Using an rf-magnetron sputtering method, highly c-axis oriented La-modifiedPb TiO₃ (PLT) thin films with composition of Pb_1-xLa_xTi_1-x/4O₃, where x=0.0, 0.05, 0.10 and 0.15 have been obtained on MgO single crystal and epitaxial Pt thin film substrates under the condition of low gas pressure and low deposition rate. It was found that the significant pyroelectric currents were detected for all as-grown specimens even without poling treatment and the directions of the currents were the same in all specimens. Relative dielectric constant ε_r decreased, and pyroelectric coefficient γ increased with increasing degree of c-axis orientation. ε_r and γ became large with increase of La content in the films. Considering the figure of merit for pyroelectric infrared detection, it is concluded that PLT films with x=0.10 are good material for pyroelectric infrared detector.

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Plumbogummite-group phosphates [MAl₃(PO₄)₂(OH)₅·H₂O (M=Pb, Ba, Sr or Ca)] were synthesized by precipitation from the mixed solution of M-salt, Al-salt and orthophosphoric acid at 90°C and pH=B. Synthesized plumbogummite-group phosphates are spherulitic cry-stals with a fibrous structure. The hexagonal unit cell has a=7.027±0.004, c=16.75±0.01Å(M=Pb, plumbogummite), a=7.074±0.006, c=16.84±0.05Å(M=Ba, georceixite), a=7.02±0.01, c=16.60±0.05Å(M=Sr, goyazite) or a=7.015±0.003, c=16.180±0.007Å(M=Ca, crandallite). When heated in air, the synthesized plumbogummite, georceixite, goyazite and crandallite became amorphous at temperatures around 500°C because of the loss of H₂O (100-200°C) and (OH)-groups (300-450°C). The amorphous phosphate obtained from geo-rceixite was stable untill 1000°C, while those obtained from plumbogummite, goyazite or crandallite were unstable producing M₃(PO₄)₂ and AlPO₄ at temperatures over 700°C (M= Pb) or 950°C (M=Sr or Ca). Florencite [CeAl₃(PO₄)₂(OH)₆] could not be synthesized by precipitation from the mixed solution of Ce (NO₃)₃·6H₂O and orthophosphoric acid at pH 2 to 8 even if kept at 90°C for 4 weeks.

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Sector-zoned manganoan aegirine-augites from the Kamisugai mine, Ehime Prefecture, have been investigated by an optical microscopy and an electron probe microanalyser. Sector-zoned crystal elongates along c-axis and is composed of the {100} and {010} sectors. The cores of the {100} sectors are rich in johannsenite and diopside molecules, while the rims become poorer in johannsenite molecule. The cores of the {010} sectores are rich in acmite and diopside molecules, and the rims become richer in acmite molecule. These zonal structures of each sector are discussed in reference to the crystallization temperature and oxygen fugacity in particular. These factors control the solubilities of johannsenite and diopside molecules to acmite molecule. The sectoral fractionation of the molecules during crystallization can be explained by the difference of the lattice energies of each molecule and that of the magnitude of misfit between Si-O tetrahedron and M-O polyhedron in the structure.

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Geobarometers used at pressures corresponding to the crust and upper mantle conditions are summarized. Geobarometers have not been established at pressures above 5 GPa. Pressure dependency of concentration of pyroxene molecule in majorite, i.e. “majorite geobarometer”, may be a candidate for a geobarometer in the pressure range above 5 GPa. Responses of the two pyroxene geothermometer and orthopyroxene-garnet geobarometer to the geologically plausible changes in tem-perature and pressure in the mantle were evaluated on the basis of the diffusion data of cations available. The basic assumption of chemical equilibrium in garnet peridotite xenolith is examined critically.

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