Publication

HRTEM simulation in determination of thickness and grain misorientation for hydroxyapatite crystals

Philippe Buffat, Pierre Stadelmann, Elena Suvorova Buffat
2004
Journal Articles

Abstract

High-resolution transmission electron microscopy (HRTEM) and HRTEM simulation by the Bloch wave method (JEMS) are used to determine the structure and thickness of micro- and nanocrystals of biominerals and hydroxyapatite grown from aqueous solutions. It is established that thin (from one to several lattice parameters) crystals, including hydroxyapatite in mineralized biological tissues, are usually formed in low-temperature (up to 40degreesC) solutions. Relatively thick (up to several tens of lattice parameters) crystals grow only in high-temperature (similar to95degreesC) aqueous solutions. HRTEM simulation showed that crystals with a thickness exceeding one lattice parameter consist of nanograins misoriented with respect to one another along various directions within an angle of 0.7degrees.

Official source

https://infoscience.epfl.ch/entities/publication/b54707be-3653-469e-becc-bf517d8acd1d

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Philippe Buffat, Pierre Stadelmann, Elena Suvorova Buffat
2004
Journal Articles

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/b54707be-3653-469e-becc-bf517d8acd1d

About this result

Related concepts (32)

Transmission electron microscopy

Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid. An image is formed from the interaction of the electrons with the sample as the beam is transmitted through the specimen. The image is then magnified and focused onto an imaging device, such as a fluorescent screen, a layer of photographic film, or a sensor such as a scintillator attached to a charge-coupled device.

Scanning transmission electron microscopy

A scanning transmission electron microscope (STEM) is a type of transmission electron microscope (TEM). Pronunciation is [stɛm] or [ɛsti:i:ɛm]. As with a conventional transmission electron microscope (CTEM), images are formed by electrons passing through a sufficiently thin specimen. However, unlike CTEM, in STEM the electron beam is focused to a fine spot (with the typical spot size 0.05 – 0.2 nm) which is then scanned over the sample in a raster illumination system constructed so that the sample is illuminated at each point with the beam parallel to the optical axis.

Hydroxyapatite

Hydroxyapatite (HA), is a naturally occurring mineral form of calcium apatite with the formula , but it is usually written to denote that the crystal unit cell comprises two entities. Hydroxylapatite is the hydroxyl endmember of the complex apatite group. The ion can be replaced by fluoride, chloride, producing fluorapatite or chlorapatite. It crystallizes in the hexagonal crystal system. Pure hydroxylapatite powder is white. Naturally occurring apatites can, however, also have brown, yellow, or green colorations, comparable to the discolorations of dental fluorosis.

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HRTEM simulation in determination of thickness and grain misorientation for hydroxyapatite crystals

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