Papers by Keyword: Film

Abstract: Poly(lactic acid) (PLA) has a variety of applications. It has been widely used in the biomedical and pharmaceutical fields due to its biocompatibility and biodegradability. Polyethylene glycol (PEG) is used as an inactive ingredient in the pharmaceutical industry as a solvent, plasticizer, surfactant, ointment base, suppository base, tablet lubricant and capsule lubricant. The aim of this study was to determine the effect of temperature change on PLA porous matrix film fabricating by solvent casting method with an addition of PEG400 to improve and increase the pore interconnectivity. Their mechanical properties such as tensile strength (TS) and % elongation at break (%E) and morphology were investigated. Porous films were prepared at 4 °C for 24 h and dry at room temperature for 24 h (4CRT), 4 °C for 24 h and dry at 60 °C for 24 h (4C60C), -20 °C for 24 h and dry at room temperature for 24 h (-20CRT), -20 °C for 24 h and dry at 60 °C for 24 h (-20C60C), -80 °C for 24 h and dry at room temperature for 24 h (-80CRT), and -80 °C for 24 h and dry at 60 °C for 24 h (-80C60C). 4C60C exhibited the highest strength and toughest, however all of samples showed the quite soft behavior. From topography study they displayed the different porous structure which sample of 4C60C displayed the smallest porous structure. Therefore, the temperature change between the fabrication processes affected the TS, %E and morphology structure of PLA porous matrix films.

Abstract: The electrical properties of Tb₂O₃-doped bismuth titanate,Bi_4-xTb_xTi₃O₁₂ (BTT) ceramics prepared by a conventional electroceramic technique have been investigated. XRD analyses indicted Bi-layered perovskite structure in all samples, and revealed that Bi ions were only substituted near the Ti-O octahedron layers by Tb ions. SEM micrographs show randomly oriented and plate-like morphology. The remanent polarization ( P_r ) and coercive field ( E_c ) of the BTT ceramics with x=0.75 were above 16μC/cm² and 75KV/cm, respectively. The large value of remanent polarization and low coercive field of Tb-doped bismuth titanate ceramics promote these materials to potential applications.

Abstract: The electrical properties of Gd-doped bismuth titanate Bi_4-xGd_xTi₃O₁₂ (BGT) ceramics prepared by a conventional electroceramic technique were investigated. XRD analyses revealed Bi-layered perovskite structure in all samples. SEM micrographs showed randomly oriented and plate-like morphology. For the ceramics with x=0.25 and 1.0 the current-voltage characteristics exhibited negative differential resistance behaviors and their P-E hysteresis loops were characterized by large leakage current, whereas for the ceramics with x=0.5 and 0.75 the current-voltage characteristics showed simple ohmic behaviors and their P-E hysteresis loops were the saturated and undistorted hysteresis loops. The remanent polarization ( P_r ) and coercive field (E_c) of the BGT ceramic with x=0.8 were above 16μC/cm² and 70KV/cm , respectively.

Abstract: The effect of La substitution on the ferroelectric properties Bi₄Ti₃O₁₂ ceramics prepared by a conventional electroceramic technique has been investigated. XRD analyses revealed Bi-layered perovskite structure in all Bi_4-xLa_xTi₃O₁₂ (BLT) ceramics samples, and indicted that Bi ions were only substituted near the Ti-O octahedron layers by La ions. SEM micrographs show randomly oriented and plate-like morphology. The remanent polarization ( P_r ) and coercive field ( E_c ) of the BLT ceramic with x=0.8 were above 15μC/cm² and 85KV/cm, respectively. The large value of remanent polarization and low coercive field of La-doped bismuth titanate ceramics promote these materials to potential applications.

