Presently, solar energy conversion is widely used to generate heat and produce electricity. A com... more Presently, solar energy conversion is widely used to generate heat and produce electricity. A comparative study on the world energy consumption released by International Energy Agency (IEA) shows that in 2050, solar array installations will supply around 45% of energy demand in the world. It was found that solar thermal is getting remarkable popularity in industrial applications. Solar thermal is an alternative to generate electricity, process chemicals or even space heating. It can be used in food, non-metallic, textile, building, chemical or even business related industries. On the other hand, solar electricity is wildly applied in telecommunication, agricultural, water desalination and building industry to operate lights, pumps, engines, fans, refrigerators and water heaters.
Three-dimensional photonic bandgap (PBG) structures using alumina (Al 2 O 3 ) as the high permitt... more Three-dimensional photonic bandgap (PBG) structures using alumina (Al 2 O 3 ) as the high permittivity material were modeled and then the structures were fabricated by Fused Deposition of Multi-materials (FDMM) technology. A nite element method and a real-time electromagnetic wave propagation software were used to simulate and design the layered PBG structures for applications in the microwave frequency range. The modeling predicted a 3-D photonic bandgap in the 16.5 -23.5 GHz range. FDMM provides a computer-controlled process to generate 3-D structures, allowing high fabrication exibility and ef ciency. Electromagnetic measurements displayed the presence of a bandgap between 17.1 -23.3 GHz, showing a good agreement with the predicted values. These PBG structures are potential candidates for applications in advanced communication systems.
ABSTRACT: The purpose of this paper is to develop a 3-D connectivity model that enables better un... more ABSTRACT: The purpose of this paper is to develop a 3-D connectivity model that enables better understanding, at the micro-structural level, the effect of fiber orientation, matrix properties, and inter-fiber contact on the effective piezoelectric properties of a composite consisting of a ...
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2000
This paper presents the fabrication and characterization of single-element ultrasonic transducers... more This paper presents the fabrication and characterization of single-element ultrasonic transducers whose active elements are made of lead-free piezoceramic, 1-3 PZT/polymer composite and PVDF film. The lead free piezoelectric KNNLT- LS(K(0.44)Na(0.52)Li(0.04))(Nb(0.84)Ta(0.10)S(0.06)b)O(3) powders and ceramics were prepared under controlled humidity and oxygen flow rate during sintering. Due to its moderate longitudinal piezoelectric charge coefficient (175 pC/N) and k(t) of 0.50, the KNN-LT-LS composition may be a good candidate for high frequency transducer applications. PZT fibers with 25 microm diameter formed by the viscose suspension spinning process were incorporated into epoxy to fabricate 1-3 composites with the averaged k(t) = 0.64 and d(33) = 400 pC/N. Using KNN-LS-LT ceramic, 1-3 PZT fiber composite, and PVDF film, 3 different unfocused single element transducers with center frequencies of 25 MHz were fabricated. The acoustic characterization of the transducers demonstrated that wideband and low insertion loss could be obtained employing KNN-LS-LT ceramic. The -6 dB bandwidth and insertion loss were 70% and -21 dB, respectively. In comparison, the insertion loss of the ceramic transducer was much smaller than those made with 1-3 composite and PVDF film. This was attributed to closer electrical impedance match to 50 ohm and higher thickness coupling coefficient of the ceramic transducer.
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2000
ABSTRACT We have studied the effect of deposition parameters on the microstructure, crystallinity... more ABSTRACT We have studied the effect of deposition parameters on the microstructure, crystallinity, and ferroelectric properties of 0.88(Bi(0.5)Na(0.5))TiO(3)-0.08(Bi(0.5)K(0.5))TiO(3)¿0.04BaTiO(3) thin films grown on SrRuO(3)-coated SrTiO(3) substrates by pulsed laser deposition. The parameters studied were the repetition rates, substrate temperatures, oxygen pressures, and laser energies. It was realized that the films prepared at 800°C, 10 Hz, 400 mtorr, and 1.2 Jcm(-2) exhibited the highest ferroelectric properties. The measured remanent polarization, dielectric constant at 1 kHz, and coercive field for this film were about 30 μCcm(-2), 645, and 85 kVcm(-1), respectively. Increasing the oxygen pressure during deposition from 200 to 400 mtorr improved the crystallinity, microstructure, dielectric constant, and polarization of the films. The leakage current and dielectric loss were suppressed at 400 mtorr because of the lower concentration of oxygen vacancies and disappearing pinholes and surface undulations in the film deposited at this pressure.
