scholarly journals Crystallography relevant to Mars and Galilean icy moons: crystal behavior of kieserite-type monohydrate sulfates at extraterrestrial conditions down to 15 K

IUCrJ ◽  
2022 ◽  
Vol 9 (2) ◽  
Author(s):  
Manfred Wildner ◽  
Boris A. Zakharov ◽  
Nikita E. Bogdanov ◽  
Dominik Talla ◽  
Elena V. Boldyreva ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Structural Phase ◽  
Negative Thermal Expansion ◽  
Remote Sensing Data ◽  
X Ray Diffraction ◽  
Icy Moons ◽  
Expansion Behavior ◽  
Anisotropic Expansion ◽  
Structural Details ◽  
Celestial Bodies

Monohydrate sulfate kieserites (M 2+SO4·H2O) and their solid solutions are essential constituents on the surface of Mars and most likely also on Galilean icy moons in our solar system. Phase stabilities of end-member representatives (M 2+ = Mg, Fe, Co, Ni) have been examined crystallographically using single-crystal X-ray diffraction at 1 bar and temperatures down to 15 K, by means of applying open He cryojet techniques at in-house laboratory instrumentation. All four representative phases show a comparable, highly anisotropic thermal expansion behavior with a remarkable negative thermal expansion along the monoclinic b axis and a pronounced anisotropic expansion perpendicular to it. The lattice changes down to 15 K correspond to an `inverse thermal pressure' of approximately 0.7 GPa, which is far below the critical pressures of transition under hydrostatic compression (Pc ≥ 2.40 GPa). Consequently, no equivalent structural phase transition was observed for any compound, and neither dehydration nor rearrangements of the hydrogen bonding schemes have been observed. The M 2+SO4·H2O (M 2+ = Mg, Fe, Co, Ni) end-member phases preserve the kieserite-type C2/c symmetry; hydrogen bonds and other structural details were found to vary smoothly down to the lowest experimental temperature. These findings serve as an important basis for the assignment of sulfate-related signals in remote-sensing data obtained from orbiters at celestial bodies, as well as for thermodynamic considerations and modeling of properties of kieserite-type sulfate monohydrates relevant to extraterrestrial sulfate associations at very low temperatures.

Structural phase transition and negative thermal expansion in Cu1.8Zn0.2V2–x P x O7 solid solutions

2022 ◽  
Author(s):  
Koshi Takenaka ◽  
Masato Kano ◽  
Ryota Kasugai ◽  
Kohei Takada ◽  
Koki Eto ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Structural Phase ◽  
Negative Thermal Expansion ◽  
Peak Position ◽  
Crystallographic Analysis ◽  
Resin Matrix ◽  
Matrix Composites ◽  
X Ray Diffraction ◽  
Lower Dielectric Constant ◽  
Microstructural Effects

Abstract Negative thermal expansion (NTE) is exhibited over the entire x range for Cu1.8Zn0.2V2–xPxO7. In particular, dilatometric measurements using epoxy resin matrix composites containing the spray-dried powder demonstrated that the thermal expansion suppressive capability was almost unchanged for x≤0.1. With increasing x, the x-ray diffraction peak position moves systematically, but some peaks are extremely broad and/or asymmetric, suggesting disorder in the internal structure. The crystallographic analysis confirmed NTE enhancement by microstructural effects at least for x=0.2. Preliminary measurements suggest higher resistivity and lower dielectric constant than that of pure vanadate, which is suitable for application to electronic devices.

Research on the Al3+，V5+ Double Ionic Substitute Negative Thermal Expansion Compound Zr1-xAlxMoW1-yVyO8

2011 ◽  
Vol 689 ◽  
pp. 407-412
Author(s):  
Shao Hua Shen ◽  
Xian Zhi Qin ◽  
Shao Bin Xiang ◽  
Fu Heng Hao ◽  
Jing Tan ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Thermal Expansion Coefficients ◽  
Expansion Behavior ◽  
Potential Applications ◽  
Conductive Property ◽  
Co Precipitation ◽  
Electronic Microscope

The ZrW2O8 family of materials has been shown to display the unusual property of an isotropic bulk contraction in volume with the rising of temperature. They have a number of potential applications, for example, they would be widely used in composite material and solid electrolyte based on its characteristic of negative thermal expansion and ionic conductive property. In this paper, an Al3+，V5+ double substitute negative thermal expansion (NTE) solid solution Zr1-xAlxMoW1-yVyO8 was synthesized by co-precipitation method. The phase composition, the micromorphology and the thermal expansion coefficient were obtained by using X-ray diffraction (XRD), scanning electronic microscope (SEM) and thermal mechanical analyzer (TMA), respectively. The results show that the sample’s density rises with the increasing of the content of V5+, while, its porosity declines. The thermal expansion coefficients of the samples are between -3.0~4.0×10-6 K-1, it indicates that their negative thermal expansion behavior is a little lower than that of ZrMoWO8. And the experiment also shows that these samples have displayed a fine behavior of heat shock resistance.

