Luminescence in Anodic ZrO 2 Doped with Eu(III)ions

Indian Journal of Pure & Applied Physics

Versatile zirconium oxide as a ceramic has propelled a rapid development of science and technology for diverse applications. Among the class of ceramics, it holds a distinctive position due to its excellent physical, chemical and mechanical properties owing to its phase transformation. Zirconia is high k-dielectric, mechanical resistance and high radiation tolerance material. Although, this material replaces SiO 2 due to its high dielectric constant so it can be employed to various memory device applications. It has essential implications in nuclear reactors, inert matrix fuel, nuclear waste systems, container for radioactive materials and designing of new materials owing to its high radiation tolerance property. Dentists proclaimed that zirconium oxide is "ceramic steel" where it has attracted prosthetic dentistry because of its strength and esthetics are admired. Addition of few percentages of stabilizers such as Y 2 O 3 , MgO and Ni etc. make it useful for specific applications. Zirconium oxide ceramic is indispensably used as an electrode and electrolyte in energy efficient solid state electrochemical devices (fuel cells) that generates electricity with good efficiency from natural gas and fuel cell plants and provides auxiliary power in vehicles. One of its important phase transformation mechanisms is being focused and extensively reviewed due to the effect of temperature variation and ion beam irradiation effect. The objective of current review is to present the knowledge of extensive properties, synthesis techniques and its various implications and guidelines for optical, medical, fuel cells, biological and electrical and memory devices and nuclear applications. The advantages of zirconia with respect to other oxide materials are also reviewed.

Journal of Physics: Conference Series, 2010

A samarium doped polycrystalline ZrO 2 bulk sample was investigated for its phase composition as well as optical properties within the temperature range 6-300 K. From micro-Raman measurements the existence of tetragonal as well as monoclinic phase was confirmed. The emission spectrum of Sm 3+ reveals drastic changes under excitation near the region of fundamental absorption. Combined excitation-emission spectroscopy (CEES) measurements reveal three different sites for the dopant ions to be present in the sample. Nature and excitation scheme of the three sites are discussed.

Journal of The European Ceramic Society, 2003

The local structure around Zr, Ce and dopant atoms (Fe and Ni) in the ZrO 2 -CeO 2 system investigated by X-ray absorption spectroscopy (XAS) is reported to better understand the tetragonal phase stabilization process of zirconia. The first coordination shell around Zr atoms is not sensitive to the introduction of dopants or to an increase in the ceria content (from 12 to 20 mol%). Ce ions maintain the eight-fold coordination as in CeO 2 , but with an altered bond distance. The formation of vacancies resulting from reduction of Ce atoms can be discarded, because XANES spectra clearly show that Ce ions are preferentially in a tetravalent state. XANES and EXAFS experiments at the Fe K-edge evidence that the local order around Fe is quite different from that of the Fe 2 O 3 oxide. On the one hand, ab initio EXAFS calculations show that iron atoms form a solid solution with tetragonal ZrO 2 . The EXAFS simulation of the first coordination shell around iron evidences that the substitution of zirconium atoms by iron ones generates oxygen vacancies into the tetragonal network. This is a driven force for the tetragonal phase stabilization process. For Ni doped samples, EXAFS results show that Ni-O mean bond length is similar to the distance found in the oxide material, i.e., NiO compound. Besides this result, no evidence of similar solid solution formation for Ni-doped systems has emerged from the EXAFS analysis . #

Crystal Research and Technology, 2015

This work reports the synthesis of nanostructured ZrO 2 by anodization of zirconium electrodes at potentials well below the range of 10-50 V used as a standard procedure. Zirconium was first anodized in a 1M (NH 4) 2 SO 4 electrolyte and then further anodized in the presence of fluoride ions added to the electrolyte as NH 4 F. The maximum potential applied to zirconium during the whole process was 1 V with respect to an Ag/AgCl (sat.) reference electrode. Amorphous films of ZrO 2 consisting of nanopores and nanowire-like structures were produced with this low-potential methodology.

