The Hexagonal ↔ Orthorhombic Structural Phase Transition in Claringbullite, Cu4FCl(OH)6

2021 ◽  
Author(s):  
Mark D. Welch ◽  
Jens Najorka ◽  
Michael S. Rumsey ◽  
John Spratt
Keyword(s):  
Phase Transition ◽  
Data Storage ◽  
Structural Phase Transition ◽  
Structural Changes ◽  
Structural Phase ◽  
Magnetic Behavior ◽  
Orthorhombic Phase ◽  
New Mineral ◽  
Storage Devices ◽  
Definition Of

ABSTRACT Frustrated magnetic phases have been a perennial interest to theoreticians wishing to understand the energetics and behavior of quasi-chaotic systems at the quantum level. This behavior also has potentially wide applications to developing quantum data-storage devices. Several minerals are examples of such phases. Since the definition of herbertsmithite, Cu3ZnCl2(OH)6, as a new mineral in 2004 and the rapid realization of the significance of its structure as a frustrated antiferromagnetic phase with a triangular magnetic lattice, there has been intense study of its magnetic properties and those of synthetic compositional variants. In the past five years it has been recognized that the layered copper hydroxyhalides barlowite, Cu4BrF(OH)6, and claringbullite, Cu4FCl(OH)6, are also the parent structures of a family of kagome phases, as they also have triangular magnetic lattices. This paper concerns the structural behavior of claringbullite that is a precursor to the novel frustrated antiferromagnetic states that occur below 30 K in these minerals. The reversible hexagonal (P63/mmc) ↔ orthorhombic (Pnma or Cmcm) structural phase transition in barlowite at 200−270 K has been known for several years, but the details of the structural changes that occur through the transition have been largely unexplored, with the focus instead being on quantifying the low-temperature magnetic behavior of the orthorhombic phase. This paper reports the details of the structural phase transition in natural claringbullite at 100−293 K as studied by single-crystal X-ray diffraction. The transition temperature has been determined to lie between 270 and 293 K. The progressive disordering of Cu at the unusual trigonal prismatic Cu(OH)6 site on heating is quantified through the phase transition for the first time, and a methodology for refining this disorder is presented. Key changes in the behavior of Cu(OH)4Cl2 octahedra in claringbullite have been identified that suggest why the Pnma structure is likely stabilized over an alternative Cmcm structure. It is proposed that the presence of a non-centrosymmetric octahedron in the Pnma structure allows more effective structural relaxation during the phase transition than can be achieved by the Cmcm structure, which has only centrosymmetric octahedra.

Light-Induced Structural Phase Transition in Confining Gallium and Associated Gigantic Optical Nonlinearity

1998 ◽  
Vol 543 ◽  
Author(s):  
V. Albanis ◽  
S. Dhanjal ◽  
V. Emelyanov ◽  
P. Petropoulos ◽  
D. J. Richardson ◽  
...  
Keyword(s):  
Phase Transition ◽  
Structural Phase Transition ◽  
Metastable Phase ◽  
Structural Phase ◽  
Relaxation Times ◽  
Orthorhombic Phase ◽  
Optical Nonlinearity ◽  
Fused Silica ◽  
Intensity Threshold ◽  
Characteristic Features

AbstractWe report a light-induced, surface-assisted structural phase transition from a common orthorhombic phase of crystalline gallium (α-gallium) to a highly reflective, metastable phase of more ‘metallic’ nature. The transition has been observed at the interface of gallium with fused silica at temperatures just below the metal's bulk melting point and affects only several tens of gallium atomic layers. The transition is fully reversible and occurs on a nanosecond/microsecond time scale. The transition appears to show some characteristic features of a second order structural phase transition, including an increase of the transition relaxation times at the critical temperature (of approximately 30°C). The transition has no apparent optical intensity threshold, and is induced by radiation of very low intensity of only 10−4 − 10−5 W/μm2. The two gallium phases involved in the phase transition have significantly different dielectric properties which gives rise to a gigantic cubic optical nonlinearity, χ(3) ∼ 1 esu. The transition can be stimulated by light at any wavelength in the visible and the infrared ranges out to at least 1.55μm. The effect is therefore of great interest for applications requiring light by light control at milliwatt power levels.

scholarly journals Crystal structures of 2D coordination networks in [M(bbtr)3](ClO4)2(M=Mn, Cd)

