Lead magnesium niobate-lead titanate(PMN-PT)piezoelectric single crystals are widely utilized due to their outstanding performance,with varying compositions significantly impacting their properties.While application o...Lead magnesium niobate-lead titanate(PMN-PT)piezoelectric single crystals are widely utilized due to their outstanding performance,with varying compositions significantly impacting their properties.While application of PMN-PT in high-power settings is rapidly evolving,material parameters are typically tested under low signal conditions(1 V),and effects of different PT(PbTiO_(3))contents on the performance of PMN-PT single crystals under high-power conditions remain unclear.This study developed a comprehensive high-power testing platform using the constant voltage method to evaluate performance of PMN-PT single crystals with different PT contents under high-power voltage stimulation.Using crystals sized at 10 mm×3 mm×0.5 mm as an example,this research explored changes in material parameters.The results exhibit that while trend of the parameter changes under high-power excitation was consistent across different PT contents,degree of the change varied significantly.For instance,a PMN-PT single crystal with 26%(in mol)PT content exhibited a 25%increase in the piezoelectric coefficient d_(31),a 13%increase in the elastic compliance coefficient s_(11)^(E),a 17%increase in the electromechanical coupling coefficient k_(31),and a 73%decrease in the mechanical quality factor Q_(m) when the power reached 7.90 W.As the PT content increased,the PMN-PT materials became more susceptible to temperature influences,significantly reducing the power tolerance and more readily reaching the depolarization temperatures.This led to loss of piezoelectric performance.Based on these findings,a clearer understanding of impact of PT content on performance of PMN-PT single crystals under high-power applications has been established,providing reliable data to support design of sensors or transducers using PMN-PT as the sensitive element.展开更多
The Cabibbo-Kobayashi-Maskawa (CKM) and Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrices in the electroweak sector are now well-known experimentally. However, there have been only a few proposals to derive these matric...The Cabibbo-Kobayashi-Maskawa (CKM) and Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrices in the electroweak sector are now well-known experimentally. However, there have been only a few proposals to derive these matrices from an underlying theory. In this note, these matrices are derived from example scalar wavefunctions associated with a permutationally symmetric mass matrix with three states for each of the four fermion families. Such a mass matrix is consistent with an anomaly-free quantum field theory for the 4 fermion families. The derivation uses three-dimensional gaussian wavefunctions with specified widths and specified separations between the 3 wells implied by the theory. This approach first fits the diagonal elements of the matrices. A fourth element is then estimated from the properties of the scalar fields in the aforementioned model. Unitarity is then applied to compute the remaining matrix elements. The example calculations produce matrices that have a normalized root-mean-square error (RMSE) from the measured matrix of 6.09 × 10−4 and 8.34 × 10−3 for the CKM and PMNS matrices, respectively. The normalized RMSE for departure from unitarity is 9.18 × 10−4 and 8.95 × 10−3 for the two respective matrices. The results are within one standard deviation of almost all of the measured parameters for both matrices. The primary objective of this paper is to show that the matrices can be fit accurately in the context of at least one anomaly-free quantum field theory.展开更多
基金Research and Development Project on Voltage Sensors by China Southern Power Grid Digital Research Institute(210000KK52220017)。
文摘Lead magnesium niobate-lead titanate(PMN-PT)piezoelectric single crystals are widely utilized due to their outstanding performance,with varying compositions significantly impacting their properties.While application of PMN-PT in high-power settings is rapidly evolving,material parameters are typically tested under low signal conditions(1 V),and effects of different PT(PbTiO_(3))contents on the performance of PMN-PT single crystals under high-power conditions remain unclear.This study developed a comprehensive high-power testing platform using the constant voltage method to evaluate performance of PMN-PT single crystals with different PT contents under high-power voltage stimulation.Using crystals sized at 10 mm×3 mm×0.5 mm as an example,this research explored changes in material parameters.The results exhibit that while trend of the parameter changes under high-power excitation was consistent across different PT contents,degree of the change varied significantly.For instance,a PMN-PT single crystal with 26%(in mol)PT content exhibited a 25%increase in the piezoelectric coefficient d_(31),a 13%increase in the elastic compliance coefficient s_(11)^(E),a 17%increase in the electromechanical coupling coefficient k_(31),and a 73%decrease in the mechanical quality factor Q_(m) when the power reached 7.90 W.As the PT content increased,the PMN-PT materials became more susceptible to temperature influences,significantly reducing the power tolerance and more readily reaching the depolarization temperatures.This led to loss of piezoelectric performance.Based on these findings,a clearer understanding of impact of PT content on performance of PMN-PT single crystals under high-power applications has been established,providing reliable data to support design of sensors or transducers using PMN-PT as the sensitive element.
文摘The Cabibbo-Kobayashi-Maskawa (CKM) and Pontecorvo-Maki-Nakagawa-Sakata (PMNS) matrices in the electroweak sector are now well-known experimentally. However, there have been only a few proposals to derive these matrices from an underlying theory. In this note, these matrices are derived from example scalar wavefunctions associated with a permutationally symmetric mass matrix with three states for each of the four fermion families. Such a mass matrix is consistent with an anomaly-free quantum field theory for the 4 fermion families. The derivation uses three-dimensional gaussian wavefunctions with specified widths and specified separations between the 3 wells implied by the theory. This approach first fits the diagonal elements of the matrices. A fourth element is then estimated from the properties of the scalar fields in the aforementioned model. Unitarity is then applied to compute the remaining matrix elements. The example calculations produce matrices that have a normalized root-mean-square error (RMSE) from the measured matrix of 6.09 × 10−4 and 8.34 × 10−3 for the CKM and PMNS matrices, respectively. The normalized RMSE for departure from unitarity is 9.18 × 10−4 and 8.95 × 10−3 for the two respective matrices. The results are within one standard deviation of almost all of the measured parameters for both matrices. The primary objective of this paper is to show that the matrices can be fit accurately in the context of at least one anomaly-free quantum field theory.
