Influence of Ceramic Particle Sizes on Electrical Properties of Lead ...
Journal of Metals, Materials and Minerals. Vol.18 No.147-151, 2008
Influence of Ceramic Particle Sizes on Electrical Properties of Lead Zirconate Titanate (PZT)/Nylon57 Composites Wilairat SUPMAK, Atitsa PETCHSUK and Aree THANABOONSOMBUT National Metal and Materials Technology Center, Pathumthani 12120, Thailand 114 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang, Pathumthani 12120 Abstract
Received Nov. 25, 2008 Accepted Feb. 11, 2009
0-3 connectivity of lead zirconate titanate (PZT) with various particle sizes and nylon57 composites were prepared using 30% PZT by volume. Electrical properties of the composites as a function of PZT particle sizes were studied. The relative permittivity, polarization and piezoelectric coefficient (d33) of composites increased with increasing of particle sizes. The optimum relative permittivity and polarization of composite was obtained when 95 μm of PZT average particle size was employed. Piezoelectric coefficient d33 of the composite was found optimum at 28 pC/N whereas the relative permittivity was about 73 and the remanent polarization was 138 µC/cm2. Key words : Lead zirconate titanate (PZT), Nylon 57, Composite, Pizoelectric properties
Introduction
Materials and Experimental Procedures
Composite materials have been intensively studied due to their excellent piezoelectric properties. They have been utilized in variety of applications such as sensors, actuators and under water acoustic transducers.(1-4) Composite materials combine the exceptional toughness of polymer materials with the excellent ferroelectric properties of ceramics. They possess good ferroelectric properties with mechanical strength, low acoustic impedance of matching to water and human tissues and ease of processing.(5-8) The simplest type of piezo ceramic/ polymer composite is a 0-3 connectivity, which consists of a polymer matrix filled with piezoceramic particles.(9-11) For 0-3 connectivity composite, it is not easy to obtain good piezoelectric properties due to the difficulty in poling ceramic particles in such composite.(12-13) One factor that affects the efficiency of poling ceramic particles is the ceramic particle size. Therefore, this work aimed at studying the influence of ceramic particle size on the electrical properties of ceramic/polymer composite. Various ceramic particle size ranges such as after ball mill 2 h, 79 μm were composited with nylon 57 in 0-3 connectivity pattern and their polarization, relative permittivity and piezoelectric coefficient (d33) were investigated.
Materials
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Lead Zirconate Titanate (PZT) powder used in the experiment was “PZT 850” (APC International Ltd.) which possess the relative permittivity of 1750 at 1 kHz, piezoelectric constant d33 of 400 pC/N and the Curie transition (Tc) of 360°C. PZT powder were consecutively calcined at 650°C and sintered at 1100°C for 2 h prior to use. Various particle size ranges of PZT were differentiated by sieving through nylon cloth. The ranges of PZT particle sizes used in this investigation were ball mill 2 h, 79 μm corresponding to average particle size of 5 µm, 12 µm, 38 µm, 76 µm, 95 µm, respectively by Mastersizer. Nylon57 was synthesized by melt polycondenzation at 190-220°C for 5 h according to Cui et al.’s method.(14) Preparation of Composite Films All composites were prepared by combined methods of colloidal and melt-press processing techniques. Typically, nylon57 was first dissolved in trifluoroethanol. 30% by volume of selected particle size range of PZT powder was then added into the nylon57 solution while sonicated. The mixture was cast on a petridish to evaporate solvent after sonicated for 20 min. Dried composite film was then hot-pressed for several times until it became homogeneous. The thickness of composite film is approximately 200-350 μm.
