Quantitative XRD analysis of zirconia-toughened alumina ceramics

Fillit, R.Y.; Homerin, R. P.; Schäfer, Robert; Bruyas, R. H.; Thevenot, R. F.

doi:10.1007/bf01161460

Cited by 46 publications

(11 citation statements)

References 10 publications

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“…Details of the reference intensity ratio method can be found in Ref [16][17][18][19]. The method is based on the measurement of integral intensities of selected peaks of the phases and relating their ratios to the weight content of a phase using a set of constants.…”

Section: X-ray Diffractionmentioning

confidence: 99%

Alumina-base plasma-sprayed materials—Part II: Phase transformations in aluminas

et al. 1997

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Aluminum oxide is widely used for plasma spraying. Alumina deposits consist of a number of metastable crystallographic modifications, which at elevated temperatures, transform to the stable c~ phase. It was shown that additions of various oxides changed the phase composition and shift phase transformation temperatures. This paper addresses the variation of phase compositions and temperatures of the phase changes for plasma-sprayed alumina deposits manufactured with alumina-base materials containing Cr203 and TiO2.This study combines the results obtained from energy dispersive analyzer of X-rays (EDAX) and scanning electron microscopy (SEM) chemical analysis, differential thermal analysis (DTA), and X-ray powder diffraction (XRD) quantitative phase analysis of as-sprayed and annealed samples of alumina deposits and shows how the two additives change the phase composition and the c~-phase formation temperature. This transformation temperature varied by nearly 200 ~ The metastable alumina sequences were also influenced by the chemical composition; for example, the content of 0 alumina varied between 0 and 55 wt %.

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Section: X-ray Diffractionmentioning

confidence: 99%

Alumina-base plasma-sprayed materials—Part II: Phase transformations in aluminas

et al. 1997

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“…Complete isotropy would be realized if + was measured up to 90" or if corrections, taking care of the range explored and of the sample orientation, were applied (20).…”

Section: X-ray Characterizationmentioning

confidence: 99%

Growth by the CSVT (close-spaced vapor transport) technique and characterization of epitaxial GaAs layers on Ge substrates

Koskiahde¹,

Cossement²,

Guelton³

et al. 1991

Can. J. Phys.

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Epitaxial layers of GaAs on (100) GaAs substrates can be grown by close-spaced vapor transport using water vapor as the transporting agent. The parameters for the transport are Ti = 755°C. AT' = 45°C. and 6 = 0.03 cm (where Ti is the temperature of the graphite heating the substrate; AT', the temperature difference between the graphite heating the source and the one heating the substrate; and 6. the thickness of the spacer separating the GaAs source and the substrate). Mirrorlike epitaxial layers of GaAs are obtained with these parameters when water vapor, at a partial pressure of 4.58 Torr ( 1 Torr = 133.3 Pa), is introduced with H, at the beginning of the temperature rise of the reactor. The dimensions of the epitaxial layer are only limited by the size of the reactor. Using the same growth conditions. it is not possible to obtain mirrorlike films of GaAs on (100) Ge substrates. Instead, the layers are dull grey (sample no. I ) . It is howcder not a polycrystalline deposition since the pole figures, obtained by X-ray diffraction. reveal only four crystallographic orientations: {loo} the main one. {221} the secondary one, and {021} + {I 12) two minor contributions. Mirrorlike films of GaAs on (100) Ge substrates of less than 1 cni' have been obtained with T: = 775OC. AT' = 25°C. and 6 = 0.03 cm. With these conditions, the growth rate is 0.25 + 0.08 k m m i n I . The time evolution of T: and AT', froni room temperature up to the equilibrium temperature also influences the surface morphology of GaAs films on Ge while this was not the case for GaAs films on GaAs substrates. When the Ge substrate is larger than I cm'. the centre of the film becomes textured but the edges reniain mirrorlike (sample no. 2). Pole figures obtained for the center and the edges of sample no. 2 are similar. They are characterized by one large diffraction due to the (100) orientation. A few random crystallographic orientations and sometimes the {221} orientation, however, bearly emerge froni the background of these pole figures. Also transmission electron microscopy does not reveal any major difference between the center and the edges of sample no. 2. The density of threading dislocations is the sanie for both regions, varying from 10' c m ', close (2-3 k m ) to the interface, to lo7 c m ' in the thickness of the film. No misfit dislocations were observed.Antiphase boundaries are present in both regions as well. The only difference between the centre and the edges of sample no. 2 involves microtwin bundles: in the center region, there are two microtwin bundles per micrometre of interface, extending up to 6 km in the GaAs film while on the edges, there is one bundle per micrometre with an extension of only one micrometre into the epitaxial layer. Mirrorlike GaAs films can be obtained on (100) Ge substrates of at least 1 in ( 1 in = 2.5 cni) in diameter by increasing 6 to 0.2 cm and by injecting water vapor in the reactor only when Ti reached 650°C: the other deposition parameters reniain the sanie as for sample no. 2. In these conditions, th...

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“…The proportion in the bulk may differ to some extent as it was shown that rather high gradients of the monoclinic to tetragonal ratio occur as a function of the depth. 3 In the x-ray-diffraction patterns the tetragonal and the monoclinic but not the cubic phase of ZrO 2 were observed. In sample 1AB, even the strongest reflections of the monoclinic phase (111) and ͑111͒ were not observed, therefore at the low ZrO 2 content the particles were all in the tetragonal phase.…”

Section: Materials Characterizationmentioning

confidence: 93%

Dielectric property measurements of ZrO2-strengthened Al2O3

Link

Heidinger

1997

Journal of Applied Physics

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Effect of poly(vinyl acetate) on structures and properties of Pb Zr 0.52 Ti 0.48 O 3 thick films Stacking effects on dielectric properties of sol-gel derived Pb(Zr 0.53 Ti 0.47 )O 3 /PbTiO 3 thin filmsCeramic composites of alumina and zirconia with ZrO 2 contents up to 20 wt % and negligible porosity were investigated at radio frequencies from 10 4 to 10 7 Hz, and in a temperature range from 20 to 550°C. If unstabilized or partially stabilized ZrO 2 is dispersed in pure alumina in order to improve the mechanical strength the dielectric properties are changed. The admixture of zirconia leads to enhanced dielectric losses and an increased temperature dependence of the permittivity. It is demonstrated that it is essential to distinguish between the contributions of the monoclinic and the tetragonal phase of zirconia. The presence of the tetragonal ZrO 2 phase is correlated with the appearance of two peaks in the temperature dependence of the dielectric loss and two smoothed steps in the temperature dependence of the permittivity. This is well described by a Debye model for dipole relaxation. The presence of the monoclinic phase leads to a higher exponential temperature rise for the dielectric loss as well as for the permittivity, due to an increased ionic conductivity. At higher frequencies the influence of ionic conductivity is smaller and the dipole relaxation processes are shifted to higher temperatures. Therefore, for high-frequency applications low-loss composites with improved mechanical properties can be realized if monoclinic zirconia is kept at low levels.

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Quantitative XRD analysis of zirconia-toughened alumina ceramics

Cited by 46 publications

References 10 publications

Alumina-base plasma-sprayed materials—Part II: Phase transformations in aluminas

Alumina-base plasma-sprayed materials—Part II: Phase transformations in aluminas

Growth by the CSVT (close-spaced vapor transport) technique and characterization of epitaxial GaAs layers on Ge substrates

Dielectric property measurements of ZrO2-strengthened Al2O3

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