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Ferroelectrics 2.1 Introduction 2.2 Point Groups and Crystal Symmetry 2.2.1 Symmetry
| Content Provider | Semantic Scholar |
|---|---|
| Abstract | The first part of this thesis is focused on producing an active MIM waveguide with a ferroelectric layer as the active material. Henceforth, the analysis of ferroelectrics will be done with two materials which acccurately represent the field, barium titanate (BaTiO 3) and lithium niobate (LiNbO 3). In this chapter, we will introduce ferroelectrics and motivate why these materials present a unique opportunity for use in active plasmonic devices. These materials exhibit a wide range of properties including piezoelectricity, ferroelectricity, pyroelectricity, and electro-optic effects. The intensity of these effects within the materials is directly related to the quality of the crystal in question. As a result, ion implantation induced layer transfer is introduced at the conclusion of this chapter as a method of producing single crystal thin film ferroelectrics. All crystalline materials can be represented by a crystal lattice and a basis. The lattice represents the three-dimensional periodic array of points in space. These points form individual " unit cells " which represent the smallest repeat unit of the lattice. The basis represents the atom or atoms which lie on each point within the lattice. These crystals can be organized by their symmetry operations and divided into 32 distinct " point groups ". Of these 32 groups, 11 have a well defined center of symmetry and are defined as centrosymmetric. Out of the remaining 21 groups, 20 are piezoelectric [the (432) point group being the only exception]. Out of the 20 piezoelectric point groups, 10 have a unique polar axis and are referred to as ferroelectric. Below a critical transition temperature, the Curie temperature (T c), ferroelectric materials exhibit a spontaneous polarization due to a distortion in the crystal structure. A diagram of the different crystal systems is shown in 13 |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://thesis.library.caltech.edu/5282/9/09Chapter2.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
