｛Y3｝ [M 9vM2-y](M蹄Si)O112ザク石(M = Als←, Fes←, Ga争, y=O。0～2,0)のIRスペクトルを一測定した。固溶にともなうスペクトル変化からザクロ石構造中の孤立四面体,孤立八面体にそれぞれ局在するグループ振動の存在が認められた。
MO4四面体の一下振動v3パソドはy=O． O is成ではいずれも3本に分裂し,縮退はすべてとけている。Alq四面体の3バンドはyの増如とともに低波数側にシフトし, y ,5組成から2本に縮退する。FeO4四面体のVsバンドはyが増加してもほとんどシフトしないが, y ．5組成から2本に,5組成から1本に縮退する。GaO4四面体のsバンドe3 yの増加とともに,わずか低波数側にシフトし,y ,2組成から2本に, y, ,5組成から1本に縮退する。以上のことは聾四面体の伸縮振動が隣接陽イオンの静電場の強さに影響されること,およびFeO4 G典04四面体と他の配位陽イオンとの相互作用は,AIQ 4の場合より弱く,むしろ自由イオンに近い性質をもっていることを示している。
固溶体のスペクトル変化から配位八面体の伸縮振動のバンドはAIO6では520,474,438 cm-i, FeO6 では382,362cm1, G06では466,400,342 cm備1, MgO6では400～350 cm"iのバンドと考える。

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{Y₃}[Mg_yAl_2-y](Al_3-ySi_y)O₁₂ザクロ石(YAMG-1)のAl³⁺,{Y_3-xMg_x}[MgAl](Al_2-xSi_1+x)O₁₂ザクロ石(YAMG-2)のMg²⁺の配位状態をそれぞれ,AlK_α,MgKK_α線のスペクトルシフトから検討した。シフトの測定には,金属アルミニウム,金属マグネシウムを標準として用いた。分光結晶,EDDT,ADPの温度変化を±0.3℃以下に制御した。YAMG-1において,6と4配位のAl³⁺の原子比が40:60であるy=0.0組成ザクロ石および原子比が14:86であるy=1.8組成ザクロ石のAlK_α.波長シフト(Δ2θ)はそれぞれ,-0.087±0.005°,-0.072°±0.002°であった。その間の組成では,AlK_αシフトはほぼ直線的に増加した。しかしAl³⁺が4配位位置のみを占めるはずであるy=2.0組成試料のAlK_α,シフトは-0.071±0.0020であった。これらの結果は,y=2.0組成試料の6配位位置に若干のAl³⁺が残っており,この系のザクロ石の固溶限界がおよそy=1.8であることを示している。この値は格子定数変化から求めた値,y=1.7とほぼ一致する。YAMG-2ザクロ石試料のMgK_αシフトは,スピネルについての4配位Mg²⁺による値(Δ2θ=-0.029°±0.005°)から,YAMG-2,x=0.0についての6配位Mg²⁺による値(-0.0480°±0.005°)をへて,紅ザクロ石についての8配位Mg²⁺による値(-0.084°±0.005°)まで引いた直線の上にのる。MgK_α波長シフトの測定結果と,X線回折強度の計算値と実測値の比較の結果は,x≅0.6程度までMg²⁺はY³⁺を置換して8配位配置に入りうることを示している。

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{Y₃-xMgx}[Mg_yAl_2-y](Al₃-(x+y)Six+y)O₁₂(YAMG)系ザクロ石の固溶範囲とMg²⁺の配位選択性を検討した。Mg²⁺が8配位位置のY³⁺,または6配位位置のAl³⁺のみを置換する場合,単一相ザクロ石の生成範囲はそれぞれ,x<0.8,y<1.0であった。一方,Mg²⁺が8配位位置と6配位位置を同時に置換する場合,最大の置換量はx=O.6,y=1.0,すなわち,{Y_2.4Mg_0.6}[MgAl](Al_1.4Si_1.6)O₁₂の組成を有し,格子定数はa0=12.008Åであった。Mg²⁺は一般にザクロ石構造中で,8配位位置より6配位位置をとり易いといわれている。しかしYAMG系ザクロ石の場合,Mg²⁺の6配位と8配位の選択性に顕著な差は見られなかった。これはMg²⁺の置換による構造中の配位多面体の歪への寄与は,Mg²⁺が8配位または6配位位置のみを占めるより,両位置を同時に占めた方がより少いためであろう。Mg²⁺の置換量が増えて単一相ザクロ石を生成し得ない領域では共存化合物は,配合組成の相違によって異り,xが増加すればスピネル,yが増加すれば,リン灰石型イットリウムマグネシウムケイ酸塩およびY2SiO5が共存し,それらの量は,いつれもxまたはyの増加とともに増加する。

