFeO2 Delafossite-Type

2014 ◽  
Vol 979 ◽  
pp. 302-306 ◽  
Author(s):  
Chalermpol Rudradawong ◽  
Aree Wichainchai ◽  
Aparporn Sakulkalavek ◽  
Yuttana Hongaromkid ◽  
Chesta Ruttanapun
Keyword(s):  
Crystal Structure ◽  
Electrical Conductivity ◽  
Solid State ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Solid State Reaction ◽  
Solid State Reaction Method ◽  
Lattice Parameter ◽  
Metal Powders ◽  
High Power Factor

In this paper, the CuFeO2compound were prepared by classical solid state reaction (CSSR) and direct powder dissolved solution (DPDS) method from starting material metal oxides and metal powders. Preparation of two methods shows that, direct powder dissolved solution faster recover phases than classical solid state reaction method. The fastest method gets from starting materials Cu and Fe metal powders, the electrical conductivity, Seebeck coefficient, carrier concentration and mobility are 10.68 S/cm, 244.59 μV/K, 12.86×1016cm-3and 494.96 cm2/V.s, respectively. In addition, each CuFeO2compounds were investigated on crystal structure and electrical properties. From XRD and SEM results, all samples have a crystal structure delafossite-typeand a large grain boundary more than 15 μm by electrical conductivity corresponds to grain boundary and lattice parameter: a increases. Within this paper, from above results exhibit that preparation CuFeO2from Cu and Fe by direct powder dissolved solution method most appropriate for thermoelectric oxide materials due to high active for preparation else high lattice strain and high power factor are 0.00052 and 0.64×10-4W/mK2, respectively.

scholarly journals Structural Analysis of Platinum Nanoparticles on Carbon Nanotube Surface as Electrocatalyst System

2017 ◽  
Vol 9 (2) ◽  
pp. 60 ◽  
Author(s):  
Sudirman Sudirman ◽  
Indriyati Indriyati ◽  
Wisnu Ari Adi ◽  
Rike Yudianti ◽  
Emil Budianto
Keyword(s):  
Cell Volume ◽  
Unit Cell Volume ◽  
Average Particle Size ◽  
Unit Cell ◽  
Lattice Parameters ◽  
Atomic Density ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Great Opportunity ◽  
X Ray

Synthesis of Pt/CNT composite by using sol gel method has been performed which the composition of CNT on the composite are vary, (x = 20, 40, 60 and 80 wt%). Performance of composite was characterized by Transmission Electron Microscope (TEM) and X-Ray Diffraction (XRD), respectively. In the refinement results of X-ray diffraction pattern, the composite consists of two phases, namely, carbon and platinum phases. Carbon phase has a structure hexagonal (P 63 m c) with lattice parameters a = b = 2.451(2) Å and c = 6.89(1) Å, α = β = 90° and γ = 120°, the unit cell volume of V = 35.8(1) A3, and the atomic density of ρ = 2.224 g.cm-3. While platinum phase has the structure of cubic (F m -3 m) with lattice parameters a = b = c = 3.921(2) Å, α = β = γ = 90°, the unit cell volume of V = 60.3(1) A3, and the atomic density of ρ = 21.487 g.cm-3.According to the image of TEM, the average particle size for Pt nano particle is estimated to range from 4.1-4.3 nm. While the cavity diameter average of CNT is estimated to range from 5.9-7.5 nm. Based on the calculation, the crystallite size of the Pt particle was around 4.31 nm. The optimum value of dispersed Pt into CNT occurred at 60 wt% CNT with the best composition of Pt in the unit cell of cystal structure. We concluded that this study successfully dispersed Pt nanoparticles onto CNT formed Pt/CNT composite. This was a great opportunity that the composite can be applied as electrocatalyst system on fuel cell application.

2,3,5′,6,6′,7-Hexamethoxy-3′H,10H-spiro[anthracene-9,1′-isobenzofuran]-3′,10-dione

2007 ◽  
Vol 63 (11) ◽  
pp. o4390-o4391 ◽  
Author(s):  
Marlon R. Lutz ◽  
Matthias Zeller ◽  
Daniel P. Becker
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Cell Volume ◽  
Unit Cell Volume ◽  
Unit Cell ◽  
Spiro Compound ◽  
Π Interactions ◽  
Rigid Molecule ◽  
Title Molecule ◽  
Solvent Molecules

The title molecule, C27H24O9, was formed via a transannular electrophilic addition of a putative cyclotriveratrylene triketone and is made up of an anthrone and an isobenzofuranone ring that are connected via one C atom to form a spiro compound. The anthracene and isobenzofuranone ring systems of the spiro compound are both essentially planar and perpendicular to each other, with an angle of 89.90 (2)° between them. The rigid molecule crystallizes with large voids of 598.7 Å3, or 21.5% of the unit-cell volume, that are partially filled with unmodelled disordered solvent molecules. The voids stretch as infinite channels along the [101] direction. The packing of the structure is partially stabilized by a range of weak C—H...O hydrogen bonds and also by C—H...π interactions. No significant π–π interactions are present in the crystal structure.

