A Focus on New Solar-Powered Device

Saturated water from the desert sky is now possible to take, thanks to a new spongelike solar device that uses sunlight to suck water vapour from the air, even in low humidity. This device can produce nearly 3 litres of water per day for every kilogram of spongelike absorber it contains, and it is said that future versions will be even better. That means homes in the driest parts of the world could soon have a solar-powered appliance able to delivering all the water they need, offering relief to billions of people.


Crystalline

New Solar Tech Using Crystalline materials similar to these can now harvest water vapour from the air

The new water harvester is made of metal-organic framework crystals pressed into a thin sheet of copper metal and placed between a solar absorber, above and a condenser plate below.

It is estimated 13 trillion litres of water floating in the atmosphere at any one time, equivalent to 10.3% of all of the freshwater in our planet’s lakes and rivers. For years researchers have been able to develop ways to grab a few trickles of water, such as using fine nets to wick water from fog banks, or power-hungry dehumidifiers to condense it out of the air. But both approaches require either very humid air or far too much electricity to be broadly useful.


At night the chamber is opened, allowing ambient air to diffuse through the porous MOF and water molecules to stick to its interior surfaces, gathering in groups of eight to form tiny cubic droplets. In the morning, the chamber is closed, and sunlight entering through a window on top of the device then heats up the MOF, which liberates the water droplets and drives them—as vapour—toward the cooler condenser. The temperature difference, as well as the high humidity inside the chamber, causes the vapour to condense as liquid water, which drips into a collector.

Metal-Organic Framework Crystal Structure for New Solar Tech

A team of researchers at the Massachusetts Institute of Technology and the University of California Berkeley have developed a prototype that captures water vapour from the air and then releases it with the application of a smaller amount of heat compared to existing commercially available technologies.

To compensate for this, specially constructed storage containers are required, which can be costly. Strong metal-ligand bonds, such as in metal-imidazolate, -triazole, and -pyrazole frameworks, are known to decrease a MOF’s sensitivity to air, reducing the expense of storage.

Recent advancement in the solvent-free preparation of MOF films and composites is their synthesis by chemical vapour deposition. This process, MOF-CVD,[16] was first demonstrated for ZIF-8 and consist of two steps. In the first step, metal oxide precursor layers are deposited. In the second step, these precursor layers are exposed to sublimed ligand molecules, that induce a phase transformation to the MOF crystal lattice. Formation of water during this reaction plays a crucial role in directing the transformation.

In addition to their tunable selectivities for different molecules, another property of MOFs that makes them a good candidate for carbon capture is their low heat capacities. Monoethanolamine (MEA) solutions, the leading method for capturing CO2 from flue gas, have a heat capacity between 3-4 J/g K since they are mostly water. This high heat capacity contributes to the energy penalty in the solvent regeneration step, i.e. when the adsorbed CO2 is removed from the MEA solution. MOF-177, a MOF designed for CO2 capture, has a heat capacity of 0.5 J/g K at ambient temperature

Crystal faces and shapes

crystal

Main article: quasicrystal a quasicrystal consists of arrays of atoms that are ordered but not strictly periodic. they have many attributes in common with ordinary crystals, such as displaying a discrete pattern in x-ray diffraction, and the ability to form shapes with smooth, flat faces. quasicrystals are most famous for their ability to show five-fold symmetry, which is impossible for an ordinary periodic crystal (see crystallographic restriction theorem ).

These are the most common type of solids. their characteristics are what we associate solids with. they are firm, hold a definite and fixed shape, are rigid and incompressible. they generally have geometric shapes and flat faces. and examples include diamonds, metals, salts etc. to understand crystals we must understand their structure. the arrangement of particles in a crystalline solid is in a very orderly fashion. these articles are arranged in a repeating pattern of a three-dimensional network. this network is known as a crystal lattice and the smallest unit of a crystal is a unit cell. if you see the x-ray of a crystal this distinct arrangement of the unit cells will be clearly visible.

