Zirconium nanoparticles

Dental Fillings. Nanoparticles of zirconium oxide (Zr02) are being used in the new UV-cured dental fillings. They give strength and are transparent to visible light, but are opaque to X-rays. Rare-earth oxides can also be used. 

The 0-d nanoparticles can be nano-metal oxides (such as silica,1 titania,2 alumina3), nano-metal carbide,4 and polyhedral oligomeric silsesquioxanes (POSS),5 to name just a few the 1-d nanofibers can be carbon nanofiber,6 and carbon nanotubes (CNT),7 which could be single-wall CNTs (SWCNT) or multiwall CNTs (MWCNT) etc. the 2-d nano-layers include, but are not limited to, layered silicates,8 layered double hydroxides (LDH),9 layered zirconium phosphate,10 and layered titanates,11 etc. 3-d nano-networks are rarely used and thus examples are not provided here. 

Metallic phosphates nanoparticles have been identified as potential components of FR systems for PP. Hu and coworkers98 99 have used a-zirconium phosphate (a-ZrP) in combination with IFR based on APP and PER. 

Nanosized ceria-zirconia materials with improved thermal stability can be prepared by using the surfactant-assisted method. Structural refinements confirm that the nanocrystals contain structural microstrain and cationic lattice defects. Zirconium addition to ceria supresses the crystal sintering and imporves the thermal stability but leads to structure distortion. Both catalytic tests and CO-chemisorption show that Pd supported ceria-zirconia nanoparticles are active for CO oxidation. 

The techniques used for preparing nanoparticles are similar to those used to prepare more conventional drug particles and include controlled precipitation, ball milling using glass or zirconium oxide pearls, and high-pressure homogenization. 

In a similar work, ultrasound radiation was used to prepare EU2O3 doped in zir-conia and yttrium-stabilized zirconium (YSZ) nanoparticles [83]. Europium oxide was also coated sonochemically on the surface of submicron spherical zirconia and YSZ, which were fabricated by wet chemical methods. Time decay measurements of the doped and coated materials were conducted using a pulsed laser source. Lifetimes < 1.1 ms radiative lifetime of the Eu+ ions were detected for the doped and coated as-prepared materials. When the doped and coated samples were an-... 

Antimicrobial nanoflbers of poly(e-caprolactone) (PCL) were prepared by electrospinning of a PCL solution with small amounts of Ag-loaded zirconium phosphate (AgZ) nanoparticles for potential use in biomedical applications [41]. SEM, EDX, and XRD investigations of the electrospun flbers confirmed that Ag-containing nanoparticles were incorporated and well-dispersed in smooth PCL nanoflbers [41]. In another study, PCL-based polyurethane (PCL-PU) nanoflbers containing Ag nanoparticles for use in antimicrobial nanofllter applications were prepared by... 

In addition to the above, preparation in w/o microemulsions of nanoparticles of various other types of compounds, viz. silica-coated iron oxide, Fe203-Ag nanocomposite, oxides of ytrium, erbium, neodymium, vanadium and cobalt, titanates of barium and lead, ferrites of barium, strontium, manganese, cobalt and zinc, oxide superconductors, aluminates, zirconium silicate, barium tungstate, phosphates of calcium, aluminium and zinc, carbonates of calcium and barium, sulphides of molybdenum and sodium, selenides of cadmium and silver etc. have been reported. Preparative sources and related elaboration can be found in [24]. 

Figure 13 TEM image of zirconia nanoparticles forming a nanofiltration membrane obtained from a zirconium oxychloride precursor.

Morooka and coworkers [104,105] and Kawai et al. [106] prepared zirconia nanoparticles by the microemulsion-mediated alkoxide sol-gel method. In all cases, zirconium tetrabutoxide (ZTBO) served as the alkoxide precursor. In the work of Morooka and coworkers [104,105], the surfactant was dioleyl phosphoric acid (DOLPA) and the microemulsion was prepared by a solvent extraction process [Eq. (20)]. After phase separation, zirconia particles were produced by introducing a butanol solution of ZTBO into the microemulsion solution. The resulting zirconia particles had an average size of 2 nm. 

In the first class of CPs nanocomposites, the oxides considered as secondary component are titanium dioxide (TiO ), zirconium dioxide (ZrOj), silicon dioxide (SiO ), aluminium oxide (Al O ), cadmium oxide (CdO) and zinc oxide (ZnO) [19, 27, 31, 48-52]. Titanium dioxide nanoparticles have excellent properties such as charge carrier, oxidising power, non-toxicity, chemical and photo stability. Conductive PANI/TiO nanocomposites combine the qualities of PANI and nanocrystalline TiO within a single material, thereby developing multifunctional materials with combined properties which have very strong potential applications. 

Most of the reported inorganic fillers used to modify Nafion are composite where the inorganic particles (usually nanoparticles) are located in the membrane bulk. Most of them are prepared using the recast method, where the filler nanoparticles dispersed in a solvent are mixed with Nafion ionomer dispersion in the same solvent or a compatible one. The solution is cast on a Petri dish or a plane surface at high temperature to form the recast composite membrane. An alternative method adopted to prepare Nafion composites with silica [31, 32, 41, 95], functionalized silica [35], and zirconium and titanium phosphate [41], is the in situ sol-gel reaction method, schematized in Fig. 6.5. 

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