Structural evolution of aqueous mercury sulphide precipitates: energy-dispersive X-ray diffraction studies

2010 ◽  
Vol 74 (1) ◽  
pp. 85-96 ◽  
Author(s):  
A. M. T. Bell ◽  
R. A. D. Pattrick ◽  
D. J. Vaughan
Keyword(s):  
High Temperature ◽  
Structural Evolution ◽  
Phase Changes ◽  
Energy Dispersive ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Synthetic Sample ◽  
X Ray ◽  
Higher Temperature ◽  
Aqueous Mercury

AbstractIn situ, high-temperature energy-dispersive X-ray powder diffraction (EDXRD) data have been collected on synthetic and a natural sample of mercury sulphide (HgS). These measurements were made between temperatures of 295 and 798 K. Synthetic samples of HgS were prepared by reaction between sulphide and mercury in aqueous solution. In a subsequently dried and aged synthetic HgS sample, heated in vacuo, there is a change from a poorly crystalline pseudocubic material into a well crystalline cubic material in the temperature region 583–623 K. At higher temperature (748 K), there is evidence for a partial phase transition to the high temperature hypercinnabar HgS structure. In a neoformed synthetic sample, heated in a sealed Ti container, the initial ‘pseudocubic’ metacinnabar phase partially transforms to a previously unknown phase (XHgS) in the temperature range 467–522 K. This phase disappears at 527 K, and the metacinnabar phase changes to a well crystalline cubic phase; cinnabar develops at 542 K. The proportion of cinnabar continues to increase up to 647 K. Both metacinnabar and cinnabar phases are retained on cooling. No phase transitions were observed for the natural cinnabar sample.

scholarly journals Thermal Behavior of Pyromorphite (Pb10(PO4)6Cl2): In Situ High Temperature Powder X-ray Diffraction Study

Crystals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1070
Author(s):  
Tingting Gu ◽  
Shan Qin ◽  
Xiang Wu
Keyword(s):  
High Temperature ◽  
Thermal Behavior ◽  
Elevated Temperatures ◽  
Lead Dioxide ◽  
Twist Angle ◽  
Structural Evolution ◽  
Phase Changes ◽  
Volume Data ◽  
X Ray Diffraction ◽  
X Ray

Pyromorphite is one of the important end member lead apatites that has potential applications in environment remediation. The thermal behavior of natural pyromorphite, Pb10(PO4)6Cl2, has been investigated up to 1373 K at room-pressure using a powder X-ray diffraction device equipped with a heating system. Pyromorphite experiences melting and decomposing at 1373 K into lead phosphate (Pb3(PO4)2), and lead dioxide (PbO2) with reaction with air. The fit of the temperature–volume data yields a linear volume expansion coefficient αV = 4.5 (±0.02) × 10−5 K−1. The linear expansion coefficients for lattice parameters present the anisotropic thermal expansibility, i.e., αa = (±0.06) × 10−5 K−1 and αc = 2.2 (±0.06) × 10−5 K−1. We looked into the crystal chemistry and proposed an expression to quantitatively evaluate the structural evolution of pyromorphite upon high temperature by calculating the twist angle of the Pb(1)O6 metaprism, which decreases at elevated temperatures. A distinct drop of the twist angle was observed at ~1100–1200 K, which might be a sign for the phase transition to a low symmetric subgroup. The variation of the twist angle is more sensitive than that of the unit cell; therefore, it can be applied to monitor the structural and phase changes of apatite group materials in general.

A Study of Phase Reactions in a Complex 4.5 Al–3.5 Ti–Ni Base Alloy

1960 ◽  
Vol 4 ◽  
pp. 233-243
Author(s):  
John F. Radavich ◽  
W. J. Boesch
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Structural Changes ◽  
Base Alloy ◽  
Phase Changes ◽  
X Ray Diffraction ◽  
High Temperature Alloy ◽  
X Ray ◽  
Nickel Base ◽  
Precipitated Phases

AbstractAn investigation of the phase changes in a complex aluminum-titanium-hardened nickel-base high-temperature alloy was carried out after solutioning at high temperatures and aging at lower temperatures. The physical distribution and size of the precipitated phases were studied by electron microscopy. X-ray diffraction and fluorescence analyses were carried out on chemically extracted residues. The results of the xtructure changes as well as correlation of some physical properties with the structural changes are presented.