Single phase Sr substituted BaZr 0.1 Ti 0.9 O 3 (also known as BZT) ceramics with a formula Ba 1−... more Single phase Sr substituted BaZr 0.1 Ti 0.9 O 3 (also known as BZT) ceramics with a formula Ba 1−x Sr x Zr 0.1 Ti 0.9 O 3 (x = 0.10, 0.20, 0.30, 0.40 and 0.50) are prepared using a solid state reaction of mixed oxides at 1250 • C for 15 h. Analysis of XRD patterns of the ceramic powders show that Sr substitutes into Ba sites and reduces the lattice parameter. The powders are sintered at 1600 • C for 6 h to investigate the microstructure and functional properties. It is found that strontium substitution significantly modifies the microstructure and greatly influences the dielectric properties. The increase in Sr content reduces the ceramic grain size and results in spherical grains. With an increase in Sr content, the Curie temperature is lowered, and the relative permittivity maximum is increased and broadened. In Ba 1−x Sr x Zr 0.1 Ti 0.9 O 3 with x = 0.30, the relative permittivity reached a maximum of 26 600 and with further increase of Sr content, the relative permittivity is lowered and the phase transition is found to be broad and diffused. The ferroelectric hysteresis characteristics are discussed in detail.
Page 1. Development of Fine-Scale Piezoelectric Composites for Transducers Ahmad Safari, Victor F... more Page 1. Development of Fine-Scale Piezoelectric Composites for Transducers Ahmad Safari, Victor F. Janas, and Amit Bandyopadhyay Dept. ... The minimum rod size is a function of both the accuracy of the dicing saw, and the ability of the ceramic to survive the process. ...
Malaysia is situated at the equatorial region with an average solar radiation of 400-600 MJ/m 2 p... more Malaysia is situated at the equatorial region with an average solar radiation of 400-600 MJ/m 2 per month. It has a promising potential to establish large scale solar power installations; however, solar energy is still at the infancy stage due to the high cost of photovoltaic (PV) cells and solar electricity tariff rate. The Malaysian government is keen to develop solar energy as one of the significant sources of energy in the country. According to the 9th Malaysia Plan (9MP), a large allocation had been dedicated for implementation of solar PV systems. On 25th July 2005, a Malaysian Building Integrated Photovoltaic (MBIPV) project had been announced and it was planned to end by 2010. The project consists of three categories which include: BIPV demonstration, national "SURIA1000" and BIPV showcase. Greater emphasis will be placed on energy efficiency under the Tenth Malaysia Plan (2011)(2012)(2013)(2014)(2015). This paper discusses present and future situation of solar power in Malaysia, utilization of solar energy and the strategies taken by the Malaysian government and Non-Government Organizations (NGOs) to promote solar energy thermal applications and electricity power generation in the future.
Presently, solar energy conversion is widely used to generate heat and produce electricity. A com... more Presently, solar energy conversion is widely used to generate heat and produce electricity. A comparative study on the world energy consumption released by International Energy Agency (IEA) shows that in 2050, solar array installations will supply around 45% of energy demand in the world. It was found that solar thermal is getting remarkable popularity in industrial applications. Solar thermal is an alternative to generate electricity, process chemicals or even space heating. It can be used in food, non-metallic, textile, building, chemical or even business related industries. On the other hand, solar electricity is wildly applied in telecommunication, agricultural, water desalination and building industry to operate lights, pumps, engines, fans, refrigerators and water heaters.
Three-dimensional photonic bandgap (PBG) structures using alumina (Al 2 O 3 ) as the high permitt... more Three-dimensional photonic bandgap (PBG) structures using alumina (Al 2 O 3 ) as the high permittivity material were modeled and then the structures were fabricated by Fused Deposition of Multi-materials (FDMM) technology. A nite element method and a real-time electromagnetic wave propagation software were used to simulate and design the layered PBG structures for applications in the microwave frequency range. The modeling predicted a 3-D photonic bandgap in the 16.5 -23.5 GHz range. FDMM provides a computer-controlled process to generate 3-D structures, allowing high fabrication exibility and ef ciency. Electromagnetic measurements displayed the presence of a bandgap between 17.1 -23.3 GHz, showing a good agreement with the predicted values. These PBG structures are potential candidates for applications in advanced communication systems.
ABSTRACT: The purpose of this paper is to develop a 3-D connectivity model that enables better un... more ABSTRACT: The purpose of this paper is to develop a 3-D connectivity model that enables better understanding, at the micro-structural level, the effect of fiber orientation, matrix properties, and inter-fiber contact on the effective piezoelectric properties of a composite consisting of a ...
