Supported sulfated zirconia catalysts with zirconia contents of 10, 20 and 50 wt% were prepared by impregnation of SiO2 and γ-Al2O3 supports with H2SO4/Zr(SO4)2 solutions followed by calcination at 923 K. The catalysts were characterized by X-ray diffraction, extended X-ray absorption fine structure measurements, thermal analysis, UV–vis spectroscopy, and electron microscopy. Tetragonal zirconi...

During the past decade, zirconia-based ceramics have been successfully introduced into the clinic to fabricate small and large restorations. Today, we have a better understanding of the physical properties, characteristics, and practical behavior of zirconia, which has led to a more predictable fabrication of clinically acceptable, long-term restorations.1 Zirconia is normally milled from block...

The surface morphology and crystal structure change of dental zirconia after hydrofluoric acid (HF) etching were evaluated. Four groups of sintered zirconia specimens were 1) control group, 2) immersion in 9.5%HF at 25°C for 1, 2, 3, or 24 h, 3) immersion in 9.5%HF at 80°C for 1, 3, 5, or 30 min and 4) immersion in 48%HF at 25°C for 30 or 60 min. The specimens were evaluated under SEM and XRD. ...

The microscopic mechanism leading to stabilization of cubic and tetragonal forms of zirconia (ZrO2) is analyzed by means of a self-consistent tight-binding model. Using this model, energies and structures of zirconia containing different vacancy concentrations are calculated, equivalent in concentration to the charge compensating vacancies associated with dissolved yttria (Y2O3) in the tetragon...

The phases of ceria–zirconia nanoparticles observed in air are studied as a function of particle size and composition by X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The emergence of two tetragonal phases t00 and t monotonically moves toward higher zirconia concentrations with decreasing particle size. A smaller particle size increases the solubility of zirconia ...

Metal sulfate formation is one of the major challenges to the emission aftertreatment catalysts. Unlike the incredibly sulfation prone nature of Pd to form PdSO4, no experimental evidence exists for PtSO4 formation. Given the mystery of nonexistence of PtSO4, we explore PtSO4 using a combined approach of an evolutionary algorithm based search technique and quantum mechanical computations. Exper...

the stabilized zirconia with different cu contents synthesized via sol-gel method. the samples were prepared by hydrolysis and condensation of orgnomatelic sol. after that the result gels were dried at 80 °c and then calcined at various temperatures.  ِ the differential thermal analysis (dta), x-ray diffraction (xrd), field emission scanning electronic microscopy (fesem) and transmission electro...

Biomass offers a renewable carbon source that could be utilized as a raw material in the chemicals industry. A potential route for the conversion of biomass feedstock’s into industrial chemicals is through the catalytic conversion of biomass sugars (glucose) to furan based compounds through an aqueous reforming process. However, to accommodate the transport of these bulky sugars within the cata...