148 SUPMAK, W. et al.
Characterization and Electrical Measurements XRD was used to investigate the crystallinity and crystallographic phase of PZT powder to ensure the tetragonal phase (ferroelectric phase). For electrical measurements, the composites films of 1 cm diameter sample were electroded by gold sputtering on both sides. The composite samples were then poled by corona poling technique at room temperature by applying voltage of 20 kV (0.055 mA). The P-E hysteresis loop was measured at room temperature using RT66A Standardized Ferroelectric Measurement Test System (radian Technology). The relative permittivity was measured using 4194A Impedance Gain/Phase analyzer (Hewlett Packard) at the frequencies from 1 kHz to 1 MHz and the temperature range of -70°C to 200°C. The piezoelectric coefficient d33 was measured after 24 h of poling by using piezoelectric d33 meter, model PM3001.
Results and Discussion
P-E hysteresis loops of the 30% PZT by volume of PZT/nylon57 composites with various PZT particle sizes measured at room temperature and 50 kv/cm applied electric field were shown in Figures 3a-3e. It can be seen that the PZT particle size has a significant influence on the polarization of composites but less influence on the coercive field. The polarization and coercive field of composites with various ceramic particle sizes were summarized in Table 1. It can be concluded that the larger the particle size, the higher the polarization. The spontaneous polarization (Ps) and remanent polarization (Pr) showed the highest value when the PZT having average particle size of 95 μm was used.
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The phase formation behavior of PZT powder calcined and sintered at various temperatures was revealed by an X-ray diffraction pattern (XRD) in Figure 1. It was shown that PZT powder calcined and sintered at the temperature range of 880 to 1250°C were mainly perovskite structure having tetragonal phase, which indicated by plane (001), (002) and (211).(15) As the sintering temperature goes higher, the intensities of the (002) and (001) x-ray reflections get higher meaning that PZT phase are getting close to perfect tetragonal phase. However, when the sintering temperature gets higher than 1100°C, the morphology of PZT is changed due to the melting of grain boundaries. Therefore, in this work, PZT powder sintering at 1100°C which retained both crystallography and morphology was used for most parts of the study.
Figure 2. Shows cross-sectional SEM images of 30% PZT by volume composites with various PZT particle ranges. The homogeneous distribution of PZT particles in the polymer matrix can be seen from these SEM images. The PZT particles were surrounded by layer of the polymer matrix and there is no large agglomeration of PZT particles. More connection of PZT particles is expected in bigger particle size which may lead to better electrical properties.
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Figure.1 XRD patterns of PZT powders calcined and sintered at various temperatures (a) 880°C (b) 1000°C (c) 1100 °C (d) 1200°C (e) 1250°C for 2 h at heating/cooling rate of 20°C/min.
Figure 2. Cross-sectional SEM image of 30% PZT by volume of PZT/nylon57 composites with various PZT particle sizes (a) ball mill 2 h (5 µm) (b) < 16 µm (12 µm) (c) 17-46 µm (38 µm) (d) 47-79 µm (76 µm) (e) > 79 µm (95 µm)
149 Influence of Ceramic Particle Sizes on Electrical Properties of Lead Zirconate Titanate (PZT)/Nylon57 Composites 200
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Figure 3. The P-E hysteresis loops of 30% PZT by volume of PZT/nylon57 composite with various PZT particle ranges (a) ball mill 2 h (5 µm) (b) < 16 µm (12 µm) (c) 17-46 µm (38 µm) (d) 47-79 µm (76 µm) (e) > 79 µm (95 µm) Table 1. A summary of polarization of 30% PZT by volume of PZT/nylon 57 composite with various PZT particle size ranges.
