Effect of Charge-balancing Species on Sm3+ Incorporation in Calcium Vanadinite

2015 ◽  
Vol 1744 ◽  
pp. 119-124
Author(s):  
M. R. Gilbert
Keyword(s):  
Experimental Approach ◽  
Secondary Phase ◽  
Monovalent Cation ◽  
Phase System ◽  
Secondary Phases ◽  
Good Potential ◽  
Phase Systems ◽  
Multi Phase ◽  
Charge Balancing ◽  
Static Lattice

ABSTRACTApatites are often seen as good potential candidates for the immobilization of halide-rich wastes. In particular, phosphate apatites have received much attention in recent years, however, their synthesis often produces complicated multi-phase systems, with a number of secondary phases forming [1.2]. Calcium vanadinite (Ca5(VO4)3Cl) demonstrates a much simpler phase system, with only a single Ca2V2O7 secondary phase which can easily be retarded by the addition of excess CaCl2. However, when doping with SmCl3 (as an inactive analogue for AnCl3) the Sm forms a wakefieldite (SmVO4) phase rather than being immobilized within the vanadinite, a result of having to form an energetically unfavourable Ca vacancy in order for the lattice to remain neutral overall. It has been postulated that charge-balancing the lattice via co-substitution of a monovalent cation will be less disfavoured and therefore help stabilise formation of a (Ca5-2xSmxAx)(VO4)3Cl solid solution (A = monovalent cation). This has been investigated using a combined modelling and experimental approach. Static lattice calculations performed using Li+, Na+ and K+ as charge-balancing species have shown the energy cost to be less than half that of charge-balancing via formation of a Ca vacancy. As a result, solid state synthesis of (Ca5-2xSmxLix)(VO4)3Cl, (Ca5−2xSmxNax)(VO4)3Cl and (Ca5-2xSmxKx)(VO4)3Cl solid solutions have been trialled, and analysis of the resulting products has shown a significant reduction in both the SmVO4 and Ca2V2O7 secondary phases across all dopant levels.

Calcium Vanadinite: An Alternative Apatite Host for Cl-rich Wastes

2014 ◽  
Vol 1665 ◽  
pp. 319-324 ◽  
Author(s):  
M. R. Gilbert
Keyword(s):  
Elevated Temperatures ◽  
Secondary Phase ◽  
Phase System ◽  
Secondary Phases ◽  
Waste Forms ◽  
Good Potential ◽  
Multi Phase

ABSTRACTApatites are often seen as good potential candidates for the immobilization of halide-rich wastes and, in particular, chlorapatite (Ca5(PO4)3Cl) has received much attention in recent years. However, synthesis of chlorapatite waste-forms can produce a complicated multi-phase system, with a number of secondary phases forming, including β-TCP (Ca3(PO4)2), spodiosite (Ca2(PO4)Cl) and pyrophosphate (Ca2P2O7), many of which require elevated temperatures and extended calcinations times to reduce. Calcium vanadinite (Ca5(VO4)3Cl) demonstrates a much simpler phase system, with calcination at 750 °C yielding Ca5(VO4)3Cl together a small quantity of a Ca2V2O7secondary phase, the formation of which can be retarded by the addition of excess CaCl2. Characterization of compositions doped with SmCl3as an inactive analogue for AnCl3show the Cl to be immobilized in the vanadinite whilst the Sm forms a wakefieldite (SmVO4) phase.

scholarly journals Power Conversion Techniques Using Multi-Phase Transformer: Configurations, Applications, Issues and Recommendations

Machines ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 13
Author(s):  
Md Tabrez ◽  
Pradip Kumar Sadhu ◽  
Molla Shahadat Hossain Lipu ◽  
Atif Iqbal ◽  
Mohammed Aslam Husain ◽  
...  
Keyword(s):  
Power Generation ◽  
Transformation Method ◽  
Sine Wave ◽  
Fault Analysis ◽  
Optimization Techniques ◽  
Phase System ◽  
Voltage Unbalance ◽  
Three Phase ◽  
Phase Systems ◽  
Multi Phase

Recently, the superiority of multi-phase systems in comparison to three-phase energy systems has been demonstrated with regards to power generation, transmission, distribution, and utilization in particular. Generally, two techniques, specifically semiconductor converter and special transformers (static and passive transformation) have been commonly employed for power generation by utilizing multi-phase systems from the available three-phase power system. The generation of multi-phase power at a fixed frequency by utilizing the static transformation method presents certain advantages compared to semiconductor converters such as reliability, cost-effectiveness, efficiency, and lower total harmonics distortion (THD). Multi-phase transformers are essential to evaluate the parameters of a multi-phase motor, as they require a multi-phase signal that is pure sine wave in nature. However, multi-phase transformers are not suitable for variable frequency applications. Moreover, they have shortcomings with regard to impedance mismatching, the unequal number of turns which lead to inaccurate results in per phase equivalent circuits, which results in an imbalance output in phase voltages and currents. Therefore, this paper aims to investigate multi-phase power transformation from a three-phase system and examine the different static multi-phase transformation techniques. In line with this matter, this study outlines various theories and configurations of transformers, including three-phase to five-, seven-, eleven-, and thirteen-phase transformers. Moreover, the review discusses impedance mismatching, voltage unbalance, and per phase equivalent circuit modeling and fault analysis in multi-phase systems. Moreover, various artificial intelligence-based optimization techniques such as particle swarm optimization (PSO) and the genetic algorithm (GA) are explored to address various existing issues. Finally, the review delivers effective future suggestions that would serve as valuable opportunities, guidelines, and directions for power engineers, industries, and decision-makers to further research on multi-phase transformer improvements towards sustainable operation and management.