Materials Letters, 2003

The nanocrystalline powders of the system SnO 2-ZrO 2 has been prepared using zirconium oxalate and tin tartarate, which are also synthesised from their organic and inorganic precursors. The aqueous solutions of oxalate and tartarate are mixed with proper proportions and with polyvinyl alcohol to form the polymer precursor solution. This is evaporated, pyrolysed and calcined to nanocrystalline powders. The phase of the powders is cubic at the temperature of calcination of 700 jC with the crystallite size ranges from 15 to 25 nm, whereas the particles size ranges from 30 to 50 nm for the sample containing 5 mol% SnO 2. The shapes of the particles are oval and spherical. The alloying can be done up to 20 mol% with SnO 2. The material is promising for chemical sensors.

physica status solidi (c), 2014

Procedia Chemistry, 2016

0.3 wt % ammonium fluoride (NH 4 F) or ammonium chloride (NH 4 Cl) was added to ethylene glycol (EG) as an active ingredient for the formation of anodic oxide comprising of ZrO 2 nanotubes (ZNTs) by anodic oxidation of zirconium (Zr) at 20 V for 10 min. It was observed that nanotubes were successfully grown in EG/NH 4 F/H 2 O with aspect ratio of 144.3. Shorter tubes were formed in EG/NH 4 F/H 2 O 2. This could be due to higher excessive chemical etching at the tip of the tubes. When fluoride was replaced by chloride in both electrolytes, multilayered oxide resembling pyramids was observed. The pyramids have width at the bottom of 3-4 µm and the top is 1-2 µm with 10.7 µm height. Oxidation of Zr in EG/NH 4 Cl/H 2 O 2 was rater rapid. The multilayered structure is thought to have formed due to the re-deposition of ZrO 2 or hydrated ZrO 2 on the foil inside pores formed within the oxide layer. XRD result revealed an amorphous structure for as-anodized samples regardless of the electrolytes used for this work.

Physica Status Solidi (a), 1993

EPR and Structural Studies of Doped (Zr02)o.8 (Y20Joe2 BY B. N. MISHRA (a), S. V. SHARMA (b), P. CHAND (b), and N. L. SHUKLA (a) Polycrystalline samples of (Zr02)o,8(Y203)o,2 ceramic oxides doped with vanadium, iron, nickel, and cobalt are synthesized and characterized using X-ray diffraction, scanning electron microscopy, and electron paramagnetic resonance techniques. It is observed from EPR studies that the nickel-doped sample exhibits a rather broad signal comprising a large number of narrow lines. It is noted from the XRD and SEM studies that all the samples consist of mainly two phases, monoclinic and tetragonal.

With the help of microwave-assisted technique, zirconia (ZrO 2) nanocrystalline powder was synthesized using a structure directing agent which could be controlled by the nucleation and particle growth. The various characterizations, namely, phase, surface morphology, surface area analysis and optical property were carried out by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) and UVevisible spectroscopy. From XRD analysis, it was found that the synthesized materials reveal the tetragonal crystalline phase. The average particle size of ZrO 2 was found 14.7 nm by TEM. Specific surface area, pore volume and the pore size for ZrO 2 are 220 m 2 /g, 0.02 cm 3 /g and 10.7 nm investigated by BET, respectively. UVevis DRS spectra of the prepared material confirmed that the Zr atoms are exclusively incorporated within silica framework. Besides, the maximum absorption peaks were observed at 215 nm and 217 nm for as-synthesized and calcined samples, respectively.

2014

The influence of low concentrations (1 mol %) of few co-dopants (Y2O3, La2O3, CeO2, Gd2O3, Er2O3, ZnO) on the structure and characteristic of 10 mol % scandia stabilized zirconia was studied. Sintering kinetics and thermal expansion coefficients of synthesized solid eletrolytes were determined. It was found that co-doping increased the conductivity of electrolytes at temperature below 550°C. However, at high temperatures, the introduction of co-dopants decreased the conductivity; moreover, this reduction was more severe the more the ionic radii of Zr4+ and co-dopant differ