Two novel metal–organic coordination polymers based on ligand 1,4-diazabicyclo[2.2.2]octane N,N′-dioxide with phase transition, and ferroelectric and dielectric properties

CrystEngComm ◽  
2017 ◽  
Vol 19 (39) ◽  
pp. 5907-5914 ◽  
Author(s):  
Lizhuang Chen ◽  
Qin Ji ◽  
Xingang Wang ◽  
Qijian Pan ◽  
Xingxing Cao ◽  
...  
Keyword(s):  
Phase Transition ◽  
Dielectric Properties ◽  
Low Temperature ◽  
Structural Phase Transition ◽  
Coordination Polymers ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Structural Phase ◽  
Metal Organic

The synthesis of two low-temperature structural phase transition compounds {[Ag3(dabcodo)(NO3)3]·H2O}n (1) and [Ca(Dabcodo)(H2O)4Cl2]n (2) are described. Compound 1 displayed ferroelectric–ferroelectric phase transition.

scholarly journals The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Đorđe Dangić ◽  
Olle Hellman ◽  
Stephen Fahy ◽  
Ivana Savić
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Phase Transitions ◽  
Thermoelectric Materials ◽  
Ferroelectric Phase Transition ◽  
Lattice Thermal Conductivity ◽  
Ferroelectric Phase ◽  
Structural Phase ◽  
High Symmetry ◽  
Structural Phase Transitions

AbstractThe proximity to structural phase transitions in IV-VI thermoelectric materials is one of the main reasons for their large phonon anharmonicity and intrinsically low lattice thermal conductivity κ. However, the κ of GeTe increases at the ferroelectric phase transition near 700 K. Using first-principles calculations with the temperature dependent effective potential method, we show that this rise in κ is the consequence of negative thermal expansion in the rhombohedral phase and increase in the phonon lifetimes in the high-symmetry phase. Strong anharmonicity near the phase transition induces non-Lorentzian shapes of the phonon power spectra. To account for these effects, we implement a method of calculating κ based on the Green-Kubo approach and find that the Boltzmann transport equation underestimates κ near the phase transition. Our findings elucidate the influence of structural phase transitions on κ and provide guidance for design of better thermoelectric materials.

scholarly journals Elastic Properties and Energy Loss Related to the Disorder–Order Ferroelectric Transitions in Multiferroic Metal–Organic Frameworks [NH4][Mg(HCOO)3] and [(CH3)2NH2][Mg(HCOO)3]

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3125
Author(s):  
Zhiying Zhang ◽  
Hongliang Yu ◽  
Xin Shen ◽  
Lei Sun ◽  
Shumin Yue ◽  
...  
Keyword(s):  
Phase Transition ◽  
Energy Loss ◽  
Elastic Properties ◽  
Ferroelectric Phase ◽  
Loss Modulus ◽  
Structural Phase ◽  
Metal Organic Frameworks ◽  
First Order ◽  
Metal Organic ◽  
Elastic Anomalies

Elastic properties are important mechanical properties which are dependent on the structure, and the coupling of ferroelasticity with ferroelectricity and ferromagnetism is vital for the development of multiferroic metal–organic frameworks (MOFs). The elastic properties and energy loss related to the disorder–order ferroelectric transition in [NH4][Mg(HCOO)3] and [(CH3)2NH2][Mg(HCOO)3] were investigated using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The DSC curves of [NH4][Mg(HCOO)3] and [(CH3)2NH2][Mg(HCOO)3] exhibited anomalies near 256 K and 264 K, respectively. The DMA results illustrated the minimum in the storage modulus and normalized storage modulus, and the maximum in the loss modulus, normalized loss modulus and loss factor near the ferroelectric transition temperatures of 256 K and 264 K, respectively. Much narrower peaks of loss modulus, normalized loss modulus and loss factor were observed in [(CH3)2NH2][Mg(HCOO)3] with the peak temperature independent of frequency, and the peak height was smaller at a higher frequency, indicating the features of first-order transition. Elastic anomalies and energy loss in [NH4][Mg(HCOO)3] near 256 K are due to the second-order paraelectric to ferroelectric phase transition triggered by the disorder–order transition of the ammonium cations and their displacement within the framework channels, accompanied by the structural phase transition from the non-polar hexagonal P6322 to polar hexagonal P63. Elastic anomalies and energy loss in [(CH3)2NH2][Mg(HCOO)3] near 264 K are due to the first-order paraelectric to ferroelectric phase transitions triggered by the disorder–order transitions of alkylammonium cations located in the framework cavities, accompanied by the structural phase transition from rhombohedral R3¯c to monoclinic Cc. The elastic anomalies in [NH4][Mg(HCOO)3] and [(CH3)2NH2][Mg(HCOO)3] showed strong coupling of ferroelasticity with ferroelectricity.

