共查询到20条相似文献,搜索用时 31 毫秒
1.
Tadashi Kokubo Satoru Yoshihara Naomi Nishimura Takao Yamamuro Takashi Nakamura 《Journal of the American Ceramic Society》1991,74(7):1739-1741
A CaO─SiO2 ─P2 O5 ─CaF2 glass powder hardened within 4 min when mixed with an ammonium phosphate solution to form CaNH4 PO4 ·H2 O. After it had soaked in a simulated body fluid for 3 d, forming hydroxyapatite, the cement showed a compressive strength of 80 MPa. Implanted into a rat tibia, the mixed paste formed a tight chemical bond to the living bone within 4 weeks. Such a bioactive cement could be useful not only for fixing various kinds of implants to the surrounding bones but also, by itself, as a bone filler. 相似文献
2.
Hideo Hosono Zhibo Zhang Yoshihiro Abe 《Journal of the American Ceramic Society》1989,72(9):1587-1590
A porous glass-ceramic in the CaO–TiO2 —P2 O5 system has been prepared by crystallization and subsequent chemical leaching of the corresponding glass. By applying a two-step heat treatment to 45CaO · 25TiO2 · 30P2 O5 glasses containing a few mol% of Na2 O, volume crystallization results in the formation of dense glass-ceramics composed of CaTi4 (PO4 )6 and β-Ca3 (PO4 )2 phases. By leaching the resultant glass ceramics with HCI, β-Ca3 (PO4 )2 is selectively dissolved out, leaving a crystalline CaTi4 (PO4 )6 skeleton. The surface area and mean pore radius of the porous glass-ceramics were approximately 40 m2 /g and 13 nm, respectively. 相似文献
3.
The phase relations were established experimentally for the system CaO-Al2 O3 -P2 O5 -H2 O at 200°C and 1710 kPa. The quaternary compound, crandallite, CaAl3 (PO4 )2 (OH)5 · H2 O, was found to be stable. Compatibility joins in the system were determined. The phase relations are presented on the isothermal-isobaric 90 wt% water plane and by projecting the primary fields of the liquidus surface onto the same plane. 相似文献
4.
Porous glass-ceramics with a skeleton of the fast-lithium-conducting crystal Li1+ x Ti2− x Al x (PO4 )3 (where x = 0.3–0.5) were prepared by crystallization of glasses in the Li2 O─CaO─TiO2 ─Al2 O3 –P2 O5 system and subsequent acid leaching of the resulting dense glass-ceramics composed of the interlocking of Li1+ x Ti2− x Al x (PO4 )3 and β-Ca3 (PO4 )2 phases. The median pore diameter and surface area of the resulting porous Li1+ x Ti2− x Al x (PO4 )3 glass-ceramics were approximately 0.2 μm and 50 m2 /g, respectively. The electrical conductivity of the porous glass-ceramics after heating in LiNO3 aqueous solution was 8 × 10−5 S/cm at 300 K or 2 × 10−2 S/cm at 600 K. 相似文献
5.
Masayuki Nogami Yoichi Goto Toshihiro Kasuga 《Journal of the American Ceramic Society》2003,86(9):1504-1507
The effect of zirconium ions on glass structure and proton conductivity was investigated for sol-gel-derived P2 O5 –SiO2 glasses. Porous glasses were prepared through hydrolysis of PO(OCH3 )3 , Zr(OC4 H9 )4 , and Si(OC2 H5 )4 . Chemical bonding of the P5+ ions was characterized using 31 P-NMR spectra. The phosphorous ions, occurring as PO(OH)3 in the ZrO2 -free glass, were polymerized with one or two bridging oxygen ions per PO4 unit with increased ZrO2 content. The chemical stability of these glasses was increased significantly on the addition of ZrO2 , but the conductivity gradually decreased from 26 to 12 mS/cm at room temperature for 10P2 O5 ·7ZrO2 ·83SiO2 glass. A fuel cell was constructed using 10P2 O5 ·5ZrO2 ·85SiO2 glass as the electrolyte; a power of ∼4.5 mW/cm2 was attained. 相似文献
6.
HALKA BILINSKI BORIS MATKOVI CARMEN MAURANI TONCCI BALI UNI † 《Journal of the American Ceramic Society》1984,67(4):266-269
The reactions leading to the formation of crystalline Mg3 (OH)5 Cl·4H2 O (phase 5), Mg2 (OH)3 ,Cl·4H2 O (phase 3), and Mg(OH)2 are compared for the systems MgO-MgCl2 -H2 O and NaOH-MgCl2 -H2 O. The crystalline phases were determined by X-ray diffraction analysis. The concentration of the total magnesium and chloride in the solution and the pH of the solution determine the reaction product(s) in both systems. The influence of MgO reactivity and the molar ratio of reactants on the formation and stability of reaction products is discussed and the mechanism of the formation of phases 3 and 5 is explained. In the system MgO-MgCl2 -H2 O, MgO serves only to increase the concentration of total magnesium and the pH of the MgCl2 solution. 相似文献
7.
