scholarly journals Identification of tetragonal and cubic structures of zirconia using synchrotron x-radiation source

1991 ◽  
Vol 6 (6) ◽  
pp. 1287-1292 ◽  
Author(s):  
Ram Srinivasan ◽  
Robert J. De Angelis ◽  
Gene Ice ◽  
Burtron H. Davis
Keyword(s):  
Particle Size ◽  
Radiation Source ◽  
Sol Gel ◽  
Yttria Stabilized Zirconia ◽  
Tetragonal Structure ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Synchrotron Source ◽  
Three Samples

X-ray diffraction from a synchrotron source was employed in an attempt to identify the crystal structures in zirconia ceramics produced by the sol-gel method. The particles of chemically precipitated zirconia, after calcination below 600 °C, are very fine, and have a diffracting particle size in the range of 7–15 nm. As the tetragonal and cubic structures of zirconia have similar lattice parameters, it is difficult to distinguish between the two. The tetragonal structure can be identified only by the characteristic splittings of the Bragg profiles from the “c” index planes. However, these split Bragg peaks from the tetragonal phase in zirconia overlap with one another due to particle size broadening. In order to distinguish between the tetragonal and cubic structures of zirconia, three samples were studied using synchrotron radiation source. The results indicated that a sample containing 13 mol% yttria-stabilized zirconia possessed the cubic structure with a0 = 0.51420 ± 0.00012 nm. A sample containing 6.5 mol% yttria stabilized zirconia was found to consist of a cubic phase with a0 = 0.51430 ± 0.00008 nm. Finally, a sample which was precipitated from a pH 13.5 solution was observed to have the tetragonal structure with a0 = 0.51441 ± 0.00085 nm and c0 = 0.51902 ± 0.00086.

scholarly journals Effect of Deposition Conditions on Phase Content and Mechanical Properties of Yttria-Stabilized Zirconia Thin Films Deposited by Sol-Gel/Dip-Coating

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Francisco J. Cano ◽  
Orlando Castilleja-Escobedo ◽  
L. J. Espinoza-Pérez ◽  
Cecilia Reynosa-Martínez ◽  
Eddie Lopez-Honorato
Keyword(s):  
Heat Treatment ◽  
Wear Rate ◽  
Adhesion Strength ◽  
Surface Defects ◽  
Sol Gel ◽  
Dip Coating ◽  
Yttria Stabilized Zirconia ◽  
Cubic Phase ◽  
Phase Content ◽  
Stabilized Zirconia

The effect of yttria concentration (0-33.4 mol%), extraction rates (0.17, 0.33, 0.50, and 0.67 mm s-1), and the number of layers (up to four) on the phase content, surface defects, thickness, hardness, adhesion strength, and wear rate of yttria-stabilized zirconia coatings produced by sol-gel/dip-coating were studied for its use on thermolabile substrates. At 700°C, a metastable tetragonal phase ( t ″ ) was obtained even with 33.4 mol% yttria when heat treated for 24 hours; however, a fully cubic structure was attained by extending the heat treatment up to 48 hours as confirmed by Raman spectroscopy. Furthermore, it was necessary to use withdrawal speeds of at least 0.67 mm s-1 to produce defect-free coatings. Although the coatings were produced at low temperature, they showed 41% lower wear rate than steel and an adhesion strength of 30 MPa. Our work stresses the importance of the heat treatment history on the stabilization of the cubic phase in sol-gel YSZ coatings.

Study of Crystallite Size of Yttria-Stabilized Zirconia Powders by Rietveld Method

2010 ◽  
Vol 660-661 ◽  
pp. 965-970 ◽  
Author(s):  
Wellington Claiton Leite ◽  
Adriana Scoton Antonio Chinelatto ◽  
André Maurício Brinatti ◽  
Mauricio Aparecido Ribeiro ◽  
André Vitor Chaves de Andrade ◽  
...  
Keyword(s):  
Rietveld Method ◽  
Pechini Method ◽  
Lattice Parameter ◽  
Yttria Stabilized Zirconia ◽  
Crystalline Size ◽  
Cubic Phase ◽  
Average Crystalline Size ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Atomic Scattering

The yttria-stabilized zirconia (YSZ) is used in a great variety of applications, for example, electrolytes of solid oxide fuel cells and oxygen sensors. In the study of YSZ, the particle size powders and sintering processes are important to define the final properties of the zirconia products. The objectives of this work were to determine the phases and the crystalline size using X-Ray Diffraction (XRD) data and the Rietveld Method (RM) of the YSZ powders obtained by chemical synthesis based on the Pechini method. It was used ZrOCl2.8H2O and Y(NO3)3.5H2O as precursors reagents. After calcination at 550oC during 24 hours, the powder was analyzed by XRD and scanning electronic microscopy (SEM). From XRD and using Rietveld method were verified that there is only cubic phase with lattice parameter a = 5.1307(1) Å and the space group Fm3m. Due to substitution of the Zr atoms in the Y atoms sites, there were vacancies in 17.72 % of O atoms sites. However, the percentage of substitution of Zr atoms in Y atoms sites in the structure not was determinate because the curves of atomic scattering of them are very similar. Using Scherrer equation and considering anisotropy effect, the average crystalline size was determinate: 10,43 nm (c axis) and 10,39 (b axis). This spherical symmetry also observed for SEM.

