Effect of Cr doping on the structure of (Pr0.55Ca0.45)(Mn1−yCry)O3: A Rietveld refinement study

2004 ◽  
Vol 19 (2) ◽  
pp. 137-140
Author(s):  
A. Martinelli ◽  
M. Ferretti ◽  
C. Castellano
Keyword(s):  
Powder Diffraction ◽  
Rietveld Method ◽  
Structural Data ◽  
Secondary Phases ◽  
X Ray ◽  
Binary Oxides ◽  
Orthorhombic Cell ◽  
Bond Valence Sum ◽  
Perovskite Type ◽  
Cr Doping

(Pr0.55Ca0.45)(Mn1−yCry)O3 (with y=0.00, 0.03, and 0.06) have been prepared by means of a solid state reaction from stoichiometric powder mixtures of binary oxides. X-ray powder diffraction analysis reveals the formation of the perovskite-type compound for the whole considered compositions; no evidence for secondary phases may be detected. The structural refinements have been carried out using X-ray powder diffraction data applying the Rietveld method; the lattice parameters of the orthorhombic cell faintly change with composition. On the contrary the tilting of the octahedra results are strongly dependent on the concentration of Cr in the 4b site. Bond valence sum method has been applied in order to evaluate the possible presence of lattice-induced strains and the amount of Mn4+. Structural data are also reported.

The crystal structure of (Ho0.50Ca0.50)MnO3 and its evolution with Cr doping: A Rietveld refinement investigation

2005 ◽  
Vol 20 (1) ◽  
pp. 22-26 ◽  
Author(s):  
A. Martinelli ◽  
M. Ferretti
Keyword(s):  
Crystal Structure ◽  
Single Phase ◽  
Rietveld Method ◽  
Ionic Species ◽  
X Ray ◽  
Jahn Teller ◽  
Bond Valence Sum ◽  
Perovskite Type ◽  
Cr Doping ◽  
Perovskite Type Structure

Single-phase (Ho0.50Ca0.50)MnO3 has been successfully prepared by means of solid state reaction at high temperature. Its crystal structure, as well as those of Cr-doped samples(Ho1−xCax)(Mn1−yCry)O3, has been refined by the Rietveld method, using X-ray powder diffraction data. All the examined compounds crystallize in the Pnma space group with a distorted perovskite-type structure. The distortion of the BO6 octahedra, due to the Jahn–Teller Mn3+ ionic species, decreases with the Cr content. Bond valence sum calculations were carried out using the refined results.

Obtaining optimal structural data from X-ray powder diffraction using the Rietveld method

2014 ◽  
Vol 29 (4) ◽  
pp. 396-403 ◽  
Author(s):  
Shanke Liu ◽  
He Li ◽  
Jianming Liu
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Low Cost ◽  
Structural Data ◽  
Preferred Orientation ◽  
X Ray

Diffraction data of calcite were collected using a conventional Bragg–Brentano diffractometer, which is a convenient, low-cost, and highly popular in-house instrument, and its crystal structure was refined by the Rietveld method. This paper shows how one treats preferred orientation and how different refinement strategies affect the accuracy of the result.

scholarly journals (Cu0.4Al0.3)TaSe2: PREPARATION AND CRYSTAL STRUCTURE ANALYSIS FROM X-RAY POWDER DIFFRACTION

2020 ◽  
Vol 28 (29) ◽  
pp. 01-06
Author(s):  
Pedro GRIMA-GALLARDO ◽  
Sonia DURÁN ◽  
Marcos MUÑOZ ◽  
Dibya P RAI ◽  
Gerzon E. DELGADO
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Alloy System ◽  
Crystal Structure Analysis ◽  
Partial Ordering ◽  
Secondary Phases ◽  
X Ray ◽  
Cell Parameters ◽  
New Phase

A new phase of the (CuAlSe2)1-x(TaSe)x alloy system was synthesized by the melt and annealing technique and studied by SEM, DTA, and XRPD techniques. Its structure has been refined by the Rietveld method using X-ray powder diffraction data. The new alloy corresponds with the stoichiometry Cu0.4Al0.3TaSe2. This compound crystallizes in the hexagonal space group 𝑃6ത𝑚2 (Nº 187) with a MoS2-type structure, and unit cell parameters a = 3.455(2) Å, c = 13.423(4) Å, V = 138.7(1) Å3, Z =2. The crystal structure is based on the MoS2- type of stacking of TaSe2 layers with a partial ordering of Cu and Al cations over the tetrahedral sites. The powder pattern was composed of 63.1% of the principal phase Cu0.4Al0.3TaSe2 and 29.9% of CuAlSe2, 7.0% of TaSe3, as the secondary phases.