The existence of stable and metastable forms of 2ZrO2 ·P2 O5 and the subsolidus phase relations in the system ZrO2 -ZrP2 O7 were confirmed before investigation of the ternary system. The synthesis and thermal behavior of ZrW2 O8 were reinvestigated, and the system WO3 -P2 O5 was examined cursorily. A ternary compound, 2ZrO2 ·WO3 ·P2 O5 , was found, and compatibility triangles for the system between 1105° and 1150°C were established. The ternary compound is compatible with ZrO2 , WO3 , and three binary compounds, giving rise to five composition triangles. In addition, ZrP2 O7 , WO3 , and "W2 O3 (PO4 )2 " were compatible. 相似文献
8.
CARMEN MAURANI HALKA BILINSKI BORIS MATKOVI 《Journal of the American Ceramic Society》1982,65(10):523-526
The precipitation process of solid phases Mg3 (OH)5 CI-4H2 O (phase 5), Mg2 (OH)3 CI-4H2 O (phase 3), and Mg(OH)2 was followed by the addition of NaOH water solution in MgCl2 water solutions of different concentrations (0.001 to 4.8 mol dm−3 ) and characterized by chemical, potentiometric, coulometric, and X-ray diffraction analyses. The concentration range in which the precipitation of solid phases occurs was determined. The phase distributions relative to the pH of solution and concentrations of magnesium and chloride were defined by the equilibrium diagram. The approximate solubility products of stable solid phases formed at different ionic strengths and at 293 K were determined. 相似文献
9.
Paste samples of tricalcium aluminate alone, with CaCl2 , with gypsum, and with gypsum and CaCl2 were hydrated for up to 6 months and the hydration products characterized by SEM, XRD, and DTA. Tricalcium aluminate hydrated initially to a hexagonal hydroaluminate phase which then changed to the cubic form; the transformation rate depended on the size and shape of the sample and on temperature. The addition of CaCl2 to tricalcium aluminate resulted in the formation of 3CaO · Al2 O3 · CaCl2 ·10H2 O and 4CaO · Al2 O3 · 13H2 O, or a solid solution of the two. The chloride retarded the formation of the cubic phase 3CaO · Al2 O3 · 6H2 O; the addition of gypsum resulted in the formation of monosulfoaluminate with a minor amount of ettringite. When chloride was added to tricalcium aluminate and gypsum, more ettringite was formed, although 3CaO · Al2 O3 · CaSO4 · 12H2 O and 3CaO · Al2 O3 · CaCl2 · 10H2 O were the main hydration products. 相似文献
10.
Sophie Jordery William E. Lee Peter F. James 《Journal of the American Ceramic Society》1999,82(8):2239-2245
Crystallization of a series of ZnO-P2 O5 based glasses was investigated. ZnO-P2 O5 -CaO glasses could be converted most readily to glass-ceramics and crystallization of these led to formation of alpha-Zn2 P2 O7 , alpha-CaZn2 (PO4 )2 , and ß-CaZn2 (PO4 )2 phases. A further phase has been tentatively identified as monoclinic (Zn,Ca)2 P2 O7 . The most promising glass-ceramic composition Z15 (59.4ZnO·33P2 O5 ·6.6CaO·1SiO2 ) crystallized to alpha-Zn2 P2 O7 and ß-CaZn2 (PO4 )2 , the latter phase being stabilized by the presence of SiO2 which also encouraged volume nucleation giving a fine-scale (submicrometer) microstructure. 相似文献
11.
Debao Zhang Baoyu Chen Zhuping Liu Shunguang Li Lili Hu 《Journal of the American Ceramic Society》2004,87(12):2228-2231
Er3+ -doped sodium lanthanum aluminosilicate glasses with compositions of (90− x )(0.7SiO2 ·0.3Al2 O3 )· x Na2 O·8.2La2 O3 · 0.6Er2 O3 ·0.2Yb2 O3 ·1Sb2 O3 (in mol%) ( x = 12, 20, 24, 40, 60 mol%) were prepared and their spectroscopic properties were investigated. Judd–Ofelt analysis was used to calculate spectroscopic properties of all glasses. The Judd–Ofelt intensity parameter Ω t ( t = 2, 4, 6) decreases with increasing Na2 O. Ω2 decreases rapidly with increasing Na2 O while Ω4 and Ω6 decrease slowly. Both the fluorescent lifetime and the radiative transition rate increase with increasing Na2 O. Fluorescence spectra of the 4 I 13/2 to 4 I 15/2 transition have been measured and the change with Na2 O content is discussed. It is found that the full width at half-maximum decreases with increasing Na2 O. 相似文献
12.