Characterizations of Synthetic 8mol% YSZ with Comparison to 3mol %YSZ for HT-SOFC

2020 ◽  
Vol 38 (4A) ◽  
pp. 491-500
Author(s):  
Abeer F. Al-Attar ◽  
Saad B. H. Farid ◽  
Fadhil A. Hashim
Keyword(s):  
Ionic Conductivity ◽  
Electrochemical Impedance ◽  
Structural Information ◽  
Impedance Analysis ◽  
High Energy ◽  
Yttria Stabilized Zirconia ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Powder Morphology ◽  
X Ray

In this work, Yttria (Y2O3) was successfully doped into tetragonal 3mol% yttria stabilized Zirconia (3YSZ) by high energy-mechanical milling to synthesize 8mol% yttria stabilized Zirconia (8YSZ) used as an electrolyte for high temperature solid oxide fuel cells (HT-SOFC). This work aims to evaluate the densification and ionic conductivity of the sintered electrolytes at 1650°C. The bulk density was measured according to ASTM C373-17. The powder morphology and the microstructure of the sintered electrolytes were analyzed via Field Emission Scanning Electron Microscopy (FESEM). The chemical analysis was obtained with Energy-dispersive X-ray spectroscopy (EDS). Also, X-ray diffraction (XRD) was used to obtain structural information of the starting materials and the sintered electrolytes. The ionic conductivity was obtained through electrochemical impedance spectroscopy (EIS) in the air as a function of temperatures at a frequency range of 100(mHz)-100(kHz). It is found that the 3YSZ has a higher density than the 8YSZ. The impedance analysis showed that the ionic conductivity of the prepared 8YSZ at 800°C is0.906 (S.cm) and it was 0.214(S.cm) of the 3YSZ. Besides, 8YSZ has a lower activation energy 0.774(eV) than that of the 3YSZ 0.901(eV). Thus, the prepared 8YSZ can be nominated as an electrolyte for the HT-SOFC.

Effect of Yttria-Stabilized Zirconia Concentration in an Electroless Bath on Microstructure and Composition of Ni/Yttria-Stabilized Zirconia Nanocomposite

2021 ◽  
Vol 21 (11) ◽  
pp. 5592-5602
Author(s):  
Samira Almasi ◽  
Ali Mohammad Rashidi
Keyword(s):  
High Performance ◽  
Yttria Stabilized Zirconia ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Nickel Ion ◽  
Nanocomposite Particles ◽  
X Ray ◽  
Ni Content ◽  
Naoh Solution ◽  
Average Size

The effect of the yttria-stabilized zirconia (YSZ) nanoparticle loading in an electro-less bath was considered as one of the vital synthesis variables for control Ni content and microstructure of prepared nanocomposite particles, which are two crucial factors to achieving high-performance SOFC anode. Nanocomposite particles were prepared using a simple electroless method without any expensive pretreatment of sensitizing by Sn2+ ions as well as activating by Pd2+ ions that are usually used to apply nickel coating on the surface of a non-conductive substrate. The process was performed by adding YSZ nanoparticles into NaOH solution, separating them from the solution by the centrifugal method, then providing several water-based nanofluids with different concentrations of activated YSZ nanoparticles, mixing them with NiCI2 solution, followed by adding the hydrazine and then NaOH solution. X-ray diffraction and scanning electron microscopy coupled with energy dispersive X-ray analysis were used to analyze the prepared nanocomposite particles. It is observed that after adding YSZ nanoparticles into the NaOH solution, the pH of the solution varied gradually from a starting pH of 10.2 to 9. Also, by increasing the YSZ nanoparticles loading in the electroless bath from 76 mg/l to 126 mg/l, the grain size of Ni deposits, the Ni content and the average size of the prepared nanocomposite particles decreased. The electrochemical mechanism previously proposed for the nickel ion reduction was modified, and a novel analytical model was proposed for variation of the efficiency of Ni deposition with YSZ nanoparticles loading.

scholarly journals Structural and Magnetic Property of Cr3+ Substituted Cobalt Ferrite Nanomaterials Prepared by the Sol-Gel Method

