Thermally stimulated electron emission in the paraelectric phase of triglycine sulfate crystals heated at a high rate

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.     

Kinetics of electron emission from lithium niobate

The kinetics of thermally stimulated electron emission from single-crystal lithium niobate has been studied. The emission current relaxation time is calculated for the temperature range 45–90°C. It is established that an increase in the heating rate brings about a considerable broadening of the temperature range within which emission occurs. The results obtained are treated in terms of the model of field emission from surface states in ferroelectrics.     

Dispersion of Dielectric Permittivity in a Nanocrystalline Cellulose–Triglycine Sulfate Composite at Low and Ultralow Frequencies

Physics of the Solid State - The dispersion of dielectric permittivity in nanocrystalline cellulose–triglycine sulfate composites is studied in the range of frequencies from 10–3 to 106...     

Properties of Triglycine Sulfate Crystals Grown from Aqueous Solutions

A dielectric study of triglycine sulfate crystals was carried out and the phase transition temperatures were determined for samples grown at temperatures below 0°C. The influence exerted by a single-crystal silicon substrate treated by various methods on the shape of triglycine sulfate crystals was examined.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 1, 2005, pp. 45–51.Original Russian Text Copyright © 2005 by Stekhanova, Yatsenko, Milovidova, Sidorkin, Rogazinskaya.     

Effect of sample thickness on electron emission from the TGS ferroelectric crystal

An experimental study of electron emission from nominally pure triglycine sulfate crystal samples of various thicknesses is reported. It is shown that the threshold field of emission, similar to the coercive field, increases with decreasing sample thickness d in inverse proportion to d.     

Internal bias field in triglycine sulphate crystals with <Emphasis Type="Italic">L</Emphasis>-, α-alanine grown at negative temperatures

The dielectric and pyroelectric properties of triglycine sulphate (TGS) crystals with L, α-alanine impurities grown at negative temperatures have been investigated. It is shown that a lower impurity concentration (2 mol % in solution) in this temperature range leads to the formation of internal bias fields of the same order of magnitude (∼800 V/cm) as for TGS crystals grown at T ⩽ 50°C but with an L, α-alanine concentration of 20 mol % in solution.     

Properties of nanoporous aluminum oxide with triglycine sulfate and Rochelle salt inclusions

The possibility of producing the ferroelectric state in nanoporous aluminum oxide loaded with triglycine sulfate and Rochelle salt has been studied. Our dielectric, pyroelectric and emission measurements give grounds to suggest that this state persists in the composites under study up to temperatures exceeding the Curie point of bulk crystals by several tens of degrees.     

Internal bias field in TGS crystals doped with different impurities

The influence of an internal bias field formed by impurity ions of heavy metals and alpha-alanine molecules on the dielectric nonlinearity and emission properties of ferroelectric triglycine sulfate crystals has been studied. It is shown that a role of defects increases near the phase transition, which manifests itself in a decrease in the maximum values of the effective permittivity and an increase in the emission current with increasing impurity concentration.     

Ferroelectric properties of SiO<Subscript>2</Subscript>-<Emphasis Type="Italic">TGS</Emphasis> nanocomposite

Dielectric and pyroelectric properties of a composite based on nanodisperse silica hydrosol and ferroelectric triglycinesulfate (TGS) were investigated. The performed studies allow us to assume that a ferroelectric state exists in this composite.