Low-Temperature Oxygen Migration and Negative Thermal Expansion in ZrW2-xMoxO8

Evans, John S. O.; Hanson, P. A.; Ibberson, R. M.; Duan, Ning; Kameswari, and U.; Sleight, A.W.

doi:10.1021/ja0013428

Cited by 90 publications

(65 citation statements)

References 27 publications

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“…For example, a few flexible PCPs showed much larger thermal expansion than common solids because the open coordination frameworks are relatively flexible [4][5][6][7][8][9][10][11][12][13][14][15] . Whereas small positive thermal expansion (PTE, 0oao20 Â 10 À 6 K À 1 , a and b V for axial and volumetric thermal expansion coefficients, respectively) is an intrinsic property of common solids 16 , negative (NTE, ao0 K À 1 ) [17][18][19][20] , very large (|a|4100 Â 10 À 6 K À 1 ), tunable and other special thermal expansion behaviours are extremely rare and have received considerable theoretical and practical interest [21][22][23][24] , which may be rationally realized by PCPs.…”

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confidence: 99%

Direct visualization of a guest-triggered crystal deformation based on a flexible ultramicroporous framework

et al. 2013

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Host-guest composites may exhibit abnormal and/or controllable physical properties that are unavailable for traditional solids. However, it is still very difficult to control or visualize the occupancy and motion of the guest. Here we report a flexible ultramicroporous coordination polymer showing exceptional guest-responsive thermal-expansion properties. The vacant crystal exhibits constant and huge thermal expansion over a wide temperature range not only in vacuum but also in air, as its ultramicroporous channel excludes air adsorption even at 77 K. More interestingly, as demonstrated by single-crystal X-ray crystallography, molecular dynamic simulations and solid-state nuclear magnetic resonance, it selectively responds to the molecular rearrangement of N,N-dimethylformamide, leading to conformation reversion of the flexible ligand, which transfers these actions to deform the whole crystal lattice. These results illustrate that combination of ultramicroporous channel and flexible pore surface could be an effective strategy for the utilization of external physical and chemical stimuli.

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Direct visualization of a guest-triggered crystal deformation based on a flexible ultramicroporous framework

et al. 2013

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“…The observed profiles of the XRD patterns for the precursors were refined using the Rietveld method contained in the GSAS program [17] by fitting to tetragonal ZrMo 2 O 7 (OH) 2 (H 2 O) 2 [8] as the model. The refinement was started with lattice parameters and atomic coordinates assigned from the model.…”

Section: X-ray Crystallographic Equipment and Temperature Calibrationmentioning

confidence: 99%

“…The considerable interest in the study of cubic AM 2 O 8 (A = Zr, Hf; M = W, Mo) compounds, [1][2][3][4] as well as their solid solutions ZrMo 2-x W x O 8 , [5][6][7][8] has been fueled recently by their isotropic negative thermal expansion (NTE) over a very wide temperature range. These compounds are usually synthesized by dehydration of the corresponding hydrate precursors.…”

Section: Introductionmentioning

confidence: 99%

“…Typically, ZrMo 2 O 8 and ZrW 2 O 8 are obtained by dehydration of the precursors ZrMo 2 O 7 (OH) 2 (H 2 O) 2 [9] and ZrW 2 O 7 (OH) 2 (H 2 O) 2 , [10] respectively. The similarity in chemical and crystallographic properties between W VI and Mo VI suggests that the compounds ZrW 2 O 8 and ZrMo 2 O 8 should be isomorphic and readily form solid solutions. Solid solutions of ZrMo 2-x W x O 8 have indeed been synthesized and the properties of ZrMoWO 8 , including thermal expansion and oxygen migration at low temperature, have also been reported.…”

Section: Introductionmentioning

confidence: 99%

“…The similarity in chemical and crystallographic properties between W VI and Mo VI suggests that the compounds ZrW 2 O 8 and ZrMo 2 O 8 should be isomorphic and readily form solid solutions. Solid solutions of ZrMo 2-x W x O 8 have indeed been synthesized and the properties of ZrMoWO 8 , including thermal expansion and oxygen migration at low temperature, have also been reported. [11] However, conspicuous gaps are seen with respect to the temperature-dependent phase behaviors of solid solutions of different compositions.…”

Section: Introductionmentioning

confidence: 99%

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Phase Behaviors of the ZrMo_2–xW_xO₈(x= 0.2–2.0) System and the Preparation of an Mo‐Rich Cubic Phase

