We report the results of investigation of dielectric spectroscopy study of single crystals of Bi_(12)GeO_(20) and Bi_(12)GeO_(20) doped with Co nanoparticles.The complex dielectric constant was measured in the tempera...We report the results of investigation of dielectric spectroscopy study of single crystals of Bi_(12)GeO_(20) and Bi_(12)GeO_(20) doped with Co nanoparticles.The complex dielectric constant was measured in the temperature interval from 5 to 450K and frequencies from 1Hz to 1MHz.The electrical conductivity of both samples was thermally activated with potential barriers of 0.55eV and 0.59eV,respectively.Doped samples had bigger complex dielectric constants and σ′ exhibited slightly steeper temperature dependence than in the pure sample.The dielectric relaxation was observed in pure and doped single crystals and relaxation frequencies showed similar activation energies as electrical conductivities.展开更多
The complex dielectric constant/ac electrical conductivity was investigated as a function offrequency and temperature in Pb_(5)Cr_(3)F_(19).The system undergoes a ferroelectric phase transition at higher temperatures....The complex dielectric constant/ac electrical conductivity was investigated as a function offrequency and temperature in Pb_(5)Cr_(3)F_(19).The system undergoes a ferroelectric phase transition at higher temperatures.At lower temperatures the real part of the complex ac electric conductivity was found to follow the universal dielectric response(UDR)σ′∝v^(s),typical for hopping or tunneling of localized charge carriers.A detailed analysis of the temperature dependence of the UDR parameter s in terms of the theoretical model for tunneling of small polarons revealed that,at low temperatures,this mechanism governs the charge transport in Pb_(5)Cr_(3)F_(19).The value of the inverse attempt frequency τ0 indicates the femtosecond tunneling of polarons in the system similar to the Büttiker-Landauer transversal time.展开更多
基金Research was supported by the Slovenian Research Agency(Grant No.P1-0125)The authors thank the Project operated within the Foun-dation for Polish Science Team Programme co-financed by the EU European Regional Development Fund and the FP7 NMP ENSEMBLE Project(GA NMP4-SL-2008-213669).
文摘We report the results of investigation of dielectric spectroscopy study of single crystals of Bi_(12)GeO_(20) and Bi_(12)GeO_(20) doped with Co nanoparticles.The complex dielectric constant was measured in the temperature interval from 5 to 450K and frequencies from 1Hz to 1MHz.The electrical conductivity of both samples was thermally activated with potential barriers of 0.55eV and 0.59eV,respectively.Doped samples had bigger complex dielectric constants and σ′ exhibited slightly steeper temperature dependence than in the pure sample.The dielectric relaxation was observed in pure and doped single crystals and relaxation frequencies showed similar activation energies as electrical conductivities.
基金Research was supported by the Slovenian Research Agency(P1-0125).
文摘The complex dielectric constant/ac electrical conductivity was investigated as a function offrequency and temperature in Pb_(5)Cr_(3)F_(19).The system undergoes a ferroelectric phase transition at higher temperatures.At lower temperatures the real part of the complex ac electric conductivity was found to follow the universal dielectric response(UDR)σ′∝v^(s),typical for hopping or tunneling of localized charge carriers.A detailed analysis of the temperature dependence of the UDR parameter s in terms of the theoretical model for tunneling of small polarons revealed that,at low temperatures,this mechanism governs the charge transport in Pb_(5)Cr_(3)F_(19).The value of the inverse attempt frequency τ0 indicates the femtosecond tunneling of polarons in the system similar to the Büttiker-Landauer transversal time.
