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1.
Single crystals of triglycine sulphate (TGS) doped with 1 mol% of 4-(dimethylamino) benzaldehyde (DB) have been grown from aqueous solution at ambient temperature by slow evaporation technique. The effect of dopant on the crystal growth and dielectric, pyroelectric and mechanical properties of TGS crystal have been investigated. X-ray powder diffraction pattern for pure and doped TGS was collected to determine the lattice parameters. FTIR spectra were employed to confirm the presence of 4-(dimethylamino) benzaldehyde in TGS crystal, qualitatively. The dielectric permittivity has been studied as a function of temperature by cooling the sample at a rate of 1 °C/min. An increase in the Curie temperature Tc=51 °C (for pure TGS, Tc=48.5 °C) and decrease in maximum permittivity has been observed for doped TGS when compared to pure TGS crystal. Pyroelectric studies on doped TGS were carried out to determine pyroelectric coefficient. The Vickers's hardness of the doped TGS crystals along (0 1 0) face is higher than that of pure TGS crystal for the same face. Domain patterns on b-cut plates were observed using scanning electron microscope. The low dielectric constant, higher pyroelectric coefficient and higher value of hardness suggest that doped TGS crystals could be a potential material for IR detectors.  相似文献   

2.
Technical Physics - An inhomogeneous ferroelectric (triglycine-sulfate (TGS) single crystal with a TGS–TGS+Cr periodic growth impurity structure) has been investigated by scanning capacitance...  相似文献   

3.
Thermally stimulated electron emission from a ferroelectric chromium-doped triglycine sulfate (TGS) crystal was experimentally observed to occur in a temperature range 6 K above the Curie point from samples heated at a relatively high rate. Increasing the heating rate q was shown to cause the emission current density to increase throughout the temperature range studied. The emission onset temperature in chromium-doped TGS depends only weakly on the rate q and is close to that for pure TGS, and the emission cutoff temperature grows monotonically with q at comparatively low heating rates and stabilizes at high q. At the same time, the interval of emission extension into the paraelectric phase here is about one half that for pure TGS heated at the same rate. The specific features of emission observed for this crystal can be assigned to relaxation of the charges screening the spontaneous polarization. The lower emission cutoff temperature for the chromium-doped TGS compared to that for pure TGS is accounted for by the shorter Maxwellian relaxation time in the doped crystal.  相似文献   

4.
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 1-20 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 30-60 °C. The dielectric constant of NBSTGS crystals decrease with the increase in NBS concentration and considerable shift in the phase transition temperature (TC) 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 P-E 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.  相似文献   

5.
Changes are found in the microhardness and dielectric permittivity of triglycine sulfate (TGS) crystals after magnetic treatment in a permanent magnetic field or in the scheme of electron paramagnetic resonance (EPR) using the Earth’s magnetic field. The temporal kinetics of microhardness reduction and the rise in dielectric permittivity (as along with their recovery) are nearly identical. The effects disappear when the crystal’s axis of symmetry is parallel to the static magnetic field in both variants of exposure.  相似文献   

6.
The electric field applied perpendicular to the ferroelectric axis bHOP (in Hoshino, Okaya, Pepinsky notation) of the TGS crystal, results new domain structure-striped domains with walls parallel to the cHOP axis. The process is accompanied by changes of the dielectric properties. We present the results of NMR study of TGS crystal with electric field applied parallel to the cHOP or to the cHOP x bHOP directions. After 12 h application of the DC field, a decrease in amplitude of the 1H NMR central line is observed.  相似文献   

7.
A hydrogen-containing ferroelectric triglycine sulfate (TGS) was comprehensively studied with an atomic force microscopy (AFM) and dielectric spectroscopy. The domain structure dynamics was in situ investigated with piezoresponse force microscopy (PFM) during heating and cooling the TGS crystal near phase transition. Relaxation dependencies of domain boundaries general perimeter and domain dimensions were obtained. TGS dielectric spectra measured at the frequency range from 10 to 1011 Hz were analyzed on basis of significant contribution of conductivity into the dielectric response of ferroelectrics and a good agreement with the experimental data was received. It allows us to obtain more information about temperature dynamics of the domain structure.  相似文献   