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2095 ◽  
Author(s):  
Jinpei Lin ◽  
Jiaqi Zhang ◽  
Hao Sun ◽  
Qing Lin ◽  
Zeping Guo ◽  
...  
Keyword(s):  
Saturation Magnetization ◽  
Sol Gel ◽  
Combustion Method ◽  
Lattice Parameter ◽  
Cubic Phase ◽  
Cobalt Chromium ◽  
X Ray Diffraction ◽  
Chromium Doping ◽  
Auto Combustion ◽  
Cr Concentration

Cobalt-chromium ferrite, CoCrxFe2−xO4 (x = 0–1.2), has been synthesized by the sol-gel auto-combustion method. X-ray diffraction (XRD) indicates that samples calcined at 800 °C for 3 h were a single-cubic phase. The lattice parameter decreased with increasing Cr concentration. Scanning electron microscopy (SEM) confirmed that the sample powders were nanoparticles. It was confirmed from the room temperature Mössbauer spectra that transition from the ferrimagnetic state to the superparamagnetic state occurred with the doping of chromium. Both the saturation magnetization and the coercivity decreased with the chromium doping. With a higher annealing temperature, the saturation magnetization increased and the coercivity increased initially and then decreased for CoCr0.2Fe1.8O4.

scholarly journals Effect of the suspension of Ag-incorporated TiO2 nanoparticles (Ag-TiO2 NPs) on certain growth, physiology and phytotoxicity parameters in spinach seedlings

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0244511
Author(s):  
Fernando Gordillo-Delgado ◽  
Jakeline Zuluaga-Acosta ◽  
Gonzalo Restrepo-Guerrero
Keyword(s):  
Particle Size ◽  
Titanium Dioxide Nanoparticles ◽  
Germination Rate ◽  
Sol Gel ◽  
Control Group ◽  
Human Consumption ◽  
X Ray Diffraction ◽  
X Ray ◽  
Growth Physiology ◽  
Powder Samples

In this work, the effect of the inoculation of silver-incorporated titanium dioxide nanoparticles (Ag-TiO2 NPs) in spinach seeds was evaluated on certain growth, physiology and phytotoxicity parameters of the plants. This is an important crop for human consumption with high nutritional value due to their low calorie and fat content, providing various vitamins and minerals, especially iron. These NPs were obtained by means of the sol-gel method and heat treatment; the resulting powder material was characterized using X-ray diffraction and scanning electron microscopy and the influence of these NPs on plants was measured by estimating the germination rate, monitoring morphological parameters and evaluating phytotoxicity. The photosynthetic activity of the spinach plants was estimated through the quantification of the Ratio of Oxygen Evolution (ROE) by the photoacoustic technique. Samples of TiO2 powder with particle size between 9 and 43 nm were used to quantify the germination rate, which served to determine a narrower size range between 7 and 26 nm in the experiments with Ag-TiO2 NPs; the presence of Ag in TiO2 powder samples was confirmed by energy-dispersive X-ray spectroscopy. The analysis of variance showed that the dependent variable (plant growth) could be affected by the evaluated factors (concentration and size) with significant differences. The statistical trend indicated that the application of the Ag-TiO2 NPs suspension of lowest concentration and smallest particle size could be a promoting agent of the growth and development of these plants. The inoculation with NPs of 8.3 nm size and lowest concentration was related to the highest average ROE value, 24.6 ± 0.2%, while the control group was 20.2 ± 0.2%. The positive effect of the Ag-TiO2 NPs treatment could be associated to the generation of reactive oxygen species, antimicrobial activity, increased biochemical attributes, enzymatic activity or improvements in water absorption.

Structural and Magnetic Properties of Nano Composite (Ni1-xSrx Fe12 O19) Prepared by Sol-gel

2021 ◽  
Vol 19 (10) ◽  
pp. 20-28
Author(s):  
Dhifaf Hussain Hassan ◽  
Sabah Jalal Fathi
Keyword(s):  
Magnetic Properties ◽  
Hysteresis Loop ◽  
Quaternary Structure ◽  
Sol Gel ◽  
Magnetic Hysteresis ◽  
Magnetic Hysteresis Loop ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Two Phases ◽  
Hematite Fe2o3