Huang

Xiao

et al. 2005

Eur J Inorg Chem

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The phase behaviors of ZrMo 2-x W x O 8 (x = 0.2 to 2.0) solid solutions have been studied systematically by variable-temperature X-ray diffraction (XRD) and differential scanning calorimetric (DSC) techniques. A low-temperature (LT) orthorhombic ZrMo 2-x W x O 8 (x = 0.2-2.0) phase is formed by dehydration of the precursors ZrMo 2-x W x O 7 (OH) 2 (H 2 O) 2 (x = 0.2-2.0) within a temperature range from 124 to 203°C. Among them, the orthorhombic ZrMo 2-x W x O 8 solid solutions are able to convert further into metastable cubic phases within an x-dependent temperature range from 502 to 552°C; the trigonal phases become dominant at higher temperature for Mo-rich solid solutions. However, no trigonal

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Thermoresponsive Inorganic Materials

Evans

2002

Encyclopedia of Smart Materials

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The effect of temperature on the vast majority of materials is well known—as materials are heated, they initially expand in volume before eventually melting, subliming, or decomposing. Thermal expansion is often viewed as a deleterious property. Thermal expansion can, however, also be put to good use. It has long been known that the walls of bowed buildings can be pulled back into shape by a cooling iron bar; steel tires can be shrink‐fitted onto the wheels of railway carriages. Although these examples represent a technologically useful response to the stimulus of increased (or decreased) temperature, they do not quite fall into the category of “smart.” However, the very simple concept of coupling together two materials, one that has a large and one a smaller coefficient of thermal expansion to produce a bimetallic strip can certainly be considered to create a smart composite body. Here, the strains induced by the higher expansion of one material cause the strip to bend as temperature is increased, leading to a simple temperature‐sensing/responsive device. The vast majority of materials known and used in technological applications have a positive coefficient of thermal expansion; the reasons for this behavior are discussed. Certain materials, however, display the opposite property and contract in volume when heated. These materials thus have a negative coefficient of thermal expansion, which has led to their somewhat confusing description as “negative thermal expansion” (NTE) materials. The properties of these materials and the origin of these effects form the main topic of this article. Materials that have this unusual thermoresponse have a number of important technological applications. Applications related to specific materials are discussed. The first major area of application is in producing composite bodies. By mixing normal materials with a negative thermal expansion phase, one can achieve a composite that has a precisely controlled positive, negative, or even zero coefficient of expansion. Second, certain of the materials discussed can be chemically doped to control their expansion properties. Thus, one can envisage a single material that could be adjusted to have zero overall expansion. Such materials are of use where repeated thermal shock might lead to mechanical failure (an everyday example is oven‐to‐table cookware) or in optical devices such as high precision mirrors where any thermal expansion might distort optical properties. Materials that have strong intrinsic thermal contraction are most likely to be used as compensators for the positive expansion of other phases. In “negative thermal expansion” materials considered in the remainder of this article, there will always be an underlying expansive component caused by vibrational modes that tend to increase bond distances. In certain circumstances, however, these modes may be dominated by other more exotic effects.

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Low-Temperature Oxygen Migration and Negative Thermal Expansion in ZrW₂_-_xMo_xO₈

Cited by 90 publications

References 27 publications

Direct visualization of a guest-triggered crystal deformation based on a flexible ultramicroporous framework

Direct visualization of a guest-triggered crystal deformation based on a flexible ultramicroporous framework

Phase Behaviors of the ZrMo_2–xW_xO₈(x= 0.2–2.0) System and the Preparation of an Mo‐Rich Cubic Phase

Thermoresponsive Inorganic Materials

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Low-Temperature Oxygen Migration and Negative Thermal Expansion in ZrW2-xMoxO8

Cited by 90 publications

References 27 publications

Direct visualization of a guest-triggered crystal deformation based on a flexible ultramicroporous framework

Direct visualization of a guest-triggered crystal deformation based on a flexible ultramicroporous framework

Phase Behaviors of the ZrMo2–xWxO8(x= 0.2–2.0) System and the Preparation of an Mo‐Rich Cubic Phase

Thermoresponsive Inorganic Materials

Contact Info

Product

Resources

About

Low-Temperature Oxygen Migration and Negative Thermal Expansion in ZrW₂_-_xMo_xO₈

Phase Behaviors of the ZrMo_2–xW_xO₈(x= 0.2–2.0) System and the Preparation of an Mo‐Rich Cubic Phase