Phase Transition and Ferroelectricity of Two Perovskite-Like Mn(II) Metal–Organic Frameworks Tuned by Phosphonium Cations and Dicyanamide Ligand

2021 ◽  
Author(s):  
Yu-Qing Wu ◽  
Jia-Yao Zhang ◽  
Xiang He ◽  
Zhao-Xi Wang ◽  
Hong-Ling Cai ◽  
...  
Keyword(s):  
Phase Transition ◽  
Metal Organic Frameworks ◽  
Metal Organic ◽  
Phosphonium Cations

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.

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.

Locking of phase transition in MOF ZIF-7: improved selectivity in mixed-matrix membranes for O2/N2 separation

2020 ◽  
Vol 7 (1) ◽  
pp. 223-228 ◽  
Author(s):  
Long Xiang ◽  
Donghui Liu ◽  
Hua Jin ◽  
Long-Wei Xu ◽  
Chongqing Wang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Metal Organic Frameworks ◽  
Gas Storage ◽  
Separation Process ◽  
Mixed Matrix Membranes ◽  
Mixed Matrix ◽  
Metal Organic ◽  
Extrusion Mechanism ◽  
Matrix Membranes

The framework flexibility of metal–organic frameworks (MOFs) is beneficial for gas storage and adsorption but is disadvantageous to the separation process based on the size-extrusion mechanism.

scholarly journals Influence of Co-adsorbates on CO2 induced phase transition in functionalized pillared-layered metal–organic frameworks

2016 ◽  
Vol 4 (33) ◽  
pp. 12963-12972 ◽  
Author(s):  
Andreas Schneemann ◽  
Yukiko Takahashi ◽  
Robin Rudolf ◽  
Shin-ichiro Noro ◽  
Roland A. Fischer
Keyword(s):  
Phase Transition ◽  
Gas Separation ◽  
Metal Organic Frameworks ◽  
Co Adsorption ◽  
Gas Mixtures ◽  
Metal Organic ◽  
Separation Behavior

Co-adsorption measurements reveal the flexible and gas separation behavior of functionalized pillared-layered MOFs when exposed to gas mixtures.

Pressure-induced isostructural phase transition of a metal–organic framework Co2(4,4′-bpy)3(NO3)4·xH2O

CrystEngComm ◽  
2014 ◽  
Vol 16 (20) ◽  
pp. 4084-4087 ◽  
Author(s):  
Mi Zhou ◽  
Kai Wang ◽  
Zhiwei Men ◽  
Chenglin Sun ◽  
Zhanlong Li ◽  
...  
Keyword(s):  
Phase Transition ◽  
Metal Organic Framework ◽  
Metal Organic Frameworks ◽  
Metal Organic ◽  
Organic Linker ◽  
Isostructural Phase Transition ◽  
Organic Framework

Based on the 4,4′-bipyridine organic linker, metal–organic frameworks of Co2(4,4′-bpy)3(NO3)4·xH2O (CB-MOF) have been prepared.

Structural phase transition in perovskite metal–formate frameworks: a Potts-type model with dipolar interactions

2016 ◽  
Vol 18 (27) ◽  
pp. 18528-18535 ◽  
Author(s):  
Mantas Šimėnas ◽  
Sergejus Balčiūnas ◽  
Mirosław Ma̧czka ◽  
Jūras Banys ◽  
Evaldas E. Tornau
Keyword(s):  
Phase Transition ◽  
Monte Carlo ◽  
Structural Phase ◽  
Metal Organic Frameworks ◽  
Monte Carlo Study ◽  
Type Model ◽  
Dipolar Interactions ◽  
Disorder Phase Transition ◽  
Metal Organic ◽  
Metal Formate

A Monte Carlo study of a statistical model describing the order–disorder phase transition in perovskite-based [(CH3)2NH2][M(HCOO)3] dense metal–organic frameworks.

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