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2000
This paper presents the fabrication and characterization of single-element ultrasonic transducers... more This paper presents the fabrication and characterization of single-element ultrasonic transducers whose active elements are made of lead-free piezoceramic, 1-3 PZT/polymer composite and PVDF film. The lead free piezoelectric KNNLT- LS(K(0.44)Na(0.52)Li(0.04))(Nb(0.84)Ta(0.10)S(0.06)b)O(3) powders and ceramics were prepared under controlled humidity and oxygen flow rate during sintering. Due to its moderate longitudinal piezoelectric charge coefficient (175 pC/N) and k(t) of 0.50, the KNN-LT-LS composition may be a good candidate for high frequency transducer applications. PZT fibers with 25 microm diameter formed by the viscose suspension spinning process were incorporated into epoxy to fabricate 1-3 composites with the averaged k(t) = 0.64 and d(33) = 400 pC/N. Using KNN-LS-LT ceramic, 1-3 PZT fiber composite, and PVDF film, 3 different unfocused single element transducers with center frequencies of 25 MHz were fabricated. The acoustic characterization of the transducers demonstrated that wideband and low insertion loss could be obtained employing KNN-LS-LT ceramic. The -6 dB bandwidth and insertion loss were 70% and -21 dB, respectively. In comparison, the insertion loss of the ceramic transducer was much smaller than those made with 1-3 composite and PVDF film. This was attributed to closer electrical impedance match to 50 ohm and higher thickness coupling coefficient of the ceramic transducer.
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2000
ABSTRACT We have studied the effect of deposition parameters on the microstructure, crystallinity... more ABSTRACT We have studied the effect of deposition parameters on the microstructure, crystallinity, and ferroelectric properties of 0.88(Bi(0.5)Na(0.5))TiO(3)-0.08(Bi(0.5)K(0.5))TiO(3)¿0.04BaTiO(3) thin films grown on SrRuO(3)-coated SrTiO(3) substrates by pulsed laser deposition. The parameters studied were the repetition rates, substrate temperatures, oxygen pressures, and laser energies. It was realized that the films prepared at 800°C, 10 Hz, 400 mtorr, and 1.2 Jcm(-2) exhibited the highest ferroelectric properties. The measured remanent polarization, dielectric constant at 1 kHz, and coercive field for this film were about 30 μCcm(-2), 645, and 85 kVcm(-1), respectively. Increasing the oxygen pressure during deposition from 200 to 400 mtorr improved the crystallinity, microstructure, dielectric constant, and polarization of the films. The leakage current and dielectric loss were suppressed at 400 mtorr because of the lower concentration of oxygen vacancies and disappearing pinholes and surface undulations in the film deposited at this pressure.
Single phase Sr substituted BaZr 0.1 Ti 0.9 O 3 (also known as BZT) ceramics with a formula Ba 1−... more Single phase Sr substituted BaZr 0.1 Ti 0.9 O 3 (also known as BZT) ceramics with a formula Ba 1−x Sr x Zr 0.1 Ti 0.9 O 3 (x = 0.10, 0.20, 0.30, 0.40 and 0.50) are prepared using a solid state reaction of mixed oxides at 1250 • C for 15 h. Analysis of XRD patterns of the ceramic powders show that Sr substitutes into Ba sites and reduces the lattice parameter. The powders are sintered at 1600 • C for 6 h to investigate the microstructure and functional properties. It is found that strontium substitution significantly modifies the microstructure and greatly influences the dielectric properties. The increase in Sr content reduces the ceramic grain size and results in spherical grains. With an increase in Sr content, the Curie temperature is lowered, and the relative permittivity maximum is increased and broadened. In Ba 1−x Sr x Zr 0.1 Ti 0.9 O 3 with x = 0.30, the relative permittivity reached a maximum of 26 600 and with further increase of Sr content, the relative permittivity is lowered and the phase transition is found to be broad and diffused. The ferroelectric hysteresis characteristics are discussed in detail.
Page 1. Development of Fine-Scale Piezoelectric Composites for Transducers Ahmad Safari, Victor F... more Page 1. Development of Fine-Scale Piezoelectric Composites for Transducers Ahmad Safari, Victor F. Janas, and Amit Bandyopadhyay Dept. ... The minimum rod size is a function of both the accuracy of the dicing saw, and the ability of the ceramic to survive the process. ...
Malaysia is situated at the equatorial region with an average solar radiation of 400-600 MJ/m 2 p... more Malaysia is situated at the equatorial region with an average solar radiation of 400-600 MJ/m 2 per month. It has a promising potential to establish large scale solar power installations; however, solar energy is still at the infancy stage due to the high cost of photovoltaic (PV) cells and solar electricity tariff rate. The Malaysian government is keen to develop solar energy as one of the significant sources of energy in the country. According to the 9th Malaysia Plan (9MP), a large allocation had been dedicated for implementation of solar PV systems. On 25th July 2005, a Malaysian Building Integrated Photovoltaic (MBIPV) project had been announced and it was planned to end by 2010. The project consists of three categories which include: BIPV demonstration, national "SURIA1000" and BIPV showcase. Greater emphasis will be placed on energy efficiency under the Tenth Malaysia Plan (2011)(2012)(2013)(2014)(2015). This paper discusses present and future situation of solar power in Malaysia, utilization of solar energy and the strategies taken by the Malaysian government and Non-Government Organizations (NGOs) to promote solar energy thermal applications and electricity power generation in the future.
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