scholarly journals Giant anisotropic thermal expansion actuated by thermodynamically assisted reorientation of imidazoliums in a single crystal

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Zi-Shuo Yao ◽  
Hanxi Guan ◽  
Yoshihito Shiota ◽  
Chun-Ting He ◽  
Xiao-Lei Wang ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Single Crystal ◽  
Molecular Motion ◽  
Bulk Material ◽  
Shape Change ◽  
Variable Temperature ◽  
Negative Thermal Expansion ◽  
Formidable Challenge ◽  
Potential Applications ◽  
Molecular Cations

Abstract Materials demonstrating unusual large positive and negative thermal expansion are fascinating for their potential applications as high-precision microscale actuators and thermal expansion compensators for normal solids. However, manipulating molecular motion to execute huge thermal expansion of materials remains a formidable challenge. Here, we report a single-crystal Cu(II) complex exhibiting giant thermal expansion actuated by collective reorientation of imidazoliums. The circular molecular cations, which are rotationally disordered at a high temperature and statically ordered at a low temperature, demonstrate significant reorientation in the molecular planes. Such atypical molecular motion, revealed by variable-temperature single crystal X-ray diffraction and solid-state NMR analyses, drives an exceptionally large positive thermal expansion and a negative thermal expansion in a perpendicular direction of the crystal. The consequent large shape change (~10%) of bulk material, with remarkable durability, suggests that this complex is a strong candidate as a microscale thermal actuating material.

Uniaxial negative thermal expansion induced by moiety twisting in an organic crystal

CrystEngComm ◽  
2018 ◽  
Vol 20 (35) ◽  
pp. 5123-5126 ◽  
Author(s):  
Dinabandhu Das ◽  
Leonard J. Barbour
Keyword(s):  
Thermal Expansion ◽  
Single Crystal ◽  
Diffraction Analysis ◽  
Variable Temperature ◽  
Negative Thermal Expansion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Anomalous Thermal Expansion ◽  
Increasing Temperature ◽  
Packing Analysis

Anomalous thermal expansion of a new diyn-diol molecule was studied by means of variable-temperature single-crystal X-ray diffraction. Analysis of the unit cell axes as a function of temperature shows that the material experiences uniaxial negative thermal expansion. Packing analysis of the crystal structures reveals twisting of the cyclopentyl moiety relative to the diyne spine with increasing temperature.

Variable-Temperature Microcrystal X-ray Diffraction Studies of Negative Thermal Expansion in the Pure Silica Zeolite IFR

2001 ◽  
Vol 123 (23) ◽  
pp. 5453-5459 ◽  
Author(s):  
Luis A. Villaescusa ◽  
Philip Lightfoot ◽  
Simon J. Teat ◽  
Russell E. Morris
Keyword(s):  
Thermal Expansion ◽  
Variable Temperature ◽  
Negative Thermal Expansion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pure Silica

Study on Synthesis and Properties of the Hafnium Tungstate by CO2 Laser

2010 ◽  
Vol 154-155 ◽  
pp. 467-470
Author(s):  
Jun Ping Wang ◽  
Qing Dong Chen ◽  
Er Jun Liang
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Raman Spectra ◽  
Co2 Laser ◽  
Wide Temperature Range ◽  
Negative Thermal Expansion ◽  
Cubic Phase ◽  
Unusual Property ◽  
Potential Applications ◽  
Nano Rods

The crystal structure of hafnium tungstate displays unusual property of isotropic negative thermal expansion in a wide temperature range which brings about a number of important potential applications. In this work, densely packed hafnium tungstate blocks are rapid synthesized by CO2 laser. The result of XRD and Raman spectra show that the samples contain single cubic phase of α-HfW2O8 with space group P213. The SEM observations show that the sample is composed of nano-rods which grow horizontally on the surface and in the interior. The nano-threads in the interior are composed of densely packed nano-crystallites.