Low-Temperature Structure (T = 235 K) and Structural Phase Transition in [(C2H5)4N]2SnCl6

1987 ◽  
Vol 103 (1) ◽  
pp. 73-78 ◽  
Author(s):  
H. Ketata ◽  
M. H. Ben Ghozlen ◽  
A. Daoud ◽  
I. Pabst
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Temperature Structure

Structural phase transition at low temperature in La2−x Sr x CuO4 aroundx=0.12 under magnetic fields

1996 ◽  
Vol 46 (S3) ◽  
pp. 1237-1238 ◽  
Author(s):  
Takao Suzuki ◽  
Kaichiro Chiba ◽  
Takayuki Goto ◽  
Tetsuo Fukase
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Magnetic Fields ◽  
Structural Phase Transition ◽  
Structural Phase

Carbon dioxide induced structural phase transition in metal–organic frameworks CPO-27

CrystEngComm ◽  
2020 ◽  
Vol 22 (26) ◽  
pp. 4353-4358
Author(s):  
Breogán Pato-Doldán ◽  
Mali H. Rosnes ◽  
Dmitry Chernyshov ◽  
Pascal D. C. Dietzel
Keyword(s):  
Phase Transition ◽  
Carbon Dioxide ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Metal Organic Frameworks ◽  
Honeycomb Structure ◽  
Metal Organic

The framework of CO2 saturated CPO-27 is deformed below 110 K into a superstructure of the original honeycomb structure.

Effects of partial substitution on Tc and low-temperature structural phase transition in La2−xBaxCuO4

1991 ◽  
Vol 185-189 ◽  
pp. 791-792 ◽  
Author(s):  
Yoji Koike ◽  
Tsutomu Kawaguchi ◽  
Syoichi Hosoya ◽  
Naoki Watanabe ◽  
Takahashi Noji ◽  
...  
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Partial Substitution

Phase transition in metal–organic complex trans-PtCl2(PEt3)2 under pressure: insights into the molecular and crystal structure

CrystEngComm ◽  
2018 ◽  
Vol 20 (26) ◽  
pp. 3728-3740 ◽  
Author(s):  
Naini Bajaj ◽  
Himal Bhatt ◽  
K. K. Pandey ◽  
H. K. Poswal ◽  
A. Arya ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Hydrogen Bond ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Molecular And Crystal Structure ◽  
Supramolecular Architecture ◽  
Organic Complex ◽  
Metal Organic Complex ◽  
Metal Organic

Molecular reorientations result in structural phase transition in trans-PtCl2(PEt3)2 under pressure, leading to a hydrogen bond assisted supramolecular architecture.

Low temperature frustrated structural phase transition in single crystal La1.85Sr0.15CuO4

1995 ◽  
Vol 197 (5-6) ◽  
pp. 439-443 ◽  
Author(s):  
Z.J. Yang ◽  
M. Yewondwossen ◽  
R.A. Dunlap ◽  
D.J.W. Geldart ◽  
S.L. Yuan ◽  
...  
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Single Crystal ◽  
Structural Phase Transition ◽  
Structural Phase
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