نوع مقاله : مقاله پژوهشی کامل
نویسندگان
گروه فیزیک، دانشگاه فردوسی مشهد
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
In this paper, samples were prepared by citrate-gel
method at different calcination temperatures in order to investigate the effect
of calcination temperature on ferromagnetism behavior in very small particles
(submicron particles) of high Tc superconductor HoBa2Cu3O7-δ.
In this method, high-purity nitrate salts of Ho, Ba and Cu were used as the
starting materials and citric acid as the complex agent. Determination of phase
and studying the structural properties of the samples with X-ray powder
diffraction (XRD) confirmed the formation of orthorhombic structure for these
small particles and bulk samples. The morphology of the samples was
investigated by scanning electron microscope (SEM). The superconducting
transition temperature of the samples, determined by AC susceptibility
measurements, was 93K for the Bulk sample, and it was lower for submicron
particles because of oxygen depletion during the citrate pyrolysis reaction in
the preparation process. Room temperature magnetizations measured using a
vibrating sample magnetometer (VSM) showed that these particles exhibit
ferromagnetism behavior at room temperature while the bulk sample, which was
prepared by heating the precursor at high temperature, shows a linear
magnetization curve, a typical behavior of bulk 123 superconductors.
کلیدواژهها [English]
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