Phase transition in the extreme: a cubic-to-triclinic symmetry change in dielectrically switchable cyanide perovskites

2019 ◽  
Vol 48 (42) ◽  
pp. 15830-15840 ◽  
Author(s):  
Monika Trzebiatowska ◽  
Anna Gągor ◽  
Lucyna Macalik ◽  
Paulina Peksa ◽  
Adam Sieradzki
Keyword(s):  
Phase Transition ◽  
Organic Compounds ◽  
Three Dimensional ◽  
Triclinic Symmetry ◽  
Metal Organic ◽  
Symmetry Change

Two novel three-dimensional metal–organic compounds of formula FA2KM(CN)6, where M = Co, Fe and FA = formamidinium (CH(NH2)2+), have been found to crystallize in a perovskite-like architecture.

scholarly journals pH Dependent Sensitization of Europium in a Hydrogen Bonded Three-Dimensional Metal-Organic Compounds with (4966)2(4462)3 Topology: Luminescence Titration and Time-resolved Studies

2021 ◽  
Author(s):  
Sudip Kumar Mondal ◽  
Partha Mahata ◽  
Pooja Daga ◽  
Sayani Hui ◽  
Sourav Sarkar ◽  
...  
Keyword(s):  
Rare Earth ◽  
Organic Compound ◽  
Dicarboxylic Acid ◽  
Organic Compounds ◽  
Three Dimensional ◽  
Time Resolved ◽  
Hydrothermal Technique ◽  
Pyridine Dicarboxylic Acid ◽  
Metal Organic ◽  
Ph Dependent

A rare-earth-based metal-organic compound (MOC), [Y2(pydc)6(H2pip)3]·20H2O (pydc = 2,6-pyridine dicarboxylate, H2pip = diprotonated piperazine), (1), was prepared by hydrothermal technique using 2,6-pyridine dicarboxylic acid, piperazine, and Y(III) ions. Applying the...

Ni-doping induced phase transition and electron evolution in cobalt hexacyanoferrate as a stable cathode for sodium ion batteries

2020 ◽  
Author(s):  
Junjie Quan ◽  
Enze Xu ◽  
Hanwen Zhu ◽  
Yajing Chang ◽  
Yi Zhu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Energy Storage ◽  
Ion Channels ◽  
Three Dimensional ◽  
Sodium Ion ◽  
Energy Storage Materials ◽  
Sodium Ion Batteries ◽  
Ni Doping ◽  
Prussian Blue Analogues ◽  
Cobalt Hexacyanoferrate

Prussian blue analogues are potential competitive energy storage materials due to its diverse metal combinations and wide three-dimensional ion channels. Here, we prepared a new high crystalline monoclinic nickel doped...

Efficient chemosensors for toxic pollutants based on photoluminescent Zn(II) and Cd(II) metal-organic networks

2021 ◽  
Author(s):  
Luis David Rosales-Vazquez ◽  
Alejandro Dorazco-González ◽  
Victor Sanchez-Mendieta
Keyword(s):  
Optical Sensors ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Environmental Research ◽  
Toxic Pollutants ◽  
Sensitivity And Selectivity ◽  
Metal Organic ◽  
Analytical Tools ◽  
Organic Networks

Optical sensors with high sensitivity and selectivity, as important analytical tools for chemical and environmental research, can be accomplished by straightforward synthesis of luminescent one-, two- and three-dimensional Zn(II) and...

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.

scholarly journals Volatile Organic Compound Vapour Measurements Using a Localised Surface Plasmon Resonance Optical Fibre Sensor Decorated with a Metal-Organic Framework

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1420
Author(s):  
Chenyang He ◽  
Liangliang Liu ◽  
Sergiy Korposh ◽  
Ricardo Correia ◽  
Stephen P. Morgan
Keyword(s):  
Surface Plasmon Resonance ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Surface Plasmon ◽  
Optical Fibre ◽  
Plasmon Resonance ◽  
Metal Organic Framework ◽  
Volatile Organic ◽  
Metal Organic ◽  
Organic Framework

A tip-based fibreoptic localised surface plasmon resonance (LSPR) sensor is reported for the sensing of volatile organic compounds (VOCs). The sensor is developed by coating the tip of a multi-mode optical fibre with gold nanoparticles (size: 40 nm) via a chemisorption process and further functionalisation with the HKUST-1 metal–organic framework (MOF) via a layer-by-layer process. Sensors coated with different cycles of MOFs (40, 80 and 120) corresponding to different crystallisation processes are reported. There is no measurable response to all tested volatile organic compounds (acetone, ethanol and methanol) in the sensor with 40 coating cycles. However, sensors with 80 and 120 coating cycles show a significant redshift of resonance wavelength (up to ~9 nm) to all tested volatile organic compounds as a result of an increase in the local refractive index induced by VOC capture into the HKUST-1 thin film. Sensors gradually saturate as VOC concentration increases (up to 3.41%, 4.30% and 6.18% in acetone, ethanol and methanol measurement, respectively) and show a fully reversible response when the concentration decreases. The sensor with the thickest film exhibits slightly higher sensitivity than the sensor with a thinner film. The sensitivity of the 120-cycle-coated MOF sensor is 13.7 nm/% (R2 = 0.951) with a limit of detection (LoD) of 0.005% in the measurement of acetone, 15.5 nm/% (R2 = 0.996) with an LoD of 0.003% in the measurement of ethanol and 6.7 nm/% (R2 = 0.998) with an LoD of 0.011% in the measurement of methanol. The response and recovery times were calculated as 9.35 and 3.85 min for acetone; 5.35 and 2.12 min for ethanol; and 2.39 and 1.44 min for methanol. The humidity and temperature crosstalk of 120-cycle-coated MOF was measured as 0.5 ± 0.2 nm and 0.5 ± 0.1 nm in the humidity range of 50–75% relative humidity (RH) and temperature range of 20–25 °C, respectively.

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