Junying Zhang Zhongtai Zhang Zilong Tang Yuanhua Lin 《Journal of the American Ceramic Society》2002,85(4):998-1000
A (Ce0.67 Tb0.33 )Mn x Mg1− x Al11 O19 phosphor powder was synthesized, using a simple sol–gel process, by mixing citric acid with CeO2 , Tb4 O7 , Al(NO3 )3 ·9H2 O, Mg(OH)2 ·4MgCO3 ·6H2 O, and Mn(CH3 COO)2 . The phosphor crystallized completely at 1200°C, and the phosphor particle size was between 1 and 5 μm. The excitation spectrum was characteristic of Ce3+ , while the emission spectrum was composed of lines from Tb3+ and Mn2+ . The Mn2+ gave a green fluorescence band, and concentration quenching occurred when x > 0.10. The luminescent properties of the phosphor were explained by a configurational coordinate model. 相似文献
13.
Subsolidus Phase Relationships in Part of the System Si,Al,Y/N,O: The System Si3 N4 ─AIN─YN─Al2 O3 ─Y2 O3
Wei-Ying Sun Tseng-Ying Tien Tung-Sheng Yen 《Journal of the American Ceramic Society》1991,74(11):2753-2758
The subsolidus phase relationships in the system Si,Al,Y/N,O were determined. Thirty-nine compatibility tetrahedra were established in the region Si3 N4 ─AIN─Al2 O3 ─Y2 O3 . The subsolidus phase relationships in the region Si3 N4 ─AIN─YN─Y2 O3 have also been studied. Only one compound, 2YN:Si3 N4 , was confirmed in the binary system Si3 N4 ─YN. The solubility limits of the α'─SiAION on the Si3 N4 ─YN:3AIN join were determined to range from m = 1.3 to m = 2.4 in the formula Y m /3 Si12- m Al m N16 . No quinary compound was found. Seven compatibility tetrahedra were established in the region Si3 N4 ─AIN─YN─Y2 O3 . 相似文献
14.
The influence of citric acid on paste hydration of 3CaO· Al2 O3 in the presence of CaSO4 ·2H2 O and Ca(OH)2 was studied using X-ray diffraction, scanning electron microscopy, and conduction calorimetry. The time at which the citric acid is added (either prior to or with the mixing water) determines how it affects the reactivity of the aluminate. Immediately after the paste is gaged citric acid promotes a more rapid reaction, but later reactions are retarded. Hexagonal calcium aluminate hydrates, ettringite, and monosulfate were all detected as early hydration products. The influence of citric acid on the hydration of 3CaO·Al2 O3 slabs immersed in saturated CaSO4 ·2H2 O solutions was also studied and a reaction scheme proposed. 相似文献
15.
The compositional range for glass formation below 1600°C in the Sm2 O3 ─Al2 O3 ─SiO2 system is (9–25)Sm2 O3 ─(10–35)Al2 O3 ─(40–75)SiO2 (mol%). Selected properties of the Sm2 O3 ─Al2 O3 ─SiO2 (SmAS) glasses were evaluated as a function of composition. The density, refractive index, microhardness, and thermal expansion coefficient increased as the Sm2 O3 content increased from 9 to 25 mol%, the values exceeding those for fused silica. The dissolution rate in 1 N HCl and in deionized water increased with increasing Sm2 O3 content and with increasing temperature to 70°C. The transformation temperature ( T g ) and dilatometric softening temperature ( T d ) of the SmAS glasses exceeded 800° and 850°C, respectively. 相似文献
16.