8.
An investigation of the influence of electric field transverse to the ferroelectric axis bHOP and parallel to cHOP axis of triglycine sulfate (TGS) single crystal on ferroelectric domain structure was performed by piezoresponse force microscopy. To check if the applied electric field changed the dielectric properties and ferroelectric domain structure the hysteresis loop measurements were carried out as well as observations of domain structure by the liquid crystal technique. The investigation revealed existence of blocked domains in the crystal modified by the electric field TGS.  相似文献   

9.
The effect of a magnetic field on the processes of relaxation of the defect structure relaxation in a triglycine sulfate (TGS) ferroelectric (nonmagnetic) crystal has been observed for the first time. The atomic-force microscopy study has shown that the application of a static weak magnetic field (2 T, 20 min) significantly changes the size distribution of defect nanoclusters characteristic of TGS. Previously known macroscopic aftereffects of the magnetic field in TGS (slow relaxation of the dielectric susceptibility, symmetrization of P–E dielectric hysteresis loops, etc.) can be explained by the redistribution of pinning centers of domain walls caused by the magnetically induced reconfiguration of the defect structure.  相似文献   

10.
A simple mathematical model of pyroelectric phenomena, for ideal ferroelectrics, is presented. Material constants for triglycine sulphate (TGS) are used to verify the model. The results of simulations were compared with the temperature characteristics of the pyroelectric coefficient measured for a TGS ferroelectric sample. Single crystal growth and preparation of samples and experimental procedure are also presented. The relatively good conformity of the model calculations with the measurements allow us to expect further useful application of the model in future work on ferroelectric single crystals.  相似文献   

11.
朱中权  陆惠秀 《物理学报》1980,29(3):400-405
本文从实验上验证了用热力学方法处理TGS晶体内偏置电场的正确性。分析了纯TGS晶体辐照改性与LATGS晶体的Eb-T关系有所区别的原因。文中还讨论了辐照改性的退化问题。 关键词:  相似文献   

12.
In order to get the exact hydrogen-bonding scheme in triglycine sulphate (TGS), which is an important hydrogen bonded ferroelectric, a single crystal neutron diffraction study was undertaken. The structure was refined to an R-factor of R[F 2] = 0.034. Earlier neutron structure of TGS was reported with a very limited data set and large standard deviations. The differences between the present and the earlier reported neutron structure of TGS are discussed.   相似文献   

13.
In this report, the properties of triglycine sulfate (TGS) crystals doped with urea and L--alanine were studied. Urea and L--alanine have successfully entered into TGS crystal, demonstrated by infrared transmission spectrum and pyroelectric study. Figures of merit and Curie temperature are increased due to these two additions. UrLATGS is more suitable for infrared detectors than pure TGS crystals.  相似文献   

14.
TGS晶体生长多形性和其表面扩散生长机制   总被引:3,自引:0,他引:3       下载免费PDF全文
孙大亮  于锡玲  王燕  顾庆天 《物理学报》2000,49(9):1873-1877
选取了TGS晶体的(001),(110),(010)和(100)四个面为研究对象,分析讨论了TGS晶体的表面扩散螺位错生长机制,发现生长基元的脱水化进入表面层过程与表面扩散过程相比,前者在TGS晶体的生长过程中起着更重要的作用;同时,在较高的相对过饱和度下,观察到了TGS自结体的两种简单晶形. 关键词: TGS晶体 生长多形性 表面扩散  相似文献   

