ChemInform Abstract: Phase Transition and Negative Thermal Expansion in Orthorhombic Dy2W3O12.

The thermal expansion of a ceramic material in general leads to a positive thermal expansion coefficient (α). In the last decennium, several families of materials which exhibit negative thermal expansion, arising from a specific geometrical effect in their so-called open framework structures, have been discovered. Usually, this negative thermal expansion coefficient is small, anisotropic and the phenomena occur in a very small temperature interval. ZrW2O8 is an exception because of its large and isotropic negative thermal expansion coefficient (NTE) in a temperature range from 0.5K to 1050K. A cubic symmetry is found over the entire stability range with a phase transition from α-ZrW2O8 to β-ZrW2O8 near 430K. This phase transition is noticed by a change in α. The aqueous citrate-gel method is a suitable synthesis route for negative thermal expansion ceramics and will give a fine, pure and homogenous oxide mixture, well suitable for the preparation of ZrW2O8. The expansion coefficient of α–ZrW2O8 is -11 μm/m K whereas for the β- ZrW2O8 a value of -3 is obtained.

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Coupling between acoustic and soft transverse optical phonons leads to negative thermal expansion of GeTe near the ferroelectric phase transition

Physical Review B ◽

10.1103/physrevb.97.224106 ◽

2018 ◽

Vol 97 (22) ◽

Cited By ~ 8

Author(s):

Đorđe Dangić ◽

Aoife R. Murphy ◽

Éamonn D. Murray ◽

Stephen Fahy ◽

Ivana Savić

Keyword(s):

Phase Transition ◽

Thermal Expansion ◽

Ferroelectric Phase Transition ◽

Ferroelectric Phase ◽

Negative Thermal Expansion ◽

Transverse Optical ◽

Optical Phonons

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Phase transition and negative thermal expansion in A2(MoO4)3 system (A=Fe3+, Cr3+ and Al3+)

Journal of Alloys and Compounds ◽

10.1016/s0925-8388(01)02003-5 ◽

2002 ◽

Vol 339 (1-2) ◽

pp. 207-210 ◽

Cited By ~ 104

Author(s):

A.K. Tyagi ◽

S.N. Achary ◽

M.D. Mathews

Keyword(s):

Phase Transition ◽

Thermal Expansion ◽

Negative Thermal Expansion ◽

System A

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Phase transition temperature and negative thermal expansion of Sc-substituted In2(MoO4)3 ceramics

Journal of Materials Science ◽

10.1007/s10853-020-04441-9 ◽

2020 ◽

Vol 55 (14) ◽

pp. 5730-5740

Author(s):

Zhiping Zhang ◽

Yuenan Wang ◽

Weikang Sun ◽

Xiuyun Zhang ◽

Hongfei Liu ◽

...

Keyword(s):

Phase Transition ◽

Thermal Expansion ◽

Transition Temperature ◽

Phase Transition Temperature ◽

Negative Thermal Expansion

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Structure, phase transition and negative thermal expansion in ammoniated ZrW2O8

Inorganic Chemistry Frontiers ◽

10.1039/c5qi00292c ◽

2016 ◽

Vol 3 (6) ◽

pp. 856-860 ◽

Cited By ~ 13

Author(s):

Weigang Cao ◽

Qingzhen Huang ◽

Yangchun Rong ◽

You Wang ◽

Jinxia Deng ◽

...

Keyword(s):

Phase Transition ◽

Thermal Expansion ◽

Structural Changes ◽

Negative Thermal Expansion ◽

Structure Phase ◽

Structure Phase Transition

The local structural changes of ZrW2O8 after ammoniation treatment.

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Study of Negative Thermal Expansion and Shift in Phase Transition Temperature in Ti4+- and Sn4+-Substituted ZrW2O8Materials

Inorganic Chemistry ◽

10.1021/ic701660w ◽

2008 ◽

Vol 47 (2) ◽

pp. 736-741 ◽

Cited By ~ 9

Author(s):

Klaartje De Buysser ◽

Isabel Van Driessche ◽

Bart Vande Putte ◽

Paul Vanhee ◽

Joseph Schaubroeck ◽

...

Keyword(s):

Phase Transition ◽

Thermal Expansion ◽

Transition Temperature ◽

Phase Transition Temperature ◽

Negative Thermal Expansion

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Polymorphism in Ho2(MoO4)3

Powder Diffraction ◽

10.1017/s0885715613001176 ◽

2013 ◽

Vol 28 (S2) ◽

pp. S33-S40 ◽

Cited By ~ 4

Author(s):

C. González-Silgo ◽

C. Guzmán-Afonso ◽

V. M. Sánchez-Fajardo ◽

S. Acosta-Gutiérrez ◽

A. Sánchez-Soares ◽

...

Keyword(s):

Phase Transition ◽

Thermal Expansion ◽

Room Temperature ◽

Linear Expansion ◽

Negative Thermal Expansion ◽

Thermal Treatments ◽

Positive Coefficient ◽

X Ray ◽

Expansion Coefficients ◽

First Time

Two polymorphs of Holmium molybdate, known as β'-phase and γ-phase, were prepared by solid state reaction with different thermal treatments. These polycrystalline samples have been studied for the first time by X-ray thermodiffractometry from room temperature up to 1300 K. We found that the initial β'-phase undergoes a transition to a β-phase and then to a γ-phase. The γ (hydrated)-phase, turns to the γ (dehydrated)-phase and then to the β-phase. Each sequence involves a reversible and an irreversible phase transition for Ho2(MoO4)3. Both polymorphs have remarkable physical properties like nonlinear optics, ferroelectricity and negative thermal expansion. We have calculated the linear expansion coefficients of both phases. We have obtained a positive coefficient for the β'-phase and a negative one for the γ-phase. Moreover, we have made a comparison of the obtained coefficients with previous results for other rare earth molybdates.

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