The use of X-ray diffraction peak-broadening analysis to characterize ground Al2O3 powders

Ekström, Thommy; Chatfield, C.; Wruss, W.; Maly-Schreiber, M.

doi:10.1007/bf01026322

Cited by 52 publications

(13 citation statements)

References 4 publications

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“…For this purpose, the Scherrer equation modified using the convolution of the Lorentz–Cauchy functions can be used. This method was successfully testified for the determination of the alumina powder crystal structure parameters . Here, the first step is the extraction of the physical components from the total broadening profile using a Gaussian distribution:

\begin{matrix} true \\ right β_{s}^{2} = β_{ph}^{2} + β_{st}^{2} \end{matrix}

where β s is the integral half‐width of the sample profile, β ph is the physical component of the broadening, and β st is the integrated half‐width of the standard sample.…”

Section: Methodsmentioning

confidence: 99%

The Study of Nonisothermal Kinetics of Dehydration of Gibbsite in a Mixture with Zinc Oxide

Prokof’ev

Petuhova

Gordina

2015

Int J of Chemical Kinetics

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Nonisothermal kinetics of dehydration of gibbsite in a mixture with zinc oxide has been studied by Friedman analysis (differential method) and Flynn-Wall-Ozawa analysis (integral method). The values of the activation energy and preexponential factor depending on the decomposition extent of gibbsite to boehmite have been determined. It has been shown that both methods give similar results. It has been established that the activation energy has a maximum value of 150-170 kJ/mol in the start stages of thermolysis (for conversion extent of less than 0.3). During further dehydration, the activation energy is reduced to 100-110 kJ/mol. It has been found that comilling of the mixture results in decreasing activation energy to 40-50 kJ/mol for a conversion extent more than 0.8. This testifies to the transition of the dehydration process out of the kinetic mode to the diffusion mode. It was explained by the accumulation of mechanical energy in the form defects of crystal lattice of gibbsite at the comilling stage. C 2015 Wiley Periodicals, Inc. Int J Chem Kinet 47: 576-585, 2015

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\begin{matrix} true \\ right β_{s}^{2} = β_{ph}^{2} + β_{st}^{2} \end{matrix}

where β s is the integral half‐width of the sample profile, β ph is the physical component of the broadening, and β st is the integrated half‐width of the standard sample.…”

Section: Methodsmentioning

confidence: 99%

The Study of Nonisothermal Kinetics of Dehydration of Gibbsite in a Mixture with Zinc Oxide

Prokof’ev

Petuhova

Gordina

2015

Int J of Chemical Kinetics

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“…XRD was also used to estimate the deposit grain size as follows. [23][24][25] The diffraction pattern of the specimen was recorded at a speed of 0.01°/s using CuK␣ radiation with a nickel filter, and the full widths at half-maximum (FWHM) of the diffraction peaks were measured. Contributions due to K␣ 1 and K␣ 2 were deconvoluted, and only the K␣ 1 peak widths were used for calculation.…”

Section: (4) Specimen Characterizationmentioning

confidence: 99%

“…XRD of a standard silica specimen was used to measure instrument broadening, and Ziegler's method was used to remove the instrument broadening for obtaining the true crystal broadening. 24 Using the Scherrer relationship for size effect and Cauchy's correction for stress effects, the following relationship is obtained:…”

Section: (4) Specimen Characterizationmentioning

confidence: 99%

“…(1), a straight line is obtained with the intercept given by the crystal size and the slope revealing the stress effect. However, it should be noted that the experimental technique, correction procedure, and deconvolution process strongly effect [23][24][25] the estimated grain size, and hence the XRD estimated grain size should be treated only as an estimate.…”

Section: (4) Specimen Characterizationmentioning

confidence: 99%

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Nanomaterial Deposits Formed by DC Plasma Spraying of Liquid Feedstocks

Karthikeyan

Berndt

Reddy

et al. 1998

Journal of the American Ceramic Society

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An experimental system consisting of an axial feed plasma gun, a variable-rate liquid delivery system, a liquid atomizer-feeder, and a substrate movement and control system was designed and assembled for preparing nanograined ceramic deposits. Sprayed deposits were produced with different spray and sol feed parameters and investigated in both the as-sprayed and heat-treated conditions. Assprayed deposits were predominately hydroxide phases and were strongly adherent to the substrates. Postspray heat treatment at 873 K led to conversion of the alumina and zirconia deposits to ␥-alumina and tetragonal zirconia phases, respectively. Subsequent heat treatment at 1273 K resulted in densification of the deposits and formation of high-temperature phases. A small increase in the grain size was observed with heat treatment, but the specimens still retained nanosized grains.

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“…However, the shortcomings of the above two methods such as poor densification were not overcome. For the method of sintering YSZ ceramic nano-powders, since nanoparticles tend to spontaneously agglomerate together to reduce the interfacial energy and the total surface area of the system, 20), 21) the final YSZ ceramic is inevitable to produce agglomerated particles, which results in the formation of large pores in the region of ceramic. 22) Introducing low-temperature assisted sintering additive can result in a decreased properties of the YSZ ceramic, such as low ionic conductivity, poor mechanical properties and low coefficient of thermal expansion due to the introduction of sintering aids.…”

Section: Introductionmentioning

confidence: 99%

Preparation of dense yttria stabilized zirconia ceramic by low-temperature sintering zirconium oxalate sol

Liu

Fang

Su-fang

et al. 2015

J. Ceram. Soc. Japan

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This article reports a novel method of sintering zirconium oxalate (ZrOC 2 O 4 ) sol to prepare dense yttria stabilized zirconia (YSZ) ceramic at a low sintering temperature below 1300°C. A YSZ ceramic as control group was also prepared by sintering its nano-powder. The thermal decomposition process and sinter programme of the YSZ green bodies were investigated by thermogravimetry and differential thermal analysis. The sintered ceramics showed a crystallization structure in cubic phase and the crystallite size increased with the increasing sintering temperature in the range of 550 to 1200°C. For preparing dense YSZ ceramic, a zirconium oxalate sol was prepared by solgel method and then sintered with a temperature of 1000, 1100, 1200 and 1300°C. Compared with the ceramic obtained from YSZ ceramic nano-powder, the ceramic prepared by zirconium oxalate sol exhibited an enhancement of densification with higher relative density of 98.5% and higher electrical conductivity at all test temperatures.

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The use of X-ray diffraction peak-broadening analysis to characterize ground Al2O3 powders

Cited by 52 publications

References 4 publications

The Study of Nonisothermal Kinetics of Dehydration of Gibbsite in a Mixture with Zinc Oxide

The Study of Nonisothermal Kinetics of Dehydration of Gibbsite in a Mixture with Zinc Oxide

Nanomaterial Deposits Formed by DC Plasma Spraying of Liquid Feedstocks

Preparation of dense yttria stabilized zirconia ceramic by low-temperature sintering zirconium oxalate sol

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