Search Results - Crystal structure
| Type in a word or phrase to search, you can also type in Article ID's separated by commas: |
 |
|
|
In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. A crystal structure is composed of a motif, a set of atoms arranged in a particular way, and a lattice. Motifs are located upon the points of a lattice, which is an array of points repeating periodically in three dimensions. The points can be thought of as forming identical tiny boxes, called unit cells, that fill the space of the lattice. The lengths of the edges of a unit cell and the angles between them are called the lattice parameters. The symmetry properties of the crystal are embodied in its space group. A crystal's structure and symmetry play a role in determining many of its properties, such as cleavage, electronic band structure, and optical properties. The crystal structure of a material or the arrangement of atoms in a crystal structure can be described in terms of its unit cell. The unit cell is a tiny box containing one or more motifs, a spatial arrangement of atoms. The units cells stacked in three-dimensional space describes the bulk arrangement of atoms of the crystal. The unit cell is given by its lattice parameters, the length of the cell edges and the angles between them, while the positions of the atoms inside the unit cell are described by the set of atomic positions (xi,yi,zi) measured from a lattice point. Although there are an infinite number of ways to specify a unit cell, for each crystal structure there is a conventional unit cell, which is chosen to display the full symmetry of the crystal (see below). However, the conventional unit cell is not always the smallest possible choice. A primitive unit cell of a particular crystal structure is the smallest possible volume one can construct with the arrangement of atoms in the crystal such that, when stacked, completely fills the space. This primitive unit cell does not always display all the symmetries inherent in the crystal. A Wigner-Seitz cell is a particular kind of primitive cell which has the same symmetry as the lattice. In a unit cell each atom has an identical environment when stacked in 3 dimensional space. In a primitive cell, each atom may not have the same environment. The defining property of a crystal is its inherent symmetry, by which we mean that under certain operations the crystal remains unchanged. For example, rotating the crystal 180 degrees about a certain axis may result in an atomic configuration which is identical to the original configuration. The crystal is then said to have a twofold rotational symmetry about this axis. In addition to rotational symmetries like this, a crystal may have symmetries in the form of mirror planes and translational symmetries, and also the so-called compound symmetries which are a combination of translation and rotation/mirror symmetries. A full classification of a crystal is achieved when all of these inherent symmetries of the crystal are identified.
|
Showing 1 to 11 of 11 Articles matching 'Crystal structure' in related articles. |
| Pages: 1 |
 |
|
|
|
1. The Advantages Of Buying An LCD TV
November 09, 2008
What does LCD TV mean and how does it function? LCD stands for liquid crystal display. Behind the screen are a number of pixels followed by a fluorescent light. When this light falls on the pixels, an electric current is generated, creating light variations, which make up the vividly colored images that we see. Generally, the twisted nematic liquid crystal is used which has a naturally twisted crystalline structure.
The screen size of an LCD TV varies between 13-46 inches and it is about 2 inches deep in thickness. They are very light and so extremely easy to install. This indicates that ... (read more)
Author: Roberto Sedycias
|
|
|
|
|
2. Six Steps to the Best Research Paper Format
November 06, 2008
Introduction Format of a research can be a difficult job if not done properly. Students and professionals alike worry a lot about the context and format of their research. The aim is to present it in its optimal condition with everything crystal clear for the reader. Diverse papers involve different approaches. However the 6 step approach is not only one of the most basic approaches but also the most efficient. It is the most basic structure that serves its purpose and can easily be changed or edited.
Discussion Regardless of the topic or subject, the 6 step approach is always the mo... (read more)
Author: Jon Oliver
|
|
|
|
|
3. Love with Crystal II --- Give a Glance at the Mysterious World of Crystal (Up part)
October 20, 2008
Crystal is one kind of intelligential minerals, it could bring us good luck while eliminate bad luck, and it has been described as a fairy treasure of natural stones. The special molecular structure of crystal is a fruit of absorbing the elites of the sun, moon and the earth endlessly, thus endowed with super powerful nimbus and magnetic energy, and with an incredible force for Aura. Keeping a crystal with as to carry a body guardian of King Kong, it has functions of self-cultivation, health care, training of qi, house guarding, gathering wealth, praying, recruiting wealth, worshiping Bu... (read more)
Author: Krista QQ
|
|
|
|
|
4. Disappearing breed of hydrogen
September 03, 2008
Water a very common chemical substance which is essential for the survival of all life forms on this Earth. Volumetric and gravimetric composition of water are 2:1 and 1:8 (H:O respectively). Pure water is a bad conductor of electricity due to very low degree of ionization. Maximum density of water is at 4ºC. Ice floats on water because density is less than that of water which in turn is due to the empty space in its crystal structure. Crystal structure of ice is regular hexagon with empty space at the centre.