Large negative thermal expansion and phase transition in (Pb1−xCax)TiO3 (0.30 ≤ x ≤ 0.45) ceramics

2005 ◽  
Vol 20 (2) ◽  
pp. 350-356 ◽  
Author(s):  
Amreesh Chandra ◽  
Dhananjai Pandey ◽  
M.D. Mathews ◽  
A.K. Tyagi
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Negative Thermal Expansion ◽  
Ferroelectric Ceramics ◽  
X Ray Diffraction ◽  
Thermal Expansion Behavior ◽  
X Ray ◽  
Expansion Behavior ◽  
Wide Range

High-temperature dilatometric studies on (Pb1−xCax)TiO3 (x = 0.35, 0.35, 0.40, 0.45) ferroelectric ceramics reveal negative thermal expansion for x ≤ 0.40. The negative thermal expansion coefficient for x = 0.30, as obtained by dilatometry and powder x-ray diffraction, were found to be −8.541 × 10−6 K−1 and −11 × 10−6 K−1, respectively, which are comparable to those of other well-known negative thermal expansion materials like ZrW2O8, NaZr2(PO4)3. Results of temperature-dependent x-ray diffraction studies are also presented to show that the large negative thermal expansion behavior for x = 0.30 persists in a very wide range of temperatures, 70–570 K. Ca2+ substitution reduces the value of the negative thermal expansion coefficient of pure PbTiO3 crystal, but it enables the preparation of strong sintered ceramic bodies. The negative thermal expansion behavior is shown to disappear above the ferroelectric Curie point and is restricted to only the tetragonal compositions of (Pb1−xCax)TiO3.

scholarly journals 2-D cyanides from square planar M(CN)4units (M(II) = Ni, Pd, Pt, Cu)

2014 ◽  
Vol 70 (a1) ◽  
pp. C865-C865
Author(s):  
Ann Chippindale ◽  
Simon Hibble ◽  
Elena Marelli
Keyword(s):  
Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Nearest Neighbour ◽  
X Ray Diffraction ◽  
Metal Cyanide ◽  
Expansion Behavior ◽  
Vertex Sharing ◽  
Square Planar ◽  
New Material ◽  
Stacking Disorder

The binary cyanide, Cu(CN)2, has never been synthesised. However, by using Ni(CN)42-as a structural synthon, copper(II) can be stabilised in a cyanide-only environment in CuNi(CN)4and in the solid-solution CuxNi1+x(CN)2(0 ≤ x < 1/4). The atomic structure of the layers in CuNi(CN)4and the stacking relationship between nearest-neighbour layers have been determined from total neutron diffraction studies at 10 and 300 K. The structure consists of flat layers of square-planar, ordered [Ni(CN)4] and [Cu(NC)4] units. (NB it is very unusual to find Cu(II) in a genuine square-planar environment within an extended solid). The layered structure of this new material is closely related to those of the Group 10 cyanides, Ni(CN)2, Pd(CN)2.xNH3and Pt(CN)2.xH2O, except that these are generated from vertex-sharing square-planar metal-cyanide units with head-to-tail disorder of the C≡N groups. The overall appearance of the powder X-ray diffraction pattern of CuNi(CN)4, including the unusual peak shapes of the observed Bragg reflections, has been successfully explained using models incorporating stacking disorder between next nearest neighbour layers. CuNi(CN)4forms less extended sheets than Ni(CN)2[1, 2], but larger sheets than those found in Pd(CN)2.xNH3and Pt(CN)2.xH2O, which are nanocrystalline [3]. CuNi(CN)4, like Ni(CN)2[1], shows interesting thermal expansion behavior i.e. intralayer negative thermal expansion (αa = -9.7 MK-1) and interlayer positive thermal expansion (αc = +89 MK-1). CuNi(CN)4forms as an anhydrous material from aqueous solution, unlike Ni(CN)2, which can form hydrates such as Ni(CN)2.nH2O (n = 3, 3/2, 2, 1). However, on investigating the Cu-Ni-CN phase diagram, it is found that nickel-rich compounds, CuxNi1+x(CN)2(0 ≤ x < 1/4), can be formed via hydrated phases, CuxNi1+x(CN)2.3H2O, and readily rehydrate. Attempts to form copper-rich phases results in partial reduction of Cu(II) with the formation of copper(I) cyanide, CuCN, in addition to CuNi(CN)4, suggesting that Cu(II) ions are stable in a cyanide environment only when connected to the nitrogen ends of bridging C≡N ligands. Hence the non existence of Cu(CN)2can now be explained.

