P. Mattocks

Laser evaporation deposition of superconducting and dielectric thin films

We describe here the deposition of superconducting and dielectric thin films by the laser evaporation technique. The characterization of this process, and possible optimization with regards to wavelength and pulse duration of the laser will be discussed.

Growth of highly oriented CdS thin films by laser-evaporation deposition

CdS films have been grown by laser‐evaporation deposition in a clean vacuum environment. The films are highly oriented with a c axis perpendicular to the surface, and are optically smooth and homogeneous. These high quality films should be useful in nonlinear integrated optics applications.

The effects of alkali impurities on the superconductivity and powder characteristics of YBa2Cu3O7

Abstract The effects of alkali impurities, Li, Na, K, Rb, and Cs, on the superconducting properties and powder characteristics of YBa 2 Cu 3 O 7 were investigated. The superconducting temperature of YBa 2 Cu 3 O 7 drops to the 70 K range in the presence of Li (0.2 mole Li/mole 1-2-3 oxide), while samples containing Rb, K, or Cs show little superconductivity deterioration. An intermediate effect between these two extremes was found for Na. The powder characteristics, inlcuding aggregate hardness, particle size, and particle morphology, of YBa 2 Cu 3 O 7 are also affected by the alkali impurities. In particular, during calcination both Li and Na enhance the intergrain bonding, resulting in increased difficulty in power comminution, while K and particularly Rb have the opposite effect.

Superconducting properties of mixtures of Y 1 Ba 2 Cu 3 O 9− x and Y 1.8 Ba 0.2 Cu 1 O 5− y

The superconducting properties of heat-treated mixtures of Y 1 Ba 2 Cu 3 O 9− x (A) and Y 1.8 Ba 0.2 Cu 1 O 5− y (B) have been studied. As the concentration of B increases, the Meissner effect decreases, while the resistance jump near the superconducting transition increases. When the fraction of B approaches about 0.5, the superconducting transition disappears. Four different phases are identified in the mixture from the x-ray spectra, i.e., Y 1 Ba 2 Cu 3 O 9− x , Y 2 Ba 1 Cu 1 O 5– z , Y 2 Cu 2 O 5 , and Y 2 O 3 . The results agree well with the published phase diagram of this system.

Laser Induced Deposition of YBa 2 Cu 3 O 7−x Thin Films

We describe here the deposition of the YBaCuO superconducting thin films by the laser evaporation technique. The characterization of this process, and possible optimization with regards to wavelength and pulse duration of the laser will be discus sed.

Process parameters for high‐yield Y:Ba:Cu:O superconductors

High Tc superconducting devices can be made from the bulk materials in a Y‐Ba‐Cu‐O system. We report here the stability of bulk materials in order to understand methods to produce higher Tc and hopefully shorten the period of processing. Systematic measurements of resistivity, magnetization and X‐ray diffraction have been made on samples that have the same chemical composition but different processing. The processing was varied to find the optimum combination of the calcining time, sintering time and annealing time at 650°C. We have found that the Tc is stable if the dominant phase remains. A ratio of Meissner: shielding magnetizations of 61:100 was found under optimum conditions. The intensity and position of the X‐ray diffraction peak for (103) was independent of time but strongly dependent on processing. The magnetizations due to shielding and Meissner effects definitely change with time but their ratio remains the same. Anomalous behavior was observed in both resistance and magnetization at a processi...

Laser Evaporation Deposition Of Superconducting And Semiconducting Thin Films

We describe here the deposition of superconducting and semiconducting thin films by the laser evaporation technique. The, characterization of this process, and possible optimization with regards to wavelength and pulse duration of the laser will be discussed. Results of laser interaction experiments will also be described.

Growth of Highly Oriented Cds X Se 1 . X Thin Films By Uv Laser Evaporation Deposition

CdS x Se 1−x thin films have been grown by uv laser-evaporation deposition in a clean vacuum environment. The films have their c-axis perpendicular to the surface, and are optically smooth and homogeneous. These high quality films should be useful in nonlinear integrated optics applications.