Electrical Transport Properties Of CaCu₃Ti₄O_12-xNiO?x=0.006? Under High Pressure

Recently,high dielectric constant materials have attracted the attention of researchers,whose dielectric constant can reach 10⁴ or even higher at room temperature.Its high dielectric characteristics can be achieved only with a simple manufacturing process,which is much higher than other low frequency dielectric constants.There is no connection between the dielectric constant value and temperature of CCTO materials,so the resulting electronic device has higher stability.In this paper,high pressure impedance spectroscopy measurements were performed on the NiO-doped CCTO material,CaCu₃Ti₄O₁₂-x NiO?x=0.006?,and then the relationship between its dielectric constant and pressure was studied and atmospheric pressure was applied XRD characterization and SEM morphological characterization,systematically studied the effect of the electrical transport properties,dielectric properties,and microscopic crystal morphology of CaCu₃Ti₄O₁₂-xNiO?x=0.006?samples under high pressure on the electrical properties,and obtained the following studies Achievements:First,XRD studies of CaCu₃Ti₄O₁₂-x NiO?x=0.006?samples were performed in the experiment and then compared with PDF standard cards and found that the position of the diffraction peak was hardly changed.Therefore,XRD results showed that Ni²⁺ions did not enter the lattice of CCTO by adding Ni O.We also performed SEM characterization of the samples and found by scanning electron microscopy that the CaCu₃Ti₄O₁₂-x NiO?x=0.006?sample was polycrystalline and inhomogeneous,sizes are on the order of microns.Measured by high-pressure Raman spectroscopy,the slope of the pressure shift at the peak position at 5.1 GPa has changed,a new peak appeared at 17.7 GPa,and the intensity of the peak gradually increased as the pressure increased.Second,we performed impedance spectroscopy measurements onCaCu₃Ti₄O₁₂-x NiO?x=0.006?samples under high pressure,We measured the increase in pressure from 0.7 GPa to 5.4 Gpa during the pressurization process,the resistance of the sample decreases gradually;from 5.4 GPa to 19.9 GPa,the resistance of the sample increases gradually with increasing pressure;from 19.9 GPa to 30.0 GPa,as the pressure increases,the resistance of the sample begins to gradually decrease.However,the experimentally obtained pressure relief impedance spectrum is obviously different from the pressure impedance spectrum.During the pressure relief process,the pressure is reduced from 30.0 GPa to 0.6 GPa,and the resistance value of the sample is always increasing as the pressure decreases.The relationship between relaxation frequency and pressure is also changed at 5.4 GPa and 19.9 GPa,pressure ranges from 0.7 GPa to 5.4 GPa,relaxation frequency gradually increases with pressure;pressure ranges from 5.4 GPa to 19.9 GPa,the relaxation frequency gradually decreases as the pressure increases;the pressure ranges from 19.9 GPa to30.0 GPa,and the relaxation frequency gradually becomes larger as the pressure increases.Finally,we investigated the relationship between dielectric constant and pressure for CaCu₃Ti₄O₁₂-x NiO?x=0.006?samples.Since the thickness of the sample is continuously reduced under the influence of pressure,the thickness of the sample is corrected in the calculation,so that the dependence relationship between the dielectric constant of the sample and the pressure is more accurately obtained.The pressure was found to change at 5.4 GPa and 19.9 GPa,respectively,and the pressure was from 0.7GPa to 5.4 GPa,the dielectric constant gradually decreased with increasing pressure and the rate was slower;the pressure ranged from 5.4 GPa to19.9 GPa,the electrical constant continues to decrease as the pressure increases,but the rate increases;pressure from 19.9 GPa to 30.0 GPa,the dielectric constant continues to decrease as the pressure increases,but the rate becomes slower.There is a slight pressure deviation between the Raman data and the impedance data in the experiment because we used a pressure-transmitting medium during the high-pressure Raman spectroscopy test;the pressure gradients present in the sample chamber can also lead to pressure deviations.