Infrared lattice dynamics in negative thermal expansion material in single-crystal ScF3

2019 ◽  
Vol 32 (3) ◽  
pp. 035403
Author(s):  
Sahan U Handunkanda ◽  
Erin B Curry ◽  
Vladimir Voronov ◽  
Jason N Hancock
Keyword(s):  
Thermal Expansion ◽  
Single Crystal ◽  
Lattice Dynamics ◽  
Negative Thermal Expansion

Designing Microstructural Architectures With Thermally Actuated Properties Using Freedom, Actuation, and Constraint Topologies

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Jonathan B. Hopkins ◽  
Kyle J. Lange ◽  
Christopher M. Spadaccini
Keyword(s):  
Thermal Expansion ◽  
Bulk Material ◽  
Negative Thermal Expansion ◽  
Element Analysis ◽  
Thermal Expansion Coefficients ◽  
Design Requirements ◽  
Expansion Coefficients ◽  
Thermally Actuated ◽  
Constraint Topologies

In this paper, we demonstrate how the principles of the freedom, actuation, and constraint topologies (FACT) approach may be applied to the synthesis, analysis, and optimization of microstructural architectures that possess extreme or unusual thermal expansion properties (e.g., zero or large negative-thermal expansion coefficients). FACT provides designers with a comprehensive library of geometric shapes, which may be used to visualize the regions wherein various microstructural elements can be placed for achieving desired bulk material properties. In this way, designers can rapidly consider and compare a multiplicity of microstructural concepts that satisfy the desired design requirements before selecting the final concept. A complementary analytical tool is also provided to help designers rapidly calculate and optimize the desired thermal properties of the microstructural concepts that are generated using FACT. As a case study, this tool is used to calculate the negative-thermal expansion coefficient of a microstructural architecture synthesized using FACT. The result of this calculation is verified using a finite element analysis (FEA) package called ale3d.

scholarly journals Thorough investigation on the high-temperature polymorphism of dipentyl-perylenediimide: thermal expansion vs polymorphic transition.

2021 ◽  
Author(s):  
Francesco Marin ◽  
Serena Tombolesi ◽  
Tommaso Salzillo ◽  
Omer Yaffe ◽  
Lucia Maini
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Solid State ◽  
Thermal Behaviour ◽  
Variable Temperature ◽  
Negative Thermal Expansion ◽  
Thermal Characterization ◽  
Polymorphic Transition ◽  
State Transitions ◽  
Scanning Calorimetry

N,N’-dipentyl-3,4,9,10-perylendiimide (PDI-C5) is an organic semiconducting material which has been extensively investigated as model compound for its optoelectronic properties. It is known to be highly thermally stable, that it exhibits solid-state transitions with temperature and that thermal treatments lead to an improvement in its performance in devices. Here we report a full thermal characterization of PDI-C5 by combination of differential scanning calorimetry, variable temperature X-ray diffraction, hot stage microscopy, and variable temperature Raman spectroscopy. We identified two high temperature polymorphs, form II and form III, which form respectively at 112 °C and at 221 °C and we determined their crystal structure from powder data. Form II is completely reversible upon cooling with low hysteresis, while form III revealed a different thermal behaviour upon cooling depending on the technique and crystal size. The crystal structure’s features of the different polymorphs are discussed and compared, and we looked into the role of the perylene core and alkyl chains during solid-state transitions. The thermal expansion principal axis of PDI-C5 crystal forms is reported showing that all the reported forms possess negative thermal expansion (X1) and large positive thermal expansion (X3) which are correlated to thermal behaviour observed.

Polymorphism in the negative thermal expansion material magnesium hafnium tungstate

2008 ◽  
Vol 23 (1) ◽  
pp. 210-213 ◽  
Author(s):  
Amy M. Gindhart ◽  
Cora Lind ◽  
Mark Green
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Variable Temperature ◽  
Negative Thermal Expansion ◽  
Orthorhombic Phase ◽  
High Energy ◽  
X Ray Diffraction ◽  
Space Group ◽  
Smooth Change ◽  
Energy Ball

Magnesium hafnium tungstate [MgHf(WO4)3] was synthesized by high-energy ball milling followed by calcination. The material was characterized by variable- temperature neutron and x-ray diffraction. It crystallized in space group P21/a below 400 K and transformed to an orthorhombic structure at higher temperatures. The orthorhombic polymorph adopted space group Pnma, instead of the Pnca structure commonly observed for other A2(MO4)3 materials (A = trivalent metal, M = Mo, W). In contrast, the monoclinic polymorphs appeared to be isostructural. Negative thermal expansion was observed in the orthorhombic phase with αa = −5.2 × 10−6 K−1, αb = 4.4 × 10−6 K−1, αc = −2.9 × 10−6 K−1, αV = −3.7 × 10−6 K−1, and αl = −1.2 × 10−6 K−1. The monoclinic to orthorhombic phase transition was accompanied by a smooth change in unit-cell volume, indicative of a second-order phase transition.

Sign in / Sign up

Export Citation Format

Share Document