Polymer matrix ferroelectric composites under pressure: Negative electric capacitance and glassy dynamics

Abstract

Abstract. This report presents the results of high-pressure and broadband dielectric spectroscopy studies in polyvinylidene difluoride (PVDF) and barium strontium titanate (BST) microparticles composites (BST/PVDF). It shows that the Arrhenius behaviour for the temperature-related dynamics under atmospheric pressure is coupled to Super-Arrhenius/Super-Barus isothermal pressure changes of the primary relaxation time. Following these results, an explanation of the unique behaviour of the BST/PVDF composite is proposed. Subsequently, it is shown that when approaching the GPa domain the negative electric capacitance phenomenon occurs. Graphical abstract

Design of a high-pressure viscosity-measurement system using two pressure balances

“…As a result, we obtained the pressure and temperature dependency of bis(2-ethylhexyl) sebacate viscosity (figure 5), and this dependency was also found to be similar to that reported in the literature [18][19][20]. In particular, the value of the fitting curve (based on the Barus equation [24]; µ = a * exp…”

Three-Dimensional Perovskite Phase Transition Materials with Switchable Second Harmonic Generation Properties Introduced by Homochiral (1S,4S)-2,5-Diazabicyclo[2.2.1]-heptane

“…Switching material is a kind of material whose internal crystal structure produces on or off states stably and reversibly without changing chemical composition under external stimulation (such as temperature, pressure, and electricity). − Making use of the characteristics of these two states, it is still a hot research field to apply them in electronic storage, data communication, sensors, and other fields. ,− At present, there are many studies on switching materials with reversible phase change and dielectrics, but it is still difficult to design and synthesize switching materials with the SHG effect. This is because only the crystals crystallized in the noncentrosymmetric space group will have the reversible SHG signal.…”

Anomalous behaviour of dynamic electrical conductivity in semiconductor ferroelectric ceramics near the phase transition temperature

“…Это проявляется в изменении характера имиттанса образца от емкостного к индуктивному. Исследование данного эффекта может привести к созданию новых устройств микро-и наноэлектроники, в частности, к увеличению емкости сверхплотных динамических систем оперативной памяти [6][7][8][9][10][11][12][13][14][15][16][17]. Так как эффект отрицательной емкости проявляется в гетерофазных структурах, разумно предположить, что он связан с явлениями на межфазных границах различной природы: на границах кристаллитов в поликристаллах, на барьерах в полупроводниковых диодах, на границах металл-полупроводник или полупроводник-диэлектрик в МДП-структурах.…”