Final writing exercise Essay

There are three varietys whereby each has a antithetical quartz glass organise at three contrasting temperatures. At way temperature (298K), microscope stage ternary is present whereby Cs3H(SeO4)2 has a lechatelierite bodily structure of a monoclinic with a space group of C2/m. At 400K, mannikin II is present whereby Cs3H(SeO4)2 has a crystal structure of a monoclinic-A2/a conformity. At 470K, Phase I is present whereby Cs3H(SeO4)2 has a crystal structure of a trigonal with a space group of R3-m. In Phase trio, as we kitty see in designing 2(a), the positioning of the tetrahedrons is parallel to the a-axis, and in between these SeO4 tetrahedrons are the henry deposits. Looking at a 2dimensional perspective, we stomach also see that there is a translation question of the SeO4 tetrahedrons along the a-axis hence the unison operator would be a glide dividing line parallel to a-axis. In a 3-dimensional perspective, we can see that Phase terzetto has a 2-fold rotati on axis and contains glide planes.In Phase II, from direct 2(b), we can see that the positioning of the SeO4 tetrahedrons are along the approximate attention 310. Observing the schematic of the crystal structure in Phase II, we can see that there is a vertical mirror line in between the SeO4 tetrahedrons. There is also an a-glide reflection vertically. In Phase I, from Figure 2(c), the positioning of SeO4 tetrahedron is similar to that of Phase II, however the difference is the crystal structure and the atomic number 1 bonding. Comparing both Phase II and Phase III crystal structures of the compound, Phase II contains two-fold screw axis, inversion center and a two-fold rotation axis, which is the sole think for Phase II to be in two ways of that of Phase III in terms of geometricalarrangement of hydrogen bonds.From the above analysis of the symmetry of the crystals structures in different courses, we can give tongue to that Phase III has the most symmetry operators and henc e achieving the highest crystal symmetry generating a economic crisis geometrical arrangement of hydrogen bonds. Due to the low geometrical arrangement of hydrogen bonds, the mobility of protons decreases giving the result of ferroelasticiy. The drastic interchange from superprotonic conductivity to ferroelasticty happens when there is a change from Phase II to Phase III. The major difference between theses 2 shapes is the hydrogen bond arrangement. split 2Under the optical microscope, we can observe that the polymorphic scene of actions get out alter at each anatomy rebirth to a different extent. We can see in physical body III that the playing fields in the Cs3H(SeO4)2 crystal are made up of poly domain of a functions separated by two kinds of domain boundaries. The two kinds of domain boundaries are categorized as the planes of 311 and 11n, where n is laid by the strain compatibility condition. The domains at the sides of each domain enclosure are related to the reflec tive symmetry or the rotational symmetry on that boundary itself. Furthermore, we can observe that the angle between any domain and its neighboring domains is approximately 120, which is very close to the theoretical value calculated using the latticework parameters.As we move on from phase III to phase II, we can observe that the domain structure alters meagrely by the phase transition of TIIIII. Similarly, the reflective symmetry and rotational symmetry also changes at the same phase transition. However, the kinds of domain and domain boundary remain the same as those in phase III contempt a change in domain pattern. This could be due to the subtle change in alignment of hydrogen bonding between the SeO4 tetrahedrons when the subsisting hydrogen bonds were broken to form new weakerones. This might explains why their lattice parameters a and b do not really change appreciably. Compared to phase III antecedently, the angle between any domain and its neighboring domains in phas e II is also approximately 120 and is justified by the theoretical values determined from the same equation we used for phase III.Hence, this suggest a slight change in the Cs3H(SeO4)2 crystal structure at the phase transition of TIIIII. From phase II to phase I, the domain boundaries is observed to have disappear just before the curie temperature of the phase transition of TIII and the crystal structure changes fromoptically biaxate to optically uniaxial. This could be due to an external stress caused by the atomic rearrangement of the SeO4 tetrahedrons in the Cs3H(SeO4)2 crystal as a result of breaking the hydrogen bonds between them.Paragraph 3Higher temperatures for most material leave alone enable atoms to move to low energy points, fitting into a everlasting(a) crystal symmetry. Cs3H(SeO4)2 however behaves differently. As the temperature increases (above 396K), its crystal symmetry decreases when it changes phase from III to II. The orientation of the hydrogen bond for pha se II and III differs. For phase II, the orientation is along 310 and 3-10 direction whereas for phase III, it is parallel to the aaxis. As the transition from phase III to II occurs, the precursor of the superprotonic conductivity is observed. In bless for movement of proton to occur, the breaking and then recombination of hydrogen bonds are required.For phase III, in order for the movement of one proton, the breaking of 2 hydrogen bonds is needed. The reason as to why 2 hydrogen bond is needed to be broken and recombined again is because for the movement of one proton to occur, it must break the hydrogen bond it resides in and then change its orientation, recombining at another site the mirroring effect of opposite hydrogen bond is required to maintain the crystal symmetry i.e. to say that the another hydrogen bond parallel to the previous hydrogen bond site needs to be broken and recombined at other site parallel to the newlyrecombined hydrogen bond.In this way, in phase III, th e recombination of two hydrogen bonds is simultaneously needed for one proton transport. Phase II however, behaves differently. The movement of the proton is independent of the other protons at other hydrogen site. The crystal structure allows for this flexibility of the proton motion, which the superprotonic conduction takes place. The mechanism in which proton theodolite occurs in the polymorphs is by the diffusion of protons through a hydrogen bond network, by the cleaving and formation of the hydrogen bonds. However, in certain phases, the cleavage and formation of the hydrogen bond might differ. The fuel cell works on the basis of the movement of protons. The movement of electrons should be disallowed as it would short lap covering the fuel cell. Hence, a membrane is used to allow only the movement of protons across and not electrons and gases. On top of that, in order for a superprotonic effect to occur, the flexibility for proton motion must be allowed. Hence, the lesser s ymmetrically patterned the phases the protons reside in, the higher this flexibility.