1.what is the advantage of heating gellium semi-conductor with sites or gold instruct of indium and boron?
2.why co-ordination number of 12 is not found in ionic crystals?
3.what kind of symmetry is exhibited by a match box?
1. To understand the advantages of heating a gallium semiconductor with sites of gold instead of indium and boron, we need to consider the properties of these elements and their interactions with gallium.
Gallium is a semiconductor material that has a unique property known as liquid phase epitaxy (LPE). In LPE, gallium is heated to a certain temperature where it becomes liquid and then it is solidified onto a substrate. This process allows for the growth of high-quality single crystal layers of gallium on the substrate.
When gold sites are used instead of indium and boron, it can have several advantages:
a) Diffusion barrier: Gold can act as a diffusion barrier and prevent unwanted impurities or vacancies from diffusing into the gallium semiconductor during the growth process. This helps in maintaining the purity and quality of the gallium layer.
b) Enhanced electrical properties: Gold can improve the electrical properties of the gallium semiconductor. It can promote better charge carrier mobility and reduce resistivity, which is beneficial for semiconductor devices.
c) Epitaxial growth: Gold can provide a suitable epitaxial surface for the gallium layer to grow on, ensuring a high-quality crystal structure with good lattice matching. This is important for achieving uniformity, good crystalline structure, and avoiding defects in the semiconductor material.
2. The coordination number refers to the number of ions or atoms that surround a central ion in an ionic crystal lattice. It represents the number of nearest neighbors of the central ion.
In ionic crystals, the coordination number is usually limited to certain specific values, such as 4, 6, and 8, but not 12. There are a few reasons why coordination number 12 is not commonly found in ionic crystals:
a) Coulomb's Law: The arrangement of ions in an ionic crystal is governed by Coulomb's Law, which describes the electrostatic interactions between charged particles. The arrangement of ions seeks to minimize the total energy of the crystal. For coordination number 12, it would result in higher energy compared to other commonly observed coordination numbers.
b) Packing Efficiency: Ionic crystals tend to have close-packed structures, where the ions are packed in a highly efficient manner to occupy maximum space. Coordination number 12 would require a different arrangement that may compromise the packing efficiency of the crystal.
c) Stability: Coordination number 12 arrangements may not be thermodynamically stable or energetically favorable for many ionic compounds. The crystal structure tends to adopt arrangements that result in lower energy states, which are typically achieved with coordination numbers 4, 6, or 8.
3. A matchbox typically exhibits two types of symmetry:
a) Reflection symmetry: A matchbox has reflection symmetry, also known as mirror symmetry or bilateral symmetry. This means that there is a plane of symmetry dividing the matchbox into two equal halves such that one half is the mirror image of the other. If you fold the matchbox in half along this plane, the two halves will perfectly overlap.
b) Rotational symmetry: A matchbox also has rotational symmetry. You can rotate it around its long axis (the line passing through the center of the matchbox and the tips of the sticks) by 180 degrees and it will still appear the same. This is a type of rotational symmetry known as a two-fold rotational symmetry, as it has rotational symmetry at every 180-degree interval.
These types of symmetry help in identifying patterns and features in objects and have various applications in mathematics, physics, and design.