Joe Eck at Superconductors.ORG reports the observation of record high superconductivity near 254 Kelvin (-19C, -2F). This temperature critical (Tc) is believed accurate +/- 2 degrees, making this the first material to enter a superconductive state at temperatures commonly found in household freezers. Only a small volume of the material is achieving superconduction, so work/research must be down to get an entire volume of material to achieve these effects.
This achievement was accomplished by combining two previously successful structure types: the upper part of a 9212/2212C and the lower part of a 1223. The chemical elements remain the same as those used in the 242K material announced in May 2009. The host compound has the formula (Tl4Ba)Ba2Ca2Cu7Oy and is believed to attain 254K superconductivity when a 9223 structure forms.
One of six magnetization tests performed on a sample pellet is shown above. In order to increase the magnetometer signal-to-noise ratio, this pellet was synthesized using the "layer-cake" method discussed here. All the tests showed a diamagnetic transition between 257K and 259K.
4-point resistance tests were performed on both a "bulk" pellet and a "layer-cake" pellet. A 254K critical transition temperature was observed on all four tests, including the plot at page top.
Sharif University has confirmed JoeEck's Y358 (Ultra YBCO) discovery in a paper published in Physica C. Ultra YCBO is an improved version of the most popular industrial superconductor.
The Y3Ba5Cu8O18 compound was synthesized through the standard solid-state reaction technique. Characteristic XRD experiment was performed on the samples and was analyzed by the MAUD software refinement program. The analysis results indicate a 358 phase structure with the initial nominal stoichiometry. The electrical resistivity and its behavior under different magnetic field were measured. The electrical resistivity indicates the transition temperature Tonset c ¼ 102 K with transition width DTc = 2.4 K. This is the first observation of such a high transition temperature in the Y-based compound.
The Y123 superconductor compound has two CuO2 planes and one CuO chain. The Y124 superconductor compound has one double chain instead of the single chain in Y123. The Y247 superconductor compound has one single, and one double CuO chain and one CuO2 plane. In comparison, the highest Tc Y358 superconductor compound studied in this paper has crystal structure similar to Y123 with the exception of the number of CuO chains and CuO2 planes, which exceed those in Y123. The Y358 has five CuO2 planes and three CuO chains. It seems that increasing the number of the CuO2 planes and also the position of the CuO chains have important effects on the value of the transition temperature in the Y358 compound.
The Y358 compound synthesized by the solid-state reaction technique has Tonset c ¼ 102 K. Finally, it seems that Y123 compound is not the optimum compound, and for reaching a still higher transition temperature in the YBCO family, further combination of the components should be synthesized and studied.
Superconductors.ORG reported the critical transition temperature (Tc) of the industrial superconductor YBCO (YBa2Cu3O7) had been successfuly increased from 92K to over 105K by reformulating to Y3Ba5Cu8Ox. No new elements were added. (3 June 2008)
BACKGROUND ON FREEZERS
Good ultralow lab freezers go to about -86C.
Subzero freezers (kitchens)
FREEZER compartment temperatures can be set from -5°F to +5°F. Pretty easily maintained. Freezers that use ammonia would be able to go down to -27F max. -27F is the boiling point of Ammonia.
Dedicated commercial freezer
Extra large evaporator coil balanced with higher horsepower compressor and large condenser; maintains -10°F (-23.3°C). Ideal for both frozen foods and ice cream.
Some confirmation of Joe Ecks work with YCBO compounds, that Joe claim can go from 92K (others) to 105K (his and now Sharif University).
Joe Ecks work seems carefully done but he has been a one man show. that a small University is doing some confirmation and getting a journal article is good.
New research indicates that the path to metallic hydrogen looks easier Metallic hydrogen could mean room temperature superconductors too.