- Crystal growth and dielectric, mechanical, electrical and ferroelectric characterization of n-bromo succinimide doped triglycine sulphate crystals
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Single crystals of triglycine sulphate (TGS) doped with n-bromo succinimide (NBS) were grown at ambient temperature by the slow evaporation technique. An aqueous solution containing 120 mol% of n-bromo succinimide as dopant was used for the growth of NBSTGS crystals. The incorporation of NBS in TGS crystals has been qualitatively confirmed by FTIR spectral data. The effect of the dopant on morphology and crystal properties was investigated. The cell parameters of the doped crystal were determined by the powder X-ray diffraction technique. The dielectric constant of NBS doped TGS crystal was calculated along the ferroelectric direction over the temperature range of 3060 °C. The dielectric constant of NBSTGS crystals decrease with the increase in NBS concentration and considerable shift in the phase transition temperature (T C) towards the higher temperature observed. Pyroelectric studies on doped TGS were carried out to determine the pyroelectric coefficient. The emergence of internal bias field due to doping was studied by collecting PE hysteresis data. Temperature dependence of DC conductivity of the doped crystals was studied and gradual increase in the conductivity with the increase of dopant concentration was observed. The activation energy (ΔE) calculated was found to be lower in both the ferroelectric and the paraelectric phases for doped crystals compared to that of pure TGS. The micro-hardness studies were carried out at room temperature on thin plates cut perpendicular to the b-axis. Less doped TGS crystals show higher hardness values compared to pure TGS. Piezoelectric measurements were also carried out on 010 plates of doped TGS crystals at room temperature.
- Rai, Chitharanjan,Byrappa,Dharmaprakash
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- Phase transition in triglycine sulfate crystals by 1H and 13C nuclear magnetic resonance in the rotating frame
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The ferroelectric phase transition in triglycine sulfate ((NH 2CH2COOH)3·H2SO4, TGS)) crystals, occurring at TC of 322 K, was studied using 1H and 13C CP/MAS NMR. From the spin-lattice relaxation time in the rotating frame, T1ρ, of 1H and 13C, we found that the slopes of the T1ρ versus temperature curve changed near TC. In addition, the change of intensities for the protons and carbons NMR signals in the ferroelectric and the paraelectric phases led to the noticeable changes in the environments of proton and carbon in the carboxyl groups. The carboxyl ordering was the dominant factor driving the phase transition. Our study of the 1H and 13C spectra showed that the ferroelectric phase transition of TGS is of the order-disorder type due to ordering of the carboxyl groups.
- Lim, Ae Ran,Jeong, Se-Young
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- Performance of crystal violet doped triglycine sulfate single crystals for optical and communication applications
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Single crystals of 0.01 and 0.02 mol% crystal violet dye doped triglycine sulfate (NH2CH2COOH)3·H2SO4 (TGS) have been grown by a slow evaporation technique. Enhanced dielectric, optical, thermal and mechanical properties have been achieved by dye doping. Monoclinic structures showing particular coloring patterns and morphology change with dye concentration were obtained. Various functional groups and dye incorporation in the grown crystals were confirmed qualitatively by FTIR and Raman analysis. A significant increase in Curie temperature from 50 to 55 °C with a decrease in maximum permittivity has been observed. The UV-vis spectra showed an increased transmittance window and an increased optical band gap from 5.61 to 6.11 eV as a result of doping. An increase in the sharpness and intensity of the photoluminescence peak with a blue shift has been observed in doped crystals. The thermal stability and the decomposition temperature were found to increase by about 10 °C in 0.01 mol% dye doped TGS. The mechanical strength of the grown crystals was estimated by the Vickers microhardness test and was found to be high for dye doped TGS. A high piezoelectric charge coefficient d33 of 16 pC N-1 was observed for pure TGS which decreased as a result of the dye effect. The fabrication of a patch antenna was carried out after simulating its resonant frequency, making it suitable for telecommunication applications.
- Sinha, Nidhi,Bhandari, Sonia,Yadav, Harsh,Ray, Geeta,Godara, Sanjay,Tyagi, Nidhi,Dalal, Jyoti,Kumar, Sonu,Kumar, Binay
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- Asymmetric autocatalysis triggered by triglycine sulfate with switchable chirality by altering the direction of the applied electric field
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Triglycine sulfate (TGS) acts as a chiral trigger for asymmetric autocatalysis with amplification of enantiomeric excess,i.e., the Soai reaction. Therefore, molecular chirality of highly enantioenriched organic compounds is controlled by a ferroelectric crystal TGS, whose polarization is altered by an electric field.
- Kawasaki, Tsuneomi,Kaimori, Yoshiyasu,Shimada, Seiya,Hara, Natsuki,Sato, Susumu,Suzuki, Kenta,Asahi, Toru,Matsumoto, Arimasa,Soai, Kenso
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- Optical, dielectric & ferroelectric studies on amino acids doped TGS single crystals
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Pure TGS and amino acids (L-arginine, L-histidine and L-alanine) doped TGS crystals were grown by slow evaporation solution growth technique at room temperature. The optical transmission window and optical band gap of the crystals were found by UV-Vis studies. The cut off wavelengths of the grown crystals were observed between 220 nm and 290 nm. The dielectric behaviour was investigated at different frequencies and temperatures. AC conductivity was determined. Photoconductivity study reveals that the grown crystals exhibit negative photoconductivity. The ferroelectric nature of the crystals was identified by P-E hysteresis loop analysis. The piezoelectric d33 coefficient has been measured for the doped TGS crystals. Two close emission bands in the luminescence spectra in the near UV region reveal their application in developing new coherent sources of radiation in this region. Among the three dopants, l-arginine doped TGS possesses low dielectric constant and high piezo electric coefficient, suggesting that this can be a potential material for infrared detectors.
- Deepthi,Shanthi
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