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Figure 4. Relative permittivity and dielectric loss of 30% PZT by volume of PZT/nylon57 composite with various PZT particle ranges (a) ball mill 2 h (5 µm) (b) < 16 µm (12 µm) (c) 17-46 µm (38 µm) (d) 47-79 µm (76 µm) (e) > 79 µm (95 µm)
The temperature dependence of relative permittivity and dielectric loss of PZT/nylon 57 composites having PZT particle size of ball mill 2 h (5 µm), 79 μm (95 µm) were investigated as a function of frequencies (1, 10, 100 and 1000 kHz) from -70 to 180°C and were shown in Figure 4a-4e. The relative permittivity increased with the increase of temperature. The relaxation located around 50-70°C and centered at 65°C was characterized as β-relaxation which associated with the glass-rubbery transition (Tg) of the polymer. Segmental mobility of the polymer molecules increased with temperature leading to an increase in relative permittivity. Conductivity relaxation appeared for temperatures far above Tg and low frequency ranges emphasizing the contribution of the conduction due to the increase in the mobility of electric charges in the polymer
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150 SUPMAK, W. et al. versus temperature.(16) The highest relative permittivity at room temperature of composite was obtained when PZT having average particle size of 95 μm was employed. As PZT particle size became smaller, the relative permittivity as well as dielectric loss was also lower.
to get comparable piezoelectric constant d33. In addition, the PZT powders used in this work were sintered at lower sintering temperature (1100°C) suggesting low energy and cost effective in preparing composites.
Conclusions The effect of PZT particle sizes on piezoelectric coefficient (d33) of PZT/Nylon57 composite was summarized in Table 2. With an increase of PZT particle size, the piezoelectric coefficient (d33) was increased. The highest piezoelectric constant d33 of the composite was obtained at 28 pC/N where PZT having average particle size of 95 μm was used. An increase of the relative permittivity and piezoelectric coefficient d33 with increasing of PZT particles size are probably due to dense connection of PZT particles resulting in higher poling efficiency. Hence, the larger PZT particle size e.g. 95 μm provides better piezoelectric properties. Table 2 also compared electrical properties of composites of the previous work (17) with our present results. From our results, it is clearly seen that the particle size of PZT has an effect on electrical properties of the PZT/Nylon57 composites, thus agreeing with earlier results by A. Chaipanich where the cement composite with larger PZT particle size of 620 μm exhibits better properties than that of smaller size (3.8 μm). However, our recent work shows that the 0-3 composite at 30% PZT by volume with average particle sizes of 95 μm exhibits a comparable piezoelectric coefficient d33 value to that of the earlier works which comprises 50% PZT by volume with particle sizes at 620 μm. This infers that less PZT was used in our composites in order
The particle size of PZT is clearly affected electrical properties of the PZT/nylon57 composite. The remanent polarization, relative permittivity and piezoelectric coefficient (d33) of composites increased with increasing of PZT particle size. The optimum remanent polarization, relative permittivity and piezoelectric coefficient (d33) of composites were obtained with PZT average particle size of 95 μm. An enhancement of the relative permittivity and piezoelectric coefficient (d33) of larger particle size PZT was contributed to dense connection of PZT particle which facilitate the poling process resulting in high poling efficiency and high electrical properties.
Acknowledgments This work is financially supported by National Metal and Materials Technology Center under the project No. MT-B-48-CER-07-186-I References 1. Dong, L., Xiong, C., Quan, H. and Zhao, G. 2006. Polyvinyl-butyral/lead zirconate titanates composites with high dielectric constant and low dielectric loss. Scripta Mater. 55 : 835-837.
Table 2. Comparing of electrical properties of present composites with those of the previous work. Ref.
(17)
A.Chaipanich
Present work
PZT sintered (°C)
PZT % vol.
PZT particle size range (μm)*
εr
loss
d33 (pC/N)
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50
3.8
167
0.95
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22
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ball mill 2 h (5μm)
23
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11
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79 (95 μm)
73
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28
*The number in parenthesis is average particle size of ceramic particle by Matersizer
151 Influence of Ceramic Particle Sizes on Electrical Properties of Lead Zirconate Titanate (PZT)/Nylon57 Composites 2. Bowen, C. R. and Topolov, V. Y. 2003. Piezoelectric sensitivity of PbTiO3-based ceramic/polymer composites with 0-3 and 3-3 conectivity. Acta Mater. 51 : 4965-4979.
