X-ray powder diffraction refinement of PbTi(1−x)FexO(3−δ) solid solution series

2013 ◽  
Vol 28 (4) ◽  
pp. 254-261 ◽  
Author(s):  
Hasitha Ganegoda ◽  
James A. Kaduk ◽  
Carlo U. Segre
Keyword(s):  
Powder Diffraction ◽  
Lead Titanate ◽  
Structural Changes ◽  
Rietveld Method ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Solubility Limit ◽  
Homogeneous Distribution ◽  
Cubic Phase ◽  
Cell Parameters

A series of iron-doped lead titanate PbTi(1−x)FexO(3−δ) samples in the x = 0–1 composition range was prepared using sol–gel synthesis at a calcination temperature of 700 °C. The room temperature CuKα powder diffraction data collected from x = 0, 0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, and 0.3 samples were analyzed using the Rietveld method. Magnetoplumbite (PbFe12O19) secondary phase formation was observed at compositions x = 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1. Fe-composition dependent decrease of tetragonal distortion has been observed. According to Vegard's law, the B-site iron solubility limit in the lead titanate host was found to be approximately 10 mol% (x = 0.1). Homogeneous distribution of dopants below the solubility limit was evidenced by the linear behavior of unit-cell parameters. The absence of a cubic phase and the persistence of distorted oxygen octahedra indicated the existence of ferroelectric properties even at the x = 0.3 composition. Beyond x = 0.3, the P4mm tetragonal model was determined to be invalid possibly because of oxygen defect driven structural changes, mainly tilting Fe-polyhedra.

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.

scholarly journals Structural Properties Analysis of Mg-β-TCP by X-ray Powder Diffraction with the Rietveld Refinement

2020 ◽  
Vol 9 (4) ◽  
pp. 1562-1568
Keyword(s):  
Powder Diffraction ◽  
Rietveld Method ◽  
Quantitative Phase Analysis ◽  
Structural Refinement ◽  
Osteoporosis Therapy ◽  
X Ray ◽  
Cell Parameters ◽  
Biomineralization Process ◽  
Resultant Powder ◽  
Rapid Reaction

The incorporation of magnesium in the synthetic apatite has been associated with the biomineralization process and osteoporosis therapy in humans and animals. β-tricalcium phosphate (β-TCP) is one of the most common bioceramics widely applied in bone cement and implants. In this work, Ca-deficient apatite (CDA) with a theoretical 0.08 Mg/(Ca+Mg) ratio was synthesized by the rapid reaction between Ca(OH)2, MgCl2.6H2O and H3PO4 at 40°C and the resultant powder calcined at 650 °C for 10h. X-ray powder diffraction analysis (XRD), in combination with the Rietveld method (Fullprof-suite), was employed for quantitative phase analysis and structural refinement. The results of XRD indicate that magnesium can substitute for calcium into a β-TCP structure inducing a reduction of the cell parameters and the compound crystallizes in the rhombohedral R3c structure, with the following unit cell constants: a = b = 10.3560 Å, c = 37.1718 Å, and cell volume V = 3452.44. The analysis indicated that the substitution of Mg2+ on the M(4) and M(5) sites were, approximately, 2.61 and 6.97 mol%, corresponding to the Ca2.72(MgIV0.07, MgV0.21)(PO4)2 stoichiometric formula and 0.09 Mg/(Ca+Mg) ratio.

X-ray powder diffraction study of K2MSiO4, M=Mg, Zn, Co, Cd

1996 ◽  
Vol 11 (1) ◽  
pp. 51-55 ◽  
Author(s):  
W. A. Dollase
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Site Occupancy ◽  
Cubic Phase ◽  
Variable Degree ◽  
Cubic Symmetry ◽  
X Ray ◽  
Constrained Model ◽  
Diffraction Patterns

The title materials are stuffed cristobalites possessing moderate to extreme pseudosymmetry. On the bases of their X-ray powder diffraction patterns, the Mg, Zn, and Cd compounds had been previously reported as cubic and, more recently, the Zn phase as orthorhombic. Newly measured X-ray powder diffraction data demonstrate that all (including the hitherto unknown Co analog) have the Pca21 structure of Na2BeSiO4 at room temperature, but with a widely variable degree of cubic pseudosymmetry. Observed X-ray diffraction data are in good agreement with those calculated by the Rietveld method using a constrained model with Pca21 M2+/Si site occupancy and pseudocentrosymmetric Pcab atom locations. For the most nearly cubic phase, the Cd compound, there is too little deviation in the pattern from cubic symmetry to support atom coordinate refinement even with the constrained model. In these derivatives of the stuffed cristobalite structure family, M2+ and Si atoms form an ordered tetrahedral array which avoids M2+–O–M2+ connections. Potassium atoms fill all of the intervening large cavity sites.

