The relationship between the properties of quartz sands and so-called glass stones (minerals within the glass) was studied by mineralogical and analytical methods. The quartz sands are obtained from dune and arkose deposits, and are used as the raw material of amber bottle glass at K and S glass works, respectively. The sorting grade in the two deposit types influences the size and form of the constituent grains. The heavy minerals found in the dune type are spherical and larger than those from the arkose type deposit. The grain size influences strongly the structure and constituent minerals in glass stones. The following peculiar structures and minerals are found in the glass stones from the K glass works; they are not present in the glass stones from the S glass works:
(1) Andalusite stones: consisting of a single crystal of andalusite and of the peritic aggregation of fine mullite crystals,
(2) Corundum stone: consisting of a single crystal,
(3) Corundum stone: consisting of an aggregation of fine crystals.
The results of mineralogical and analytical studies suggest that the peculiar glass stones are the insoluble remnants of andalusite, corundum and diaspore crystals which are included as the heavy minerals in the dune type deposit. The peculiar glass stones amount to about 15% of the total number of glass stones.

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A large dielectric relaxation was observed in the crystallized glass containing a large amount of V₂O₅. The main crystalline precipitate in the crystallized glass 70V₂O₅⋅30P₂O₅ was V₂O₅ crystal. To clarify the origin of the large dielectric relaxation, the dielectric properties of the crystallized glass were studied and compared with those of polycrystalline V₂O₅ obtained by two different methods. The ε′ of crystallized glass 70V₂O₅⋅30P₂O₅ is two or three times larger than that of the glass for the same composition. The sintered and oriented V₂O₅ polycrystalline materials show a large dielectric relaxation; the value of the static dielectric constant in the specimen sintered at 620°C for 5h is 1000. The ε′ of polycrystalline V₂O₅ changed with the sintering temperature and with the direction of the crystal axis in the oriented specimen. The results obtained were analyzed on the basis of the equivalent circuit model for a double-layer dielectric. According to this model, the ε′ and σ of the crystal (the direction of b-axis) of the specimen oriented perpendicular to the electric field were 63 and 7.06×10^-4(mho/cm), respectively. The σ of this sample is nearly equal to the value of the b-axis in the V₂O₅ single crystal. The σ of the grain boundary is 6.60×10^-7(mho/cm) and is equal to that of amorphous V₂O₅. In the sintered specimen, the ε′ values of the crystal are about 10-13; the ε′ value of the grain boundary layer increased with increasing sintering temperature. The change of ε′ in the sintered specimen is thus related to the thickness of the grain boundary. The ε′ of the precipitated V₂O₅ crystal in the crystallized glass is nearly equal to that of the crystals for the sintered V₂O₅ polycrystalline materials. The thickness corresponding to the grain boundary in the crystallized glass is larger than that of the sintered polycrystalline material, The ε′ in the sintered specimen and crystallized glass is influenced not only by the V₂O₅ crystal properties but also by the properties of the grain boundary between V₂O₅ crystals. The analysis by the double-layer dielectric model led to the conclusion that the large dielectric relaxation of the crystallized glass is not due to the contribution of the direction of the preferential crystal axis in V₂O₅ crystal, but should be attributed to the effect of the inter-surface polarization between the highly conducting crystal (V₂O₅) and the poorly conducting matrix.

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Glasses with various compositions in the systems (nNaO_0.5+mBaO)-AlO_1.5-TiO₂, where n/m is 1/0, 2/1, 1/1, 1/2 or 0/1 (Fig. 1), were heated to various temperatures from 650°C to 950°C at a rate of 5°C/min in a SiC furnace, and then cooled outside the furnace. All the glasses examined darkened on 60 min-irradiation of 365nm light of 6 W ultraviolet lamp, after heated to certain temperatures depending on their compositons (Table 1). The darkening of one of the heat-treated specimens, A 3 in Table 1, was enhanced by the addition of a small amount of FeO_1.5 or ZnO, whereas it was suppressed by the addition of CeO₂ (Table 2, Figs. 2 and 3). On the surfaces of all the heat-treated specimens showing photochromism, an unknown crystalline phase named X in Table 3 was detected. All the specimens containing the X phase, however, did not always show the photochromism (Table 3). Consequently, the cause of the photochromism of the heat-treated glasses described above was attributed to defects, probably induced by impurities, in the X phase precipitated on the surfaces of the glasses. The X phase was observed on the surfaces of both the BaO-free glasses and Na₂O-free glasses (Table 3). The fluorescence X-ray analysis of powders of a NaO_0.5-BaO-AlO_1.5-TiO₂ glass (A 9 in Table 1), which had been heated to 700°C (Fig. 5 (A)) and immersed in a 2 N NaOH solution at 95°C for 100h (Fig. 5 (B)) showed that the X phase is deficient in Al and rich in Ti (Table 4). The X phase was, therefore, considered to be mostly composed of TiO₂. The structure of the X phase was identified as one of the cubic structures in Pa 3, P 4₁32, P 4₂32, Pn 3m and P_*3_* diffraction groups with a lattice constant of a=11.54Å by indexing the powder diffraction peaks of this phase (Fig. 4).

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Additivity for the molar volumes of alkali silicate glasses (0<R₂O<33.3mol%) was discussed in terms of two structural units, SiO_4/2 and ROSiO_3/2. The units were represented by the cristobalite-type cage skeletons composed of Si-O-Si and Si-OR⋅RO-Si bonds. The cages involved voids associated with the units and the glasses were regarded as the aggregates of those cage skeletons. The deviation from the linearity (additivity) of molar volumes against R₂O molar fraction was excellently approximated by the random packing of two kinds of spheres which corresponded to the SiO_4/2 and ROSiO_3/2 units. Furthermore, based on the cage structure model, Si-Si distances at the bridging and non-bridging parts were evaluated. It was shown that the two Si and two O atoms at the non-bridging parts were arranged in an array of a line, ≡Si-O--O-Si≡, in rubidium and cesium glasses, while in lithium, sodium and potassium glasses the two non-bridging oxygens were located at the sites away from the Si-Si tie line, ≡Si-O--O-Si≡.

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The Effect of grain orientation on dielectric properties of a ferroelectric BaBi₄Ti₄O₁₅ ceramic thick film fabricated by a modified doctor blade method was investigated. For evaluation of the grain orientation, the equation f=P₀(W_hkl^t-1)/(1-P₀) proposed by Zhang was fully examined and the degree of orientation F was newly defined. The F value for each crystal plane was calculated from an X-ray diffraction pattern, which was further correlated with the measured permittivity and dielectric loss (tanδ). The diffraction intensity of the crystal planes perpendicular to c-axis such as (008) and (0010) was observed to be higher than that for a non-oriented sample and resulted in F>0. The intensity of the crystal planes parallel to c-axis such as (020), on the other hand, was lower, resulting in F<0. The permittivity of a film was smaller than that of a normally sintered specimen in the temperature range 15°-480°C. It was concluded that the permittivity along c-axis was smaller than that along a- or b-axis for BaBi₄Ti₄O₁₅.

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