Sol-gel Process for the Manufacturing of Translucent Lead Zirconate Titanate Gel-monolith

Translucent Lead Zirconate Titanate (PZT) gel-monolith was prepared by partially hydrolyzing metal alkoxides solution which modified with acetylacetone(acacH). Metal alkoxides, lead di-i-propoxide, zirconium tetra-nbutoxide and titanium tetra-i-propoxide were used as starting materials. In Infrared spectra for the translucent monolithic gel after aging at room temperature for several days or drying at 90°C for 18h, the most significant feature is the presence of band at around 1554 cm-1 which can be assigned to the v (C-O) and v (C-C) vibrati-ons of acetylacetanate group coordinated to the metal cations Ti and Zr. The diffraction peaks of PbO were found after heating at 300°C for 2h. After heating at 450 °C for 2 h, diffraction peaks of pyrochlore Pb2 Ti206 and perovskite PZT phase were observed. The diffraction peaks of PbO and pyrochlore phase disappeared after heating at 600°C, and tetragonal perovskite phase was stable up to 1000 °C. The diffraction peaks of perovskite phase were also found after heating at 430 ° for 24 h. The density of the compacted pulverizedgel after heating at 1000°C for 30 min. was 6.9 g/cm3 , about 86% of the theoretical value

Crystallization Behavior And Micromorphology Of Sol-gel Derived Mesoporous Nano-particles Titania

CRYSTALLIZATION BEHAVIOR AND MICROMORPHOLOGY OF SOL-GEL DERIVED MESOPOROUS NANO-PARTICLES TITANIA. In this work, effects of drying methods on the micro-morphology ofinesoporpous TiO2 prepared by the sol-gel method has been studied using transmission electron microscopy (TEM), X-ray diffraction analysis (XRD) and N2 gas adsorption. Mesoporous TiO2 consists of anatase nano-particles, about 5nm in diameter, have been obtained by hydrolysis of titanium alkoxide in a methanol solution and supercritical extraction in CO2 at 60°C and 22Mpa. XRD peaks ofrutile have been found after annealing at 600°C. The particle sizes of anatase and rutile are about 13 and 25nm in diameter, respectively. The surface morphology of Ti02 nano-particles has been discussed with the surface fractal dimensions estimated from the N2 gas adsorption isotherms

Pengaruh Metode Pemisahan Pelarut Dalam Gel Terhadap Sifat Fisik Titania-alumina Sebagai Penyangga Katalis

PENGARUH METODE PEMISAHAN PELARUT DALAM GEL TERHADAP SIFAT FISIK TITANIA-ALUMINA SEBAGAI PENYANGGA KATALIS. TiO2-Al2O3 gel monolitik dalam nisbah mol 0,2 untuk TiO2 dan 0,8 untuk Al2O3 telah dibuat dengan cara hidrolisis dari aluminium sec-butoksida, Al (OC4H9sec)3 dan titanium isopropoksida Ti(OC3H7iso)4 dalam larutan n-propanol dengan katalis asam. Pemisahan pelarut dalam gel dilakukan dengan dua cara, pertama pengeringan pada tekanan atmosfer hingga terbentuk xerogel. Kedua, pemisahan pelarut pada kondisi CO2 superkritik, hingga terbentuk aerogel. Terbentuknya gugus Ti-O, salah satu dari titanium dioksida atau jaringan polimer –Ti-O-Ti-O-Al-O- ditunjukkan dengan adanya puncak antara 500 dan 900 cm-1 yang tajam tetapi lebar pada spektrum infra merah. Puncak yang kuat pada 1635 cm-1 menandakan adanya gugus –OH uluran yang merupakan derajat yang tinggi dari permukaan hidroksilasi. Volume kumulatif pori-pori dari xerogel sangat kecil jika dibandingkan dengan aerogel hasil pemisahan pelarut pada kondisi CO2 superkritik. Fase anatase TiO2 tidak terbentuk selama proses kristalisasi hingga kalsinasi sampai suhu 1000oC. Pengkristalan alumina terjadi secara langsung dari fasa amorf Al2O3 ke fasa α-Al2O3 dan fasa-fasa antara θ- dan γ-Al2O3 tidak teramati. Dari hasil tersebut dapat diperkirakan bahwa selama kalsinasi partikel TiO2 terpisah dari partikel Al2O3 membentuk inti atom rutil sebelum terbentuknya kristal α-Al2O3. Karena itu pembentukan fasa rutile TiO2 akan mempercepat terbentuknya fasa α-Al2O3. Keasaman campuran titania alumina setelah dikalsinasi pada suhu 500 oC lebih tinggi daripada oksidanya masing-masing, yaitu TiO2 dan Al2O3. Hal ini disebabkan oleh terbentuknya asam Lewis dari campuran titania-alumina

Anomalous Transport Phenomena in Fermi Liquids with Strong Magnetic Fluctuations

In many strongly correlated electron systems, remarkable violation of the relaxation time approximation (RTA) is observed. The most famous example would be high-Tc superconductors (HTSCs), and similar anomalous transport phenomena have been observed in metals near their antiferromagnetic (AF) quantum critical point (QCP). Here, we develop a transport theory involving resistivity and Hall coefficient on the basis of the microscopic Fermi liquid theory, by considering the current vertex correction (CVC). In nearly AF Fermi liquids, the CVC accounts for the significant enhancements in the Hall coefficient, magnetoresistance, thermoelectric power, and Nernst coefficient in nearly AF metals. According to the numerical study, aspects of anomalous transport phenomena in HTSC are explained in a unified way by considering the CVC, without introducing any fitting parameters; this strongly supports the idea that HTSCs are Fermi liquids with strong AF fluctuations. In addition, the striking \omega-dependence of the AC Hall coefficient and the remarkable effects of impurities on the transport coefficients in HTSCs appear to fit naturally into the present theory. The present theory also explains very similar anomalous transport phenomena occurring in CeCoIn5 and CeRhIn5, which is a heavy-fermion system near the AF QCP, and in the organic superconductor \kappa-(BEDT-TTF).Comment: 100 pages, Rep. Prog. Phys. 71, 026501 (2008

Benzyltrimethylammonium Chloride Immersion Effect on Physical Properties of Tio2 – Al203

BENZYLTRIMETHYLAMMONIUM CHLORIDE IMMERSION EFFECT ON PHYSICAL PROPERTIES OF TiO2 – Al2O3. Mesoporous TiO2 - Al2O3 powders have potential applications in catalysts or support catalysts. A novel method to control pore size of sol--gel by a cationic surfactant benzyltrimethylammonium chloride (BTAC) Immersion was investigated. The gels of TiO2- Al2O3 in molar ratio of 0.2 of TiO2, and 0.8 of Al2O3 were prepared by hydrolysis of aluminium sec-butoxide, Al(OC4H9sec)3 and titanium isopropoxide Ti(OC3H7iso)4 in an n-propanol solution with acid catalyst. The structures and porosities of the modified TiO2-A|2O3 was depended on the dimensions of surfactant, as long as the calcination was carried out at 500℃ to avoid aggregation process during removal of excess BTAC. If the calcinations were carried out at 800℃ no significant change of the pore volume of modified samples was remarkably not observed, even though formation of TiO2 rutile has been taken place. It indicated that samples modification by initial immersion of gel into BTAC may avoid the sintering. These results suggest that during the calcinations TiO2, was segregated from the Al2O3 particles to form nuclei of rutile and was crystallized prior to formation of α- Al2O3. Therefore, the formation of rutile TiO2 induced the formation of α- Al2O3