Abstract: The electrical properties of Pr₂O₃-doped bismuth titanate,Bi_4-xPr_xTi₃O₁₂ (BPT) ceramics prepared by a conventional electroceramic technique were investigated. XRD analyses revealed Bi-layered perovskite structure in all ceramics. SEM micrographs showed randomly oriented and plate-like morphology. For the ceramics with x=0.25 and 1.0 P-E hysteresis loops were characterized by large leakage current, whereas for the ceramics with x=0.5 and 0.75 P-E hysteresis loops were the saturated and undistorted hysteresis loops. The remanent polarization ( P_r ) and coercive field (E_c) of the BPT ceramic with x=0.75 were above 18μC/cm² and 65KV/cm , respectively.

Abstract: Dy-doped Bi₄Ti₃O₁₂ thin films were fabricated on Pt/Ti/SiO₂/Si substrates by pulsed laser deposition technique, and the structures and electrical properties of the films were investigated. XRD results indicated that all of Bi_4-xDy_xTi₃O₁₂ films consisted of single phase of a bismuth-layered structure with well-developed rod-like grains. The remanent polarization ( P_r ) and coercive field (E_c) of the Bi_4-xDy_xTi₃O₁₂ Film with x=0.75 were 25μC/cm² and 85KV/cm , respectively.

Abstract: Pr₂O₃-doped bismuth titanate (Bi_4-xPr_xTi₃O₁₂: BPT) thin films with random oriention were fabricated on Pt/Ti/SiO₂/Si substrates by rf magnetron sputtering technique, and the structures and ferroelectric properties of the films were investigated. XRD studies indicated that all of BPT films consisted of single phase of a bismuth-layered structure with well-developed rod-like grains. For samples with x=0..0 , 0.25, 1.0 and 1.25, I-E characteristics exhibited negative differential resistance behaviors and their ferroelectric hysteresis loops were characterized by large leakage current, whereas for samples with x=0.5 and 0.75, I-E characteristics were simple ohmic behaviors and their ferroelectric hysteresis loops were the saturated and undistorted hysteresis loops. The remanent polarization ( P_r ) and coercive field (E_c) of the BPT Film with x=0.75 were above 30μC/cm² and 75KV/cm , respectively.

Abstract: The electrical properties of Dy-doped bismuth titanate,Bi_4-xDy_xTi₃O₁₂ (BDT) ceramics prepared by a conventional electroceramic technique were investigated. XRD analyses revealed Bi-layered perovskite structure in all samples. SEM micrographs showed randomly oriented and plate-like morphology. For the samples with x=0.25 and 1.0 the current-voltage characteristics exhibited negative differential resistance behaviors and their P-V hysteresis loops were characterized by large leakage current, whereas for the samples with x=0.5 and 0.75 the current-voltage characteristics showed simple ohmic behaviors and their P-E hysteresis loops were the saturated and undistorted hysteresis loops. The remanent polarization ( P_r ) and coercive field (E_c) of the BDT ceramic with x=0.75 were above 16μC/cm² and 75KV/cm , respectively.

Abstract: Gd2O3-doped bismuth titanate (Bi4-xGdxTi3O12: BGT) and pure Bi4Ti3O12 (BIT) thin films with random orientation were fabricated on Pt/Ti/SiO2/Si substrates by rf magnetron sputtering technique. These samples had polycrystalline Bi-layered perovskite structure without preferred orientation, and consisted of well developed rod-like grains with random orientation. Gd-doping into BIT caused a large shift of the Curie temperature ( TC ) from 675 °C to lower temperature and a improvement in dielectric property. The experimental results indicated that Gd doping into BIT also result in a remarkable improvement in ferroelectric property. The Pr and the Ec values of the BGT film with x=0.75 were 28 μC/cm2 and 65 kV/cm, respectively.

Abstract: Three typical solution schemes of adjoint problems of heat transfer, phase transformations and chemical reaction at the forest fuel material surface were analyzed in this work. Characteristic times of thermal decomposition reaction suppression of forest fuel materials (needles of pine and fir-tree, leaves of birch) were presented for concerned heat transfer models. Effective heat exchange conditions which are characterized by minimal times of chemical reaction suppression in forest fuel materials and minimal extinguishing agent's expenditure were established.