Incorporation of Pb into the Crystal Structure of Ba6−3xNd8+2xTi18O54 Solid Solution

2000 ◽  
Vol 15 (8) ◽  
pp. 1735-1741 ◽  
Author(s):  
Mojca Podlipnik ◽  
Danilo Suvorov ◽  
Matjaz Valant ◽  
Drago Kolar
Keyword(s):  
Crystal Structure ◽  
Solid Solubility ◽  
Microwave Dielectric Properties ◽  
Solubility Limit ◽  
Nominal Composition ◽  
Secondary Phases ◽  
Q Value ◽  
X Ray Diffraction ◽  
Solid Solubility Limit ◽  
X Ray

Investigations of a substitutional mechanism of Pb incorporation into the crystal structure of Ba6−3xNd8+2xTi18O54 performed by x-ray diffraction analysis, scanning electron microscopy, and energy dispersive and wavelength dispersive x-ray spectroscopy revealed that Pb2+ substitutes for Ba2+ according to the formula (Ba1−zPbz)6−3xNd8+2xTi18O54. The solid solubility limit for 0.5 = x = 0.6 compositions was determined to be at 0.35 ≤ z < 0.4 (nominal composition) which, according to measurements of PbO loss occurring during the heat treatment, gives 0.30 ≤ z < 0.35 (analyses of matrix phase). Increasing the Pb2+ concentration in (Ba1−zPbz)4.5Nd9Ti18O54, results in tf decreasing from an initial positive value (80 ppm/K) to a negative value at the solid solubility limit (−25 ppm/K at z = 0.35). In the same concentration range the Q-value decreases from an initial 2000 to 1250 (z. = 0.35), measured at 4 GHz, while permittivity remains almost constant (k = 87 ± 1.5). After exceeding the solid solubility limit of Pb2+ in (Ba1−zPbz)4.5Nd9Ti18O54 the appearance of secondary phases (Nd4Ti9O24 and Pb-rich phase at grain boundaries) changes the trends of the microwave dielectric properties; permittivity decreases, Q-value remains almost constant, and Tf increases.

Effect of Li0.8Ca0.2F1.2 on Sintering and Microwave Dielectric Properties of (Mg0.95Zn0.05)(Ti0.8Sn0.2)O4 Ceramics

2013 ◽  
Vol 538 ◽  
pp. 266-269
Author(s):  
Guo Guang Yao ◽  
Hong Ma ◽  
Xiu Lao Tian
Keyword(s):  
Crystal Structure ◽  
Dielectric Properties ◽  
Liquid Phase ◽  
Microwave Dielectric Properties ◽  
Liquid Phase Sintering ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Dielectric

The effects of Li0.8Ca0.2F1.2 doped on the sinterability, phase constitutions and microwave dielectric properties of (Mg0.95Zn0.05)2(Ti0.8Sn0.2)O4 (MZTS) ceramics were investigated. The crystal structure was analyzed using X-ray diffraction. With 3.0 wt% Li0.8Ca0.2F1.2 addition, the densification sintering of MZTS ceramics was significantly lowed from 1325 oC to 1150 oC due to the liquid phase sintering. Secondary phases CaTiO3 and MgO were formed by reaction between MZTS and CaF2. 3.0wt% Li0.8Ca0.2F1.2-doped MZTS ceramics at 1150 oC for 5 h exhibited dielectric properties: εr=13.4, Qxf=46 672.3 GHz (at 9.3 GHz).

Structure Maps and Phase Stability in AlTi3 Alloyed with Rare-Earth Elements

1988 ◽  
Vol 133 ◽  
Author(s):  
C. T. Liu ◽  
J. A. Horton ◽  
D. G. Petitifor
Keyword(s):  
Crystal Structure ◽  
Rare Earth ◽  
Rare Earth Elements ◽  
Solubility Limit ◽  
Size Factor ◽  
X Ray Diffraction ◽  
Atomic Size ◽  
X Ray ◽  
Dependent Parameter ◽  
Rare Earth Additions

ABSTRACTRare-earth elements including Y, Er and Sc were added to AlTi3 for stabilizing the Ll2 ordered crystal structure, as predicted by the AB3 structure map. The crystal structure and phase composition in the AlTi3 alloys were studied by electron microprobe analysis, X-ray diffraction and TEM. The solubility limit of the rare-earth elements were determined and correlated with the atomic size factor. The results obtained so far indicate that rare-earth additions are unable to change the crystal structure of AlTi3 from DO19 to Ll2. The inability to stabilize the Ll2 structure demonstrates the need to characterize the structure map domains with a further period-dependent parameter.