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The very fine oxide particles in TiO₂-SnO₂ system were prepared by the hydrolysis of titanium isopropoxide and tin isopropoxide in propanol solution. The following hydrolysis conditions were found to be necessary for the controlled synthesis of crystalline oxide precipitates, 1) process of water addition to propanol solution of metal isopropoxides, 2) the amount of water added to the metal isopropoxide solution, 3) hydrolysis time and aging time of the precipitate at boiling temperature (reflux time).
The crystalline TiO₂ of anatase structure was precipitated by the hydrolysis of 0.05mol/l titanium isopropoxide with the amount of water 300 times more of the equivalent value for the oxide formation and the subsequent reflux, while the decrease of the amount of water to 70 times of the equivalent value resulted in the formation of amorphous TiO₂. The crystalline phase of the precipitate changed depending on the amount of SnO₂ in the system. The precipitate of the composition Ti_0.9Sn_0.1O₂ was the mixture of anatase and rutile phases with the particle size of 50Å, and the increase of SnO₂ to x=0.2 in Ti_1-xSn_xO₂ solid solution gave the oxide precipitate composed of only rutile phase with the particle size of 23∼25Å.
On heating the precipitates, the grain of the anatase phase of TiO₂ precipitates grew significantly at about 630°C, at which the phase transformation from anatase to rutile phase took place. On the precipitates of rutile structure, grain growth seemed to be more constrained and the neck growth between the grains became remarkable with an increase of the amount of SnO₂.

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合成アルミ質ケイ酸塩ザクロ石[Mg₃Al₂Si₃O₁₂(Py),Mn₃Al₂Si₃O₁₂(Sp)]およびライム質ケイ酸塩ザクロ石[Ca₃・Al₂Si₃O₁₂(Gr),Ca₃Fe₂AlSi₃O₁₂(GA),Ca₃Fe₂Si₃O₁₂(An),Ca₃Cr₂Si₃O₁₂(Uv)]の赤外吸収スペクトルを測定した。
1000～800cm^-1の領域の強い吸収バンドは,PyとSpではA～Dの4本,GrとGAでは2本,AnとUvでは3本が観測された。天然ケイ酸塩ザクロ石ではつねに4本の吸収バンドが観測されている。
因子群解析およびサイト群解析の結果から,B,C,Dの吸収バンドについて,B-(C+D)/2をSiO₄四面体のV_s振動のサイト群分裂と考え,SiO₄四面体の共有綾と非共有稜の長さの差から求めた四面体ひずみとの関係を考察し0た。アルミ質ザクロ石からライム質ザクロ石のGrまで,四面体ひずみの減少とともに分裂の幅は減少するが,ライム質ザクロ石ではとくに相関関係は見られない。これは,四面体の振動は,6配位陽イオンよりも8配位陽イオンの格子振動と強くカップリングしていることを示唆する。A～Dスペクトルの形と四面体ひずみと分裂の幅との関係から,8配位陽イオンのイオン半径の小さいものほどカップリングは強く,四面体のひずみはGA,Gr,An,Uv,Sp,Al,Pyの順に増加すると推定された。
SiO₄四面体に関係すると考えられるA～Gの波数はアルミ質ザクロ石では8配位陽イオン,ライム質ザクロ石では6配位陽イオンのイオン半径の増加とともに減少する。
八面体に関する吸収バンド(H,I)はつぎの領域に観測された。AlO₆:480～450cm^-1,FeO₆:430～380cm^-1,CrO₆:450～410cm^-1。

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{Y₃} [Mg_yGa_3-y] (Ga_2-ySi_y)O₁₂ 系ザクロ石を合成し, {Y₃} [Mg_yGa_2-y] (M³⁺_3-ySi_y)O₁₂ 系ザクロ石 (M=Fe, Ga, Al) の生成過程および安定性を比較した。ザクロ石の生成過程において, YIMG (M=Fe ) では y=0.0～2.0にわたってYFeO₃, Y₂SiO₅ が準安定相としてザクロ石と共存するが, 加熱処理の繰り返しによって単一相のザクロ石を得た。YAMG (M=Al) では y=0.0～1.7にわたって YAlO₃, Y₄Al₂O₉, Y₂SiO₅, リン灰石型化合物などが準安定相として生成されるが, y>1.7 では Y₂SiO₅ とリン灰石型化合物は安定相としてザクロ石と共存し, 加熱処理の繰り返しによってザクロ石単一相を得ることはできない。YGaMG (M=Ga)では y=0.0～1.0においてはザクロ石以外の複酸化物は生成されず, y=2.0において準安定相として Y₂SiO₅, リン灰石型化合物が生成されるが, 加熱処理の繰り返しによって比較的容易にザクロ石単一相を得た。このように Ga³⁺ イオンを含むザクロ石は Fe³⁺ イオン,Al³⁺ イオンを含むザクロ石より生成され易く, より安定である。これは Ga³⁺ イオンが Fe³⁺ イオン, Al³⁺ イオンより4配位位置を取り易いためと考えられる。YGaMG の y=2.0組成ザクロ石は格子定数 a₀ =12.147±0.002Å,屈折率 n=1.820±0.05であった。
三つの系のザクロ石の格子定数, 屈折率と組成yとの関係を示す直線は y=0.0から y=2.0に向って次第に互に接近し外挿すると一点に集中する。その点の組成は {Y₃} [Mg₂] (Mg_0.5Si_2.5)O₁₂ に相当するが, 常圧下でこの組成のザクロ石を生成することはできなかった。この組成の推定格子定数および屈折率は, それぞれ α₀=12.125Å, n=1.792 である。