15.
Thermally stimulated electron emission is experimentally observed in ferroelectric triglycine sulfate (TGS) crystals in a temperature range whose upper limit is 10–15 K above the Curie point. Samples of a nominally pure and a chromium-doped TGS crystal, heated at different constant rates q=dT/dt, are investigated. It is shown that an increase in the heating rate results in increased emission current density over the entire temperature range investigated. The temperature at which emission arises depends only slightly on the rate q. At the same time, the temperature at which emission ceases increases monotonically with increasing q; if q is less than 1 K/min, this temperature is below the Curie point, while at q=4–5 K/min, this temperature becomes as large as 60–65°C, which is more than 15°C above the Curie point. In chromium-doped TGS crystal, the electron emission onset temperature is close to that of pure TGS, but the width of the temperature range over which emission is observed in the paraelectric phase is approximately two times less than in the case of pure TGS heated at the same rate. The emission disappearance below the Curie point (in the ferroelectric phase) at low q is explained as a result of full emptying of the electron traps under slow heating. The reason for the occurrence of emission above the Curie point is related to the charges that shield the spontaneous polarization and, because of their slow relaxation, persists in the paraelectric phase.  相似文献   

16.
The permittivity of TGS was measured as a function of temperature, crystal thickness, and electrode material. The conductivity of the electrode material was influenced by the switching process in the ferroelectric substrate. This effect was studied in order to obtain information on the surface layer of TGS. A model is proposed which approximately explains the measurements.  相似文献   

17.
Possibility of the ferroelastoelectric behavior manifestations in a uniaxial ferroelectric TGS crystal was investigated. Analysis of the spontaneous piezoelectric moduli tensors for each of the 180°-domains formed as a result of the phase transition in TGS revealed possible directions for simultaneous application of the electric field and mechanical stresses to induce the switching effect in TGS. Influence of the uniaxial mechanical stresses σ11, σ22, σ33 on the parameters of saturated and unsaturated dielectric hysteresis loops in TGS is considered. It was found that a nontraditional E 3σ12 combination of fields may lead to the domain switching in TGS crystals.  相似文献   

18.
The dielectric constant, pyroelectric coefficient, and loss tangent of triglycine sulphate (TGS) crystals that had been poled and subsequently irradiated with x-rays are presented as a function of x-ray exposure and temperature. The results are compared with similar measurements made on poled Co60 gamma irradiated TGS. An estimated x-ray dosage of 1.5−2.0 × 106 R min-1 for 1–2 min gave equivalent results to 2.3 Mr of Co60 gamma rays in achieving optimum non-ferroelectric pyroelectric in TGS ir detectors.  相似文献   

19.
《Current Applied Physics》2009,9(5):1155-1159
Pure and sodium chloride (NaCl)-added Triglycine sulfate (TGS) crystals were grown from aqueous solutions by slow evaporation technique. The values of concentration of dopants in the mother solution were 0.2, 0.6 and 1 mol%. The solubility of the grown samples have been found out at various temperatures. The determination of unit cell parameters was carried out by single crystal XRD method and found that the grown crystals crystallize in monoclinic structure. The dielectric characterization for the pure and NaCl-doped TGS crystals was performed by measuring the dielectric parameters like dielectric constant and dielectric loss with various frequencies in the range 102–106 Hz and with the temperatures ranging from 30 to 70 °C and this study reveals an increase of dielectric constant and loss with the increase of NaCl concentration. Studies on mechanical properties like microhardness and density of the grown pure and NaCl-doped TGS crystals were carried out. UV–Visible transmittance studies were carried out for the grown samples. A sharp fall in the transmittance is observed at 228 nm for pure and NaCl-doped TGS crystals. Atomic absorption spectroscopic (AAS) study was done on the NaCl-doped TGS crystals to ascertain the presence of Na+ ions in the lattice.  相似文献   

20.
The results of studying triglycine sulphate (TGS) imbedded into nanoscale silicate matrices (opal matrices and SBA-15) by methods of linear and nonlinear dielectric spectroscopy are presented. The ferro-electric phase transition becomes noticeably smeared out, as compared to that in a single crystal, and its temperature rises, both effects becoming more pronounced with the decrease in pore sizes.  相似文献   

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