Analysis of free volumes and light transmission in hydrogel and silicone-hydrogel polymer contact lenses

The free volume holes and light transmission of hydrogel and silicone-hydrogel polymer contact lenses were investigated. As the material, the Proclear family (omafilcon A) of hydrogel contact lenses and the Biofinity family (comfilcon A) of silicone-hydrogel contact lenses were used. Positron annihilation lifetime spectroscopy was used to characterize geometrical sizes and fractions of the free volume holes in the investigated samples. There was a clear difference in the size of free volume holes and the fractional free volume between silicone-hydrogel and hydrogel polymer contact lenses. These changes are shown by a thorough analysis of the long-lived component of lifetime of ortho-positronium. At the same time, UV-vis-NIR in the spectral range 200-1000 nm studies were performed on the same samples of contact lenses spectrometry

Influence of Annealing Conditions on Magnetic Properties and Phase Constitution of the Rapidly Solidified Fe₆₅Pr₉B₁₈W₈ Alloy Ribbons

In the present work, the influence of annealing conditions on magnetic properties and phase constitution of the rapidly solidified Fe₆₅Pr₉B₁₈W₈ alloy ribbons, were investigate. Samples were prepared by arc-melting of high purity constituent elements under the Ar atmosphere. Ribbons were obtained by melt-spinning technique under low pressure of Ar. The ribbons in as-cast state had amorphous structure and soft magnetic properties. Heat treatment, carried out at various temperatures (from 923 K to 1023 K) for 5 min, resulted in an evolution of the phase constitution that caused changes in magnetic properties of the alloy. The crystallization behavior was studied using differential scanning calorimetry and X-ray diffractometry. The room temperature magnetic properties were determined from hysteresis loops measured by VSM magnetometer in the external magnetic field up to 2 T

Magnetic Properties and Phase Constitution of the Nanocrystalline Fe₆₅Pr₉B₁₈W₈ Alloy Ribbons

The aim of the present work was to investigate the phase constitution and magnetic properties of the rapidly solidified Fe₆₅Pr₉B₁₈W₈ alloy ribbons in the as-cast state and subjected to annealing. The base alloy was prepared by arc-melting of the high purity elements under the Ar atmosphere. The ribbon samples were obtained by the melt-spinning technique under a low pressure of Ar. The studies have shown an amorphous structure of the ribbon in the as-cast state and its soft magnetic properties. Annealing at various temperatures for 5 min resulted in an evolution of the phase constitution that caused changes in magnetic properties of the alloy. The crystallization behavior was studied using differential scanning calorimetry. In order to determine the phase composition of annealed ribbons, X-ray diffractometry was used. The evolution of microstructure and phase constitution was verified by the Mössbauer spectroscopy. The magnetic properties were determined from hysteresis loops measured by a vibrating sample magnetometer in the external magnetic field up to 2 T at room temperature

Magnetic Properties and Phase Constitution of the Nanocrystalline Fe 65

The aim of the present work was to investigate the phase constitution and magnetic properties of the rapidly solidified Fe₆₅Pr₉B₁₈W₈ alloy ribbons in the as-cast state and subjected to annealing. The base alloy was prepared by arc-melting of the high purity elements under the Ar atmosphere. The ribbon samples were obtained by the melt-spinning technique under a low pressure of Ar. The studies have shown an amorphous structure of the ribbon in the as-cast state and its soft magnetic properties. Annealing at various temperatures for 5 min resulted in an evolution of the phase constitution that caused changes in magnetic properties of the alloy. The crystallization behavior was studied using differential scanning calorimetry. In order to determine the phase composition of annealed ribbons, X-ray diffractometry was used. The evolution of microstructure and phase constitution was verified by the Mössbauer spectroscopy. The magnetic properties were determined from hysteresis loops measured by a vibrating sample magnetometer in the external magnetic field up to 2 T at room temperature

Phase Composition and Magnetic Properties of the Nanocrystalline Fe64.32Pr9.6B22.08W4Fe_{64.32}Pr_{9.6}B_{22.08}W_{4} Alloy

The aim of the present work was to study the influence of annealing conditions on magnetic properties and the phase constitution of rapidly solidified $Fe_{64.32}Pr_{9.6}B_{22.08}W_{4}$ alloy ribbons. The base alloy was prepared by arc-melting of the high purity elements under an Ar atmosphere. Subsequently the ribbon samples were obtained by melt-spinning technique under low pressure of Ar. In order to develop nanocrystalline structure, the samples were annealed at 1003 K for 5, 10, 20 and 30 min. The room temperature magnetic properties were determined from hysteresis loops measured by VSM magnetometry in the external magnetic field up to 2 T. For comparison the influence of annealing temperature on magnetic properties was studied for the same alloy composition. The ribbons were annealed at temperatures from 929 K to 1023 K for 5 min. X-ray diffractometry was used to determine the phase composition of annealed ribbons. Heat treatment resulted in an evolution of the phase constitution, that caused changes in magnetic properties of the alloy

The Effect of Annealing Temperature on the Phase Constitution and Magnetic Properties of the Pr₈Dy₁Fe₆₀Co₇Mn₆B₁₄Zr₁Ti₃ Alloy Ribbons

Melt-spun ribbons were produced from the Pr₈Dy₁Fe₆₀Co₇Mn₆B₁₄Zr₁Ti₃ base alloy at the surface velocity of the cooper wheel of 30 m/s. The studies showed amorphous structure of ribbons and their soft magnetic properties. X-ray diffraction was used to determine phase constitution of all obtained samples. Annealing of ribbons caused formation of nanocomposite structure, which was a result of coexistence of hard magnetic RE₂(Fe,Co)₁₄B and soft magnetic α-Fe phases. Basic magnetic properties such as: coercivity $\text{}_{J}H_{c}$, remanence $J_{r}$ and maximum energy product $(BH)_\text{max}$ were determined from the measured hysteresis loops. The microstructure of selected specimens was observed by transmission electron microscopy technique

The Effect of Annealing Temperature on the Phase Constitution and Magnetic Properties of the Pr 8

Melt-spun ribbons were produced from the Pr8Dy1Fe60Co7Mn6B14Zr1Ti3 base alloy at the surface velocity of the cooper wheel of 30 m/s. The studies showed amorphous structure of ribbons and their soft magnetic properties. X-ray diffraction was used to determine phase constitution of all obtained samples. Annealing of ribbons caused formation of nanocomposite structure, which was a result of coexistence of hard magnetic RE2(Fe,Co)14B and soft magnetic α-Fe phases. Basic magnetic properties such as: coercivity JHc, remanence Jr and maximum energy product (BH)max were determined from the measured hysteresis loops. The microstructure of selected specimens was observed by transmission electron microscopy technique. DOI: 10.12693/APhysPolA.128.94 PACS: 75.20.En, 91.60.P

Thermomagnetic Properties of LaFe11.0Co0.8(Si1−xAlx)1.2LaFe_{11.0}Co_{0.8}(Si_{1-x}Al_{x})_{1.2} (x=0, 0.6) Alloys

In the present work, Curie temperature, refrigeration capacity and cooling power of the $LaFe_{11.0}Co_{0.8}(Si_{1-x}Al_{x})_{1.2}$ (where x=0, 0.6) alloys, are investigated. The value of Curie temperature was found to be 280 and 290 K for x=0 and 0.6, respectively. The determined values of cooling power (RCP) and refrigeration capacity (RC) differ only slightly for both investigated alloys. The maximum values of RCP and RC obtained under the change of external magnetic field from 0 to 5 T are 433 J/kg (for x=0) and 290 J/kg (for x=0.6), respectively