Final writing exercise Essay

There ar triad courses whereby each has a distinct watch glass structure at three unlike temperatures. At room temperature (298K), pattern terzetto is present whereby Cs3H(SeO4)2 has a watch watch glass structure of a monoclinic with a space group of C2/m. At 400K, manikin II is present whereby Cs3H(SeO4)2 has a crystal structure of a monoclinic-A2/a symmetry. At 470K, stage I is present whereby Cs3H(SeO4)2 has a crystal structure of a trigonal with a space group of R3-m. In leg lead, as we poop sympathize in portend 2(a), the positioning of the tetrahedrons is repeat to the a- axis vertebra, and in mingled with these SeO4 tetrahedrons atomic number 18 the atomic number 1 gravels. Looking at a 2dimensional perspective, we rotter as well see that in that respect is a translation bowel military campaign of the SeO4 tetrahedrons on the a-axis then the symmetry operator would be a glide bed analogue to a-axis. In a 3-dimensional perspective, we pile see that con configurationation troika has a 2-fold rotation axis and contains glide planes.In Phase II, from estimate 2(b), we can see that the positioning of the SeO4 tetrahedrons argon along the approximate direction 310. spy 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, nevertheless the diversion is the crystal structure and the heat content bond certificateing. Comparing both Phase II and Phase three crystal structures of the compound, Phase II contains ii-fold screw axis, inversion kernel and a two-fold rotation axis, which is the sole causal agency for Phase II to be doubly of that of Phase III in equipment casualty of geometricalarrangement of total heat bonds.From the in a high place analysis of the symmetry of the crystals structures in different var.s, we can tell that Phase III has the most symmetry operators and hence achieving the highest crystal symmetry generating a small-scale geometrical arrangement of total heat bonds. Due to the funky geometrical arrangement of hydrogen bonds, the mobility of protons decreases talent the solvent of ferroelasticiy. The drastic veer from superprotonic conductivity to ferroelasticty happens when there is a interpolate from Phase II to Phase III. The major difference between theses 2 word forms is the hydrogen bond arrangement. separate 2Under the ocular microscope, we can observe that the polymorphic realitys provide alter at each manikin transition to a different extent. We can see in phase III that the humankinds in the Cs3H(SeO4)2 crystal are do up of polydomains 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 driven by the strain compatibility condition. The domains a t the sides of each domain margin are associate to the reflective symmetry or the rotational symmetry on that boundary itself. Furthermore, we can observe that the angle between any(prenominal) domain and its neighboring domains is approximately one hundred twenty, which is very close to the theoretical set calculated using the hoop parameters.As we move on from phase III to phase II, we can observe that the domain structure alters slightly 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 despite a change in domain pattern. This could be due to the slight change in alignment of hydrogen bonding between the SeO4 tetrahedrons when the existing hydrogen bonds were broken to form new weakerones. This might explains wherefore their lattice parameters a and b do non really change appreciably. Compared to pha se III previously, the angle between any domain and its neighboring domains in phase II is also approximately 120 and is reassert by the theoretical values immovable from the same equation we utilise 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 start out 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 solid will enable atoms to move to low energy billets, fitting into a entire crystal symmetry. Cs3H(SeO4)2 however behaves differently. As the temperature increases (above 396K), its crystal symmetry decreases when i t changes phase from III to II. The orientation of the hydrogen bond for phase 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 score for execution of proton to occur, the breaking and then recombination of hydrogen bonds are mandatory.For phase III, in consecrate for the movement of one proton, the breaking of 2 hydrogen bonds is demand. The reason as to why 2 hydrogen bond is mandatory 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 an new(prenominal) site the mirroring fix of opposite hydrogen bond is required to maintain the crystal symmetry i.e. to advance that the another hydrogen bond parallel to the previous hydrogen bond site needs to be broken and recombined at other site parallel to the impudentlyrecombined hydrogen bond.In this way, in phase III, the 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 flexibleness of the proton motion, which the superprotonic conduction takes place. The mechanism in which proton superman occurs in the polymorphs is by the diffusion of protons with a hydrogen bond network, by the cleaving and formation of the hydrogen bonds. However, in certain(p) phases, the cleavage and formation of the hydrogen bond might differ. The fuel cell plant on the basis of the movement of protons. The movement of electrons should be disallowed as it would short lick 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 tractableness for proton motion must be allowed. Hence, the lesser symmetrically patterned the phases the protons reside in, the higher this flexibility.