Dielectric and I-V Characteristic of Lead Titanate Thin Films Prepared on ITO Glass Substrate

2015 ◽  
Vol 1109 ◽  
pp. 461-465 ◽  
Author(s):  
Nurbaya Zainal ◽  
Mohd Hafiz Wahid ◽  
Mohammad Rusop
Keyword(s):  
Thin Films ◽  
Lead Titanate ◽  
High Performance ◽  
Annealing Temperature ◽  
Low Cost ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Soda Lime ◽  
Soda Lime Glass ◽  
Ito Glass

Performance of lead titanate, (PbTiO3) thin films have been successfully investigated on microstructural properties, I-V characteristic, dielectric properties, and ferroelectric properties. PbTiO3offers variety of application as transducer, ferroelectric random access memory, transistor, high performance capacitor, sensor, and many more due to its ferroelectric behavior. Preparation of the films are often discussed in order to improve the structural properties, like existence of grain boundaries, particle uniformity, presents of microcrack films, porosities, and many more. Yet, researchers still prepare PbTiO3thin films at high crystallization temperature, certainly above than 600 ̊C to obtain single crystal perovskite structure that would be the reason to gain high spontaneous polarization behavior. Although this will results to high dielectric constant value, the chances that leads to high leakage current is a major failure in device performance. Thus, preparation the thin films at low annealing temperature quite an essential study which is more preferable deposited on low-cost soda lime glass. The study focuses on low annealing temperature of PbTiO3thin films through sol-gel spin coating method and undergo for dielectric and I-V measurements.

Combined effect of grain size and tensile stresses on the ferroelectric properties of sol-gel (Pb,La)TiO3 thin films

1999 ◽  
Vol 14 (12) ◽  
pp. 4570-4580 ◽  
Author(s):  
M. Alguerá ◽  
M. L. Calzada ◽  
L. Pardo ◽  
E. Snoeck
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Lead Titanate ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Precursor Solution ◽  
Grain Size Effect ◽  
Transmission Electron ◽  
Switchable Polarization

Transmission electron microscopy has shown that the grain size of sol-gel-prepared lanthanum-modified lead titanate films increases from ∼100 to ∼1 μm when the excess of PbO in the precursor solution is reduced from 20 to 10 mol%. Switchable polarization is higher in the films with a smaller grain size. Profilometry and the temperature dependence of the dielectric permittivity indicate that films are tensile stressed by the substrate. The grain-size effect on polarization switching is explainedby taking into account this tensile stress, which is thought to induce some a-domain orientation and 90° domain wall clamping in the grains attached to the substrate.

Structural, Dielectric and Pyroelectric properties of Lanthanum modified Lead Titanate Thin Films

2004 ◽  
Vol 811 ◽  
Author(s):  
Sonalee Chopra ◽  
Seema Sharma ◽  
T.C. Goel ◽  
R.G. Mendiratta
Keyword(s):  
Thin Films ◽  
Lead Titanate ◽  
Mechanical Stability ◽  
Perovskite Phase ◽  
Ferroelectric Properties ◽  
Sol Gel ◽  
Microstructural Analysis ◽  
Pyroelectric Coefficient ◽  
Structural Investigations ◽  
Glass Substrates

