Pseudo-cubic symmetry

Phase relations in the pseudo-binary systems NdAlOa RAIO3 (R = Eu, Dy, and Er) at RT have been examined by Brusset et al. (1975). According to their study, two kinds of Ndi xEuj A103 solid solutions with rhombohedral and pseudo-monoclinic structure exist in the NdAlOs—EuAlOs system at x < 0.18 and x > 0.25, respectively. It was also claimed that a solid solution with pseudo-cubic symmetry exists in the Ndi j-Erj A103 system when 0.07 phase region between two perovskite-type phases with rhombohedral and orthorhombic structures. In the NdAlOs—DyAlOs system, the boimdary between rhombohedral and pseudo-cubic phases is located near 0.08 molar fractions of DyAlOs-... 

These experiments were made upon a most complex zeolite, heulandite, and were later extended to analcite, which lias only one type of lattice hole and a cubic or pseudo-cubic symmetry (7).. Once more the optical experiments were performed upon narrow plates cut parallel to cube or diagonal faces. The material was thoroughly outgassed and the sorption processes with ammonia were observed. In Table 16, wliich... 

As a consequence of its pseudo-cubic symmetry, the spectrum of the 1,2,3-tricyano complex may be predicted from Fig. 6 at Dt = 0, or from Tanabe-Sugano diagrams for cubic complexes. In the trigonal (C3J field of the 1,2,3-tricyano complex, however, the term designations given for the energy levels in cubic symmetry transform as follows M... 

In Fig. 3a, cubic and octahedral faces are evident, and in Fig. 3b the twinned crystals with pseudo-fivefold symmetry can be clearly seen. This twinned fivefold symmetry is prevalent in CVD diamond thin films and apparently never develops on homoepitaxially grown crystals.Balllike diamond crystals are grown at high supersaturationsf (Fig. 3c). 

Ultrafme pure BaTi03 powders were obtained by a modified oxalate precipitation method as described previously [13], The powders had a specific surface area of 57 m g and the particle size was nearly spherical from 20 to 30 nm. The main impurities contained in the powders were at the following levels 0.04 wt% Sr, 0.02 wt% Na, and 0.006 wt% K. The Ba/Ti atomic ratio was 1 0.003 for all the powders. The X-ray diffraction (XRD) patterns of nanocrystalline powders apparently correspond to a pseudo-cubic structure without peak splitting of lines such as (002) and (200). We also used Raman spectra to detect local symmetry of the nanocrystalline powder samples. It showed that the local symmetry in the nanopowder appears to be a cubic structure even at a very low temperature of 123 K. Therefore, XRD patterns and Raman spectra revealed that the BaTiOs powder exhibited the commonly reported pseudocubic perovskite structure. 

As described below, the rule of average environments is invoked to predict electronic properties of mixed-ligand complexes with pseudo-octahedral symmetry. The concept of the magnitude of a cubic ligand field is appropriate for complexes that exhibit approximate cubic symmetry. For example, if represents a normalized... 

The spectra of the partially substituted cyanoaquochromium(III) complexes may be most easily approached by reference to the unsubstituted cubic parent complexes, Cr(CN) and Cr(H20), and the intermediate 1,2,3-tricyanotriaquo complex, which can be considered pseudo cubic. In the regular octahedral complexes of O symmetry, the spin-allowed absorption bands observable in the visible and near ultraviolet regions result from transitions from the ground state (M2g) to higher energy quartet states, i.e.,... 

The structure of the fast ion conducting phase can be most clearly understood with reference to the straightforward, fully ordered and insulating a phase observed at room temperature. The monoclinic cell of this structure can be related to a face-centred pseudo-cubic array as illustrated in Figure 3.4. The departure from cubic symmetry leads to the presence of two crystallographically inequivalent lithium cations in the structure. However, the chemical environments for these two cations are... 

The nature of M7O12 phases involving tungsten and the lighter rare earths appears to depend substantially on the preparative temperature. At 1400°C such phases appear to be defective pyrochlores of formula R2(RW]/2)07-i (Chang and Phillips, 1964), whereas at lower temperatures (1250°C) lower symmetry phases, described as pseudo-cubic, have been obtained (McCarthy 1972 Trunov et al., 1968). 

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