Detailed Structural X-Ray Study of (Betaine Phosphate)1?x(Betaine Phosphite)x Compounds

Santos, Mónica; Andrade, L. C. R.; Costa, Μ. M. R.; Chaves, M. R.; Almeida, A.; Klöpperpieper, A.; Albers, J.

doi:10.1002/1521-3951(199702)199:2<351::aid-pssb351>3.0.co;2-d

Cited by 13 publications

(8 citation statements)

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“…The temperature dependence of the static dielectric permittivity of both crystals fits very well a quasionedimensional Ising model. So, the coupling between the dipoles within the chains is much stronger than that one between the dipoles in neighboring chains [4,7]. Antiferro electric order is established in BP at T c = 81 K [8] in such a way that the O-H···O bonds order ferroelec trically within the onedimensional chains whereas neighbouring chains are linked antiferroelectrically [5].…”

Section: Introductionmentioning

confidence: 81%

Crossover between ferroelectric order and dipolar glass disorder in betaine phosphate_0.06betaine phosphite_0.94mixed crystals

Banys¹,

Macutkevič²,

Klimm³

et al. 2015

Lith. J. Phys.

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The dielectric properties of mixed betaine phosphate 0.06 betaine phosphite 0.94 (BP 0.06 BPI 0.94 ) ferroelectric crystals were investigated in a wide frequency range from 20 Hz to 3 GHz. Although the dielectric anomaly is clearly observed close to the ferroelectric phase transition temperature T c = 121 K, the dielectric dispersion is very broad around and below this temperature. Temperature dependences of the dielectric strength, the mean relaxation frequency and the spontaneous polarization cannot be described together according to the Landau theory for ferroelectric phase transition with a single order parameter or according to the quasione-dimensional Ising model. The polarization shows a pronounced distribution in the ferroelectric phase and only a partial ordering of hydrogen atoms occurs down to the lowest temperatures. The unordered hydrogen atoms form a glassy phase and its formation is observed in dielectric spectra at very low temperatures. The proton freezing temperature was estimated.

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Section: Introductionmentioning

confidence: 81%

Crossover between ferroelectric order and dipolar glass disorder in betaine phosphate_0.06betaine phosphite_0.94mixed crystals

Banys¹,

Macutkevič²,

Klimm³

et al. 2015

Lith. J. Phys.

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“…The structures of the mixed systems of BP and BPI have been well documented by Santos et al [28]. The unit cell volumes of BP and BPI are 968 Å 3 and 948 Å 3 respectively.…”

Section: Earlier Studies Of Bp-bpi Systemsmentioning

confidence: 99%

NMR relaxation study of disorder in condensed matter – low temperature studies in the mixed system − BPI_(1−x)BP_x – transition from classical to quantum rotation

Ramanuja

Ramesh²,

Ramakrishna

2008

Molecular Physics

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1 H NMR spin-lattice relaxation time (T 1 ) studies have been carried out in the mixed system, betaine phosphitebetaine phosphate (BPI (1Àx) BP x ), to study the effects of disorder. The T 1 data in the temperature range 100 K to 4 K, at two Larmor frequencies 11.4 and 23.3 MHz, has been analysed following Lourens' model, which shows a gradual transition from classical reorientations to quantum tunnelling motions. At lower temperatures, (when thermal motions become too slow) differences (due to disorder) in the local environments of the reorienting groups result in a distribution in the activation energy (E a ) and the energy gap of the ground to the first excited torsional level (E 01 ). Below 50 K, the system moves into the quantum tunneling regime and the magnetisation recovery shows biexponential behaviour which is another signature of disorder. These results are compared with those of the parent compounds BP and BPI.

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“…The properties of betaine phosphate (BP), (CH 3 ) 3 NCH 2 COOH 3 PO 4 , betaine phosphite (BPI), (CH 3 ) 3 NCH 2 COOH 3 PO 3 and the respective deuterated compounds (DBP and DBPI), as well as the mixed crystal system DBP 1−x DBPI x , have been studied extensively during recent years using x-ray, dielectric [6][7][8][9][10][11][12][13] and magnetic resonance techniques [14][15][16][17]. Together with other ferroelectrics which also contain hydrogen bonds, these crystals are considered to be model substances for the study of the phase behaviour and of structural phase transitions.…”

Section: Introductionmentioning

confidence: 99%

A microscopic model for the concentration dependence of the antiferrodistortive phase transition in mixed betaine phosphate/phosphite crystals

Braeter

Totz

Michel

1999

J. Phys.: Condens. Matter

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The concentration dependence of the high temperature antiferrodistortive (afd) phase transition temperature TC in single crystals of the mixed crystal system betaine phosphate and betaine phosphite (BP1-xBPIx) is studied. New experimental data obtained by 2H nuclear magnetic resonance (NMR) spectroscopy on deuterated single crystals of this system confirm the nonlinear behaviour of TC(x), in particular the maximum at intermediate concentrations. A microscopic model is proposed which in extension of the treatment of a small defect concentration makes use of the virtual crystal approximation (VCA) to be applicable to the mixed crystal system DBP1-xDBPIx with finite concentrations x. By this means the experimentally observed behaviour of the afd phase transition temperature as a function of x is elucidated and the nonlinear behaviour of TC(x) is explained in agreement with the afd character of the transition.

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Detailed Structural X-Ray Study of (Betaine Phosphate)1?x(Betaine Phosphite)x Compounds

Cited by 13 publications

References 0 publications

Crossover between ferroelectric order and dipolar glass disorder in betaine phosphate_0.06betaine phosphite_0.94mixed crystals

Crossover between ferroelectric order and dipolar glass disorder in betaine phosphate_0.06betaine phosphite_0.94mixed crystals

NMR relaxation study of disorder in condensed matter – low temperature studies in the mixed system − BPI_(1−x)BP_x – transition from classical to quantum rotation

A microscopic model for the concentration dependence of the antiferrodistortive phase transition in mixed betaine phosphate/phosphite crystals

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Detailed Structural X-Ray Study of (Betaine Phosphate)1?x(Betaine Phosphite)x Compounds

Cited by 13 publications

References 0 publications

Crossover between ferroelectric order and dipolar glass disorder in betaine phosphate0.06betaine phosphite0.94mixed crystals

Crossover between ferroelectric order and dipolar glass disorder in betaine phosphate0.06betaine phosphite0.94mixed crystals

NMR relaxation study of disorder in condensed matter – low temperature studies in the mixed system − BPI(1−x)BPx – transition from classical to quantum rotation

A microscopic model for the concentration dependence of the antiferrodistortive phase transition in mixed betaine phosphate/phosphite crystals

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Crossover between ferroelectric order and dipolar glass disorder in betaine phosphate_0.06betaine phosphite_0.94mixed crystals

Crossover between ferroelectric order and dipolar glass disorder in betaine phosphate_0.06betaine phosphite_0.94mixed crystals

NMR relaxation study of disorder in condensed matter – low temperature studies in the mixed system − BPI_(1−x)BP_x – transition from classical to quantum rotation