Structures and microwave dielectric properties of Ba6−3x(Nd,Biy)8+2xTi18O54 (x = 2/3) solid solution

2001 ◽  
Vol 16 (6) ◽  
pp. 1734-1738 ◽  
Author(s):  
Yong Jun Wu ◽  
Xiang Ming Chen
Keyword(s):  
Solid Solution ◽  
Dielectric Properties ◽  
Resonant Frequency ◽  
Temperature Coefficient ◽  
Solid Solubility ◽  
Microwave Dielectric Properties ◽  
Solubility Limit ◽  
Solid Solubility Limit ◽  
Continuous Increase ◽  
Microwave Dielectric

The effects of Bi substitution for Nd in Ba6−3xNd8+2xTi18O54 (x = 2/3) solid solution upon the microstructures and microwave dielectric properties were investigated. The solid solubility limit of Bi in Ba6−3xNd8+2xTi18O54 (x = 2/3) solid solution was about 15 mol%, the same as that for x = 0.5, and densification of the present solid solutions could be performed well at lower temperatures. However, the variation tendency of microwave dielectric properties with composition in the present ceramics quite differed from that for x = 0.5: (1) The temperature coefficient of resonant frequency in the present ceramics showed a continuous variation from positive to negative and did not indicate extreme value at the solid solubility limit. (2) Near-zero temperature coefficient of resonant frequency combined with high-ε and high-Qf values could be obtained in the present ceramics, while that for x = 0.5 had a lower limit of +15 ppm/°C. (3) The dielectric constant also showed a continuous increase for the present compositions, while that in x = 0.5 had an extreme at solid solubility limit. Ceramics with composition of Ba6−3x(Nd0.85,Bi0.15)8+2xTi18O54 (x = 2/3) showed excellent dielectric properties of ε = 99.1, Qf = 5290 GHz, and τf = −5.5 ppm/°C.

Solubility of Mn in ZnO Crystallites Synthesized Using Solid State Techniques

2020 ◽  
Vol 3 (1) ◽  
pp. 28-39
Author(s):  
Esau Nii Abekah Akwetey Armah ◽  
Martin Egblewogbe ◽  
Hubert Azoda Koffi ◽  
Alfred Ato Yankson ◽  
Francis Kofi Ampong ◽  
...  
Keyword(s):  
Solid Phase ◽  
Solubility Limit ◽  
Phase Method ◽  
Regular Pattern ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
X Ray ◽  
Powder Samples ◽  
Solid Phase Method ◽  
Mn Concentration

Powder samples of Zn1-xMnxO nanocrystal were synthesized at a temperature of 200 °C using solid phase method. Dopant concentrations of 0.005 ≤ x ≤ 0.5 were studied. Powder x-ray diffraction (PXRD) patterns of the samples were analyzed with a view of determining the onset of secondary phases, hence the solubility limit of the dopant. The solubility limit for Mn in ZnO samples synthesized at 200 °C is realized at x < 0.3. With a regular pattern in increment of the Mn concentration, there were variations observed in the trend of the relative intensity, 2θ position and d-spacing indicating uneven addition of Mn (thus Mn2+, Mn3+ or Mn4+).

Thermodynamic Analysis of the Extension of Solid Solubility of the Cu-Cr System Processed by Mechanical Alloying

2011 ◽  
Vol 311-313 ◽  
pp. 392-395 ◽  
Author(s):  
Kun Yu Shi ◽  
Tao Shen ◽  
Li Hong Xue ◽  
Chun Hao Chen ◽  
You Wei Yan
Keyword(s):  
Mechanical Alloying ◽  
Thermodynamic Analysis ◽  
Solid Solubility ◽  
Structural Changes ◽  
Milling Time ◽  
Solubility Limit ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cr System

The nanocrystalline Cu-5wt.%Cr alloy powders were prepared by mechanical alloying. The structural changes were characterized by X-ray diffraction (XRD) technique. A thermodynamic analysis was carried out to predict the change in the solubility limit of this system. It was found that the energy resulting from the MA process is sufficient to increase the solid solubility of immiscible Cr-Cu system. The solid solubility may be extended up to 5 wt.% Cr in Cu after 20 h milling. The formation of the supersaturated solid solution leads to the decrease of Cu lattice parameter. However, it decomposes with the further increase of the milling time, which leads to the increase of Cu lattice parameter.

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.