11. Marra, S. P., Remesh, K. T. and Douglas. 1999. The mechanical properties of lead-titanate/ polymer 0-3 composite. Compos. Sci. Technol. 59 : 2163-2173.
3. Dietze, M. and Es-Souni, M. 2008. Structural and functional properties of screen-printed PZT-PVDF-TrFE composites. Sensors Actuators A 143 : 329-334.
12. Liu, X.-F., Xiong, C.-X., Sun, H.-J., Dong, L-J., Li, R. and Liu, Y. 2006. Piezoelectric and dielectric properties of PZT/PVC and graphite doped with PZT/PVC composites. Mater. Sci. Eng. B 127 : 261-266.
4. Chen, H., Dong, X., Zeng, T., Zhou, Z. and Yang, H. 2007. The mechanical and electric properties of infiltrated PZT/polymer composites. Ceram. Inter. 33 : 1369-1374. 5. Wang, L., Zhu, J., Zou, X. and Zhang, F. 2000. PbTiO3–P(VDF/TeFE) composites for piezoelectric sensors. Sensors Actuators B 66 : 266-268. 6. Wang, X. X., Lam, K. H., Tang, X. G. and Chan, H. L. W. 2004. Dielectric characteristics and polarization response of lead-free ferroelectric(Bi 0.5 Na 0.5 ) 0.94 Ba 0.06 TiO 3 P(VDF-TrFE) 0-3 composites. Solid State Commun. 130 : 695-699. 7. Pan, B., yang, Y., Yu, L–C., Liu, J–M., Li, K., Liu, Z.G. and Chan, H.L.W. 2003. Low frequency of Ferroelectric hysteresis in 1-3 Pb0.95La0.05TiO3/polymer ferroelectric composites. Mater. Sci. Eng. B 99 : 179-182. 8. Park, J-M., Kong, J-W., Kim, D-S. and Yoon, D-J. 2005. Nondestructive damage detection and interfacial evaluation of single fibers/epoxy composites using PZT, PVDF and P(VDFTrFE) copolymer sensors. Compos. Sci. Technol. 65 : 241-256. 9. Barranco-P, A. 2006. Modeling of dielectricrelaxation response of ceramic/polymer composite based on lead titanate. Scripta Mater. 54 : 47-50. 10. Ng, K. L., Chan, H. L. W. and Choy, C. L. 2000. Piezoelectric and pyroelectric properties of PZT/P(VDF-TrFE) composites with constituent phases poled in parallel or antiparallel directions. IEEE Transactions on Ultrasonics Ferroelectrics Frequency control 47(6) : 1308-1315.
13. Rujijanagul, G., Jompruan, S. and Chaipanich, A. 2008. Influence of graphite particle size on electrical properties of modified PZTpolymer composites. Curr. Appl. Phys. 8 : 359-362. 14. Cui, X., Li, W. and Yan, D. 2004. Investigation on odd-odd nylon based on undecanedioic acid: 1. synthesis and characterization. Polym. Inter. 53 : 1729-1734. 15. Bouzid, A., Bourim, E. M., Gabbay, M. and Fantozzi, G. 2005. PZT phase diagram determination by measurement of elastic moduli. J. Eur. Ceram. Society 25 : 32133221. 16. Hammami, H., Arous, M., Lagache, M. and Kallel, A. 2006. Experimental study of relaxations in unidirectional piezoelectric composites. Composites : Part A: Applied Science and Manufacturing. 37 : 1-8. 17. Chaipanich, A. 2007. Effect of PZT particle size on dielectric and piezoelectric properties of PZT-cement composites. Current Appl. Phys. 7 : 574-577.
