Question

Description of measured/observed of superconductor YBa2Cu3o7-X.

- What type of superconductor YBa2Cu3o7-X?

- What is magnetic properties YBa2Cu3o7-X?

- Transition between superconducting phase to other phases such as normal or magnetic for YBa2Cu3o7-X?

-What is critical temperature for YBa2Cu3o7-X?

- What is critical field for YBa2Cu3o7-X?

- Mechanism of superconductivity for YBa2Cu3o7-X?

Answer 1

~Yttrium barium copper oxide (YBCO) is a family of crystalline chemical compounds, famous for displaying high-temperature superconductivity. It includes the first material ever discovered to become superconducting above the boiling point of liquid nitrogen (77 K) at about 92 K. Many YBCO compounds have the general formula YBa₂Cu₃O_7−x (also known as Y123), although materials with other Y:Ba:Cu ratios exist, such as YBa₂Cu₄O_y (Y124) or Y₂Ba₄Cu₇O_y (Y247). At present, there is no singularly recognised theory for high-temperature superconductivity.

~YBa2Cu3O7-x powder was heat treated in hermetically sealed gold capsules at 100 kbar and 945 degrees C. The resulting product is superconducting without further oxygen treatment. Magnetically determined transition temperatures are near 92.6 K. The product consists of fine particles with diameters in the range 50 to 1000 nm and much reduced density of twins. At low fields the magnetization is reversible from Tc to 10 K. Results for 18O-substituted samples treated by this process show an isotope shift of the transition temperature of about 0.6 K.

~Thin foils of bulk YBa 2 Cu 3 O 7-x (YBCO) superconductors were subjected to electron irradiation in a Transmission Electron Microscope (TEM). The resulting disordering of the oxygen atoms and vacancies in the Cu-O planes was monitored by measuring the splitting of the (110) diffraction spots in the [001] diffraction pattern. Samples were irradiated at 83K with 100, 150, 200 and 300kV electrons. The 100kV electrons did not cause any disordering, even after prolonged irradiation. The results of the higher energy irradiations showed an excellent fit to a disordering model, indicating a lack of radiation assisted ordering at 83K. This was further confirmed by the insensitivity of the disordering to the dose rate of 300kV electrons at 83K. However, at 300K, an increase in the dose rate of 300kV electrons increased the disordering rate, indicating that radiation assisted reordering was occurring at that temperature.

~The critical temperature of YBa2Cu3O7 superconductor was measured
to be Tc = 108.1 ± 0.8 K , which is 14% from the accepted value of Tc = 93 K.

~The upper critical field (Hc2) of the high-Tc superconductor YBa2CU3O7–x (YBCO) is expected to be >100T at 0 K1–6. Because magnetic fields of >100 T can be produced only for a short time and by destructive methods, direct measurements of Hc2 at these field strengths have not so far been performed. Here we report the first observation of superconductivity at >100 T, using a method in which a voltage induced by a magnetization jump is measured in pulsed high magnetic fields. Superconductivity in YBCO was confirmed up to 101 T at 6 K.

~the structural and magnetic
properties affect the mechanisms of superconductivity in YBa2Cu3O7−x. Despite
extensive research on YBa2Cu3O7−x spanning nearly three decades, there are still
inconsistencies between studies. Therefore, it is important that further research be
conducted to resolve those inconsistencies. In a recent paper by Biscaras et al. [1],
magnetization measurements were performed on oxygen-deficient YBCO samples in
normal state in order to study the interchange betwen hole doping and magnetic
properties. The intention of this study is to synthesize samples of YBa2Cu3O7−x and
determine how the crystal structure and critical temperature, Tc, change with oxygen
content as the first stage for studying the normal state of the samples in the future. In
doing this, we will compare results of this study with those of past studies and create
a starting point that complements the work by Biscaras et al. Crystal structures of
the samples were determined by using X-ray diffraction technique, while magnetic
moment measurements were made to determine Tc of each sample.