Phase and lattice parameter relationships in rapidly solidified and heat-treated (Mn0.53Al0.47)100−xCx pseudo-binary alloys

1992 ◽  
Vol 7 (7) ◽  
pp. 1690-1695 ◽  
Author(s):  
C.T. Lee ◽  
K.H. Han ◽  
I.H. Kook ◽  
W.K. Choo
Keyword(s):  
Carbon Content ◽  
Cell Volume ◽  
Unit Cell Volume ◽  
Binary Alloys ◽  
Lattice Parameter ◽  
Unit Cell ◽  
Type I ◽  
Heat Treated ◽  
Melt Spun ◽  
Rapidly Solidified

The phase constitution and the lattice parameter relationships in the rapidly solidified and heat-treated (Mn0.53Al0.47)100−xCx pseudo-binary alloys (x = 0–6) have been investigated by means of x-ray diffraction and transmission electron microscopy. The melt-spun alloys contained a single ∊ phase (cph) with 0.63–4.0 at. % C, and below and beyond this carbon composition range small traces of γ2-MnAl and Al4C3 compounds were formed, respectively. The heat treatment of the melt-spun alloys at 823 K produced a single τ phase (ordered bct, CuAu type I, L10) with 0.63–3.6 at.% C. The c lattice parameter of the ∊ unit cell was observed to increase pronouncedly with the carbon content whereas that of the a-axis revealed no apparent change; the corresponding increase of the unit cell volume was taken to indicate an interstitial dissolution of the carbon atoms in the ∊ lattice. On the other hand, for the τ phase, the c lattice parameter increased markedly with the carbon content while the a parameter decreased slightly, so that a large increase of c/a ratio was produced. The lattice parameter data for the τ phase thus indicated an increase of the unit cell volume with the carbon content, providing new evidence that the carbon atoms dissolve interstitially in the bct lattice. In addition, it was deduced that the higher c/a ratio with increasing carbon content may arise from a preferential site occupation of the carbon atoms at a specific type of octahedral interstitial site lying in the manganese atom layers.

scholarly journals Preparation and study the structure of pure and impure barium titanate with Mg2+ ion

2018 ◽  
Vol 16 (37) ◽  
pp. 190-198
Author(s):  
Wasan Abd Alsatar Hekmt
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Barium Titanate ◽  
Solid State Reaction ◽  
Lattice Parameters ◽  
Magnesium Ion ◽  
Solid State Reaction Technique ◽  
Molar Ratios ◽  
Two Temperatures ◽  
Doped Barium Titanate

Pure and doped barium titanate with Mg2+ ion at two molar ratios x= (5%, 10%) mol. has been synthesized by solid state reaction technique. The powders sintered at two temperatures (1000 °C and 1400 °C). An XRD technique was used in order to study the crystal structure of pure and doped barium titanate, which confirmed the formation of the tetragonal phase of BaTiO3, and then calculate the lattice parameters of pure and doped barium titanate, the addition of magnesium ion Mg2+ can lead to decreases lattice parameters.

scholarly journals Polder maps: improving OMIT maps by excluding bulk solvent

2017 ◽  
Vol 73 (2) ◽  
pp. 148-157 ◽  
Author(s):  
Dorothee Liebschner ◽  
Pavel V. Afonine ◽  
Nigel W. Moriarty ◽  
Billy K. Poon ◽  
Oleg V. Sobolev ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Cell Volume ◽  
Electron Density ◽  
Unit Cell Volume ◽  
Model Building ◽  
Unit Cell ◽  
Structure Factors ◽  
Structure Solution ◽  
Solvent Model ◽  
Solvent Molecules

The crystallographic maps that are routinely used during the structure-solution workflow are almost always model-biased because model information is used for their calculation. As these maps are also used to validate the atomic models that result from model building and refinement, this constitutes an immediate problem: anything added to the model will manifest itself in the map and thus hinder the validation. OMIT maps are a common tool to verify the presence of atoms in the model. The simplest way to compute an OMIT map is to exclude the atoms in question from the structure, update the corresponding structure factors and compute a residual map. It is then expected that if these atoms are present in the crystal structure, the electron density for the omitted atoms will be seen as positive features in this map. This, however, is complicated by the flat bulk-solvent model which is almost universally used in modern crystallographic refinement programs. This model postulates constant electron density at any voxel of the unit-cell volume that is not occupied by the atomic model. Consequently, if the density arising from the omitted atoms is weak then the bulk-solvent model may obscure it further. A possible solution to this problem is to prevent bulk solvent from entering the selected OMIT regions, which may improve the interpretative power of residual maps. This approach is called a polder (OMIT) map. Polder OMIT maps can be particularly useful for displaying weak densities of ligands, solvent molecules, side chains, alternative conformations and residues both in terminal regions and in loops. The tools described in this manuscript have been implemented and are available inPHENIX.

The Ion Conducting Properties of Perovskite-Type Solid Solutions (La0.5Li0.5) [Ti1-x(M0.5Nb0.5)x]O3 (M = Al, Ga)

2006 ◽  
Vol 514-516 ◽  
pp. 407-411 ◽  
Author(s):  
Elena A. Fortalnova ◽  
Alexander V. Mosunov ◽  
Marina G. Safronenko ◽  
Nikolay U. Venskovskii ◽  
Ekaterina D. Politova
Keyword(s):  
Phase Transitions ◽  
Low Temperature ◽  
Cell Volume ◽  
Solid Solutions ◽  
Unit Cell Volume ◽  
Relaxation Effect ◽  
Unit Cell ◽  
Temperature Dependences ◽  
Ion Conducting ◽  
Perovskite Type

The influence of B-site substitution on electroconducting properties of perovskite-type solid solutions (La0.5Li0.5)[Ti1-x(M0.5Nb0.5)x]O3 with M = Al, Ga, have been studied. A decrease in the conductivity due to the unit cell contraction with increasing x in case of M = Al has been revealed. In case of Ga and Nb substitutions for Ti the unit cell volume has been found to increase with increasing x while the conductivity decreases due to the impurity phases presence. The high and low temperature anomalies on the temperature dependences of dielectric characteristic related to both the relaxation effect and phase transitions have been revealed.

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