Spherulite

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spherulite

[′sfir·ə‚līt]
(geology)
A spherical body or coarsely crystalline aggregate having a radial internal structure arranged about one or more centers.

Spherulite

 

a small sphere consisting of an aggregate of very fine acicular crystals radiating from a central point. Spherulites are found in magmatic and sedimentary rocks and vary in mineral composition and size. In magmatic rocks, spherulites are usually interpreted as endogenic contact formations in the marginal sections of diorites. In acidic lavas, they may occur through consolidation when the primary glassy mass cools; in basic lavas (variolites), such formations are called varióles. Spherulites also form in gas bubbles of already hardened rock during secondary precipitation of zeolites, quartz, and similar minerals; in such cases they may be called pseudospherulites. Carbonate, iron-manganese phosphate, chalcedonic, and other types of spherulites are found in sedimentary rocks. They usually result from the crystallization of material in colloidal nodules, and many are close in origin to concretions.

References in periodicals archive ?
8, where an increase of growth rate of PLA spherulites with the content of the noncrystallizable polyfpropylene carbonate) is instead demonstrated.
Charred PPL: dark <650-750 brown/black or ash [degrees]C XPL: spherulites Discrete PPL: rounded, orange, bone inclusions XPL: dark Spherulites PPL: not visible XPL: distinctive spherical with extinction cross <5-20[micro]m.
Figure 2 shows the polarized optical micrographs of the spherulites grown at 140[degrees]C observed in the blends that contained PDLA content, after being quenched from 190[degrees]C.
The micromorphology did highlight further evidence of redeposited animal dung through the presence of dense concentrations of dung spherulites and some scattered reed phytoliths, in addition to greyish ash with high biofringence, which may indicate melted dung.
When the resin cools, the clarifier crystals form a fine fibrous network that contributes to clarity by providing a very high crystal density with very small spherulites.
Morikawa et al have developed a simple method for manufacturing a porous membrane based on an internal, molecular three-dimensional network structure linked with spherulites.
Some PP makers have emulated HCPP's crystalline structure of fine, densely packed spherulites by means of nucleating agents, whereas HCPP achieves its unusual structure catalytically.
Therefore, the polymer is able to build a larger morphological superstructure such as axial structures or spherulites which are then observable in polarization light microscopy (PLM) [5].
Milliken explains that Hyperform HPN-20E works efficiently in PE by "providing a physical molecular-level trigger point around which highly ordered crystalline structures called spherulites form rapidly.
For crystalline materials, this slow cooling causes rigid or nonextensible crystalline sites called spherulites to form throughout the cross-section of the material, which hampers or sometimes eliminates the possibility of orientation.