2014 ◽  
Vol 70 (a1) ◽  
pp. C1361-C1361
Author(s):  
Joachim Kusz ◽  
Maria Nowak ◽  
Robert Bronisz ◽  
Grzegorz Szklarz
Keyword(s):  
Phase Transition ◽  
Structural Phase Transition ◽  
Structural Changes ◽  
Structural Phase ◽  
Cooling Mode ◽  
Structural Modifications ◽  
Polymeric Networks ◽  
Polymeric Layer ◽  
Higher Temperature

[Fe(bbtr)3](ClO4)2 (bbtr=1,4-di(1,2,3-triazol-1-yl)butane) represents a spin crossover (SCO) system where the first coordination sphere consists of 1,2,3-triazole rings coordinated by exodentate nitrogen atoms [1]. Iron(II) ion is linked to six other iron(II) ions by bbtr ligands. This creates two dimensional (2D) polymeric layers. SCO is abrupt, accompanied by hysteresis loop. In the cooling mode P-3 -> P-1 structural phase transition precedes SCO. The non-magnetic structural transformation is accompanied by reorganization of weak intermolecular interactions and shift of 2D layers with respect to each other. Surprisingly, an analog [Fe(bbtr)3](BF4)2, does not exhibit in cooling mode neither thermally SCO nor structural phase transition [2]. To clarify the role of structural phase transition on SCO we have performed structural modifications by exchanging the kind of anions and/or metal ions. An exchange of perchlorate on triflate anion involves deeper structural changes. A topology of the polymeric layer remains the same, but the SCO is shifted to higher temperature and structural phase transition is not observed. The studies of isostructural zinc(II) analogs confirmed the crucial role of anion in the occurrence of non-magnetic structural phase transition. The [Zn(bbtr)3](ClO4)2 exhibites P-3 -> P-1 structural phase transition which is not present in tetrafluoroborate analog [2]. We expand studies on other hexacoordinating metal(II) ions. Reactions between manganese(II) or cadmium(II) perchlorates and bbtr in acetonitrile lead to [M(bbtr)3](ClO4)2 (M=Mn, Cd) complexes. Single crystal X-ray diffraction studies revealed that both compounds create a 2D polymeric networks. The temperature dependence of lattice parameters for these complexes showed that, in contrast to [Fe(bbtr)3](ClO4)2 and [Zn(bbtr)3](ClO4)2 systems, the structural phase transition is not present. This work was funded by the Polish National Science Centre Grant No. DEC-2011/01/B/ST5/06311.

Structural Phase Transition of Multilayer VSe2

2020 ◽  
Vol 12 (22) ◽  
pp. 25143-25149 ◽  
Author(s):  
Dian Li ◽  
Xiong Wang ◽  
Chi-ming Kan ◽  
Daliang He ◽  
Zejun Li ◽  
...  
Keyword(s):  
Phase Transition ◽  
Structural Phase Transition ◽  
Structural Phase

scholarly journals Raman spectroscopy study of the behavior of the soft mode in a structural phase transition in the Pr3Sb5O12 crystal

2015 ◽  
Vol 57 (11) ◽  
pp. 2286-2289 ◽  
Author(s):  
A. S. Oreshonkov ◽  
A. K. Khodzhibaev ◽  
A. S. Krylov ◽  
M. F. Umarov ◽  
A. N. Vtyurin
Keyword(s):  
Phase Transition ◽  
Raman Spectroscopy ◽  
Structural Phase Transition ◽  
Soft Mode ◽  
Structural Phase ◽  
Spectroscopy Study

High-pressure structural phase transition and metallization in Ga2S3 under non-hydrostatic and hydrostatic conditions up to 36.4 GPa

2021 ◽  
Author(s):  
Linfei Yang ◽  
Jianjun Jiang ◽  
Lidong Dai ◽  
Haiying Hu ◽  
Meiling Hong ◽  
...  
Keyword(s):  
Phase Transition ◽  
Raman Spectroscopy ◽  
High Pressure ◽  
Structural Properties ◽  
Structural Phase Transition ◽  
First Principles ◽  
Theoretical Calculations ◽  
Structural Phase

The vibrational, electrical and structural properties of Ga2S3 were explored by Raman spectroscopy, EC measurements, HRTEM and First-principles theoretical calculations under different pressure environments up to 36.4 GPa.

scholarly journals Study of the structural phase transition in diamond (100) & (111) surfaces

Carbon Trends ◽  
2021 ◽  
Vol 3 ◽  
pp. 100033
Author(s):  
H. Gomez ◽  
M.N. Groves ◽  
M.R. Neupane
Keyword(s):  
Phase Transition ◽  
Structural Phase Transition ◽  
Structural Phase
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