Preparation of Yb3+-doped silica fiber preform at low temperature

With the development of military weapons, the demand of weapons is growing. But now 2.5 D silica fiber reinforced silica composites have long production period, high cost,which limited the production and schedule of weapons. This paper studied low cost manufacturing technology from two aspects of fiber preform weaving mode and molding process. The preforms were prepared with needling process.CT images of needling preform, thermophysical properties and mechanical properties and dielectric properties of needling silica fiber reinforced silica composites were studied inthis paper.The results showed that needling SiO2f/SiO2 composites had short production period and low cost, which had good mechanical properties.Tensile strength was 20.1MPa, compressive strength of XY direction was 88.3MPa,bending strength was 52.2MPa. Dielectric contant was less than 3.05 and dielectric loss was less than 8×10-3.

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Photoluminescence of sol-gel silica fiber preform doped with Bismuth-containing heterotrinuclear complex

Optical Materials Express ◽

10.1364/ome.2.000205 ◽

2012 ◽

Vol 2 (2) ◽

pp. 205 ◽

Cited By ~ 12

Author(s):

Igor Razdobreev ◽

Hicham El Hamzaoui ◽

Géraud Bouwmans ◽

Mohamed Bouazaoui ◽

Vladimir B. Arion

Keyword(s):

Sol Gel ◽

Silica Fiber ◽

Fiber Preform ◽

Heterotrinuclear Complex

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Exsolution and inversion in pigeonite from the Whin Sill, Northern England

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109513 ◽

1978 ◽

Vol 36 (1) ◽

pp. 474-475

Author(s):

P.P.K. Smith

Keyword(s):

High Temperature ◽

Low Temperature ◽

Homogeneous Nucleation ◽

Silicate Mineral ◽

Antiphase Boundaries ◽

Two Phase ◽

Primitive Form ◽

The Core ◽

Nucleation Mechanisms ◽

And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

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Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100111537 ◽

1984 ◽

Vol 42 ◽

pp. 284-285

Author(s):

S. Edith Taylor ◽

Patrick Echlin ◽

May McKoon ◽

Thomas L. Hayes

Keyword(s):

Low Temperature ◽

Lemna Minor ◽

Root Tips ◽

Tobacco Leaves ◽

X Ray ◽

Whole Cells ◽

Carbon Coated ◽

The Right ◽

Beam Currents ◽

The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

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