Thermal structural stability of a multi-component olivine electrode for lithium ion batteries

CrystEngComm ◽  
2016 ◽  
Vol 18 (39) ◽  
pp. 7463-7470 ◽  
Author(s):  
Kyu-Young Park ◽  
Hyungsub Kim ◽  
Seongsu Lee ◽  
Jongsoon Kim ◽  
Jihyun Hong ◽  
...  
Keyword(s):  
High Temperature ◽  
Neutron Diffraction ◽  
Lithium Ion Batteries ◽  
Structural Stability ◽  
Cathode Materials ◽  
Structural Evolution ◽  
Lithium Ion ◽  
X Ray Diffraction ◽  
X Ray

In this paper, the structural evolution of Li(Mn1/3Fe1/3Co1/3)PO4, which is a promising multi-component olivine cathode materials, is investigated using combined in situ high-temperature X-ray diffraction and flux neutron diffraction analyses at various states of charge.

A furnace for the in situ study of the formation of inorganic solids at high temperature using time-resolved energy-dispersive x-ray diffraction

2000 ◽  
Vol 71 (11) ◽  
pp. 4177 ◽  
Author(s):  
Margret J. Geselbracht ◽  
Richard I. Walton ◽  
E. Sarah Cowell ◽  
Franck Millange ◽  
Dermot O’Hare
Keyword(s):  
High Temperature ◽  
Energy Dispersive ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Inorganic Solids ◽  
In Situ Study

scholarly journals X-Ray Diffraction Study of Oxygen-Conducting Compounds Ln2Mo2O9(Ln = La, Pr)

2014 ◽  
Vol 70 (a1) ◽  
pp. C48-C48
Author(s):  
Alexander Antipin ◽  
Olga Alekseeva ◽  
Natalya Sorokina ◽  
Alexandra Kuskova ◽  
Michail Presniakov ◽  
...  
Keyword(s):  
High Temperature ◽  
Single Crystals ◽  
Basic Research ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Oxide Systems ◽  
Transmission Microscopy ◽  
X Ray ◽  
Oxygen Conductivity ◽  
Oxygen Atoms

Lanthanum molibdate La2Mo2O9(LM) and the compounds on its basis (LAMOX) attract much attention because of the high oxygen conductivity (6x10-2Sm/cm), which were found by Lacorre group. LM has the first-order phase transition at about 5800C and two phases: low-temperature monoclinic α-phase (P21) and high-temperature β-phase (P213) [1]. In the present work single crystals Ln2Mo2O9(Ln = La, Pr) were obtained by spontaneous flux crystallization in the Ln2O3–MoO3oxide systems. The LM and PM single crystals are studied by precision X-ray diffraction and high-resolution transmission microscopy. A cubic cell with a = 7.155(1) and 7.155(1) Å was chosen for two LM samples (LM_I and LM_II, respectively). More than 90% (LM_I) and 60% (LM_II) of the reflections measured were indexed in this cell. The unit cell parameter of the PM compound is slightly shorter: a = 7.087(1) and 7.089(1) Å for the PM_I and PM_II samples, respectively. More than 90% of the reflections measured were indexed for both PM crystals. It was found that the LM_II crystal consists of two cubic components grown together; a ≍ 7.155 Å for both components. The crystal structures for two LM and two PM samples are determined in space group P213. It is found that La and Pr atoms, as well as Mo1 and O1 atoms, are located in the vicinity of 3-fold axes rather than on the axes like in the high-temperature cubic phase. In both structures, the O2 and O3 positions are partially occupied. The coexistence of different configurations of the Mo coordination environment facilitates the oxygen ion migration in the structure. Based on the X-ray data, activation energies of oxygen atoms are calculated and migration paths of oxygen ions in the structures are analyzed. The conductivity of PM crystals is close to that of LM crystals. Oxygen atoms O2 and O3 make main contributions to ion conductivity of LM and PM. This study was supported in part by part by the Russian Foundation for Basic Research (project no. 14-02-00531).