Effect of Annealing Temperature and External Tensile Stress on Negative Thermal Expansion to Cold Rolled Ti–23Nb–0.7Ta–2Zr Alloy

2020 ◽  
Vol 12 (9) ◽  
pp. 1409-1412
Author(s):  
Jeong-Tae Moon ◽  
Tae-Hyun Nam
Keyword(s):  
Thermal Expansion ◽  
Annealing Temperature ◽  
Negative Thermal Expansion ◽  
Constant Load ◽  
External Stress ◽  
Expansion Rate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cold Rolled ◽  
The Difference

The effect of annealing temperature and external stress on the thermal expansion of a Ti–23Nb–0.7Ta–2Zr alloy were investigated by means of thermal expansion tests under constant load and X-ray diffraction (XRD). Negative thermal expansion (NTE), which is a shrinkage during heating, was observed in both a cold rolled and annealed specimens. The intensity of (200)β peak decreased while that of (211)β peak increased as the annealing temperature increased. The difference in expansion rate between 50 °C and 250 °C is found to decrease with an increasing annealing temperature from 600 °C to 800 °C, above which it kept almost constant. The expansion rate decreased as the applied stress increased.

Thermally boosted upconversion and downshifting luminescence in Sc2(MoO4)3:Yb/Er with two-dimensional negative thermal expansion

2021 ◽  
Author(s):  
Jinsheng Liao ◽  
Minghua Wang ◽  
Fulin Lin ◽  
Zhuo Han ◽  
Datao Tu ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Near Infrared ◽  
Negative Thermal Expansion ◽  
Thermal Quenching ◽  
Relative Sensitivity ◽  
Strong Temperature Dependence ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Higher Temperature

Abstract Lanthanide (Ln3+)-doped phosphors generally suffer from thermal quenching, in which their photoluminescence (PL) intensities decrease at the higher temperature. Herein, we report a class of unique two-dimensional negative-thermal-expansion phosphor of Sc2(MoO4)3:Yb/Er. By virtue of the reduced distances between sensitizers and emitters as well as confined energy migration with increasing the temperature, a 45-fold enhancement of green upconversion (UC) luminescence and a 450-fold enhancement of near-infrared downshifting (DS) luminescence of Er3+ are achieved from 25 to 500 ˚C. The thermally boosted UC and DS luminescence mechanism is systematically investigated through in situ temperature-dependent Raman spectroscopy, synchrotron X-ray diffraction and PL dynamics. Moreover, the luminescence lifetime of 4I11/2 of Er3+ in Sc2(MoO4)3:Yb/Er displays a strong temperature dependence, enabling ratiometric thermometry with the highest relative sensitivity of 13.4%/K at 298 K. These findings may gain a vital insight into the design of negative-thermal-expansion Ln3+-doped phosphors for versatile applications.

Structure and Thermal Expansion Behavior of Dy2-xGdxMo4O15 Solid Solution

2008 ◽  
Vol 368-372 ◽  
pp. 1665-1667
Author(s):  
M.M. Wu ◽  
X.L. Xiao ◽  
Y.Z. Cheng ◽  
J. Peng ◽  
D.F. Chen ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Thermal Expansion ◽  
Monoclinic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Behavior ◽  
Expansion Coefficients ◽  
Cell Volumes

A new series of solid solutions Dy2-xGdxMo4O15 (x = 0.0-0.9) were prepared. These compounds all crystallize in monoclinic structure with space group P21/c. The lattice parameters a, b, c and unit cell volumes V increase almost linearly with increasing gadolinium content. The intrinsic thermal expansion coefficients of Dy2-xGdxMo4O15 (x = 0.0 and 0.25) were obtained in the temperature range of 25 to 500°C with high-temperature X-ray diffraction. The correlation between thermal expansion and crystal structure was discussed.

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