The compound was prepared by sol-gel method for spontaneous combustion with certain weight ratios (x=0.0,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9), the samples were calcined at a temperature (900oC) for a period of two hours(2h), then studied its structural and magnetic properties.one of the most prominent results that we obtained from the X-ray diffraction technique (XRD) is that compound has several phases. Where the sample (NiFe2O4) appeared to be polycrystalline and the dominant phase in it is the cubic phase, while the other phase is (Hematite)(Fe2O3) A crystal structure rhomboid (Rhombohedral), in addition to these two phases, the phase with the existing quaternary structure appeared (Sr2Fe2O5) its called (Orthorhombic). The results of the magnetic properties that were obtained through the (VSM) device, and one of the most important of these properties is the magnetic hysteresis loop by analyzing the magnetic hysteresis loop at (x=0.3), where the least area of the hysteresis loop or the least width of the hysteresis loop One of the most important parameters of the magnetic properties is the saturation magnetism (μS) and its value ranges from (19.76-3.86) (emu/gr), the highest value was at (X=0.3) and its value is (19.76emu/gr) and in general its value decreases with increasing concentration of strontium. The residual magnetism (Mr) ranges between (7.45-1.58) (emu/gr), where it reached its highest value at (x=0.3) and its value is (7.45emu/gr), and generally its value decreases with increasing concentration of strontium. In addition to that, there is another parameter which is coercion or Magnetic coercivity (Hc) ranges in value (1751.104-209.26) (Oe), reaching its lowest value at (x=0.3), and then increases with increasing strontium concentration until it reaches its highest value at (x=0.9), where it reached its value is (1751.104Oe). The square rate represented by the symbol (μi) has high values. This means that there is a mutual coupling between the soft and hard magnetic phases, which was the highest value at (x=0.3) and its value is (4.93).

scholarly journals High Performance Mixed Potential Type NO2 Gas Sensor Based on Porous YSZ Layer Formed with Graphite Doping

Sensors ◽  
2019 ◽  
Vol 19 (15) ◽  
pp. 3337 ◽  
Author(s):  
Hao Hong ◽  
Jianwen Sun ◽  
Cinan Wu ◽  
Zewen Liu
Keyword(s):  
High Performance ◽  
Sol Gel ◽  
Yttria Stabilized Zirconia ◽  
Mixed Potential ◽  
Stabilized Zirconia ◽  
No2 Gas Sensor ◽  
Potential Type ◽  
Measurement Results ◽  
Good Repeatability ◽  
Sensor Measurement

High performance mixed potential type NO2 sensors using porous yttria-stabilized zirconia (YSZ) layers doped with different concentration graphite as solid electrolyte and LaFeO3 as sensing electrode were fabricated and characterized. LaFeO3 was prepared by a typical citrate sol–gel method and characterized using XRD. The surface morphology and porosity of porous YSZ layers were characterized by field emission scanning electron microscope (FESEM). The sensor doped with 3 wt% graphite shows the highest response (−76.4 mV to 80 ppm NO2) and the response is linearly dependent on the logarithm of NO2 concentration in the range of 10–200 ppm. The sensor measurement results also present good repeatability and cross-sensitivity.

Corrosion Resistance of Partially Stabilized Zirconia Materials to Alkaline Steel Slag

2020 ◽  
Vol 852 ◽  
pp. 119-128
Author(s):  
Liang Zhao ◽  
Qian Huang ◽  
Hua Yin Sun ◽  
Xiang Li
Keyword(s):  
Corrosion Resistance ◽  
Steel Slag ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Zirconia Powder ◽  
Slag Film ◽  
Partially Stabilized Zirconia ◽  
Stabilizing Agents ◽  
The Relationship

Partially stabilized zirconia (PSZ) materials were fabricated using 4 wt% CaO, 3 wt% MgO, and 5.4 wt% Y2O3 as stabilizing agents together with monoclinic zirconia powder. The physical properties, phase compositions, and microstructures of the Ca-PSZ, Mg-PSZ, and Y-PSZ samples were investigated by X-ray diffraction, scanning electron microscopy, and energy spectrum analysis. A crucible method was used to explore the relationship between the stabilizing agent and erosion resistance to alkaline steel slag. The results revealed that the zirconia materials stabilized by different stabilizing agents showed obvious differences in their bulk densities, apparent porosities, microstructures, and erosion resistances to alkaline steel slag. The structure of Y-PSZ showed highest density, containing a small number of uniformly distributed pores. In terms of Mg-PSZ, the intergranular bonding in its structure was observed to not be close, and the sample contained some cracks, but no pores. A large number of intragranular pores and a small number of overall pores was observed in Ca-PSZ, resulting in this material having the lowest bulk density. The pores and cracks provide the path to penetrate and diffuse for alkaline steel slag, which weakens the corrosion resistance of PSZ materials. The phase composition of the affected layers in all of the samples after corrosion was almost completely transformed from monoclinic phase to cubic phase, and the phase transition of both the original and transition layers was not obvious due to the formation of a slag film. Y-PSZ did not react with components of the steel slag such as SiO2 and Al2O3, showing the best corrosion resistance to alkaline steel slag.

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