scholarly journals Mechanochemical synthesis of NaBH4 starting from NaH–MgB2 reactive hydride composite system

2013 ◽  
Vol 38 (5) ◽  
pp. 2363-2369 ◽  
Author(s):  
S. Garroni ◽  
C. Bonatto Minella ◽  
D. Pottmaier ◽  
C. Pistidda ◽  
C. Milanese ◽  
...  
Keyword(s):  
Mechanochemical Synthesis ◽  
Composite System

Processing and characterization of YBa2Cu3O7−x/Ag composites

1990 ◽  
Vol 48 (4) ◽  
pp. 46-47
Author(s):  
Jafar Javadpour ◽  
Bradley L. Thiel ◽  
Sarikaya Mehmet ◽  
Ilhan A. Aksay
Keyword(s):  
Composite System ◽  
Precursor Solution ◽  
Microstructural Development ◽  
Superconducting Properties ◽  
Practical Applications ◽  
Nitrate Precursor ◽  
Cold Pressed ◽  
Tape Cast ◽  
Composite Samples

Practical applications of bulk YBa2Cu3O7−x materials have been limited because of their inadequate critical current density (jc) and poor mechanical properties. Several recent reports have indicated that the addition of Ag to the YBa2Cu3O7−x system is beneficial in improving both mechanical and superconducting properties. However, detailed studies concerning the effect of Ag on the microstructural development of the cermet system have been lacking. Here, we present some observations on the microstructural evolution in the YBa2Cu3O7−x/Ag composite system.The composite samples were prepared by mixing various amounts (2.5 - 50 wt%) AgNO3 in the YBa2Cu3O7−x nitrate precursor solution. These solutions were then spray dried and the resulting powders were either cold pressed or tape cast. The microstructures of the sintered samples were analyzed using SEM (Philips 515) and an analytical TEM (Philips 430T).The SEM micrographs of the compacts with 2.5 and 50 wt% Ag addition sintered at 915°C (below the melting point of Ag) for 1 h in air are displayed in Figs. 1 and 2, respectively.

Under Pressure: Mechanochemical Effects on Structure and Ion Conduction in the Sodium-Ion Solid Electrolyte Na3PS4

2020 ◽  
Author(s):  
Theodosios Famprikis ◽  
O. Ulas Kudu ◽  
James Dawson ◽  
Pieremanuele Canepa ◽  
François Fauth ◽  
...  
Keyword(s):  
Ionic Conductivity ◽  
Mechanochemical Synthesis ◽  
Activation Volume ◽  
External Pressure ◽  
Sodium Ion ◽  
Variable Pressure ◽  
Ion Conductor ◽  
Ceramic Synthesis ◽  
Solid State Batteries ◽  
Fast Ion

<div> <p>Fast-ion conductors are critical to the development of solid-state batteries. The effects of mechanochemical synthesis that lead to increased ionic conductivity in an archetypical sodium-ion conductor Na<sub>3</sub>PS<sub>4</sub> are not fully understood. We present here a comprehensive analysis based on diffraction (Bragg, pair distribution function), spectroscopy (impedance, Raman, NMR, INS) and <i>ab-initio</i> simulations aimed at elucidating the synthesis-property relationships in Na<sub>3</sub>PS<sub>4</sub>. We consolidate previously reported interpretations about the local structure of ball-milled samples, underlining the sodium disorder and showing that a local tetragonal framework more accurately describes the structure than the originally proposed cubic one. Through variable-pressure impedance spectroscopy measurements, we report for the first time the activation volume for Na<sup>+</sup> migration in Na<sub>3</sub>PS<sub>4</sub>, which is ~30% higher for the ball-milled samples. Moreover, we show that the effect of ball-milling on increasing the ionic conductivity of Na<sub>3</sub>PS<sub>4</sub> to ~10<sup>-4</sup> S/cm can be reproduced by applying external pressure on a sample from conventional high temperature ceramic synthesis. We conclude that the key effects of mechanochemical synthesis on the properties of solid electrolytes can be analyzed and understood in terms of pressure, strain and activation volume.</p> </div>

Theoretical and Experimental Evaluation of the Effect of Fluorinated Substituent on the Topological Landscape and Thermodynamic Stability of Zeolitic Imidazolate Framework Polymorphs

2018 ◽  
Author(s):  
Mihails Arhangelskis ◽  
Athanassis Katsenis ◽  
Novendra Novendra ◽  
Zamirbek Akimbekov ◽  
Dayaker Gandrath ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Mechanochemical Synthesis ◽  
Thermodynamic Stability ◽  
Experimental Evaluation ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Zeolitic Imidazolate Framework ◽  
Functional Theory ◽  
Calorimetric Measurements ◽  
And Calorimetry

By combining mechanochemical synthesis and calorimetry with theoretical calculations, we demonstrate that dispersion-corrected periodic density functional theory (DFT) can accurately survey the topological landscape and predict relative energies of polymorphs for a previously inaccessible fluorine-substituted zeolitic imidazolate framework (ZIF). Experimental screening confirmed two out of three theoretically anticipated polymorphs, and the calorimetric measurements provided an excellent match to theoretically calculated energetic difference between them.<br>

Islamic Law and Society

1990 ◽  
Vol 7 (2) ◽  
pp. 177-191
Author(s):  
Louay M. Safi
Keyword(s):  
Composite System ◽  
Islamic Law ◽  
Legal Theory ◽  
Fifth Century ◽  
Muslim Community ◽  
Social Growth ◽  
The Social ◽  
Collective Experience ◽  
Law And Morality ◽  
The Impact

Shari'ah (Islamic law) has been the dominant moral and legal code ofMuslim societies for the gnxter part of their history. During the early centuriesof Islam, Shari'ah hcilitated the social growth and develojment of the Muslims,growth that culminaa in the establishment of a vast emph and an outstandmgcivilization. By the close of the fifth century of Islam, however, Shari'ahbegan to lose its role as the guiding force that inspired Muslim creativityand ingenuity and that nurtured the growing spirit of the Muslim community(Ummah). Consequently, the Ummah entered a period of stagnation thatgradually gave way to intellectual decline and social decadence. Regrettably,this painful trend continues to be more or less 'part of the individualconsciousness and collective experience of Muslims.This paper attempts to trace the development of the principles of Islamicjurisprudence, and to assess the impact of Shari'ah on society. It argues thatthe law ceased to grow by the sixth century of Islam as a result of thedevelopment of classical legal theory; more specifically, law was put on hold,as it were, after the doctrine of the infallibility of ijma' (juristic consensus)was articulated. The rigid principles of classical theory, it is contended, havebeen primarily induced by the hulty epistemology employed.by sixth-centuryjurists.Shari'ah, or Islamic law, is a comprehensive system encompassing thewhole field of human experience. It is not simply a legal system, but rathera composite system of law and morality. That is, Islamic law aspires to regulateall aspects of human activities, not only those that may entail legalconsequences. Hence, all actions and relationships are evaluated in accordancewith a scale of five moral standards.According to Shari'ah, an act may be classified as obligatory (wajib),recommended (mandub), permissible (mubah), reprehensible (makruh), orprohibited (haram). These five categories reflect the varying levels of moral ...

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