Aliev points out that the team's published results provide only partial evidence of superconductivity, but the group is working hard to establish the full story and has high hopes for its material.

"The extremely high surface area of tungsten bronzes infiltrated into shell-type inverted carbon opals with very tiny heat capacity and low thermal conductivity could be employed in various sensors like IR bolometers, SQUIDs and nano switch devices for microwave detectors in MRI," Aliev told nanotechweb.org.

The researchers deposit the tungsten oxide film on to the host porous matrix by dipping a bar-shaped test structure into peroxotungstic acid. Next, they apply a vacuum to encourage the solution to penetrate deep into the nanoporous network.

To get a higher filling factor, the dipping process is repeated at least 4–5 times. After each infiltration, the test material is left to dry at room temperature for 10 minutes and then sintered at 130 °C for 30 minutes to help fix the freshly deposited film on to the host surface.

Electrochemical intercalation is performed by connecting the tungsten rich matrix to a three electrode set-up featuring various electrolytes.

Upon investigation, the treated material displays magnetic and electrical behaviour that suggests the possibility of localized non-percolated superconductivity, although why nanostructured matrices are able to exert this effect is up for debate.

"The behavior of electronic states under light excitation in tungsten bronzes suggests a bipolaronic mechanism of electron coupling. Regarding the nanostructure, perhaps the quantum confinement of carriers within the small islands (10–15 nm) leads to discretization of the quasiparticle density-of-state, which can account for the slight increase in the transition temperature from 91 K for bulk tungsten bronze to 125 K for nanostructured ones," commented Aliev. "However, I believe that below ~5 nm the superconductivity is totally suppressed due to the lack of any states around the bandgap."

Ali Aliev presented his work in Superconductor Science and Technology.