Influence of Ceramic Particle Sizes on Electrical Properties of Lead Zirconate Titanate (PZT)/Nylon57 Composites Wilairat SUPMAK, Atitsa PETCHSUK and Aree THANABOONSOMBUT National Metal and Materials Technology Center, Pathumthani 12120, Thailand 114 Thailand Science Park, Paholyothin Road, Klong 1, Klong Luang, Pathumthani 12120 Abstract
Received Nov. 25, 2008 Accepted Feb. 11, 2009
0-3 connectivity of lead zirconate titanate (PZT) with various particle sizes and nylon57 composites were prepared using 30% PZT by volume. Electrical properties of the composites as a function of PZT particle sizes were studied. The relative permittivity, polarization and piezoelectric coefficient (d33) of composites increased with increasing of particle sizes. The optimum relative permittivity and polarization of composite was obtained when 95 μm of PZT average particle size was employed. Piezoelectric coefficient d33 of the composite was found optimum at 28 pC/N whereas the relative permittivity was about 73 and the remanent polarization was 138 µC/cm2. Key words : Lead zirconate titanate (PZT), Nylon 57, Composite, Pizoelectric properties
Introduction
Materials and Experimental Procedures
Composite materials have been intensively studied due to their excellent piezoelectric properties. They have been utilized in variety of applications such as sensors, actuators and under water acoustic transducers.(1-4) Composite materials combine the exceptional toughness of polymer materials with the excellent ferroelectric properties of ceramics. They possess good ferroelectric properties with mechanical strength, low acoustic impedance of matching to water and human tissues and ease of processing.(5-8) The simplest type of piezo ceramic/ polymer composite is a 0-3 connectivity, which consists of a polymer matrix filled with piezoceramic particles.(9-11) For 0-3 connectivity composite, it is not easy to obtain good piezoelectric properties due to the difficulty in poling ceramic particles in such composite.(12-13) One factor that affects the efficiency of poling ceramic particles is the ceramic particle size. Therefore, this work aimed at studying the influence of ceramic particle size on the electrical properties of ceramic/polymer composite. Various ceramic particle size ranges such as after ball mill 2 h, 79 μm were composited with nylon 57 in 0-3 connectivity pattern and their polarization, relative permittivity and piezoelectric coefficient (d33) were investigated.
Materials
Phone 0-2564-6500, E-Mail: [email protected]
Lead Zirconate Titanate (PZT) powder used in the experiment was “PZT 850” (APC International Ltd.) which possess the relative permittivity of 1750 at 1 kHz, piezoelectric constant d33 of 400 pC/N and the Curie transition (Tc) of 360°C. PZT powder were consecutively calcined at 650°C and sintered at 1100°C for 2 h prior to use. Various particle size ranges of PZT were differentiated by sieving through nylon cloth. The ranges of PZT particle sizes used in this investigation were ball mill 2 h, 79 μm corresponding to average particle size of 5 µm, 12 µm, 38 µm, 76 µm, 95 µm, respectively by Mastersizer. Nylon57 was synthesized by melt polycondenzation at 190-220°C for 5 h according to Cui et al.’s method.(14) Preparation of Composite Films All composites were prepared by combined methods of colloidal and melt-press processing techniques. Typically, nylon57 was first dissolved in trifluoroethanol. 30% by volume of selected particle size range of PZT powder was then added into the nylon57 solution while sonicated. The mixture was cast on a petridish to evaporate solvent after sonicated for 20 min. Dried composite film was then hot-pressed for several times until it became homogeneous. The thickness of composite film is approximately 200-350 μm.
148 SUPMAK, W. et al.
Characterization and Electrical Measurements XRD was used to investigate the crystallinity and crystallographic phase of PZT powder to ensure the tetragonal phase (ferroelectric phase). For electrical measurements, the composites films of 1 cm diameter sample were electroded by gold sputtering on both sides. The composite samples were then poled by corona poling technique at room temperature by applying voltage of 20 kV (0.055 mA). The P-E hysteresis loop was measured at room temperature using RT66A Standardized Ferroelectric Measurement Test System (radian Technology). The relative permittivity was measured using 4194A Impedance Gain/Phase analyzer (Hewlett Packard) at the frequencies from 1 kHz to 1 MHz and the temperature range of -70°C to 200°C. The piezoelectric coefficient d33 was measured after 24 h of poling by using piezoelectric d33 meter, model PM3001.
