Mg-doped Nd-Ba-Cu-O generic seed crystals for the top-seeded melt growth of large-grain (rare earth)-Ba-Cu-O bulk superconductors

2006 ◽  
Vol 21 (6) ◽  
pp. 1355-1362 ◽  
Author(s):  
Y. Shi ◽  
N. Hari Babu ◽  
K. Iida ◽  
D.A. Cardwell
Keyword(s):  
Rare Earth ◽  
Volume Fraction ◽  
Seed Crystal ◽  
Superconducting Properties ◽  
Seed Crystals ◽  
Bulk Superconductors ◽  
Wide Range ◽  
Single Grain ◽  
Basic Characteristics ◽  
Mg Doped

We report the fabrication of Mg-doped NdBCO generic seed crystals, which have been developed recently for the fabrication of any rare earth (RE) based (RE)-Ba-Cu-O single-grain superconductor, with a wide range of Nd1+xBa2-xCu3-yMgyO7-δ compositions. Three basic characteristics of the seed crystals required for effective seeding of bulk (RE)BCO materials were studied in detail. We report the chemical, crystallographic, microstructural, and superconducting properties of the seeds and demonstrate clearly their potential to process various (RE)BCO superconductors in single-grain form. The melting point, volume fraction of Mg-rich inclusions in the bulk microstructure, and the chemical composition of the Nd1+xBa2-xCu3-yMgyO7-δ superconducting matrix of the seed crystals were studied as a function of initial MgO content. Finally, the suitable range of MgO-content within the generic seed crystal that controls effectively the orientation of the seeded grain without compromising its superconducting properties relative to those of the Mg-free compound is identified based on the wide range of seed crystal compositions investigated.

The Influence of CeO2 Addition on Microstructure and Superconducting Properties of GdBCO-Ag Single Grain Bulk Superconductors

2021 ◽  
pp. 161697
Author(s):  
Petra Hajdova ◽  
Pavel Diko ◽  
Michal Rajnak ◽  
Jozef Bednarcik ◽  
Vitaliy Antal ◽  
...  
Keyword(s):  
Superconducting Properties ◽  
Bulk Superconductors ◽  
Single Grain ◽  
Grain Bulk

scholarly journals Factors Affecting Acoustic Properties of Natural-Fiber-Based Materials and Composites: A Review

Textiles ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 55-85
Author(s):  
Tufail Hassan ◽  
Hafsa Jamshaid ◽  
Rajesh Mishra ◽  
Muhammad Qamar Khan ◽  
Michal Petru ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Natural Fiber ◽  
Volume Fraction ◽  
Fiber Type ◽  
Alkali Treatment ◽  
Acoustic Properties ◽  
Synthetic Fiber ◽  
Sound Insulation ◽  
Factors Affecting ◽  
Wide Range

Recently, very rapid growth has been observed in the innovations and use of natural-fiber-based materials and composites for acoustic applications due to their environmentally friendly nature, low cost, and good acoustic absorption capability. However, there are still challenges for researchers to improve the mechanical and acoustic properties of natural fiber composites. In contrast, synthetic fiber-based composites have good mechanical properties and can be used in a wide range of structural and automotive applications. This review aims to provide a short overview of the different factors that affect the acoustic properties of natural-fiber-based materials and composites. The various factors that influence acoustic performance are fiber type, fineness, length, orientation, density, volume fraction in the composite, thickness, level of compression, and design. The details of various factors affecting the acoustic behavior of the fiber-based composites are described. Natural-fiber-based composites exhibit relatively good sound absorption capability due to their porous structure. Surface modification by alkali treatment can enhance the sound absorption performance. These materials can be used in buildings and interiors for efficient sound insulation.

scholarly journals Structure and Properties of Ln2MoO6 Oxymolybdates (Ln = La, Pr, Nd) Doped with Magnesium

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 611
Author(s):  
Ekaterina Orlova ◽  
Elena Kharitonova ◽  
Timofei Sorokin ◽  
Alexander Antipin ◽  
Nataliya Novikova ◽  
...  
Keyword(s):  
Rare Earth ◽  
Infrared Spectroscopy ◽  
Room Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Spectroscopy Data ◽  
Structure And Properties ◽  
Hygroscopic Properties ◽  
Thermogravimetric Studies ◽  
Mg Doped

The literature data and the results obtained by the authors on the study of the structure and properties of a series of polycrystalline and single-crystal samples of pure and Mg-doped oxymolybdates Ln2MoO6 (Ln = La, Pr, Nd) are analyzed. Presumably, the high-temperature phase I41/acd of Nd2MoO6 single crystals is retained at room temperature. The reason for the loss of the center of symmetry in the structures of La2MoO6 and Pr2MoO6 and the transition to the space group I4¯c2 is the displacement of oxygen atoms along the twofold diagonal axes. In all structures, Mg cations are localized near the positions of the Mo atoms, and the splitting of the positions of the atoms of rare-earth elements is found. Thermogravimetric studies, as well as infrared spectroscopy data for hydrated samples of Ln2MoO6 (Ln = La, Pr, Nd), pure and with an impurity of Mg, confirm their hygroscopic properties.

scholarly journals Conduction and convection heat transfer characteristics of water-based au nanofluids in a square cavity with differentially heated side walls subjected to constant temperatures

2014 ◽  
Vol 18 (suppl.1) ◽  
pp. 189-200 ◽  
Author(s):  
Primoz Ternik ◽  
Rebeka Rudolf
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Base Fluid ◽  
Volume Fraction ◽  
Heat Transfer Characteristics ◽  
Square Cavity ◽  
Onset Of Convection ◽  
Transfer Characteristics ◽  
Wide Range ◽  
Water Based

The present work deals with the natural convection in a square cavity filled with the water-based Au nanofluid. The cavity is heated on the vertical and cooled from the adjacent wall, while the other two horizontal walls are adiabatic. The governing differential equations have been solved by the standard finite volume method and the hydrodynamic and thermal fields were coupled together using the Boussinesq approximation. The main objective of this study is to investigate the influence of the nanoparticles? volume fraction on the heat transfer characteristics of Au nanofluids at the given base fluid?s (i.e. water) Rayleigh number. Accurate results are presented over a wide range of the base fluid Rayleigh number and the volume fraction of Au nanoparticles. It is shown that adding nanoparticles in a base fluid delays the onset of convection. Contrary to what is argued by many authors, we show by numerical simulations that the use of nanofluids can reduce the heat transfer rate instead of increasing it.

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