Synthesis and structure stability of Ba2CuO3+δ under high pressure

2015 ◽  
Vol 29 (25n26) ◽  
pp. 1542024 ◽  
Author(s):  
W. M. Li ◽  
Q. Q. Liu ◽  
Y. Liu ◽  
S. M. Feng ◽  
X. C. Wang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Equation Of State ◽  
Room Temperature ◽  
Text Structure ◽  
Structure Stability ◽  
Nominal Composition ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
X Ray

The [Formula: see text] sample with the nominal composition was synthesized. Powder X-ray diffraction (XRD) experiments confirm that it crystallizes in an orthorhombic structure with space group Immm. The synchrotron powder XRD results suggest that the crystal structure of [Formula: see text] keeps stable under pressure up to 34 GPa at room temperature with nearly isotropic compressibility. The equation of state for [Formula: see text] was obtained. The results offer opportunities to further synthesize and research [Formula: see text] superconductor with tetragonal [Formula: see text] structure.

THE COPPER VALENCE STATE AND THE STRUCTURE OF Li, Ce, Eu, V-DOPED Y-Ba-Cu-O SYSTEM

1989 ◽  
Vol 03 (12) ◽  
pp. 955-960 ◽  
Author(s):  
J.B. ZHANG ◽  
L.F. QU ◽  
K.Y. HOU ◽  
D.L. YANG ◽  
D.J. CHEN ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Diffraction Analysis ◽  
Solid State Reaction ◽  
Valence State ◽  
Nominal Composition ◽  
Iodometric Titration ◽  
X Ray Diffraction ◽  
X Ray ◽  
Copper Valence

High-Tc superconductors with nominal composition of YBa 2 Cu 3 O y and Y 1−x L x Ba 2 Cu 3 O y ( L=Li , Ce, Eu, V) were synthesis by the solid state reaction of appropriate amount of Y 2 O 3, BaO or BaCO 3, Cu 2 O , CuO, and LO x. The Cu 3+/ Cu 2+ ratio was determined by Iodometric titration and oxygen content in the oxides calculated from the ratio. The crystal structure was determined by electron and powder X-ray diffraction analysis. It shows that that ratio of Cu 3+/ Cu 2+ and the crystal structure could be changed as dopping appropriate amount of metal in the Y-Ba-Cu-O system.

scholarly journals Change in lattice parameter of tantalum due to dissolved hydrogen

2012 ◽  
Vol 6 (2) ◽  
pp. 73-76 ◽  
Author(s):  
Manju Taxak ◽  
Sanjay Kumar ◽  
Nagaiyar Krishnamurthy ◽  
Ashok Suri ◽  
Gyanendra Tiwari
Keyword(s):  
Hydrogen Concentration ◽  
Constant Pressure ◽  
Solubility Limit ◽  
Lattice Parameter ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
Solid Solubility Limit ◽  
X Ray ◽  
Peak Broadening ◽  
Dissolved Hydrogen

The volume expansion of tantalum due to the dissolved hydrogen has been determined using Bragg equation. The hydrogen was dissolved in the pure tantalum metal at constant temperature (360?C) and constant pressure (132 mbar) by varying the duration of hydrogen charging. The amount of dissolved hydrogen was within the solid solubility limit. The samples with different hydrogen concentration were analyzed by X-ray diffraction technique. Slight peak shifts as well as peak broadening were observed. The relative changes of lattice parameters plotted against the hydrogen concentration revealed that the lattice parameters varied linearly with the hydrogen concentration.

Electron Microscopy/Diffraction Study of the Ternary Mn-Er-S System

1990 ◽  
Vol 48 (1) ◽  
pp. 76-77
Author(s):  
A. R. Landa Canovas ◽  
L.C. Otero Diaz ◽  
T. White ◽  
B.G. Hyde
Keyword(s):  
Electron Microscopy ◽  
Gas Flow ◽  
Graphite Crucible ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Alumina Crucible ◽  
X Ray ◽  
Intermediate Phases ◽  
Twin Band ◽  
Ar Gas

X-Ray diffraction revealed two intermediate phases in the system MnS+Er2S3,:MnEr2S4= MnS.Er2S3, and MnEr4S7= MnS.2Er2S3. Their structures may be described as NaCl type, chemically twinned at the unit cell level, and isostructural with CaTi2O4, and Y5S7 respectively; i.e. {l13} NaCl twin band widths are (4,4) and (4,3).The present study was to search for structurally-related (twinned B.) structures and or possible disorder, using the more sensitive and appropiate technigue of electron microscopy/diffraction.A sample with nominal composition MnEr2S4 was made by heating Mn3O4 and Er2O3 in a graphite crucible and a 5% H2S in Ar gas flow at 1500°C for 4 hours. A small amount of this material was thenannealed, in an alumina crucible, contained in sealed evacuated silica tube, for 24 days at 1100°C. Both samples were studied by X-ray powder diffraction, and in JEOL 2000 FX and 4000 EX microscopes.

Sign in / Sign up

Export Citation Format

Share Document