Characterization of Nanocrystalline Yttria-Stabilized Zirconia: An In Situ HTXRD Study

Nanocrystalline yttria-stabilized zirconia powders, synthesized by the citrate nitrate gel combustion route, with yttria concentration varying from 8 to 12 mol% were studied by in situ high temperature X-ray diffraction in the temperature range of 25–1000°C. The sample obtained has a high specific surface area of 35 m2/g while calculated surface area was around 123 m2/g. The in situ high temperature X-ray diffraction study revealed that crystallite size remains in the range of 7–9 nm up to 800°C and then rapidly grows up to 21–23 nm upto 1000°C; only holding the material at 1000°C for 30 minutes can promote grain growth in the range of 42–49 nm. Coefficient of thermal expansion ranges from 9.65 to 9.03 ppm/°C for 8–12 mol% nanocrystalline yttria-stabilized zirconia.

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Probing the Dehydroxylation of Kaolinite and Halloysite by In Situ High Temperature X-ray Diffraction

Minerals ◽

10.3390/min10050480 ◽

2020 ◽

Vol 10 (5) ◽

pp. 480

Author(s):

Imane Daou ◽

Gisèle Lecomte-Nana ◽

Nicolas Tessier-Doyen ◽

Claire Peyratout ◽

Maurice Gonon ◽

...

Keyword(s):

High Temperature ◽

Coefficient Of Thermal Expansion ◽

Tape Casting ◽

Treatment Temperature ◽

Structure Evolution ◽

X Ray Diffraction ◽

X Ray ◽

Pole Figures ◽

Basal Distance

Textured kaolinite and halloysite-based materials were shaped by tape casting in order to promote the alignment of clay particles along the tape casting direction and to investigate the structure evolution of these phyllosilicates during the dehydroxylation process. The crystallinity indexes HI and R2 of the starting kaolins (KRG and KCS) were determined and appeared close to values found for the well-ordered reference kaolin KGa-1b. The halloysite clay exhibited trimodal grain size distribution and tended to be less textured than KRG and KCS according to the (002) pole figures performed on green tapes. The constant heating rate derived kinetic parameters matched the expected range. We followed the dehydroxylation of kaolinite and halloysite through in situ high-temperature X-ray diffraction measurements at the ESRF synchrotron radiation source on the D2AM beamline. The dehydroxylation of these kaolinite and halloysite occurred between 425 °C and 675 °C for KRG and KCS and from 500 °C to 650 °C for halloysite. In addition, the evolution of the basal distance of kaolinite regarding the heat treatment temperature confirmed that the dehydroxylation process occurred in three steps: delamination, dehydroxylation, and formation of metakaolinite. The calculated coefficient of thermal expansion (CTE) along the c axe values were close to 17 × 10−6 °C−1 for kaolinite (KCS and KRG) and 14 × 10−6 °C−1 for halloysite.

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Application of in situ Transmission Electron Microscopyfor Tribological Investigations of Magnetron Sputter Assisted Pulsed Laser Deposition of Yttria-stabilized Zirconia-gold Composite Coatings

Journal of Materials Research ◽

10.1557/jmr.2005.0232 ◽

2005 ◽

Vol 20 (7) ◽

pp. 1860-1868 ◽

Cited By ~ 12

Author(s):

J.J. Hu ◽

A.A. Voevodin ◽

J.S. Zabinski

Keyword(s):

Electron Microscopy ◽

High Temperature ◽

Composite Coatings ◽

Pulsed Laser ◽

Yttria Stabilized Zirconia ◽

Stabilized Zirconia ◽

X Ray ◽

Transmission Electron ◽

Wide Range

Yttria-stabilized zirconia (YSZ)-Au composite coatings have great potential as solid film lubricants for aerospace applications over a wide range of environmental conditions. They were grown on steel disks or silicon wafers by pulsed laser ablation of YSZ and simultaneous magnetron sputtering of a Au target. Such a combination of ceramics with soft metals improved the toughness of the composite coating and increased its ability to lubricate at high temperature. Information on the time-dependent response of these microstructures to changes in temperature is essential to tribological investigations of high temperature performance. In situ transmission electron microscopy was used to directly measure the dynamic change of YSZ-Au coating structure at elevated temperatures. High-resolution electron microscopy and electron diffraction showed that amorphous YSZ-5 at.% Au coatings proceeded to crystallize under the irradiation of electron beams. Time varying x-ray energy dispersive spectra measured a loss of oxygen in the sample during about 10 min of irradiation with subsequent slight oxygen recovery. This behavior was related to the activation of oxygen diffusion under electron irradiation. X-ray diffraction patterns from vacuum annealed samples verified crystallization of the coatings at 500 °C. Real-time growth of Au nanograins in the sample was observed as the temperature was increased to 500 °C in a TEM specimen holder that could be heated. The grain growth process was recorded using a charge-coupled device camera installed on the transmission electron microscope. The crystallization and growth of zirconia and Au nanograins resulted in low friction during tribological tests. The nucleation of Au islands on heated ball-on-flat specimens was responsible for lowering friction.

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

Engineering and Technology Journal ◽

10.30684/etj.v38i4a.351 ◽

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.

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Thermal expansion of ellinaite (β-CaCr2O4): an in-situ high temperature X-ray diffraction study

Physics and Chemistry of Minerals ◽

10.1007/s00269-020-01126-2 ◽

2021 ◽

Vol 48 (1) ◽

Author(s):

Weihong Xue ◽

Kuan Zhai ◽

Shuangmeng Zhai

Keyword(s):

Thermal Expansion ◽

High Temperature ◽

Diffraction Study ◽

X Ray Diffraction ◽

X Ray

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In-Situ X-ray Diffraction Measurement for Pure Niobium Metal in High Temperature Hydrogen Atmosphere

Journal of the Japan Institute of Metals and Materials ◽

10.2320/jinstmet.70.467 ◽

2006 ◽

Vol 70 (6) ◽

pp. 467-472 ◽

Cited By ~ 2

Author(s):

Tomonori Nambu ◽

Nobue Shimizu ◽

Hisakazu Ezaki ◽

Hiroshi Yukawa ◽

Masahiko Morinaga ◽

...

Keyword(s):

High Temperature ◽

Hydrogen Atmosphere ◽

Diffraction Measurement ◽

X Ray Diffraction ◽

X Ray ◽

Pure Niobium

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

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2021.19461 ◽

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.

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