Symmetry-mode analysis of the phase transitions in SrLaZnRuO6and SrLaMgRuO6ordered double perovskites

2013 ◽  
Vol 46 (4) ◽  
pp. 1085-1093 ◽  
Author(s):  
E. Iturbe-Zabalo ◽  
J. M. Igartua ◽  
M. Gateshki
Keyword(s):  
Phase Transition ◽  
Structural Phase ◽  
Mode Analysis ◽  
Double Perovskites ◽  
Decomposition Approach ◽  
X Ray ◽  
First Order ◽  
Mode Decomposition ◽  
Two Phases ◽  
Symmetry Mode

The crystal structures of double perovskites SrLaMRuO6(M= Zn and Mg) have been studied using X-ray and neutron diffraction data. Both compounds have monoclinic structure at room temperature with space groupP21/n. A first-order structural phase transitionP21/n→R{\overline 3} has been observed in SrLaZnRuO6and SrLaMgRuO6, at about 800 and 500 K, respectively, with the two phases coexisting in a temperature interval of 150 K. The temperature- and tolerance-factor-dependent phase diagram of the SrLnMRuO6(Ln = La, Nd and Pr;M= Zn, Co, Cu, Mg and Ni) family shows two different phase transition sequences depending on theA-site cation. The structures of the title compounds at room and high temperatures have been analyzed using the symmetry-mode decomposition approach.

Structural phase transitions and magnetic and spectroscopic properties of the double perovskites Sr2Co1−xMgxTeO6 (x = 0.1, 0.2 and 0.5)

2015 ◽  
Vol 44 (30) ◽  
pp. 13716-13734 ◽  
Author(s):  
B. Orayech ◽  
L. Ortega-San-Martín ◽  
I. Urcelay-Olabarria ◽  
L. Lezama ◽  
T. Rojo ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Phase Transitions ◽  
Structural Phase ◽  
Spectroscopic Properties ◽  
Mode Analysis ◽  
Double Perovskites ◽  
Structural Phase Transitions ◽  
X Ray ◽  
Structural And Magnetic Properties ◽  
Symmetry Mode

Structural and magnetic properties of a series of double perovskites are investigated by X-ray and Neutron diffraction, EPR and magnetic susceptibility. The structural and phase-transitions analysis are done using symmetry mode-analysis approach.

Structure of the X-phase of 38% brominated betaine calcium chloride dihydrate

2001 ◽  
Vol 57 (3) ◽  
pp. 296-302
Author(s):  
L. G. Vieira ◽  
O. Hernandez ◽  
J. L. Ribeiro ◽  
A. Cousson ◽  
J.-M. Kiat ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Low Temperature ◽  
Neutron Diffraction ◽  
Calcium Chloride ◽  
Mode Analysis ◽  
Chloride Dihydrate ◽  
Two Phases ◽  
Calcium Chloride Dihydrate ◽  
Symmetry Mode

The structures of the high- and low-temperature phases of 38% brominated BCCD [betaine (trimethylammonioacetate) calcium chloride dihydrate], the latter being known as the X-phase, have been determined by single-crystal neutron diffraction at 295 and 20 K, respectively. The symmetry of the X-phase is described by the P212121 space group. The distortion with respect to the high-temperature Pnma phase is characterized by anti-symmetric displacements of the betaine molecules as well as of the Ca octahedra. On the basis of a symmetry-mode analysis, we propose an interpretation of the direct phase transition that occurs around 80 K between these two phases.

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.

Temperature-triggered order–disorder phase transition in molecular-ionic material N-butyldiethanolammonium picrate monohydrate

RSC Advances ◽  
2016 ◽  
Vol 6 (73) ◽  
pp. 69546-69550 ◽  
Author(s):  
Tariq Khan ◽  
Muhammad Adnan Asghar ◽  
Zhihua Sun ◽  
Chengmin Ji ◽  
Lina Li ◽  
...  
Keyword(s):  
Phase Transition ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Dielectric Materials ◽  
Disorder Phase Transition ◽  
First Order ◽  
Oxygen Atoms

We report an organic–ionic material that undergoes a first-order structural phase transition, induced by order–disorder of oxygen atoms in picrate anion. This strategy offers a potential pathway to explore new switchable dielectric materials.

The role of π-bonding on the high temperature structure of the double perovskites Ba2CaUO6and BaSrCaUO6

2015 ◽  
Vol 44 (36) ◽  
pp. 16036-16044 ◽  
Author(s):  
Emily Reynolds ◽  
Gordon J. Thorogood ◽  
Maxim Avdeev ◽  
Helen E. A. Brand ◽  
Qinfen Gu ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Neutron Diffraction ◽  
Temperature Structure ◽  
Double Perovskites ◽  
Phase Transition Behavior ◽  
X Ray ◽  
Progressive Loss ◽  
Octahedral Tilting

High temperature synchrotron X-ray and neutron diffraction powder diffraction studies of the uranium perovskites Ba2CaUO6and BaSrCaUO6reveal unusual phase transition behavior associated with the progressive loss of cooperative octahedral tilting.

Structural-phase transition in (Cu2Te)2−x(ZnTe)x at high temperature

2021 ◽  
pp. 2150113
Author(s):  
H. B. Gasimov ◽  
R. M. Rzayev
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
High Temperature ◽  
Single Crystals ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Range ◽  
Xrd Study ◽  
Xrd Method

Cu2Te single crystal was grown by the Bridgman method. X-ray diffraction (XRD) study of Cu2Te single crystals in the temperature range of 293–893 K was performed and possible phase transitions in the mentioned range of temperature have been investigated. (Cu2Te)[Formula: see text](ZnTe)[Formula: see text] single crystals also were grown with [Formula: see text], 0.05, 0.10 concentrations and structural properties of the obtained single crystals were investigated by the XRD method in the temperature range 293–893 K. Lattice parameters and possible phase transitions in the mention temperature range were determined for (Cu2Te)[Formula: see text](ZnTe)[Formula: see text] single crystals for [Formula: see text], 0.05, 0.10 concentrations.

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