On the Crystal Structure of NbTe4.

Selte, Kari; Kjekshus, Arne; Petersen, Cherry Schiander; Halvarson, Hans; Nilsson, Lennart

doi:10.3891/acta.chem.scand.18-0690

Cited by 93 publications

(51 citation statements)

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“…This distance is only slightly longer than the Gd--Te distances in the binary telluride Gd2Te3 (<Gd--Te> = 3.126 and 3.189 A for the two crystaUographically independent Gd atoms; Swinnea, Steinfink & Danielson, 1987). The Cs CsGdTe4 <Cs2mTe> = 3.925 A,; B6ttcher & Kretschmann, 1985) or Cs3Te22 (<CsmTe> = 3.892 ~,; Sheldrick & Wachhold, 1995 (Selte & Kjekshus, 1964). In NbTe4, the Nb atoms are in a similar squareantiprismatic Te environment to Cs and Gd in CsGdTe4.…”

Section: Commentmentioning

confidence: 94%

Caesium Gadolinium Tetratelluride

Bensch¹,

Dürichen²

1997

Acta Crystallogr C

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cations are in the same square-antiprismatic environment of Te as the Gd cations. The Cs--Te distance of 3.9112 (5) ,~ is in good agreement with the values o reported for CsTe4 ( = 3.954A; B6ttcher & Kretschmann, 1982), Cs2Te5 ( --3.929, (Received 18 June 1996; accepted 3 October 1996) Gd Te AbstractThe new ternary gadolinium telluride CsGdTe4 was prepared via the molten flux method. It is a layer compound containing Te~-tellurium dianions. Layers of Gd centres are sandwiched by Te layers leading to [GdTe4] n-layers which are separated by Cs cations. Within a [GdTen]n n-layer, the Gd cations are in a square-antiprismatic coordination of eight Te anions. CommentIn the alkali metal-lanthanoid-chalcogenide system, beside the two structure types of composition ALnQ2 crystallizing in the simple NaCl-type structure with statistically distributed A ÷ and Ln 3+ cations or the a-NaFeO2 structure type, a number of new structure types for ternary and quaternary alkali metallanthanoid-chalcogenide compounds have been prepared recently using the polychalcogenide flux method.

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Section: Commentmentioning

confidence: 94%

Caesium Gadolinium Tetratelluride

Bensch¹,

Dürichen²

1997

Acta Crystallogr C

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“…Their basic structure was determined by Selte & Kjekshus (1964) (NbTe4) and Bjerkelund & Kjekshus (1964) 0108-7681/87/040305-09501.50 and characterized by Gressier, Meerschaut, Guemas, Rouxel & Monceau (1984). However, unlike the structures of these compounds, the columns in NbTe4 and TaTe4 are linked to each other by Te-Te bonds, which should decrease the one-dimensional character.…”

Section: Introductionmentioning

confidence: 99%

The determination of the commensurately modulated structure of tantalum tetratelluride

Bronsema¹,

Smaalen²,

Boer³

et al. 1987

Acta Crystallogr Sect B

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The incommensurately modulated structure of tantalum tetratelluride (TaTe4) has been determined by X-ray diffraction on the basis of a 2a x2a x3c supercell. Mo Ka radiation, A=0.71069/~, /z= 405.0 cm -~. The space group of the subcell is P4/mcc, that of the supercell P4/ncc. a=6.5154(5), c= 6-8118 ~, RF =0.064 for 6422 observed reflections.The structure is characterized by TaTe4 chains along the c axis. These chains are modulated in such a way that Ta3 clusters are formed. The Te atoms respond to the displacements of the Ta atoms, keeping the bonds of the Te dimers, which link the chains, equal in length. The clusters in neighbouring chains are shifted with respect to each other with a phase shift of ~, causing the doubling of the a axis. A simple model is proposed to account for the observed modulations in NbTe4 and TaTe4.

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“…Selte & Kjekshus (1964) and Boswell et al (1983) (Spek, 1983). Finally, for the equivalent reflections the average value was taken and all systematic extinctions were removed.…”

Section: Methodsmentioning

confidence: 99%

“…The reflections of the first group are at the nodes of the reciprocal lattice A*, spanned by the vectors a*, b* and c*, as was also used by Selte & Kjekshus (1964). The corresponding direct lattice gives the periodicity of the average structure.…”

Section: Description Of the Diffraction Patternmentioning

confidence: 99%

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The determination of the incommensurately modulated structure of niobium tetratelluride

Smaalen¹,

Bronsema

Mahy³

1986

Acta Crystallogr Sect B

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type seen in Au22Mn6 (Hiraga et aL, 1982). In the present case, there is a sliding offset of Mn-column positions as indicated, for example, by the arrows in Fig. 7(b) and the width of Dla along the long-period axis is different. Careful observation of these images enables a schematic model for this lattice 'side-step' to be obtained, as drawn in Fig. 7(c) where the difference in brightness of spots is indicated by the lined, half-filled or solid circles (and the regions of D la type are shown in screen-tone). The structure model of Au22Mn6 is also shown in Fig. 7(d) for comparison. Some apparent nearest-neighbour MnMn pairs, the brightness of which is lower than that of other parts, are visible at the side-step. However, no nearest-neighbour Mn-Mn pairs are known to exist in this alloy. Moreover, the recorded image comes from the projection of the structure along the incident-beam direction. Thus, it can be concluded that the occupation probability of the Mn atoms in the columns is less than unity in order to avoid true nearest-neighbour Mn-Mn pairs, and this causes the lower contrast of the pairs, as discussed for the 'superstructure' image condition (Shindo, Hiraga & Hirabayashi, 1984). It is not possible to distinguish where the Mn atoms are located in the columns, whether there is perfect order along the tilt boundary or if the Mn atoms occupy the columns randomly along the beam direction. It should be noted that the superstructure shown in Fig. 7 AbstractA complete analysis of the modulated structure of NbTe4 is presented, using the newly developed formalism of de Wolff [Acta Cryst. (1974 up to the fifth harmonic in the modulation wave. However, the values found for higher harmonics do not describe the real modulation wave, but assume values to account for the variation in intensities due to experimental errors. Therefore, only the amplitudes up to the second order are considered to be reliable.

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On the Crystal Structure of NbTe4.

Cited by 93 publications

References 0 publications

Caesium Gadolinium Tetratelluride

Caesium Gadolinium Tetratelluride

The determination of the commensurately modulated structure of tantalum tetratelluride

The determination of the incommensurately modulated structure of niobium tetratelluride

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