Charge Compensation in Trivalent Doped Ca3(SiO4)Cl2

2015 ◽  
Vol 1744 ◽  
pp. 113-118 ◽  
Author(s):  
M. R. Gilbert
Keyword(s):  
Charge Compensation ◽  
Monovalent Cation ◽  
Ionic Radii ◽  
Substitution Process ◽  
Solution Energy ◽  
Site Selectivity ◽  
Trivalent Cations ◽  
Charge Balancing ◽  
Pyrochemical Reprocessing ◽  
Static Lattice

ABSTRACTCalcium chlorosilicate (Ca3(SiO4)Cl2) is seen as a potential host phase for the immobilization of Cl-rich wastes arising from pyrochemical reprocessing, a waste stream often containing a mix of both di- and trivalent cations. Substitution of trivalent cations into the lattice requires some form of charge compensation to ensure the lattice remains charge neutral overall. Whilst previous work has only examined this through the formation of Ca vacancies, this study investigates the feasibility of charge-balancing via the substitution of a monovalent cation onto the Ca sites of the lattice. To that end, a series of static lattice calculations were performed to determine the site selectivity of monovalent cations of differing size when substituted onto the Ca sites of the calcium chlorosilicate lattice and the solution energies for the overall substitution processes compared with those for charge compensation via vacancy formation. In all cases the monovalent charge-balancing species shows a clear preference for substitution onto the Ca1 site in the calcium chlorosilicate lattice. The solution energy of the substitution process increases with the increasing ionic radii of both the mono- and trivalent species as the steric stresses associated with substitution of larger cations than the Ca2+ host increase. As such, only charge-balancing using Li+, Na+ or K+ is more favourable than via formation of a Ca vacancy.

scholarly journals Morphology Development and Flow Characteristics during High Moisture Extrusion of a Plant-Based Meat Analogue

Foods ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1753
Author(s):  
Patrick Wittek ◽  
Felix Ellwanger ◽  
Heike P. Karbstein ◽  
M. Azad Emin
Keyword(s):  
Transition Zone ◽  
Flow Characteristics ◽  
Phase System ◽  
Shear Stresses ◽  
High Moisture ◽  
Tensile Stresses ◽  
Morphology Development ◽  
A Minor ◽  
Multi Phase ◽  
High Moisture Extrusion

Plant-based meat analogues that mimic the characteristic structure and texture of meat are becoming increasingly popular. They can be produced by means of high moisture extrusion (HME), in which protein-rich raw materials are subjected to thermomechanical stresses in the extruder at high water content (>40%) and then forced through a cooling die. The cooling die, or generally the die section, is known to have a large influence on the products’ anisotropic structures, which are determined by the morphology of the underlying multi-phase system. However, the morphology development in the process and its relationship with the flow characteristics are not yet well understood and, therefore, investigated in this work. The results show that the underlying multi-phase system is already present in the screw section of the extruder. The morphology development mainly takes place in the tapered transition zone and the non-cooled zone, while the cooled zone only has a minor influence. The cross-sectional contraction and the cooling generate elongational flows and tensile stresses in the die section, whereas the highest tensile stresses are generated in the transition zone and are assumed to be the main factor for structure formation. Cooling also has an influence on the velocity gradients and, therefore, the shear stresses; the highest shear stresses are generated towards the die exit. The results further show that morphology development in the die section is mainly governed by deformation and orientation, while the breakup of phases appears to play a minor role. The size of the dispersed phase, i.e., size of individual particles, is presumably determined in the screw section and then stays the same over the die length. Overall, this study reveals that morphology development and flow characteristics need to be understood and controlled for a successful product design in HME, which, in turn, could be achieved by a targeted design of the extruders die section.

Morphology of highly porous conducting polyaniline nanofibres synthesized in a multi-phase system

2012 ◽  
Vol 13 (6) ◽  
pp. 703-708 ◽  
Author(s):  
R. Fryczkowski ◽  
M. Gorczowska ◽  
B. Fryczkowska ◽  
J. Janicki
Keyword(s):  
Phase System ◽  
Conducting Polyaniline ◽  
Multi Phase ◽  
Highly Porous

scholarly journals A new paradigm on the chemical potentials of components in multi-component nano-phases within multi-phase systems

RSC Advances ◽  
2017 ◽  
Vol 7 (65) ◽  
pp. 41241-41253 ◽  
Author(s):  
George Kaptay
Keyword(s):  
New Paradigm ◽  
Surface Areas ◽  
Chemical Potentials ◽  
Multiphase Systems ◽  
Phase Systems ◽  
Multi Phase

A new paradigm is offered claiming that the thermodynamic nano-effect in multi-component and multiphase systems is proportional to the increased surface areas of the phases and not to their increased curvatures (as the Kelvin paradigm claims).

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