Incommensurate Phase in β-ThBr4

Currat, R.; Bernard, L.; Delamoye, P.

doi:10.1016/b978-0-444-86970-8.50012-3

Cited by 13 publications

(12 citation statements)

References 34 publications

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“…In addition, an extinction parameter and an overall scale factor were also refined. The final parameters describing the static atomic displacement fields are in accordance with the estimates of Currat, Bernard & Delamoye (1986). The results obtained indicate that the refined value of ,~ll,2Br 0(~[2/2"n', --0.8) verifies almost exactly the theoretical prediction given in (5.6) (X~[.2/2rr = 2Oxa, r~ + rr = 0.884) if, as is normally expected, the effect of phase fluctuations overcomes that due to amplitude modes.…”

Section: Resultsmentioning

confidence: 75%

“…The high site symmetry of Th and Br atoms and the direction of the modulation wavevector simplifies its structural distortion. On the other hand, phase and amplitude branches have been clearly observed by inelastic neutron scattering (Bernard et al, 1983;Currat, Bernard & Delamoye, 1986).…”

Section: Introductionmentioning

confidence: 98%

“…Below this temperature, neutron diffraction measurements (Bernard et al, 1983;Currat, Bernard & Delamoye, 1986) show the presence of weak first-order satellites, which indicates a structural distortion with wavevector q = 0.32e*. No lock-in transition has been detected within the temperature range 95 to 1.5 K. Weak second-order satellites seemed to be observed at very low temperatures (Currat, Bernard & Delamoye, 1986) but they could not be accurately measured. This fact, together with the observed temperature independence of the wavevector (Currat, Bernard & Delamoye, 1986), implies that the static distortion remains almost sinusoidal even at temperatures far below 95 K.…”

Section: Introductionmentioning

confidence: 99%

“…No lock-in transition has been detected within the temperature range 95 to 1.5 K. Weak second-order satellites seemed to be observed at very low temperatures (Currat, Bernard & Delamoye, 1986) but they could not be accurately measured. This fact, together with the observed temperature independence of the wavevector (Currat, Bernard & Delamoye, 1986), implies that the static distortion remains almost sinusoidal even at temperatures far below 95 K.…”

Section: Introductionmentioning

confidence: 99%

“…In Table 2 the approximate values extracted from Fig. 5 of Currat, Bernard & Delamoye (1986) are also included for comparison.…”

Section: Nobs W R (%) Wr (%) S A/~rmentioning

confidence: 99%

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Phasons modulate the atomic Debye–Waller factors in incommensurate structures: experimental evidence in ThBr₄ at 55 K

Madariaga¹,

Pérez-Mato²,

Aramburu³

1993

Acta Crystallogr Sect B

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The incommensurate displacive structure of fl-ThBr4 at 55 K has been determined from a neutron diffraction data set including main reflections and firstorder satellites. The superspace group is DI4damdJr-s-f sl.Final agreement factors are 0.0193, 0.0186 and 0.045 for all, main and satellite reflections, respectively. It is shown that the effect of phasons on the atomic Debye-Waller factors can be quantified by two additional structural parameters: the modulus Br fill.2 and the phase Br XI1.2 of a second harmonic that spatially modulates the temperature factors of Br atoms. Results are in good agreement, within the resolution of the experimental data, with the theoretically expected value for Br X IL2. Crystal data for the average structure: Mr=551.65, tetragonal, 141/amd, a= 8.919(1), c=7.902(1) A, V=628.6(2) A 3, Z=4,

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Section: Resultsmentioning

confidence: 75%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…In Table 2 the approximate values extracted from Fig. 5 of Currat, Bernard & Delamoye (1986) are also included for comparison.…”

Section: Nobs W R (%) Wr (%) S A/~rmentioning

confidence: 99%

See 3 more Smart Citations

Phasons modulate the atomic Debye–Waller factors in incommensurate structures: experimental evidence in ThBr₄ at 55 K

Madariaga¹,

Pérez-Mato²,

Aramburu³

1993

Acta Crystallogr Sect B

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Vibrational study of crystal phase transitions in pyrrole (C₄H₅N) and C₄D₅N

Lautié¹,

Romain²

1990

J Raman Spectroscopy

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Infrared and Raman spectra of crystalline pyrrole and pyrrole-d5 were recorded in the range M O O 0 cm-'. The behaviour of internal and external modes was studied as a function of temperature between 200 and 5 K. Two phase transitions were observed at 67 and 30 K and their mechanism is discussed. For the incommensurate phase, between 67 and 30 K, the amplitude and phase modes were identified at about 20 and 10 cm-', respectively; for the first, a critical expownt of 030 was determined. No evidence of NH R hydrogen bond participation in the transitions has been detected.

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Experimental Results Related to the Normal-Incommensurate Phase Transition in A2MX4 Compounds

Quilichini

1987

NATO ASI Series

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Incommensurate Phase in β-ThBr4

Cited by 13 publications

References 34 publications

Phasons modulate the atomic Debye–Waller factors in incommensurate structures: experimental evidence in ThBr₄ at 55 K

Phasons modulate the atomic Debye–Waller factors in incommensurate structures: experimental evidence in ThBr₄ at 55 K

Vibrational study of crystal phase transitions in pyrrole (C₄H₅N) and C₄D₅N

Experimental Results Related to the Normal-Incommensurate Phase Transition in A2MX4 Compounds

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Incommensurate Phase in β-ThBr4

Cited by 13 publications

References 34 publications

Phasons modulate the atomic Debye–Waller factors in incommensurate structures: experimental evidence in ThBr4 at 55 K

Phasons modulate the atomic Debye–Waller factors in incommensurate structures: experimental evidence in ThBr4 at 55 K

Vibrational study of crystal phase transitions in pyrrole (C4H5N) and C4D5N

Experimental Results Related to the Normal-Incommensurate Phase Transition in A2MX4 Compounds

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Phasons modulate the atomic Debye–Waller factors in incommensurate structures: experimental evidence in ThBr₄ at 55 K

Phasons modulate the atomic Debye–Waller factors in incommensurate structures: experimental evidence in ThBr₄ at 55 K

Vibrational study of crystal phase transitions in pyrrole (C₄H₅N) and C₄D₅N