Material Specification for Hg:1223; [Hg-Ba-Ca-Cu-O]
Process: Solid State Reaction
Notes: "Samples were synthesized in two steps, that is production of precursor pellet and formation of the superconducting samples inside the quartz tubes. The precursor pellets of Ba-Ca-Cu-O were prepared by mixing the appropriate amount of nitrates: Ba(NO3)3, Ca(NO3)24H2O, and Cu(NO3)22.5H2O. After the heat treatment of these reagents, a stoichiometric amount of HgO was added to the precursor and mixed in a glove box in nitrogen atmosphere. Then the sample was heated with a high Hg vapor pressure of about (20 MPa = 200 atm). The oxygenation of samples was carried out in flowing oxygen at 300 °C for 20 h."
Formula: HgBa2Ca2Cu3O8+x
Informal Name: Hg:1223
Chemical Family: Hg-Ba-Ca-Cu-O
Chemical Class: Oxide
Structure Type: Polycrystalline
Manufacturer: In House
Commercial Name: In House
Production Date:
Lot Number:
Production Form:
Critical Temperature for Hg:1223; [Hg-Ba-Ca-Cu-O]
| Critical Temperature (K) |
| 132 |
Measurement Method: Four-probe resistance
"The zero-resistance temperature of the sample was... obtained from the four-probe resistance measurement." No additional measurement details were noted.
Cautions: Unevaluated Data
Energy Gap(2 delta) for Hg:1223; [Hg-Ba-Ca-Cu-O]
| Gap Order () |
2Δ/KTc () |
Energy Gap (2Δ) (meV) |
| Primary |
8.5 |
96 |
| Secondary |
3.9 |
44 |
Measurement Method: Tunneling microscopy
"In this work, we performed an electron tunneling measurement for a bulk HgBa
2Ca
2Cu
3O
8+δ by a point-contact spectroscopy using a low-temperature scanning tunneling microscope (LTSTM). ... The mechanical part of the low-temperature STM system was mounted in a long cylindrical stainless tube filled with He gas to reduce the thermal drift effect. Helium exchange gas pressure was kept at about (0.13 Pa = 1 mTorr), high enough to maintain a thermal equilibrium during the tunneling experiment and also low enough to prevent an electric discharging effect. ... The mechanical part in the cylindrical tube was then immersed in liquid helium cryostat. The maximum scan lengths of the constructed LTSTM along lateral and vertical directions (at) 4.2 K were about 0.8 µm and 0.2 µm, respectively. ... The typical radius of the Pt-Rh tip used in this experiment is estimated to be about 0.2 µm... To overcome the possible degradation of the sample surface, the... sample surface was scraped with a file just before mounting on the sample stage of LTSTM. Immediately after mounting the sample, the cylinder was filled with helium exchange gas. The air exposure time of the scratched surface was less than 20 min. ... Tunneling spectroscopy was performed using the usual lock-in technique. The magnitude of the modulation voltage was 1.65 mV with the sweep rate of about 10 s."
Cautions: Evaluated Data
"Although one still cannot rule out the possibility of other impurity phases being responsible for the smaller gap, the absence of any impurity phase in the magnetic-susceptibility measurement is interpreted as an indication that the observed two different gaps are due to the gap anisotropy in this material reflected in the normal layer through the proximity effect."
