Determining europium compositional fluctuations in partially stabilized zirconia nanopowders: a non-line-broadening-based method

2016 ◽  
Vol 72 (1) ◽  
pp. 29-38 ◽  
Author(s):  
Riccardo Marin ◽  
Gabriele Sponchia ◽  
Michele Back ◽  
Pietro Riello
Keyword(s):  
Tetragonal Phase ◽  
Rietveld Analysis ◽  
Lattice Parameters ◽  
Crystalline Lattice ◽  
Precipitation Method ◽  
Stabilized Zirconia ◽  
Partially Stabilized Zirconia ◽  
Log Normal ◽  
Co Precipitation

A method is reported for assessing the compositional fluctuations in a ceramic sample, based only on the determination of the crystalline lattice parameters. Pure tetragonal phase partially stabilized zirconia powders are synthesized through the co-precipitation method by incorporating 4% Eu3+. The powder is subjected to compression cycles to promote the tetragonal-to-monoclinic transformation. The Rietveld analysis of the X-ray powder diffraction patterns, recorded after each compression cycle, gives information about the lattice parameters and monoclinic phase content. The determination of europium content in the residual tetragonal phase is accomplished considering the unit cell volume oft-ZrO2using Vegard's law. Using this information the compositional fluctuations over the sample were determined by considering two possible distributions of lanthanide ion content in the powders: a Gaussian and a Log-normal one. It was found that the Gaussian distribution better fits the experimental data. It was eventually demonstrated that these results are physically meaningful.

scholarly journals Equimolar Yttria-Stabilized Zirconia and Samaria-Doped Ceria Solid Solutions

Ceramics ◽  
2018 ◽  
Vol 1 (2) ◽  
pp. 343-352 ◽  
Author(s):  
Reginaldo Muccillo ◽  
Daniel de Florio ◽  
Eliana Muccillo
Keyword(s):  
Tetragonal Phase ◽  
Room Temperature ◽  
Single Phase ◽  
Rietveld Analysis ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Ceria Solid Solutions ◽  
Attrition Milling

Compositions of (ZrO2)0.92(Y2O3)0.08 (zirconia: 8 mol % yttria—8YSZ) and (CeO2)0.8(Sm2O3)0.2 (ceria: 20 mol % samaria—SDC20) ceramic powders were prepared by attrition milling to form an equimolar powder mixture, followed by uniaxial and isostatic pressing. The pellets were quenched to room temperature from 1200 °C, 1300 °C, 1400 °C and 1500 °C to freeze the defects configuration attained at those temperatures. X-ray diffraction analyses, performed in all quenched pellets, show the evolution of the two (8YSZ and SDC20) cubic fluorite structural phases to a single phase at 1500 °C, identified by Rietveld analysis as a tetragonal phase. Impedance spectroscopy analyses were carried out in pellets either quenched or slowly cooled from 1500 °C. Heating the quenched pellets to 1000 °C decreases the electrical resistivity while it increases in the slowly cooled pellets; the decrease is ascribed to annealing of defects created by lattice micro-tensions during quenching while the increase to partial destabilization of the tetragonal phase.

Effect of PEG on Structural and Magnetic Properties of Mn Doped ZnO Nanocrystals

2013 ◽  
Vol 678 ◽  
pp. 234-238 ◽  
Author(s):  
Vishwanath D. Mote ◽  
Babasaheb N. Dole
Keyword(s):  
Room Temperature ◽  
Magnetic Hysteresis ◽  
Lattice Parameters ◽  
Precipitation Method ◽  
Average Crystalline Size ◽  
X Ray ◽  
Zno Nanocrystals ◽  
Doped Zno ◽  
Co Precipitation ◽  
Mn Doped

Nanosized Mn doped ZnO samples were synthesized by co-precipitation method using Polyethylene glycol (PEG) as a capping agent. X- ray diffraction patterns confirm that the pure and Mn doped ZnO nanocrystals have wurtzite structure without any seconadary phases. Lattice parameters of pure and Mn doped ZnO nanocrystals increase slightly with increasing Mn concentration. The average crystalline size of pure and Mn doped ZnO nanocrystals are in the range of 14-18 nm. The X-ray density for pure and Mn doped ZnO sample is calculated using lattice parameters. It is found that almost static for Mn doped ZnO samples. In the Zn1-xMnx samples, room temperature magnetic hysteresis is observed and the saturation magnetization increases with increasing Mn content. However, these samples show room temperature ferromagnetic in nature. Result of the present investigation compared without PEG.

