Raree arth carbonatehydroxides,R E(CO 3 )OH, werehydrothermallys ynthesized from formica cida ndthe hydroxide gels ofN d, Sm,E u,G d, Tb, Dy,H o,E r,T m, Yb, andY .Ano rthorhombicphasewith akozoite-type structurewaso btained for RE ¼ Nd andS m. Another orthorhombicmodification ofthekozoite-typestructure waso btained for RE ¼ Eu,G d, Tb, Dy,H o,E r,T m,a nd Y.Thelatterp hasehasalowers ymmetry( space group: P 2 1 2 1 2 1 )i ncomparison to thetruekozoite-typestructure ( Pnma ). Anewt etragonalp hase(space group: P 4 2Thec rystals tructureso fR E(CO 3 )OH wererefined for Pnma (RE ¼ Nd andS m), P 2 1 2 1 2 1 (RE ¼ Eu,G d, Tb, Dy, Ho,Er,TmandY),and P 4 2 / nmc phases(RE ¼ TmandYb) usingsingle-crystalX-raydiffraction intensity data.The distinctfeatureso fthed ifferencesamongthethree structuresarethec oordination numbers oftheR E 3 þ ions:10, 9,a nd8for the Pnma , P 2 1 2 1 2 1 ,a nd P 4 2 / nmc phases,respectively.Asystematicc omparison ofthetwo orthorhombicstructuresr evealed ad ynamicvariation in thec oordination environment oftheR E 3 þ ions accompanied by variationsi nt heir ionicradii.Althought heinteratomic RE--Od istancest endto decreasewith thelanthanide contraction,e xceptions wereobserved for two oftheR E--O distances. Themutualcloseproximity ofC O 3 2 À anions caused byt helanthanide contraction led to repulsion betweent heC O 3 2 À anions,whichdecreased thesymmetry ofthec onfiguration ofC O 3 2 À anions aroundthec entral RE 3 þ ion,a ndsomeoxygenatoms ofC O 3 2 À moved away from thef irst coordinations hell oftheR E 3 þ ions dueto thee longation oftheR E-Od istances.Thec rystals tructureso fthetetragonalRE(CO 3 )OH are distinctfrom thoseoftheorthorhombicphases. Theyconsist ofladders ofR E 3 þ ions 8-coordinated byt heC O 3 2 À andO H À anions arrangedin thef orm ofadoublec ross. ThepowderXRD patternso fthetetragonalRE(CO 3 )OH areidenticalt ot hato fasyntheticmaterialp reviously reported asTm 6 (OH) 4 (CO 3 ) 7 .

is a new member of the perrierite-chevkinite group found in the jades from the Itoigawa-Ohmi district, central Japan. It is monoclinic, P2 1 /a, a = 13.97(1), b = 5.675 (7), c = 11.98(1) A Ê , b = 114.26 (8)8, V = 866 A Ê 3 and Z = 2. The six strongest lines in the X-ray powder diffraction pattern are 3.12 (s) (40-3), 3.05 (vvs) (31-3), 2.99 (vs) (311), 2.84 (s) (020), 2.74 (s) (004), 2.20 (s) (31-5). Electron microprobe analysis gave SiO 2 22.58, TiO 2 29.88, ZrO 2 9.49, Nb 2 O 5 0.24, Ta 2 O 5 0.07, Al 2 O 3 0.20, FeO 0.10, CaO 0.43, SrO 34.32, BaO 0.13, La 2 O 3 0.00, Ce 2 O 3 0.38, Pr 2 O 3 0.10, Nd 2 O 3 0.29, Sm 2 O 3 0.04, total 98.25 wt.%, corresponding to on the basis of O = 22.The unitcell parameters and chemical composition imply that rengeite is the Sr and Zr-analogue of perrierite or high-b analogue of strontiochevkinite. It is transparent, dark brown with adamantine lustre. Its streak is pale greenish brown, and no cleavage was observed. The hardness is VHN 100 606 698 kg mm 2 (Mohs 5 5.5). The calculated density is 4.12 g cm 3 . It is strongly pleochroic from pale green to pale greenish brown where the REE contents are <1 wt.% and pale violet to greenish brown where the REE contents are between 3 and 10 wt.%. It occurs as anhedral grains in close association with titanite, zircon and tausonite in a pebble of blue titanian omphacite-jadeite rock from the seashore of Oyashirazu, Ohmi Town, in a boulder of lavender-coloured Ti-bearing jadeitite from the bed of the Kotaki-gawa river, Itoigawa City, and in a boulder of green jade from the bed of the Hime-kawa river, Itoigawa City, Niigata Prefecture, central Japan. Rengeite is considered to have crystallized by interaction between pre-existing minerals (rutile, anatase, titanite and zircon) and Sr-rich metamorphic fluid during later stage activity of high-P/T metamorphism. The name is for Mt. Renge near the locality and the Renge metamorphic belt where jadeitite deposits are found.

High dielectric constant SrTiO3 thin films were sputter deposited on barrier layers/Si substrate to fabricate a capacitor for dynamic random access memories. Dielectric constant (εr) values of 140–210 were achieved for the 150-nm-thick SrTiO3 films using a Pt/Ti or Pt/Ta double-layer barrier. In the Pt(50 nm)/Ti(10 nm), Pt(50 nm)/Ti(50 nm), and Pt(50 nm)/Ta(10 nm) barrier, effective εr decreased by annealing in the temperature range between 450 and 550 °C, where the interdiffusion of Pt and Si was confirmed by x-ray diffraction analysis and cross-sectional transmission electron microscopy. In the Pt(50 nm)/Ta barrier, increase of the Ta thickness from 10 to 50 nm brought out a remarkable improvement of endurance to high-temperature annealing. That is, in the Pt(50 nm)/Ta(50 nm) barrier, large εr value (∼200) was maintained even with annealing at up to 700 °C.

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