Howlers of the week 1998-9
These are all genuine sentences and paragraphs that were written by students in their write-ups for the 2nd year practical on High Temperature Superconductivity. Remember that all spelling mistakes, grammatical errors, and errors of logic are all entirely theirs, and have been reproduced exactly as they appeared on the student's script.
- Either side of this figure the Tc falls sharply - reducing the profitableness
of a superconducter with a corresponding complex.
- You wouldn't expect all the Cu-O distances to be the same because although
the oxygen atoms are in an octahedral shape around the Cu ion but due to the
Jahn-Teller effect are distorted. This effect is due to the fact that the
oxygen atoms which to be in the more stable square planar form and so the
molecules becomes compressed and elongated.
- You can also think about it as if the change in oxidation state of O causes the
superconductivity, and that Cu doesn't change its oxidation state, which would
mean that the type of superconductor one considers it to be, if they decide Cu
is changing in oxidation state, is the wrong way round!
- One electron will be at a higher energy, but this works out better energetically
than 3 electrons all in the middle.
- Cu is being reduced by the addition of Ce, unlike the addition of Sr where the
Cu is being reduced.
- From this graph what I have created, there is a diffinate area of superconductivitity.
- The graph is a symmetrical hump shape.
- The extra Sr may cause a slight uncoupling affect on the phonons or may disrupt the
- Using computers gives scientists the opportunity to work on a problem but not waste
any money on unnessassery experiments.
- The experiment was carried out using the diagram below.
- The conductor is p-type which means that electrons 'jump' along the complex
to fill the hole.
- Using the PC reduces the experiment to a matter of minuets.
- When the oxygen ligands are added this results in weaking bond orbitals.
- A superconductor could be thought of as a row of Cu atoms with an average
oxidation state of 2.15 therefore as the +3 oxidation state is not preferred
the Cu atom passes it on to the next Cu atom so there is a free electron
flowing along the wire and hence this conducts with zero resistivity as the
number of Cu3+ ions increase or decrease the temperature needs to be lowered
for it to superconduct but when oxidation state of Cu is 2.15 it works at
- Since the manfuctor of liquid helium in the 1930's supercondictivity of metels
has been observed.
- NdCeCuO4 is also a high Tc superconductor - with a twist.
- High temperature superconductors are synthesised by lengthy roots.
- Cu has a flexible oxidation state.
- This means that 2 go down on energy and one goese up. The overall effect is overall
the energy decreases and thus is more stable overall.
- These Cu(III) are very unhappy and are desperate to become Cu(II).
- When an electric current travels along a wire, the electrons crash against
the sides of the wire, and a resistance is formed. In superconductors, the
resistance is zero, so any current in a loop will continue - so long as
it is cold.
- The race is on to develop a room temperature superconductor, and the money
that would result from the discovery of this is unimaginable!
- This experiment has shown me a lot about superconductors. Weather n- or p-type.
YBCO, like most high temperature superconductors work at liquid nitrogen temperatures,
this is a far more accessible temperature as liquid nitrogen is so cheep.
- That is why there are no plops on the graph.
- When electrons flow through a wire they experience ethical resistance.
- One of the metals is in two oxidation states and as more oxygen is added oxidises
beyond 2+ in one section promoting electrons into a conduction band which is
stobalised by the other metals which have stable oxidation states.
- The temperature at which the compounds superconduct is probably to do with the
amount of vibration of the walls of the conduction band, or the metal ions in them;
it may be a good thing to have large conduction bands!
- Before the discovery of high Tc superconductors, only low Tc superconductors were known.