Water is one of the most important compounds of hydrogen. It is colourless liqu... (read more)
Author: lalit sharma
|
|
|
|
|
5. Easy Crystal Experiments You Can Share With Your Kids
August 30, 2008
Crystals are formed with atoms line up in patterns when the substance solidifies (or the liquid evaporates and leaves the rest behind). There are crystals everywhere – in the form of salt, sugar, sand, diamonds, quartz, and many, many more. But how do the atoms know how and when to line up (in a crystalline structure)? Let’s take a closer look at atoms while teaching homeschool science: Suppose we have a drop of water. If we look at it very closely, we’ll see a drop of water, nice and smooth. If you grab your microscope and magnify it roughly 2,000 times (the drop is now 40 feet across, th... (read more)
Author: Aurora Lipper
|
|
|
|
|
6. Diamond Types
August 24, 2008
Diamonds are classified broadly under the categories of Natural Diamond, Synthetic Industrial Diamond and Thin Film Diamonds on the basis of their process of origination.
Diamonds remain to be the most fascinating gift that a woman can ever dream about. The word “diamond” is derived from a Greek word “adamas” which stands for “invincible". Due to its atomic structure, diamond is the hardest natural matter. This expensive and translucent gem is made of carbon.
Diamonds can be scientifically classified into 4 types, known as type 1a, 1b, 2a, and 2b.Diamonds are made of carbon, and are ... (read more)
Author: Addie Jakson
|
|
|
|
|
7. The Dazzling Topaz
July 15, 2008
Topaz is a semi-precious stone that is derived from the Sanskrit word ‘tapas’ which means fire. It comes in various earthly tones. Of the available hues it comes in, the most valuable would be the ones with pink or deep golden yellow hues. Topaz could also come in blue, after color enhancement is done through the process of irradiation.
Topaz has a kind of an orthorhombic crystal structure. It has a hardness of 8 on the Moh’s scale. It also occasionally has several tear-shaped cavities that encompasses varies immiscible liquids or a gas bubble. There are some that come with diamond-shape... (read more)
Author: Priyanka Arora
|
|
|
|
|
8. Peridot: The Evening Stone
July 15, 2008
Peridot is actually gem quality variety of the forsteritic olivine. The name of this semi-precious stone is believed to have been derived from the Arabic word ‘faridat’ which means "gem" or from the French word ‘peritot’ which means "unclear." Peridot is just one of the very few gemstones which is available in only one color.
With this gemstone, the depth of green basically depends on the amount of which is contained in its crystal structure. This varies from a yellow-green hue to an olive shade to a brownish green hue. It is also often known as the "poor man's emerald". Now, olivine, wh... (read more)
Author: Priyanka Arora
|
|
|
|
|
9. An Amazing Purple Semi-Precious Stone: The Amethyst
July 15, 2008
The term for the semi-precious stone Amethyst comes from the Greek word “Amethystos”, which means not drunken. This stone was actually believed by the Greeks of ancient times to prevent intoxication. It is also the birthstone for those people born in February.
The amethyst is a purple semi-precious stone, with its color ranging from a pale pinkish violet to a very deep purple. It is made from the chemical silicon dioxide. It has a vitreous luster and could be mined from alluvial deposits. The amethyst has a structure that is a trigonal crystal structure and has a hardness of 7 on the Moh’... (read more)
Author: Priyanka Arora
|
|
|
|
|
10. Why Laser Teeth Whitening Is An Expensive Solution For A Dull Smile
February 12, 2008
Considered the most advanced medical bleaching procedure, laser teeth whitening is an expensive solution for a dull smile. The laser light is used in combination with a certain type of whitening gel, and the procedure is entirely confined to performance within a medical environment. After the gel is applied on the teeth, the light forces the active substances to enter the crystal like structure and start the discoloration process. Depending on how damaged your teeth are, the laser teeth whitening treatment could take more or less time; usually a session is enough for the mild cases, whereas s... (read more)
Author: Peter Gitundu
|
|
|
|
|
11. Ultra Slim Structure Samsung U600
January 18, 2008
The Samsung U600 is an attractive slider phone with an impressive large screen of 2.2 inches that displays 262k colour of 240 x 320 pixels. The 3.2 mega pixel camera with auto-focus and flash lets you take crystal clear pictures. Coming to music features, the handset has a built-in digital music player and an FM radio that lets you enjoy high quality music.
Samsung-U600 is a light weight handset that emits 256,000 colours through its TFT display. Weighing only 81 g, this light weight gadget can slip easily in your palm and adds on to your style statement. Technically speaking, Samsung U6... (read more)
Author: swornambigai ambika
|
|
|
|
|
