X-Ray Diffraction Studies of the Crystalline Structure of the Avian Egg Shell

Cain, C.J.; Heyn, A. N. J.

doi:10.1016/s0006-3495(64)86767-9

Cited by 29 publications

(21 citation statements)

References 4 publications

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“…In an analysis of texture, Perrott et al (1981) found using TEM and diffraction that the calcite columns within the palisade layer consisted of crystallites of diameter 20-30 mm. Also, Cain & Heyn (1964) found the mineral particle sizes to be 200 mm by using the number of diffraction A typical X-ray transmission image of an eggshell, obtained using the defocused beam. The arrows shows the areas where X-ray scattering patterns were recorded: three vertical scans were made 48 mm apart.…”

Section: Resultsmentioning

confidence: 99%

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Microfocus X-ray scattering investigations of eggshell nanotexture

Lammie

Bain

Wess

2005

J Synchrotron Radiat

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The avian eggshell is a highly ordered calcitic bioceramic composite, with both inorganic and organic constituents. The interactions between the inorganic and organic components within the structure are poorly understood but are likely to occur at the nanometre level. Thus structural variation at this level may impinge on the overall structural integrity and mechanical performance of the eggshell, and therefore analysis at this level is fundamental in fully understanding this ordered structure. In this study, structural changes in the mineral crystallites were investigated by microfocus small-angle X-ray scattering (mSAXS) using synchrotron radiation. Small-angle X-ray scattering (SAXS) can be used to investigate structures on the nanometre scale such as size, shape, arrangement and internal porosity. A microfocused X-ray beam, 1.5 mm vertically by 7 mm, was used to produce vertical linear scans of the eggshell section. SAXS patterns were taken from the eggshell membrane (inner surface of the eggshell) to the cuticle (outer surface of the eggshell). This allowed textural variations within the eggshell to be mapped. The scattering intensity profile was then used to derive the dimension of scattering objects that define the nanotexture. The nanotexture observed may result from the presence of the organic matrix, which is embedded as intracrystalline particles producing voids within the calcified framework of large (> 1 mm) calcite crystals. Porod analysis revealed the average size of a scattering interface to be approximately 4.5 nm with small changes that had a depth-dependent variation. These were largest at the mammillary layer/ membrane boundary. The palisade layer displayed a small upward trend in size of scattering object. Parallel scans showed that the textural variations observed within the palisade layer are significant and indicate local subtextures. In addition, many of the patterns exhibit diffuse scattering streaks that could result from reflectivity from the larger crystallite interfaces. Changes in the orientation of diffuse streaks were observed within the different layers, the membranes, mammillary layer, palisade layer, vertical crystal layer and cuticle, indicating certain preferred orientations of the crystallites within the layers. The nanotextural variations that are apparent could have implications at the macroscopic level of the resulting eggshell.

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Section: Resultsmentioning

confidence: 99%

“…1). From the inner membranes, the first mineralized layer is the mammillary layer, thought to contain randomly orientated crystals (Cain & Heyn, 1964). The calcite crystal sizes are large, > 1 mm, as evidenced from a number of studies including analysis using the Rietveld method (T. Wess, unpublished data) and also powder line broadening.…”

Section: Introductionmentioning

confidence: 99%

Microfocus X-ray scattering investigations of eggshell nanotexture

Lammie

Bain

Wess

2005

J Synchrotron Radiat

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“…Terepka [3] and Schmidt [4] concluded from polarized light examinations that the crystal columns of the palisade layer of the domestic fowl had the caxis of the hexagonal unit cell [5] perpendicular to the shell surface. In contrast, Cain and Heyn [6] deduced from X-ray diffraction studies that the c-axis of the columns was inclined at angles between 12 ~ and 44 ~ to the surface normal. A more limited X-ray diffraction study carried out by Favejee et al [7] gave no data on the palisade layer but indicated the presence of a preferred orientation in the surface layers such that {10i4} planes were aligned parallel to the surface.…”

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confidence: 89%

Crystal orientation in the shell of the domestic fowl: An electron diffraction study

1981

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The eggshell of the domestic fowl has been studied by transmission electron microscopy and diffraction. Thin sections of shell were prepared by chemical and ion-beam thinning techniques. Each calcite column of the palisade layer consisted of crystallites of diameter 20 to 30 micrometer with some tendency for crystallite alignment within a single column. Evidence indicates that there was no significant preferred orientation in the palisade layer as a whole. Only in the surface layer was any preferred orientation detected, and here (1014) planes tended to lie parallel to the surface. The results are compared with previously published data, and calcite nucleation and growth are discussed.

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“…This may be further attributed to the transition in bond angles of hydrocarbons based on number of carbon atoms. Calcite crystal in eggshell has been reported to exist in a definite inclination of 28°to 16°from the normal of the shell surface [28]. Although calcination decreases crystallinity, it is possible that the CaO active sites in the calcined eggshell retain certain degree of orientation which facilitates surface bound coupling or aromatization reaction.…”

Section: Probable Mechanism For Methane Oxidationmentioning

confidence: 99%