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Ca(OH)₂ and H₃PO₄ were used as starting materials for synthesizing hydroxyapatite (HAp). When the stoichiometric amount of 1mol/l solution of H₃PO₄ was added dropwise to a Ca(OH)₂ slurry in a N₂ at-mosphere, pH of the slurry was shifted from 11.7 to 3.7, and resultant HAp became Ca-deficient. The Ca/P molar ratio of HAp was strongly affected by pH of the reaction slurry. Stoichiometric HAp(Ca/P=1.67) was prepared by keeping the slurry at pH=7.0 with a tris (hydroxymethyl) aminomethane solution (Tris buffer) and by aging for 48h at 60°Cin a N₂ atmosphere. The Ca/P molar ratio of HAp was regulated by using Tris buffer to 1.66 under pH=6.0 and to 1.68 under pH=8.0, respectively. The stoichiometric HAp was stable up to 1300°C, and the lattice constants of the HAp calcined at 1100°C were a₀=0.94185(2)nm and c₀=0.68807(2)nm.

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The submicron samples of barium titanate were prepared by (1) the hydrolysis of titanium iso-propoxide in barium hydroxide solution (BT-I), (2) the simultaneous hydrolysis of barium iso-propoxide and titanium iso-propoxide (BT-II), and (3) the grinding of barium titanate prepared from barium carbonate and titanium oxide (BT-III) in iso-propyl alcohol or in air, and the species adsorbed on their surface were examined by means of TGA, DTA and IR spectroscopy.
On the as-prepared BT-I having the particle size of 100 to 300Å, the surface species identified were the hydrogen-bonded hydroxyl group, iso-propyl or iso-propoxy groups, the carboxyl group and the carbonate ion. Adsorbed alcohol began to be removed at about 200°C and all species disappeared completely above 800°C.
On the as-prepared BT-II having the particle size of about 100Å, the concentration of the iso-propoxy group and the carboxyl group seemed to be higher than those of as-prepared BT-I. Since the carbonate ion was not found on the as-prepared surface but appeared on heating it at 500°C, it is suggested that the carbonate ion would be formed from the carboxyl group.
When the BT-III was ground in iso-propyl alcohol, its IR spectra were similar to those of the as-prepared BT-I, but when ground in air, the large broad doublet spectra appeared in the stretching vibration region of carbonate salt, suggesting the monodentate bonding of the carbonate ion on the barium ion site.
The difference of the surface species and of the bonding character are considered to be related to the preparation method, the character of the surface ions, and the surface activity or the space charge layer near the surface of ferroelectric fine powder.

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The stability of several compounds in the system BaO-TiO₂ coprecipitated from the alkoxides were investigated. The samples in which the mole ratios of BaO to TiO₂ were 2/1, 1/1, 1/2, 1/3, 1/4, 2/9, 1/5 and 1/9 were prepared by the simultaneous hydrolysis of barium isopropoxide and titanium isopropoxide. On the as-prepared specimens, only 1/1 specimen crystallized as a single phase of cubic BaTiO₃, 2/1 was composed of cubic BaTiO₃ and Ba(OH)₂·H₂O, and all others in the TiO₂-rich region were of amorphous forms. It is suggested that Ba₂₊ in the 1/1 solution reacts as a strong Lewis acid and directly combines with Ti(OiPr)₆^2-, and a double alkoxide, Ba[Ti(OiPr)₆] is formed in isopropanol solution. In the TiO2-rich region, the polymerization takes place on the formation of Ti-O-Ti bridge following the hydrolysis of Ti(OiPr)₄, resulting in the precipitation of amorphous phase.
By heating at 800°C of 1/2 and 1/5 specimens, the single phases of BaTi₂O₅ and BaTi₅O₁₁ were formed respectively. Thus far the single phases of these compounds have not been obtained. Since BaTi₂O₅ and BaTi₅O₁₁ begin to decompose above 1200°C, they are considered to be a low temperature form or a metastable form.