Results and Discussion
P-E hysteresis loops of the 30% PZT by volume of PZT/nylon57 composites with various PZT particle sizes measured at room temperature and 50 kv/cm applied electric field were shown in Figures 3a-3e. It can be seen that the PZT particle size has a significant influence on the polarization of composites but less influence on the coercive field. The polarization and coercive field of composites with various ceramic particle sizes were summarized in Table 1. It can be concluded that the larger the particle size, the higher the polarization. The spontaneous polarization (Ps) and remanent polarization (Pr) showed the highest value when the PZT having average particle size of 95 μm was used.
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The phase formation behavior of PZT powder calcined and sintered at various temperatures was revealed by an X-ray diffraction pattern (XRD) in Figure 1. It was shown that PZT powder calcined and sintered at the temperature range of 880 to 1250°C were mainly perovskite structure having tetragonal phase, which indicated by plane (001), (002) and (211).(15) As the sintering temperature goes higher, the intensities of the (002) and (001) x-ray reflections get higher meaning that PZT phase are getting close to perfect tetragonal phase. However, when the sintering temperature gets higher than 1100°C, the morphology of PZT is changed due to the melting of grain boundaries. Therefore, in this work, PZT powder sintering at 1100°C which retained both crystallography and morphology was used for most parts of the study.
Figure 2. Shows cross-sectional SEM images of 30% PZT by volume composites with various PZT particle ranges. The homogeneous distribution of PZT particles in the polymer matrix can be seen from these SEM images. The PZT particles were surrounded by layer of the polymer matrix and there is no large agglomeration of PZT particles. More connection of PZT particles is expected in bigger particle size which may lead to better electrical properties.
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Figure.1 XRD patterns of PZT powders calcined and sintered at various temperatures (a) 880°C (b) 1000°C (c) 1100 °C (d) 1200°C (e) 1250°C for 2 h at heating/cooling rate of 20°C/min.
Figure 2. Cross-sectional SEM image of 30% PZT by volume of PZT/nylon57 composites with various PZT particle sizes (a) ball mill 2 h (5 µm) (b) < 16 µm (12 µm) (c) 17-46 µm (38 µm) (d) 47-79 µm (76 µm) (e) > 79 µm (95 µm)
149 Influence of Ceramic Particle Sizes on Electrical Properties of Lead Zirconate Titanate (PZT)/Nylon57 Composites 200
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Figure 3. The P-E hysteresis loops of 30% PZT by volume of PZT/nylon57 composite with various PZT particle ranges (a) ball mill 2 h (5 µm) (b) < 16 µm (12 µm) (c) 17-46 µm (38 µm) (d) 47-79 µm (76 µm) (e) > 79 µm (95 µm) Table 1. A summary of polarization of 30% PZT by volume of PZT/nylon 57 composite with various PZT particle size ranges.
