Synthetic analogues of rare mineral murataite, a complex oxide of titanium, iron, rare earth and other elements, attract special attention as perspective matrixes for the radioactive waste streams with complex composition. Murataite ceramics are usually obtained either by solidphase sintering at 1200-1300 °С, or by melting at 1500-1600 °С with subsequent melt crystallization. Transmission electron microscope studies [1] allowed to identify four synthetic murataite varieties with 3×3×3, 5×5×5, 7×7×7 and 8×8×8 fluorite cubic supercells referred as murataite-3C,-5C,-7C and-8C. Structural investigations reveal that these varieties can be considered as members of murataite-pyrochlore polysomatic series based upon incorporation of high-actinide pyrochlore nanoclusters into modified murataite-like frameworks [2]. Here we report results of structural analysis of the synthetic murataite-3C. Natural murataite [3] (Mu-3C), space group F43m, a = 14.89 Å, Z = 4, has the ideal and simplified formula R 6 М1 12 М2 4 ТХ 43 (R = Y, Na, Са, Мn; М1 = Ti, Fe; М2 = Fe, Ti; T = Zn; X = O, F). The crystal structure contains four cation sites: R site is [8]-coordinated, M1 site is octahedrally coordinated, M2 site is [5]-coordinated by a triangular bipyramid and T site is tetrahedrally coordinated. The structure is based upon a nanoporous 3D framework consisting of polymerized α-Keggin [Zn [4] Ti [6] 12 O 40 ] 30clusters with T d symmetry. Polymerization of Keggin units results in a creation of two types of voids that can be characterized as a truncated tetrahedron 3 4 6 4 and cubooctahedron 4 6 6 8. The framework accommodates complex fluorite-like substructure of Y, Fe and Na cations and O 2and Fanions. The crystal chemical formula of synthetic murataite derived from structure refinement and determined on the basis of site-scattering power of cation sites is [Ca 3.24 Mn 2.66 Ti 1.90 Tb 1.20 Fe 0.76 0.24 ](Al 0.71 Fe 0.29)(Ti 3.92 Al 0.08) (Ti 9.96 Zr 2.04)O 42 or Ca 3.24 (Mn 2.66 Fe 1.06) Σ=3.72 Ti 15.78 Tb 1.20 Al 0.79 Zr 2.04 O 42 which is in reasonable agreement with the formula derived from chemical analysis. In comparison with the natural murataite, the synthetic material has noticeably less quantities of vacancies in the cation substructure. Structural investigations reveal that, in contrast to natural murataite, its synthetic analogue contains five instead of four cation positions. The additional site is [8]-coordinated and contains Ca 2+ и Tb 3+. Structural and chemical differences between synthetic and natural murataites is the consequence of the significant amounts of fluoride present in natural samples, which compensates the absence of additional cation site in its structure.
New liquid chromatography/mass spectrometry (LC/MS) coupled with a new interface, LC/laser spray MS was developed. The laser spray was found to be particularly suitable for the low-concentration aqueous sample solutions because the enrichment of the sample concentration takes place near the meniscus of the liquid sample protruded from the stainless steel capillary. The extracts from the young leaves were measured using the present method coupled with the dual spray technique. Owing to much better sensitivities for laser spray than for electrospray, molecular formulas for some components in the sample could be postulated.
Poster Sessions 0 1 1 the Mahabaleshwar area of Maharashtra state, India. The feldspar phenocrysts contain different types of melt inclusions. These melt inclusions significantly show variation in melting temperature. Presence of different types of melt inclusions along crystal boundaries indicated the change in composition and this may be the function of temperature. Different types of melt inclusions found in plagioclase phenocrysts are amorphous and crystalline (monophase, biphase and multiphase).Variation in the commodity of these melt inclusions, itself reveals the immiscibility as well as the degassing phenomena of magma. An attempt has been made to correlate the melt inclusion geothermometry with the evolution pattern of magma/melt that of calcic-plagioclase phenocrysts present in a deccan basalts. Petrographic results were confirmed by the XRD and Cathodoluminescence studies. Heating stage experiment was carried out to find out the formation temperatures/melting temperatures of melt inclusions. [42][43][44][45][46][47][48][49][50]. In this method, each periodic infinite net can be expressed by a labelled directed finite graph which is called also labelled quotient graph. Each point and each line in the quotient graph corresponds to a set of equivalent vertices and edges in the three periodic net. Quotient graphs and spanning trees can obtained with given numbers of vertices and edges in this calculation. We use the determinant and trace of the matrix representing the quotient graph for the criteria of isomorphism of quotient graph. Special algorithm is applied to this program because the isomorphism of quotient graphs seriously delays the computation time with increase of the number of vertices and edges. The labelling to the quotient graphs can be applied. The structure of the network also can be obtained from the labelled graphs with least square fitting. A computation method for the enumeration of three periodic regular nets with a given number of vertices and edges will be discussed in detail. Twins in which the lattice nodes (quasi) restored by the twin operation belong to more than one sublattice are termed hybrid twins [1]. The fraction of (quasi) restored nodes takes into account all these sublattices and an effective twin index nE is defined. In Friedelian twins (twin index not higher than 6), the hybrid character shows that the choice of the sublattice is not unique. In non-Friedelian twins, nE allows a rationalization of these twins within the framework of the classical reticular theory [2]. A survey of twins in minerals has shown that a number of them should be reinterpreted as hybrid twins. For high-symmetry twins (cubic and uniaxial minerals), this is normally the case for twin elements of relatively high indices. E.g., (031) twin in cassiterite (four sublattices, nE = 3.8), (311) twin in nickeline (three sublattices, nE = 6.3), (203) twin in maucherite (three sublattices, nE = 5.83, (241) twin in diaphorite (two sublattices, nE = 4.0), and [313] twin in staurolite (two sublattices, nE = 6...
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