ABSTRACTFerroelectric lead lanthanum titanate (Pb1−xLaxTi1−x/4O3) (PLTx) thin films (x=0.04,0.08 and 0.12) have been prepared by sol-gel spin coating process on ITO coated 7059 Corning glass substrates. Investigations have been made on the crystal structure, surface morphology, dielectric and ferroelectric properties of the thin films. For a better understanding of the crystallization mechanism, the structural investigations were carried out at various annealing temperatures (350°C, 450°C, 550°C and 650°C). Characterization of these films by X-ray diffraction shows that the films annealed at 650°C exhibit tetragonal structure with perovskite phase. Replacement of lanthanum in lead titanate results in reduction of tetragonal ratio (c/a), resulting in better mechanical stability. Microstructural analysis of the films are carried out by taking the Atomic Force Microscope (AFM) pictures. AFM images are characterized by slight surface roughness with a uniform crack free, densely packed structure. Dielectric, pyroelectric and ferroelectric studies carried out on these films have been reported. Dielectric constant and pyroelectric coefficient increase while Curie temperature decreases with increase in La content. The pyroelectric figures of merit of the films have also been calculated which suggest that 8% lanthanum is best suited material for pyroelectric detectors owing to its high pyroelectric coefficient (∼ 29nC/cm2 K), high voltage responsivity (∼420Vcm2/J), high detectivity (∼1.04×10−5Pa−1/2) and low variation of pyrocoefficient with temperature.

Powder diffraction study of Pd2HgSe3

2017 ◽  
Vol 32 (4) ◽  
pp. 244-248 ◽  
Author(s):  
F. Laufek ◽  
A. Vymazalová ◽  
M. Drábek
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Silica Glass ◽  
Rietveld Method ◽  
Glass Tube ◽  
Layered Crystal ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Layered Crystal Structure ◽  
Silica Glass Tube

The Pd2HgSe3 phase was synthetized from individual elements by the silica glass tube technique and its crystal structure has been refined by the Rietveld method. The Pd2HgSe3 phase crystalizes in P$\bar 3$m1 space group with the unit-cell parameters a = 7.3096(2) Å, c = 5.2829(1) Å, V = 244.45(1) Å3, Dc = 8.84 g/cm3, and Z = 2. In its layered crystal structure, the [PdSe6] octahedra share opposing Se–Se edges with adjacent [PdSe4] squares forming layers parallel with the (001) plane. The layers show AA type stacking along the c-axis. Hg atoms occupy the anti-cubooctahedral voids between two consecutive layers. Pd2HgSe3 is isostructural with Pt2HgSe3 and Pt4Tl2X6 (X = S, Se, or Te) phases. The structure can be viewed as a 2a.2a.c superstructure of PtSe2.

Fine Nanophased ZnO:Ru and ZnO:Pt Powder Synthesis through Aerosols

2005 ◽  
Vol 494 ◽  
pp. 149-154 ◽  
Author(s):  
Lydia Mančić ◽  
S. Grgurić-Šipka ◽  
V.M. Djinović ◽  
Z. Marinković ◽  
T. Sabo ◽  
...  
Keyword(s):  
Metal Ions ◽  
Noble Metal ◽  
Structural Changes ◽  
Ultrasonic Spray Pyrolysis ◽  
Precursor Chemistry ◽  
Homogeneous Distribution ◽  
Particle Structure ◽  
Powder Synthesis ◽  
Cell Parameters ◽  
Doped Zno

Pt/Ru-doped ZnO nanophase particles were synthesized using ultrasonic spray pyrolysis. Particles were obtained through decomposition of zinc nitrate and newly developed Pt(IV) and Ru(III) complexes. The particle morphology, phase composition and chemical structure were revealed in accordance to various analysis methods (XRD, DSC, SEM/EDS, TEM) and discussed in terms of precursor chemistry and process parameters. The shape of DSC curves, indicating two exothermic effects above 6000C in both ZnO:Ru and ZnO:Pt, gave an indication of irreversible structural changes and high reactivity of as-prepared powders. The hexagonal wurtzite-type ZnO phase was revealed in both powdered samples. Small content of an intermediate Zn5(NO3)2(OH)8·2H2O and cubic Zn2PtO4 phase were detected in the Pt-doped ZnO particles. Structural refinements, performed by Koalariet-XFit, suggest the composite internal particle structure composed of primary particles sized less than 100 nm. The estimated values for the unit cell parameters and Zn-O bond lengths imply noble metal ions incorporation into ZnO matrix interstitially, probably in octahedral interstitial environment. It has been shown that different particle growing morphologies (either spheroidally or pyramidally shaped) were influenced by the precursor chemistry, processing parameters and the presence of noble metal ions. Among the many parameters, attaining of the particle shape uniformity and homogeneous distribution of the noble metal cations in as-prepared particles are regarded as the most important factors for dominating microstructure evolution.

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