The influence of an order-disorder type structural phase transition on the isotope effect

A structural phase transition study of Ba2YCu3O6+x (x = 0 to 1) has been conducted on a series of 13 quenched samples. These samples were prepared from an orthorhombic material by annealing at temperatures from 400 to 1000 °C in air, followed by rapid quenching. All quenchings were performed by using a liquid-nitrogen-cooled copper cold well with a continuous flow of cooled helium gas. Various measurements including x-ray diffraction, thermogravimetric analysis, Meissner effect, and scanning electron microscopy were carried out in order to correlate the nature of the phase transition with erystallographic data, superconductivity, and annealing temperature. The phase transition from Ba2YCu3,O7 to Ba2YCu3O6 appears to involve two orthorhombic regions: region A with a <b ≈ c/3 below approximately 600 °C and region B with cell parameters of a < b < c/3 from & 600 to 708–720 °C. The transformation from orthorhombic to tetragonal takes place in the temperature range of 708–720 °C. This transition appears to be a second-order, order-disorder type.

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Stoructural science and various functions in hydorogen-bond materials. Geometric Isotope Effect and Structural Phase Transition.

Nihon Kessho Gakkaishi ◽

10.5940/jcrsj.40.10 ◽

1998 ◽

Vol 40 (1) ◽

pp. 10-18 ◽

Cited By ~ 1

Author(s):

Mizuhiko ICHIKAWA

Keyword(s):

Phase Transition ◽

Isotope Effect ◽

Structural Phase Transition ◽

Structural Phase

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Simple model of a structural phase transition of the order-disorder type

Physical Review B ◽

10.1103/physrevb.18.1446 ◽

1978 ◽

Vol 18 (3) ◽

pp. 1446-1454 ◽

Cited By ~ 4

Author(s):

K. R. Subbaswamy ◽

D. L. Mills

Keyword(s):

Phase Transition ◽

Simple Model ◽

Structural Phase Transition ◽

Structural Phase ◽

Disorder Type

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Dynamic Order-Disorder Transition in the S = ½ Kagome Antiferromagnets Barlowite and Claringbullite

10.26434/chemrxiv.7468070.v1 ◽

2018 ◽

Author(s):

Alyssa Henderson ◽

Lianyang Dong ◽

Sananda Biswas ◽

Hannah Revell ◽

Yan Xin ◽

...

Keyword(s):

Phase Transition ◽

Structural Phase Transition ◽

Density Functional ◽

Structural Phase ◽

Density Functional Theory Calculations ◽

Temperature Dependent ◽

Orthorhombic Space Group ◽

Functional Theory ◽

Dynamic Disorder ◽

Disorder Type

The nature of the structural phase transition in the quantum magnets barlowite, Cu4(OH)6FBr, and claringbullite, Cu4(OH)6FCl was investigated. These materials consist of parallel-stacked Cu2+ kagome layers, separated by planes that contain Cu2+ cations and halide anions. The structural transition is of an order-disorder type, where at ambient temperature the interlayer Cu2+ ions are disordered over three equivalent positions. In barlowite, the dynamic disorder becomes static as the temperature is decreased, resulting in a lowering of the overall symmetry from hexagonal P63/mmc to orthorhombic. The dynamic disorder in claringbullite persists to lower temperatures, with a transition to orthorhombic space group Pnma observed in some samples. Ab initio density functional theory calculations explain this temperature-dependent structural phase transition and provide additional insights regarding the differences between these two materials.

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Dynamic Order-Disorder Transition in the S = ½ Kagome Antiferromagnets Barlowite and Claringbullite

10.26434/chemrxiv.7468070 ◽

2018 ◽

Author(s):

Alyssa Henderson ◽

Lianyang Dong ◽

Sananda Biswas ◽

Hannah Revell ◽

Yan Xin ◽

...

Keyword(s):

Phase Transition ◽

Structural Phase Transition ◽

Density Functional ◽

Structural Phase ◽

Density Functional Theory Calculations ◽

Temperature Dependent ◽

Orthorhombic Space Group ◽

Functional Theory ◽

Dynamic Disorder ◽

Disorder Type

The nature of the structural phase transition in the quantum magnets barlowite, Cu4(OH)6FBr, and claringbullite, Cu4(OH)6FCl was investigated. These materials consist of parallel-stacked Cu2+ kagome layers, separated by planes that contain Cu2+ cations and halide anions. The structural transition is of an order-disorder type, where at ambient temperature the interlayer Cu2+ ions are disordered over three equivalent positions. In barlowite, the dynamic disorder becomes static as the temperature is decreased, resulting in a lowering of the overall symmetry from hexagonal P63/mmc to orthorhombic. The dynamic disorder in claringbullite persists to lower temperatures, with a transition to orthorhombic space group Pnma observed in some samples. Ab initio density functional theory calculations explain this temperature-dependent structural phase transition and provide additional insights regarding the differences between these two materials.

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