Synthesis and Electrical Characterization of PLZT Piezoelectric-Ceramic

This research describes the synthesis of an outstanding ceramic-composite piezoelectric CCP (lead-lanthanum-zirconate-titanate, PLZT) by means of powders technique procedures. Full dense CCP compacts were obtained with a platinum wire implanted in the center of the piezoelectric, which were used to investigate the microstructural and opto-thermal properties. The microstructural details of this ceramic were investigated by optical microscopy; whereas the opto-thermal characterization was performed by measuring the electrical signal in a bidimensional setup under four different temperatures: 20°C, 35°C, 50°C and 75°C. A 160mW/cm2 LASER beam was used in order to produce the optical energy which is detected by the CCP. A total of one hundred of measurements were registered. Measurements showed that, in the explored thermal range, the CCP signal magnitude increased from 87.2 to 147.2 pA. About the microstructural analysis, the microstructure obtained show different phases as characteristic of the processing method, including porosity. The peculiar optical and thermal properties observed in the piezoelectric ceramic are promising for possible applications in temperature-controlled optical devices that require electrical outputs

Electrical analysis of piezoelectric ceramics of BaTiO3 doped with Cu and Ag

En esta investigación se estudia el efecto de la incorporación de partículas metálicas de cobre (Cu) <75μm y plata (Ag) <100nm, ambas de forma esférica de la marca ALDRICH, en la matriz del cerámico de titanito de bario (BaTiO3). La fabricación de estos materiales se realizó mediante la técnica de polvos; a partir de una mezcla, en un molino de giro planetario formando composiciones químicas en polvo como: BaTiO3 + 1% Cu, BaTiO3 + 3% Cu, BaTiO3 + 1% Ag, BaTiO3 + 3% Ag, BaTiO3 + 1% Cu & Ag, BaTiO3 + 3% Cu & Ag, cada muestra fue de 10 g. Los polvos fueron sometidos a un proceso de prensado para su conformación en muestras de forma cilíndricas y finalmente sinterizadas en un horno eléctrico a una temperatura de 1240 °C. A los materiales se le determinaron sus propiedades eléctricas, así como la determinación de la permitividad relativa del material, la capacitancia y la obtención de sus diagramas de magnitud - frecuencia eléctricas usando un generador de funciones. Los resultados obtenidos muestran que la incorporación de partículas de Cobre y Plata como un reforzamiento metálico en una base cerámica de BaTiO3 modifica las propiedades eléctricas - ferroeléctricas y dieléctricas

Comparative Performance of PLZT and PVDF Pyroelectric Sensors Used to the Thermal Characterization of Liquid Samples

Among the photothermal methods, the photopyroelectric (PPE) technique is a suitable method to determine thermal properties of different kinds of samples ranging from solids to liquids and gases. Polyvinylidene difluoride (PVDF) is one of the most frequently used pyroelectric sensors in PPE technique but has the disadvantage that it can be easily deformed by the sample weight. This deformation could add a piezoelectric effect to the thermal parameters assessment; also PVDF has a narrow temperature operation range when compared with ceramic pyroelectric sensors. In order to minimize possible piezoelectric effects due to sensor deformation, a ceramic of lanthanum modified lead zirconate (PLZT) was used as pyroelectric sensor in the PPE technique. Then, thermal diffusivity of some liquid samples was measured, by using the PPE configuration that denominated the thermal wave resonator cavity (TWRC), with a PLZT ceramic as pyroelectric detector. The performance obtained with the proposed ceramic in the TWRC configuration was compared with that obtained with PVDF by using the same configuration

Keratinocytes Growth Using Polyvinylidenefluoride (PVDF) Fiber Mats by Electrospun

There is a growing demand for skin transplants; however, immunological incompatibility to such transplants emains as an unsolved issue. It is necessary to improve the current production methods for epidermal originated tissue. PVDF-based membranes have the potential to be used as an appropriate scaffold for skin cell growth. There are a wide range of medical applications and potential medical applications of PVDF. Keratinocytes on PVDF scaffolds had the greatest alkaline phosphatase activity and early mineralization. The results demonstrate the potential for the use of PVDF scaffolds for keratinocytes growth applications.

Electrical response in poled (Bi0.5Na0.5)0.935Ba0.065TiO3 ceramics

A ferroelectric material (Bi0.5Na0.5)0.935Ba0.065TiO3 (BNBT) with a perovskite structure was poled and characterized by electrical impedance spectroscopy as a function of temperature, X-ray diffraction, and Rietveld refinement. The ac conductivity showed a low-frequency dispersion, supporting the idea of heterogeneous potential wells favored by Bi3þ, Naþ, and Ba2þ on the A site of the perovskite type of structure. The activation energies for ac conduction depended on the studied frequency. The permittivity and electrical modulus showed a distribution of the relaxation time associated with the delay in the orientation of the dipoles and an important contribution to the short-range conductivity