Structure of Rb3D(SeO4)2 at 25, 110 and 297 K

Ichikawa, M.; Gustafsson, T.; Olovsson, Ivar

doi:10.1107/s0108270191011708

Cited by 20 publications

(14 citation statements)

References 8 publications

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“…These relations are characteristic of all M3H(XO4)2-type crystals so far studied. The disk-shaped anisotropy of the displacement parameters for 0(2) and 0(3) is also analogous to that observed for Rb3D(SeO4)2 (Ichikawa et al, 1992). Displacement ellipsoids are scaled to include 50% probability.…”

Section: General Features Of the Structurementioning

confidence: 54%

“…There are two kinds of Cs atoms: Cs(1) occupies a special position on a twofold axis; Cs (2) CsaD(SeO4)2 in the hydrogen-bonded dimers are related by a twofold axis, with hydrogen either on the twofold axis or in two disordered positions about it. The systematic trends in the bond distances and angles of the SeO4 tetrahedra are analogous to those in Rb3D(SeO4)2 (Ichikawa et al, 1992); for a detailed discussion this paper should be consulted. It is noted that at RT the 0(2)---0(3) distance is larger than the O(1)---O(2) distance and rather close to other O---O distances involving O atoms without an attached proton, in contrast to the regular HSeO4 group.…”

Section: General Features Of the Structurementioning

confidence: 83%

“…For further information on the characteristics of, and interest in, these compounds, see Ichikawa, Gustafsson & Olovsson (1992). All M3H(XOa)2-type crystals have the same trigonal (R3m) superionic and paraelastic phase (I) above the transition temperature To, (range 339-456 K).…”

Section: Introductionmentioning

confidence: 99%

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Structural study of the low-temperature phase transition in Cs₃D(SeO₄)₂

Ichikawa¹,

Gustafsson²,

Olovsson³

1992

Acta Crystallogr Sect B

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The X-ray structure of tricaesium deuteriumbiselenate, Cs3D(SeO4)2, M, = 686.7, has been studied at 25, 190 and 297 K with particular attention being paid to the low-temperature phase transition at 7",.3 = 180 K. The structure of Cs3H(SeO4)2 has also been studied at 297 K. The data were refined in the mono- per 100 K on average). Accompanying the 1",.3 transition, the space group changes from C2/m to P21/m, and the two SeO4 groups in the dimer become nonequivalent with one adopting HSeO£ character and the other SeO 2-character. As a result, the dimers have a net dipole moment and are arranged in an antipolar way, similar to K3D(SO4)2. An examination of the room-temperature structure of Cs3D(SeO4) 2 and other M3H(XO4)2-type crystals reveals that the non-H atoms lie in approximately the same position in both cases and that the only major difference is that half of the hydrogens in other M3H(XOa)2-type crystals are involved in hydrogen-bonded dimers which are formed with two different adjacent selenate groups. The successive transitions in Cs3D(SeO4)2 are characterized as an order-disorder transition of the donor-oxygen atom at T,.~, reorganization of the hydrogen bonds at To2 and an order~tisorder transition of the proton at 7",.3.

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Section: General Features Of the Structurementioning

confidence: 54%

Section: General Features Of the Structurementioning

confidence: 83%

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Structural study of the low-temperature phase transition in Cs₃D(SeO₄)₂

Ichikawa¹,

Gustafsson²,

Olovsson³

1992

Acta Crystallogr Sect B

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“…The large B value of the H atom appears to favour the disordering ( Table 2). The dimensions and systematic trends in distortion from a regular tetrahedron of the SeO4 anion, as shown from the bond lengths and angles, are close to those in TRHSe and TRDSe [for detailed discussion consult Ichikawa et al (1992a)]. Furthermore, a trend among the values of the equivalent isotropic displacement parameters and the disk-like anisotropy in the O(2)(H) and 0(3) atoms are similarly observed in the Rb and Cs analogues [see the deposited list of anisotropic displacement parameters and Ichikawa, Gustafsson & Olovsson (1992b)].…”

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confidence: 61%

“…Intensity data were collected on a Rigaku AFC-3 automatic four-circle X-ray diffractometer at the Institute of Solid State Physics, the University of Tokyo. Graphite monochromator; at-20 scan; Aoo = (1.5 + 0.5tan0)°; 4 < 20 < 70 ° (h The least-squares refinement was started with the room-temperature structure of Rb3D(SeO4)2 (Ichikawa, Gustafsson & Olovsson, 1992a). The K3H(SeO4)2 (1) 39881 (25) 1293 (38) 15747 (16) 2.73 (3) 0 (2) 43475 (24) 18139 (41) 184 (14) 2.86 (3) 0 (3) 62361 (19) 24982 (46) 15443 (15) 1.97 (3) 0(4) 38256 (26) 46412 (40) 12910 (17) 3.70 (3) a 50000 0 0 9.8 (26) Final positional and displacement parameters are given in Table 1.…”

mentioning

confidence: 99%