Publication

Effects of yttrium and sodium addition on preparation and humidity sensitivity of porous apatite ceramics

Nava Setter
1999
Journal Articles

Abstract

Sodium yttrium calcium-oxyhydroxyapatites powders with compositions of {Ca9.98-0.9xY0.9Na0.02(6)[(OH)(1.98-0.9x)O(0.9)square(0.02)],x=0.1.0(here square denotes vacancies at OH lattice sites} were synthesized by the wet process. Porous (Ca, Y, Na)-Ap (here Ap denotes apatite) ceramics having apparent porosities of around 33% were prepared at high temperature under steam flow. On the basis of the results of X-ray diffraction, all the obtained ceramics exhibited almost single-phase (Ca, Y, Na)-Ap with hexagonal structure, The impedance for all samples linearly changed from 106 to 104 Omega at 50degreesC in the humidity range of 40-95%RH. Apatites produced by substituting Y3+ and Na+ for Ca2+ in apatite structure showed an excellent conductivity. This is attributed to both ordinary protonic conduction caused by the self-dissociation of physically adsorbed water and another conduction caused by OH vacancies introduced by substituting Y3+ and Na+ for Ca-sites.

Official source

https://infoscience.epfl.ch/entities/publication/f92baa78-b311-4952-9ea3-5f7c44e8f83c

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Nava Setter
1999
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/f92baa78-b311-4952-9ea3-5f7c44e8f83c

About this result

Related concepts (32)

Humidity

Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity depends on the temperature and pressure of the system of interest. The same amount of water vapor results in higher relative humidity in cool air than warm air. A related parameter is the dew point. The amount of water vapor needed to achieve saturation increases as the temperature increases.

Powder diffraction

Powder diffraction is a scientific technique using X-ray, neutron, or electron diffraction on powder or microcrystalline samples for structural characterization of materials. An instrument dedicated to performing such powder measurements is called a powder diffractometer. Powder diffraction stands in contrast to single crystal diffraction techniques, which work best with a single, well-ordered crystal. Diffraction grating The most common type of powder diffraction is with x-rays, the focus of this article although some aspects of neutron powder diffraction are mentioned.

X-ray crystallography

X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal. From this electron density, the mean positions of the atoms in the crystal can be determined, as well as their chemical bonds, their crystallographic disorder, and various other information.

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Effects of yttrium and sodium addition on preparation and humidity sensitivity of porous apatite ceramics

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