Phase transitions in DyVO4 and DyAsO4

Kasten, A.

doi:10.1007/bf01321204

Cited by 32 publications

(18 citation statements)

References 49 publications

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“…Insets show the base temperature achievable with the respective setups and the average and maximum intensity on the image. (Gö bel & Will, 1972;Kasten, 1980). With the new setup the transition was seen to occur within the error of this temperature, verifying the calibration of the apparatus (see Section S1).…”

Section: Overviewsupporting

confidence: 65%

Reducing the background of ultra-low-temperature X-ray diffraction data through new methods and advanced materials

McMonagle

Probert

2019

J Appl Cryst

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New methods and advanced materials that significantly reduce the background when collecting single-crystal X-ray diffraction data at ultra-low temperatures using a closed-cycle helium refrigerator are presented here. These include a magnetically controlled internal beamstop and a separate internal collimator that together completely remove the scattering contribution to the background from the beryllium vacuum chamber. Additionally, a new radiation shield made from flexible graphite significantly reduces the background and maintains excellent thermal properties. In combination these improvements have led to a sixfold reduction in the average intensity and a 15-fold reduction in peak intensity of the background observed for diffraction experiments conducted with a closed-cycle helium refrigerator. Moreover, access to ultra-low base temperatures, 2.05 K, has been maintained. The design and implementation of these methods are discussed along with a case study of vitamin C to demonstrate the effectiveness of the improvements.

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Section: Overviewsupporting

confidence: 65%

Reducing the background of ultra-low-temperature X-ray diffraction data through new methods and advanced materials

McMonagle

Probert

2019

J Appl Cryst

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“…Comparing the different curves, it is striking that for x = 0.4 (and less distinct also for x = 0.3) the measured birefringence does not saturate for T+ 0. Effects of the magnetic phase transition, which is present in the mixed substances (see paper I) as well as in pure DyV04 [27], cannot account for the observed behaviour, as the cnange of the birefringence caused by the magnetic phase transition is very small even for pure DyVO, ( The birefringence in higher magnetic fields is characterised by a smearing-out of the curves for T = T,, which is increasing for growing concentration x (see also paper I, The measured curves are compared with calculations of the distortion eA in the compressible Ising model [28] modified with a distribution of pre-strains. For details of the calculations, see paper I.…”

Section: R: Distorted Crystals (X C 04)mentioning

confidence: 95%

Effect of Hydrostatic Pressure on Dielectric Behavior and Phase Transition in Ferroelectric Polymers

Yuki¹,

Ito²,

Koda³

et al. 1998

Jpn. J. Appl. Phys.

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Measuremcnts of the linear birefringence at different wavelengths A in the visible part of the spectrum are presented for the two orthorhombic phases of the mixed Jahn-Teller system (Tb, ,Dy, -, ) V 0 4 . These two phases have different crystal structures according to different distortion types of the pure substances. For low concentrations x , the crystals distort like DyVO,, and the measured curves are proportional to each other for different A. For high x , however, where the crystals distort like TbVO,. the measured curves are not proportional to eachother and are not proportional to the order parameter (distortion). The measured curves are explained by calculations within the frame of a modified mean-field formalism including higher-order contributions to the birefringence.

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“…D y V 0 4 and DyAsO, undergo cooperative Jahn-Teller phase transitions near 14 K from tetragonal (Dii) to orthorhombic (Dii) symmetry (Elliott et af 1972, Gehring and Gehring 1975, Kasten 1980, Page et af 1984. The order parameter is a B,, bulk strain, and has been measured directly by x-ray diffraction (Gobel and Will 1972a, b).…”

Section: Introductionmentioning

confidence: 99%

Neutral acyclic analogues of crown-ethers and cryptands and their complex-forming properties

Крон¹,

Tsvetkov²

1990

Russ. Chem. Rev.

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The origins of the dielectric anomalies associated with the Jahn-Teller phase transitions in DyV0, and DyAsO, are examined in detail. The lowest, nearly degenerate, Dy electronic levels couple strongly to distortions that carry an electric dipole moment parallel to the tetragonal axis. The electric susceptibility as a function of temperature, xc, accordingly shows Curie-like behaviour above TD and a prominent cusp at the phase transition. In the perpendicular direction the electric dipole moments are negligible, and xo, xb have a temperature dependence similar to that of the order parameter. In sensitive experiments x. and x b are observed to differ in magnitude and temperature dependence, suggesting a non-linear dependence on order parameter. Analysis shows that the principal contribution to xa, x b comes from matrix elements of the electric dipole operator between the ground doublets and excited crystal-field levels. These Van Vleck contributions lead to a temperature dependence both linear and quadratic in the order parameter in good agreement with experimental results. IntroductionD y V 0 4 and DyAsO, undergo cooperative Jahn-Teller phase transitions near 14 K from tetragonal (Dii) to orthorhombic (Dii) symmetry (Elliott et af 1972, Gehring and Gehring 1975, Kasten 1980, Page et af 1984. The order parameter is a B,, bulk strain, and has been measured directly by x-ray diffraction (Gobel and Will 1972a, b).The lowest Dy electronic levels are two Kramers doublets which are nearly degenerate above TD. These levels have finite couplings to distortions transforming according to the B1, B2 and E representations of the D2,, Dy site symmetry. It is of interest to note that the distortion which actually occurs, BZ, transforms like z , and that the E distortion transforms like x , y . This implies that the Dy electronic levels couple to electric fields E, and E,, E,. and hence that electric susceptibility measurements parallel and perpendicular to the tetragonal axis ( z I/ c) can provide information on the interactions and the phase transition.Measurements of xc on D y V 0 4 and DyAs04 (Unoki and Sakudo 1977, Harley and Taylor 1978, Page et a1 1979, 1984 showed a prominent dielectric anomaly indicating antiferroelectric (zone-centre) ordering at TD. On the other hand, electric susceptibility measurements perpendicular to the tetragonal axis showed negligible basal plane electric dipole moments. xu and X b were found to change substantially below T,, with Ax,, and AXb apparently proportional to the order parameter. In a recent detailed investigation (Page ef a1 1984, hereafter referred to as PTS), it was found that AX,, and AXb differed 0022-3719/85/173285 + 12 $02.25

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Phase transitions in DyVO4 and DyAsO4

Cited by 32 publications

References 49 publications

Reducing the background of ultra-low-temperature X-ray diffraction data through new methods and advanced materials

Reducing the background of ultra-low-temperature X-ray diffraction data through new methods and advanced materials

Effect of Hydrostatic Pressure on Dielectric Behavior and Phase Transition in Ferroelectric Polymers

Neutral acyclic analogues of crown-ethers and cryptands and their complex-forming properties

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