Crystallographic study of ternary ordered skutterudite IrGe1.5Se1.5

2010 ◽  
Vol 25 (3) ◽  
pp. 247-252 ◽  
Author(s):  
F. Laufek ◽  
J. Návrátil
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Crystallographic Data ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Crystallographic Study ◽  
Related Phase ◽  
The Ideal

The crystal structure of skutterudite-related phase IrGe1.5Se1.5 has been refined by the Rietveld method from laboratory X-ray powder diffraction data. Refined crystallographic data for IrGe1.5Se1.5 are a=12.0890(2) Å, c=14.8796(3) Å, V=1883.23(6) Å3, space group R3 (No. 148), Z=24, and Dc=8.87 g/cm3. Its crystal structure can be derived from the ideal skutterudite structure (CoAs3), where Se and Ge atoms are ordered in layers perpendicular to the [111] direction of the original skutterudite cell. Weak distortions of the anion and cation sublattices were also observed.

Ion size effect on chemical bonds of the RBa2Cu2.9Zn0.1Oy system

2018 ◽  
Vol 33 (3) ◽  
pp. 209-215
Author(s):  
R. Benredouane ◽  
C. Boudaren
Keyword(s):  
Single Phase ◽  
Rietveld Method ◽  
Solid State Reaction Method ◽  
X Ray ◽  
Bond Angles ◽  
Bond Valence Sum ◽  
Ion Size ◽  
First Time ◽  
Unique Variation ◽  
Strong Curvature

Single-phase polycrystalline samples of RBa2Cu2.9Zn0.1Oy (R = Y, Nd, Gd, Er, and Tm) (ZnR123) were synthesized using the standard solid-state reaction method. They were characterized by X-ray powder diffraction (XRD) and scanning electron microscope. XRD shows that all samples consist essentially of a single phase and retain the orthorhombic structure. The structure of the samples was refined by the Rietveld method with the help of the bond valence sum method. The variation of the lattice parameters and some meaningful bond angles and lengths with the ionic radius are discussed. In these compounds, the variations of the buckling angles Cu2–O(2,3)–Cu2 and Cu2–Cu2–O(2,3) are unique: the bond angles Cu2–O3–Cu2 and Cu2–Cu2–O2 increase, whereas the bond angles Cu2–O2–Cu2 and Cu2–Cu2–O3 decrease. The variation of these bond angles brings about a strong curvature of the Cu2O plane. Furthermore, we have found tree fixed triangles formed by the Cu2, O2, and O3 atoms in addition to another fixed triangle O1–Ba–O1 observed for the first time. BVS of Cu2 atom shows a specific and unique variation compared with other compounds.

Rietveld refinement of the solid-solution series: (Cu,Mg)SO4·H2O

1995 ◽  
Vol 10 (3) ◽  
pp. 189-194 ◽  
Author(s):  
C. L. Lengauer ◽  
G. Giester
Keyword(s):  
Solid Solution ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Structure Refinement ◽  
Solid Solution Series ◽  
Cation Site ◽  
Tg Analysis ◽  
X Ray ◽  
Solution Series

The kieserite-type solid-solution series of synthetic (Cu,Mg)SO4·H2O was investigated by TG-analysis and X-ray powder diffraction using the Rietveld method. Representatives with Cu≥20 mol% are triclinic distorted () analogous to the poitevinite (Cu,Fe)SO4·H2O compounds. Cation site ordering with preference of Cu for the more distorted M1 site was additionally proven by the structure refinement.

Rietveld Refinement of the BaTiO3 from X-Ray Powder Diffraction

2009 ◽  
Vol 79-82 ◽  
pp. 593-596
Author(s):  
Feng Sun ◽  
Yan Sheng Yin
Keyword(s):  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Structural Parameters ◽  
Ferroelectric Ceramic ◽  
Powder Diffraction Data ◽  
Ceramic Powders ◽  
Space Group ◽  
X Ray

The ferroelectric ceramic BaTiO3 was synthesized at 1000 °C for 5 h. The structure of the system under study was refined on the basis of X-ray powder diffraction data using the Rietveld method. The system crystallizes in the space group P4mm（99）. The refinement of instrumental and structural parameters led to reliable values for the Rp, Rwp and Rexp.We use the TOPAS software of Bruker AXS to refine this ceramic powders and show its conformation

Crystal structure of potassium tetraperoxomolybdate (VI) K2[Mo(O2)4]

2005 ◽  
Vol 20 (3) ◽  
pp. 203-206 ◽  
Author(s):  
M. Grzywa ◽  
M. Różycka ◽  
W. Łasocha
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Structure Refinement ◽  
Crystal Structure Refinement ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters

Potassium tetraperoxomolybdate (VI) K2[Mo(O2)4] was prepared, and its X-ray powder diffraction pattern was recorded at low temperature (258 K). The unit cell parameters were refined to a=10.7891(2) Å, α=64.925(3)°, space group R−3c (167), Z=6. The compound is isostructural with potassium tetraperoxotungstate (VI) K2[W(O2)4] (Stomberg, 1988). The sample of K2[Mo(O2)4] was characterized by analytical investigations, and the results of crystal structure refinement by Rietveld method are presented; final RP and RWP are 9.79% and 12.37%, respectively.

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