High-temperature single-crystal X-ray diffraction study of tetragonal and cubic perovskite-type PbTiO3phases

2016 ◽  
Vol 72 (3) ◽  
pp. 381-388 ◽  
Author(s):  
Akira Yoshiasa ◽  
Tomotaka Nakatani ◽  
Akihiko Nakatsuka ◽  
Maki Okube ◽  
Kazumasa Sugiyama ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Single Crystal ◽  
Diffraction Study ◽  
Relative Displacement ◽  
High Temperature Phase ◽  
Cubic Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray

A high-temperature single-crystal X-ray diffraction study of a synthetic PbTiO3perovskite was carried out over the wide temperature range 298–928 K. A transition from a tetragonal (P4mm) to a cubic (Pm \bar 3 m) phase has been revealed near 753 K. In the non-centrosymmetricP4mmsymmetry group, the difference in relative displacement between Pb and O along thec-axis is much larger than that between Ti and O. The Pb and Ti cations contribute sufficiently to polarization being shifted in the opposite direction compared with the shift of O atoms. Deviation from the linear changes in Debye–Waller factors and bonding distances in the tetragonal phases can be interpreted as a precursor phenomenon before the phase transition. Disturbance of the temperature factorUeqfor O is observed in the vicinity of the transition point, whileUeqvalues for Pb and Ti are continuously changing with increasing temperature. The O site includes the clear configurational disorder in the cubic phase. The polar local positional distortions remain in the cubic phase and are regarded as the cause of the paraelectricity. Estimated values of the Debye temperature ΘDfor Pb and Ti are 154 and 467 K in the tetragonal phase and decrease 22% in the high-temperature phase. Effective potentials for Pb and Ti change significantly and become soft after the phase transition.

scholarly journals Coefficients of Thermal Expansion of Al- and Y-Substituted NaSICON Solid Solution Na3+2xAlxYxZr2−2xSi2PO12

Batteries ◽  
2018 ◽  
Vol 4 (3) ◽  
pp. 33 ◽  
Author(s):  
Sahir Naqash ◽  
Marie-Theres Gerhards ◽  
Frank Tietz ◽  
Olivier Guillon
Keyword(s):  
Solid Solution ◽  
Thermal Expansion ◽  
High Temperature ◽  
Sodium Content ◽  
Phase Changes ◽  
Central Metal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sodium Batteries ◽  
The Difference

Because of an increasing interest in NaSICON materials as electrolyte materials in all-solid state sodium batteries, their thermal expansion was investigated in this study. The thermal expansion coefficient (CTE) of the Al and Y-substituted NaSICON compositions Na3+2xAlxYxZr2−2xSi2PO12 with 0 ≤ x ≤ 0.3 was obtained by dilatometry and compared to the CTE derived from the lattice parameters using high-temperature X-ray diffraction. The difference in CTE obtained from techniques, the influence of sodium content and central metal cation on CTE, as well as other observations such as phase changes are described and rationalized.

Phase Relations and Conductivity in Ba2 (In2. xMx)O5, System

1999 ◽  
Vol 575 ◽  
Author(s):  
Akihiko Yamaji ◽  
Kazuya Kawakami ◽  
Masahiro Arai ◽  
Tadaharu Adachi
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Transition Temperature ◽  
Ion Conductivity ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Changes ◽  
Element Doping ◽  
Mole Percentage

ABSTRACTThe high temperature cubic phase of Ba2 nr2O5 shows large ion conductivity. It is interestingto examine, if the cubic phase can be stabilized in the low temperature region (920 C) by making solid solution of another element. In the present study, we investigated the ion conductivity and the crystal structure of Ba2(In2-x.Mx)O5 system by substituting In site for element M such as Sc, Y, La, Ce, Nb, Ta etc. By substituting 3 mole % Nb for In, the transition temperature decreased by about 300 C. High temperature X-ray diffraction analysis shows the crystal structure changes from orthorhombic to cubic at this transition temperature. The effective elements which decreased the transition temperature were pentavalent or tetra valent elements such as Nb or Si ,Ce. The substitution In site for 20 mole percentage Nb stabilizes the cubic structure down to room temperature. Considering the transport number, the tetravalent element doping is very effective to stabilize the cubic phase of Ba2In2O5 without lose of excellent characteristic of pure Ba2ln2O5.

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