The superconducting transition with onset temperature of 95K has been confirmed in SmBa₂Cu₃O_7−δ system by resistivity and AC susceptibility measurements. Pressure dependence ofT_co andT_cf of the title superconductor is described. The superconducting transition onset temperature and complete transition temperature increases with increase of pressure.

Critical exponent of the electrical conductivity in the paracoherence region (γ) of the high temperature superconductor YBa₂Cu₃O_7−x (YBCO) has been estimated for high quality thin film on ZrO₂ substrate prepared by high pressure oxygen sputtering. High energy ion irradiation was carried out using 100 MeV¹⁶O⁷⁺ ions at liquid nitrogen temperature to see the effects of disorder on the value of the exponent. The critical exponent (γ) changes from a value of about 2 to 1·62 upon irradiation. Studies were also carried out on this film to see the effect of ageing and annealing.

Thin films of zirconia have been synthesized using reactive DC magnetron sputtering. It has been found that films with good optical constants, high refractive index (1·9 at 600 nm) and low extinction coefficient can be prepared at ambient temperatures. The optical constants and band gap and hence the composition are dependent on the deposition parameters such as target power, rate of deposition and oxygen background pressure. Thermal annealing of the films revealed that the films showed optical and crystalline inhomogeneity and also large variations in optical constants.

The antioxidant, antibacterial and photocatalytic activity of gold (Au) nanocatalyst derived utilizing Catharanthus roseus leaf extracts are originally described in this investigation. The colour transformation of the developed gold nanoparticles (AuNPs) was originally validated optically. Besides that, UV–visible spectroscopy and scanning electron microscopy were used to interpret the derived Au catalyst’s emergence, size and structure. The existence of phytochemical constituents essential for the encapsulation, accumulation, bio-reduction and anchoring of AuNPs was established by descriptive preliminary phytochemicals, as proven by the Fourier transform infrared spectrum. Cumulative antioxidants, reducing and 2, 2-diphenyl-1-picrylhydrazyl radical activities have been used to assess the antioxidant effects of the AuNPs and their appropriate leaf extract. In comparison to those associated with plant extract, the Au nanocatalyst exhibited increased antioxidant effects in the antioxidant assessments. When compared to Bacillus subtilis (Gram-positive) assayed by the agar well diffusion approach, the derived AuNPs showed tremendous antimicrobial effects against Pseudomonas aeruginosa (Gram-negative). Interestingly, upon UV-light irradiation, the AuNPs displayed substantial photocatalytic performance in destroying rhodamine B dye for approximately 105 min. Therefore, the C. roseus leaf was found to be an environmentally benign feedstock for the greener synthesis of AuNPs, which can be employed as a powerful antioxidant, antimicrobial and photocatalytic ingredient, and hence is used in an array of applicants to enhance social survival chances.