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Barium titanate (BaTiO₃) powders were prepared by hydrolysis of Ba-Ti bimetallic alkoxides containing octyl groups. The as-prepared BaTiO₃ particles were amorphous in submicron size (-0.5μm). Crystalline BaTiO₃ particles were obtained on preheating at 393K in a flow of oxygen/water vapor mixed gas and successive heating at 673K in oxygen atmosphere. The introduction of water vapor suppressed the formation of BaCO₃, resulting in the formation of highly crystalline BaTiO₃. The microstructure of BaTiO₃ bodies sintered at 1573K exhibited grain sizes of 10-15 μm. They showed dielectric constant of about 2500 and the loss tangent of about 0.02 at the room temperature (1kHz).

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LiTaO₃ was prepared by hydrolyzing an ethanol solution of lithium ethoxide and tantalum ethoxide with H₂O in N₂ atmosphere. The samples with 25, 45, 46, ......, 54, 55 and 75 mole percent of Li₂O (Li₂O/Li₂O+Ta₂O₅ mol%) were coprecipitated.
The as-prepared samples with 45 to 55 mol% Li₂O were amorphous, but crystallized to LiTaO₃ byheating at 500°C for 2 h. Stability range of LiTaO₃ solid solution phase below 1100°C could be determined from change of the lattice constants of LiTaO₃ ss in 45 to 55 mol% samples heated at temperatures up to 1100°C. The ranges of LiTaO₃ ss phase were 49.9 to 51.2 mol% at 800°C, 49.1 to 51.6 mol% at 950°C and 48.0 to 52.0 mol% at 1100°C. The lattice constants of stoichiometric LiTaO₃ heated at 1100°C for 20 h were a_c=5.153+0.001 A, and c_o=13.78+0.01 A.
The as-prepared sample with 25 mol% Li₂O was amorphous, and crystallized to LiTaO₃ and fl-Ta₂O₅
at 700°C. Above 800°C, LiTa₃O₈ was formed by the reaction of LiTaO₃ with β-Ta₂O₅. A disordered NaCl type of Li₃TaO₄ was formed from the as-prepared sample with 75 mol% Li₂O which changed to ordered tetragonal phase above 800°C.

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Water base magnetic fluids were obtained by allowing anionic or nonionic surfactant to adsorb on the hydrophobic surface of magnetite colloid prepared by monomolecular adsorption of oleate. Sodium oleate, sodium dodecylbenzene sulfonate and polyoxyehtylene nonylphenyl ether (HLB=12) were used as a surfactant giving a double adsorption layer. In this paper, the influence of temperature and pH on the dispersion stability in water base magnetic fluids was investigated.
The influence of electrolytes on the dispersion stability was less in the fluid obtained by the use of nonionic surfactant than in that obtained by anionic one. When the temperature was raised, the viscosity of the fluid obtained by the use of nonionic surfactant suddenly increased at the cloud point of the solution of the surfactant. As a result, it was found that the fluid obtained by the use of sodium dodecylbenzene sulfonate was fairly stable against the change in temperature and pH.
Furthermore, it was found that when ethylene glycol was added to magnetic fluid, the freezing point of it was lowered, and simultaneously the evaporation of solvent was suppressed. Added amount of ethylene glycol over 60 vol% of magnetic fluid caused it to coagulate.

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Semiconducting tin dioxide particles were covered with insulating layer and its effect on electrorheological (ER) properties of the suspensions was examined under oscillatory and steady shear. When the particles were coated with titanium dioxide by hydrolyzing titanium tetraisopropoxide and heat-treated at 600°C, the suspension in a silicone oil showed a high yield stress at an electric field of 2.0 kV·mm^-1. However, since the titanium dioxide layer was semiconducting, the current density was about 0.2 mA·cm^-2 and would not be applicable to practical device. Using aluminium ion, the titanium dioxide can be doped from a semiconducting to an insulating state. The particles covered with surface layer consisting of titanium dioxide and aluminium oxide provided excellent ER fluids in water-free systems. The coating of semiconducting particles by hydrolysis of alkoxides is very useful for surface modification of particles to improve the ER performance of suspensions.

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OMCVD of TiO₂-SnO₂ mixed films using titanium isopropoxide and tetrabutyltin as starting materials was investigated. In the temperature region between 500° and 550°C crystalline films with desired composition were obtained. Pure titania films had the anatase crystal form, but the doped ones with more than 25% SnO₂ exhibited the rutile form. The size of crystallites in as-deposited films depended on the film composition and was found to be smallest near Ti/Sn ratio of 1:1. When the films were annealed at 1000°C over 50h, the crystalline size increased, however, its composition dependence was the same as that in as-deposited films. From this tendency and the composition dependence of lattice constants of the annealed films, it is concluded that the phase separation takes place through the spinodal decomposition during heat treatment. The as-deposited mixed films had no photo-conductivities but had moderate dark conductivities which strongly depended on the ambient gas components. Thus they are applicable to a basic material for gas sensors.

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