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Figure 4. Relative permittivity and dielectric loss of 30% PZT by volume of PZT/nylon57 composite with various PZT particle ranges (a) ball mill 2 h (5 µm) (b) < 16 µm (12 µm) (c) 17-46 µm (38 µm) (d) 47-79 µm (76 µm) (e) > 79 µm (95 µm)
The temperature dependence of relative permittivity and dielectric loss of PZT/nylon 57 composites having PZT particle size of ball mill 2 h (5 µm), 79 μm (95 µm) were investigated as a function of frequencies (1, 10, 100 and 1000 kHz) from -70 to 180°C and were shown in Figure 4a-4e. The relative permittivity increased with the increase of temperature. The relaxation located around 50-70°C and centered at 65°C was characterized as β-relaxation which associated with the glass-rubbery transition (Tg) of the polymer. Segmental mobility of the polymer molecules increased with temperature leading to an increase in relative permittivity. Conductivity relaxation appeared for temperatures far above Tg and low frequency ranges emphasizing the contribution of the conduction due to the increase in the mobility of electric charges in the polymer
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100
-40
0
1200
150
100
-200 -60
0 -60 -40 -20
o
Temperature ( C)
200
(c)
150
Loss
-400
0 -60 -40 -20
E (kV/cm)
200
Polarization (uC/cm2)
20
Loss
Loss
-40
2
-200
Relative permitivity
-200 -60
Loss
Polarization (uC/cm2)
100
50
10
1200
Loss
Polarization (uC/cm2)
100
10
(b)
150
Relative permitivity
150
Relative permitivity
200
150 SUPMAK, W. et al. versus temperature.(16) The highest relative permittivity at room temperature of composite was obtained when PZT having average particle size of 95 μm was employed. As PZT particle size became smaller, the relative permittivity as well as dielectric loss was also lower.
to get comparable piezoelectric constant d33. In addition, the PZT powders used in this work were sintered at lower sintering temperature (1100°C) suggesting low energy and cost effective in preparing composites.
Conclusions The effect of PZT particle sizes on piezoelectric coefficient (d33) of PZT/Nylon57 composite was summarized in Table 2. With an increase of PZT particle size, the piezoelectric coefficient (d33) was increased. The highest piezoelectric constant d33 of the composite was obtained at 28 pC/N where PZT having average particle size of 95 μm was used. An increase of the relative permittivity and piezoelectric coefficient d33 with increasing of PZT particles size are probably due to dense connection of PZT particles resulting in higher poling efficiency. Hence, the larger PZT particle size e.g. 95 μm provides better piezoelectric properties. Table 2 also compared electrical properties of composites of the previous work (17) with our present results. From our results, it is clearly seen that the particle size of PZT has an effect on electrical properties of the PZT/Nylon57 composites, thus agreeing with earlier results by A. Chaipanich where the cement composite with larger PZT particle size of 620 μm exhibits better properties than that of smaller size (3.8 μm). However, our recent work shows that the 0-3 composite at 30% PZT by volume with average particle sizes of 95 μm exhibits a comparable piezoelectric coefficient d33 value to that of the earlier works which comprises 50% PZT by volume with particle sizes at 620 μm. This infers that less PZT was used in our composites in order
The particle size of PZT is clearly affected electrical properties of the PZT/nylon57 composite. The remanent polarization, relative permittivity and piezoelectric coefficient (d33) of composites increased with increasing of PZT particle size. The optimum remanent polarization, relative permittivity and piezoelectric coefficient (d33) of composites were obtained with PZT average particle size of 95 μm. An enhancement of the relative permittivity and piezoelectric coefficient (d33) of larger particle size PZT was contributed to dense connection of PZT particle which facilitate the poling process resulting in high poling efficiency and high electrical properties.
Acknowledgments This work is financially supported by National Metal and Materials Technology Center under the project No. MT-B-48-CER-07-186-I References 1. Dong, L., Xiong, C., Quan, H. and Zhao, G. 2006. Polyvinyl-butyral/lead zirconate titanates composites with high dielectric constant and low dielectric loss. Scripta Mater. 55 : 835-837.
Table 2. Comparing of electrical properties of present composites with those of the previous work. Ref.
(17)
A.Chaipanich
Present work
PZT sintered (°C)
PZT % vol.
PZT particle size range (μm)*
εr
loss
d33 (pC/N)
1250/3h
50
3.8
167
0.95
17
1250/3h
50
148.5
170
0.83
22
1250/3h
50
620
176
0.79
26
1100/2h
30
ball mill 2 h (5μm)
23
0.10
11
1100/2h
30
79 (95 μm)
73
0.20
28
*The number in parenthesis is average particle size of ceramic particle by Matersizer
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