Zhong Zhuang Xian Ping Wang Dan Li Tao Zhang Qian Feng Fang 《Journal of the American Ceramic Society》2009,92(4):839-844
Dense, crack-free, and uniform La2 Mo2− x W x O9 ( x =0, 0.1, and 0.2) nanocrystalline films were successfully synthesized on poly-alumina substrates via a modified sol–gel method, with inorganic salt of La(NO3 )3 ·6H2 O, (NH4 )6 Mo7 O24 ·4H2 O, and (NH4 )6 H2 W12 O24 as precursors. Pure La2 Mo2 O9 phase was confirmed by X-ray diffractometer when the annealing temperature was >500°C. The average grain size of the La2 Mo2− x W x O9 films is in the range of 90–400 nm, depending upon the conditions of thermal treatment, and the thickness of films can reach 1 μm by repetitive spin-coating. The electrical conductivity increases with decreasing grain size and reaches 0.074 S/cm at 600°C in the film with a grain size of 90 nm, which is one order of magnitude higher than that in the corresponding bulk materials. W-doping can suppress the phase transition that occurs at 580°C in pure La2 Mo2 O9 and enhance the low-temperature ionic conductivity. Furthermore, the activation energy of conductivity in the nanocrystalline La2 Mo2 O9 films decreases to about 0.6 eV in comparison with 1.0 eV in the bulk ones, which implies that the grain resistance prevails in the total resistance, when grain size reduces to nanometer domain. 相似文献
17.
Takeshi Shiono Koji Shiono Kazuyo Miyamoto Giuseppe Pezzotti 《Journal of the American Ceramic Society》2000,83(1):235-37
A precursor was synthesized from a heterogeneous alkoxide solution that contained fine MgO powder, which allowed the preparation of MgAl2 O4 spinel powder with high sinterability characteristics. The precursor consisted of a mixture of boehmite (AlO(OH)) and a mixed hydroxide (Mg4 Al2 (OH)14 · 3H2 O). The spinel phase formed through two steps: (i) decomposition of the mixed hydroxide at low temperature and (ii) solid-state reaction between MgO and γ-Al2 O3 at higher temperatures. Dense polycrystalline spinel could be obtained from the calcined powders at sintering temperatures as low as 1400°C. 相似文献
18.
Sashi Tandon Ranchhor D. Agrawal Madan L. Kapoor 《Journal of the American Ceramic Society》1994,77(4):1032-1036
The viscosity of sodium borate slags at high Na2 O concentrations (37.3 to 49.4 mol%) and high temperatures (1000° to 1300°C) follows an Arrhenius-type relationship. This relationship was also observed for sodium borate slags (mass% Na2 O/mass% B2 O3 = 0.86) containing CaO and CaF2 for the same temperature range. There has been a reduction in viscosity of the sodium borate slags (mass% Na2 O3 mass% B2 O = 0.53 to 0.86) with increase in Na2 O concentration. On adding CaO (10 to 50 mass%) to the sodium borate slag (mass% Na2 O/mass% B2 O3 = 0.86), the viscosity increased considerably, while an addition of CaF2 (S to 15 mass%) to the slag (30.9 mass% Na2 O3 35.8 mass% B2 O3 , 33.3 mass% CaO) decreased the viscosity. The average activation energies of Na2 O─B2 O3 , Na2 O─B2 O3 ─CaO3 and Na2 O─B2 O3 ─CaO─CaF2 slag systems have been estimated as 14.6, 124.7, and 41.4 kJ/mol, respectively, for the given composition ranges and 1000° to 1300°C temperature range. 相似文献
19.
Phase equilibria have been determined in the system CaO-Al2 O3 -H2 O in the temperature range 100° to 1000°C. under water pressures of up to 3000 atmospheres. Only three hydrated phases are formed stably in the system: Ca(OH)2 , 3CaO·Al2 O3 ·6H2 O, and 4CaO·3Al2 O3 -3H2 O. Pressure-temperature curves delineating the equilibrium decomposition of each of these phases have been determined, and some ther-mochemical data have been deduced therefrom. It has been established that both the compounds CaO·Al2 O3 and 3CaO·Al2 O3 have a minimum temperature of stability which is above 1000°C. The relevance of the new data to some aspects of cement chemistry is discussed. 相似文献
20.
Kousuke Yamamoto Toshihiro Kasuga Yoshihiro Abe 《Journal of the American Ceramic Society》1997,80(3):822-824
A novel porous glass-ceramic with a skeleton of CuTi2 (PO4 )3 was prepared by controlled crystallization of a glass and subsequent chemical leaching of the resulting dense glass-ceramic. A volume-crystallized dense glass-ceramic composed of CuTi2 (PO4 )3 and Cu3 (PO4 )2 whose surface was covered by a CuO thin layer was prepared by reheating a glass with a nominal composition of 50CuO·20TiO2 30P2 O5 (in mol%) glass in air. When the resultant glass-ceramic was leached with dilute H2 SO4 , Cu3 (PO4 )2 and CuO phases were dissolved out selectively, leaving a crystalline CuTi2 (PO4 )3 skeleton. The specific surface area and the average pore radius of the porous glass-ceramic obtained were approximately 45 m2 g-1 and 9 nm, respectively. The porous glass-ceramic showed catalytic activity in the conversion reaction of propene into acrolein. 相似文献