Local structures around transition-metal atoms in silicate glasses of the systems CaMgSi₂O₆ (Di)-CaMnSi₂O₆(CaMnPx), Di-CaCoSi₂O₆ (CaCoPx) and Di-CaNiSi₂O₆ (CaNiPx) were investigated with the XAFS (X-ray Absorption Fine Structure) spectroscopy, by making use of SR (Synchrotron Radiation). The obtained distances suggest that the preference to the octahedral coordinations is in the decreasing order Ni²⁺, Co²⁺ and Mn²⁺. This order can be explained in view of the difference between the crystal-field stabilization energies for octahedral and tetrahedral coordinations in the high-spin states. ELNES (Energy-Loss Near Edge Structure) spectra were also measured around the Mn L_2,3 edges to determine the oxidation states of Mn ions in glasses of the system Di-CaMnPx. Chemical shifts of the L_2,3 edge threshold-energy and the ratios of L₃/L₂ threshold peaks in all the examined glasses were similar to those in MnO but unlike those in MnO₂. The observed tendency of chemical shifts in the XANES spectra of Mn K-edges was identical with that in ELNES. The shifts of Co K- and Ni K-edges in the XANES spectra of all the examined glasses were similar to those of Co-olivine and NiO, respectively. These facts suggest that Mn, Co and Ni ions in the glasses are in divalent states.

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A number of sartorite specimens from Binnathal have been examined by single-crystal X-ray and electron diffractions. The substructure reflections of any crystal picked out from those specimens are consistent with the space group Pbnm and have the subcell with a∼19.6, b∼7.9 and c∼4.2Å as reported to date. The reported peculiar mode in diffraction-intensity distribution that it varies from one crystal to another or even from one portion to another in the same crystal has also been observed both in the single-crystal X-ray diffraction and in the selected-area electron diffraction. The mode of intensity distribution of the superstructure reflections, however, has been found to have two distinct types, one has a monoclinic symmetry and the other an orthorhombic symmetry. Crystalline phases showing the former type have been denoted ‘clinosartorite’ and those showing the latter ‘orthosartorite’. In addition to them there are a variety of disordered types as well. The complexity in diffraction patterns can be interpreted essentially as composites of the patterns from the coexisting two distinct types (clinosartorite is frequently twinned). The monoclinic phase has features suggesting a periodic antiphase boundary structure (APBs) with two-dimensional structural modulation. The relationship between the new monoclinic true cell, in which cell edges are chosen in accordance with the structural features, and the conventional cell is described as: a_NR=3×a_CS–11×c_CS, b_NR=b_CS, c_NR=11×c_CS, where suffixes NR and CS indicate the newly-derived true cell and the conventional subcell, respectively. On the other hand, ‘orthosartorite’ has the same three cell edges as those reported for the conventional true cell, namely, 3×a_CS, b_CS, and 11×c_CS. The periodic antiphasing and expected modulation of the structure would be rationalized, in terms of a mechanism of reducing lattice strain that may occur owing to the dimensional misfit between Pb–S and As–S links in the structure.

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Kimzeyite solid solution series (Ca₃Zr₂Al₂SiO₁₂–Ca₃Zr₂Fe₂SiO₁₂ abbreviated to Al₁₀₀Fe₀–Al₀Fe₁₀₀) have been investigated by hydrothermal syntheses and X-ray powder diffraction. The latter confirmed the splitting or broadening of the diffraction peaks on the specimens with the initial composition Al₅₀Fe₅₀ and quenched from the temperature below 650°C. The electron microprobe analyses were also carried out and indicated the existence of two kinds of crystal grains of kimzeyite, each having a different composition. The cell dimensions calculated from the peaks of X-ray powder diffraction concluded that the splitting or broadening of these peaks is ascribed to the existence of two exsolved garnet phases both having a cubic symmetry. The existence of an exsolution region below 650°C in kimzeyite solid solution series has been confirmed.

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Pale green and purple jadeites have been studied by a microscope spectrophotometric method. Absorption and photoluminescence spectra of these jadeites revealed that the green and purple colors were attributed to the existence of Fe³⁺ and Ti³⁺ ions in the octahedral site, respectively. The crystal-field parameters of these ions were successfully obtained. Fe³⁺ parameters derived from five absorption bands were: Dq=1290cm⁻¹, B=566cm⁻¹, C=3470cm⁻¹. Ti³⁺ had a broad absorption band of 70nm, full width at half maximum (fwh) with a peak at 545nm and a crystal-field splitting of Dq=1840cm⁻¹. Fe³⁺ gave rise to a broad emission band (81 nm fwh) with a peak at 796nm, while Ti³⁺ did not give luminescent centers in the infrared region. These facts support that both ions occupy the octahedral site.

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