Research Centre for Crystalline Materials for Solar

The research centre for crystalline materials was established to be a focus for the determination of molecular structure by x-ray crystallographic methods, to understand how molecules assemble in the crystalline state and to develop novel metal-based therapeutics agents (anticancer, antimicrobial, antiviral, etc. ). under the leadership of distinguished professor Edward rt Tiekink, our work has been described in nearly 2,000 research publications and received over 20,000 citations (Scopus).

Crystalline and Amorphous Solids for New Solar Tech

With few exceptions, the particles that compose a solid material, whether ionic, molecular, covalent, or metallic, are held in place by strong attractive forces between them. when we discuss solids, therefore, we consider the positions of the atoms, molecules, or ions, which are essentially fixed in space, rather than their motion (which are more important in liquids and gases). the constituents of a solid can be arranged in two general ways: they can form a regular repeating three-dimensional structure called a crystal lattice, thus producing a crystalline solid, or they can aggregate with no particular order, in which case they form an amorphous solid (from the greek ámorphos, meaning “shapeless”).

Concurrent atomistic-continuum modelling of crystalline materials

crystalline

In this work, we present a concurrent atomistic-continuum (CAC) method for modelling and simulation of crystalline materials. the CAC formulation extends the Irving-Kirkwood procedure for deriving transport equations and fluxes for homogenized molecular systems to that for polyatomic crystalline materials by employing a concurrent two-level description of the structure and dynamics of crystals.

Multiscale representation of conservation laws is formulated, as a direct consequence of newton’s second law, in terms of instantaneous expressions of unit cell-averaged quantities using the mathematical theory of distributions. finite element (FE) solutions to the conservation equations, as well as fluxes and temperature in the FE representation, are introduced, followed by numerical examples of the atomic-scale structure of interfaces, dynamics of fracture and dislocations, and phonon thermal transport across grain boundaries. in addition to providing a methodology for concurrent multiscale simulation of transport processes under a single theoretical framework, the CAC formulation can also be used to compute fluxes (stress and heat flux) in atomistic and coarse-grained atomistic simulations.

Crystalline Materials and Microstructure

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First of all, it’s important to understand what crystalline materials are and the concept of microstructure. familiar materials such as metals, minerals or ceramics are crystalline. in crystalline materials, the atoms that form the material are arranged to repeat periodically in space. the imaginary three-dimensional grid of points on which the atoms sit is called the crystal lattice. of course, the size of the atoms and the distances between the repeating groups of atoms are tiny. for example, in aluminium, the atoms are arranged at the corners and face centres of a cube. the length of the edge of the cube is 0.405 nanometre – about 200,000 times smaller than a human hair. (1 nanometre is 10-9m).

Compared with crystalline materials, the sintering behaviour of noncrystalline materials is quite simple. the rate is relatively insensitive to the details of the microstructure, so the time needed to reach full density can be estimated with reasonable accuracy given only the viscosity and the mean pore size. To predict in detail the evolution of the density and pore size distribution with time, it is necessary to know the initial state of the sample (distribution of pore size, density, and viscosity); however, such calculations are possible with the existing theory. the most challenging problem remaining in the field of viscous sintering is to develop appropriate constitutive equations for the analysis of constrained sintering.

The difficulty is that the functions f and n are sensitive to the microstructure (particle shape, contact area, connectivity of voids, and so on). moreover, the properties may be anisotropic as a result of the processing of the unfired body (such as pressing of powder compacts) or maybe isotropic at the start of sintering, then become anisotropic as a result of the constraint (e.g., during uniaxial pressing). considerable progress is being made in this area through careful experimental work and detailed numerical simulations. much of this work is described in the review by Olevsky (1998).

Elements of Structures and Defects of Crystalline Materials

elements of structures and defects of crystalline materials have been written to cover not only the fundamental principles behind structures and defects but also to provide deep insights into understanding the relationships of properties, defect chemistry and processing of the concerned materials. part one deals with structures, while part two covers defects. since the knowledge of the electron configuration of elements is necessary for understanding the nature of chemical bonding, it is discussed in the opening chapter. chapter two then describes the bonding formation within the crystal structures of varied materials, with chapter three delving into how a material’s structure is formed.

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