Hysteresis-like Behavior in MBANP Crystals
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- 作者：Adenilson O. dos Santos ; Luis H. Avanci ; Lisandro P. Cardoso ; Ronaldo Giro ; Sé ; rgio B. Legoas ; Douglas S. Galvã ; o ; and John N. Sherwood
- 刊名：Crystal Growth & Design
- 出版年：2004
- 出版时间：September 2004
- 年：2004
- 卷：4
- 期：5
- 页码：1079 - 1081
- 全文大小：101K
- 年卷期：v.4,no.5(September 2004)
- ISSN：1528-7505
文摘
In a previous study of (-)-2-(
-methylbenzylamino)-5-nitropyridine (MBANP) [Avanci, L. H. et. al.,Phys. Rev. B 2000, 61, 6507], X-ray multiple diffraction assessments of the small changes in the unit cell parametersdue to a strain produced by 
, together with the resulting variations in the (hkl) peak position and the observedstrain, were used to calculate the piezoelectric coefficients of this material. In the present work, we report the extensionof these measurements to the determination of the variation of the unit cell parameters of this material under theinfluence of an externally applied dc electric field. Rocking curves were measured using a SIEMENS P4 single-crystal diffractometer equipped with encoders to ensure omega axis step sizes smaller than 1 mdeg. At the beginningof the experiments, the electric field was increased from zero to 3.2 × 105 V/m and then decreased to zero. It wasthen reversed in polarity from zero to -3.2 × 105 V/m and returned to zero again to complete the E-cycle. Themeasured strain versus E-cycle showed an interesting butterfly wing shape hysteresis behavior. Quantum mechanicalcalculations on isolated MBANP molecules show that the main features of the hysteresis shape can be explained interms of field-induced changes in the charge profiles and geometry of isolated MBANP molecules.
-methylbenzylamino)-5-nitropyridine (MBANP) [Avanci, L. H. et. al.,Phys. Rev. B 2000, 61, 6507], X-ray multiple diffraction assessments of the small changes in the unit cell parametersdue to a strain produced by , together with the resulting variations in the (hkl) peak position and the observedstrain, were used to calculate the piezoelectric coefficients of this material. In the present work, we report the extensionof these measurements to the determination of the variation of the unit cell parameters of this material under theinfluence of an externally applied dc electric field. Rocking curves were measured using a SIEMENS P4 single-crystal diffractometer equipped with encoders to ensure omega axis step sizes smaller than 1 mdeg. At the beginningof the experiments, the electric field was increased from zero to 3.2 × 105 V/m and then decreased to zero. It wasthen reversed in polarity from zero to -3.2 × 105 V/m and returned to zero again to complete the E-cycle. Themeasured strain versus E-cycle showed an interesting butterfly wing shape hysteresis behavior. Quantum mechanicalcalculations on isolated MBANP molecules show that the main features of the hysteresis shape can be explained interms of field-induced changes in the charge profiles and geometry of isolated MBANP molecules.