Near-Infrared Downconversion in LuPO4: Tm3+, Yb3+ Phosphors

2016 ◽  
Vol 16 (4) ◽  
pp. 3511-3516 ◽  
Author(s):  
Li Li ◽  
Yongjie Wang ◽  
Jun Shen ◽  
Wenxuan Chang ◽  
Tianting Jin ◽  
...  
Keyword(s):  
Tetragonal Phase ◽  
Diffuse Reflectance ◽  
Near Infrared ◽  
Luminescent Properties ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Good Crystallinity ◽  
Nir Emission ◽  
Co Precipitation

Tm3+ and Yb3+ codoped LuPO4 phosphors were synthesized by the reverse-strike co-precipitation method. The obtained LuPO4:Tm3+, Yb3+ phosphors were characterized by X-ray diffraction (XRD), diffuse reflectance spectra, photoluminescence (PL) spectra, and decay lifetime to understand the observed near-infrared downconversion (DC) phenomena. The XRD results show that all the prepared phosphors can be readily indexed to the pure tetragonal phase of LuPO4 and exhibit good crystallinity. The experimental results showed that the strong visible emission around 649 nm from Tm3+(1G4 → 3F4) and near-infrared (NIR) emission around 1003 nm from Yb3+(2F5/2 → 2F7/2) of LuPO4:Tm3+, Yb3+ phosphors were observed under 468 nm excitation, respectively. The Yb3+ concentration dependence of luminescent properties and lifetimes of both the visible and NIR emissions have also been investigated. The quenching concentration of Yb3+ ions approaches 30 mol%. The DC mechanism is also discussed in detail.

Effect of SiCp Addition on Microstructure and Mechanical Properties of ZTA Ceramics by Microwave Sintering

2018 ◽  
Vol 281 ◽  
pp. 217-223 ◽  
Author(s):  
Yong Qiang Chen ◽  
Sai Li ◽  
Wei Li ◽  
Ting Ting Su ◽  
Bing Bing Fan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Microwave Heating ◽  
Bending Strength ◽  
Microwave Sintering ◽  
Precipitation Method ◽  
Stabilized Zirconia ◽  
Oriented Growth ◽  
Directional Growth ◽  
Partially Stabilized Zirconia ◽  
Microstructure And Mechanical Properties

The effects of SiCp addition on the microstructure and mechanical properties of ZTA ceramics was investigated by microwave sintering. Partially stabilized zirconia（3Y-ZrO2）nanopowder containing SiCp was prepared by microwave pyrolysing precursor which was was achieved by co-precipitation method. The powders of alumina, yttria partially stabilized zirconia containing SiCp were mixed to prepare ZTA ceramics green body by die pressing and cold isostatic pressing and subsequently sintered at the range of 1350°C-1550°C for 30min by microwave. XRD revealed that 3Y-ZrO2/SiC powder contained more tetragonal phase than 3Y-ZrO2 powder which was also confirmed by SEM and particle size distribution. The phenomenon was because of SiCp forming the microwave heating spot that promoted pyrolysis progress when 3Y-ZrO2/SiC powder was prepared by microwave heating. Microstructure showed that the grain of ZTA ceramics had directional growth by microwave sintering. SiCp firstly absorbed microwave that made more uniform sintering of ZTA ceramics and caused local oriented growth of zirconia and alumina. Thus, the bending strength of ZTA ceramics was higher than ZTA without SiCp. The ladder type heating mode of microwave sintering ZTA ceramics reduced relatively sintering time by 20min due to the addition of SiCp.Introduction

Mechanical properties of ytterbia stabilized zirconia ceramics (Yb-TZP) fabricated from powders prepared by co-precipitation method

2000 ◽  
Vol 26 (2) ◽  
pp. 207-211 ◽  
Author(s):  
Susumu Nakayama ◽  
Sachihiko Maekawa ◽  
Tetsuji Sato ◽  
Yoshio Masuda ◽  
Shinji Imai ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Precipitation Method ◽  
Stabilized Zirconia ◽  
Zirconia Ceramics ◽  
Co Precipitation
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