This work investigated the structure and dielectric behavior of precursor-derived spark plasma sintered(SPS)hafnium dioxide(HfO_(2)).X-ray diffractograms confirmed the presence of monoclinic HfO_(2)(m-HfO_(2))and scan...This work investigated the structure and dielectric behavior of precursor-derived spark plasma sintered(SPS)hafnium dioxide(HfO_(2)).X-ray diffractograms confirmed the presence of monoclinic HfO_(2)(m-HfO_(2))and scanning electron micrographs revealed micron/nanosized grains and grain boundaries in SPS m-HfO_(2).The theoretical density of ceramics is 94%,and the porosity is very low.In the temperature interval of 25-200℃,the real part of the permittivity(ε')is almost frequency-and temperature-independent and the e'value is about 21 in the frequency range 10^(2)-10^(6)Hz.ε'of SPS ceramics is higher than that of traditionally sintered HfO_(2) ceramics.At temperatures above 225℃,there is a sharp increase in the permittivity and loss at low measuring frequencies.In order to comprehend the underlying conduction mechanisms,an analysis of the dispersion dependences of the dielectric response was undertaken.High permittivity values were attributed to the space charge polarization mechanism occurring at grain boundaries due to the thermally activated movement of oxygen vacancies.The DC conductivity of SPS m-HfO_(2) is thermally activated,and conductivity is determined by oxygen vacancies through hopping mechanism.展开更多
基金supported by the grant received from the Department of Science and Technology,Ministry of Science and Technology,Government of India(project no.DST/ICD/BRICS/Call-3/RaviKumar-PORMAT/2019)supported by the Ministry of Science and Higher Education of the Russian Federation within the State task FSEG-2023-0016.
文摘This work investigated the structure and dielectric behavior of precursor-derived spark plasma sintered(SPS)hafnium dioxide(HfO_(2)).X-ray diffractograms confirmed the presence of monoclinic HfO_(2)(m-HfO_(2))and scanning electron micrographs revealed micron/nanosized grains and grain boundaries in SPS m-HfO_(2).The theoretical density of ceramics is 94%,and the porosity is very low.In the temperature interval of 25-200℃,the real part of the permittivity(ε')is almost frequency-and temperature-independent and the e'value is about 21 in the frequency range 10^(2)-10^(6)Hz.ε'of SPS ceramics is higher than that of traditionally sintered HfO_(2) ceramics.At temperatures above 225℃,there is a sharp increase in the permittivity and loss at low measuring frequencies.In order to comprehend the underlying conduction mechanisms,an analysis of the dispersion dependences of the dielectric response was undertaken.High permittivity values were attributed to the space charge polarization mechanism occurring at grain boundaries due to the thermally activated movement of oxygen vacancies.The DC conductivity of SPS m-HfO_(2) is thermally activated,and conductivity is determined by oxygen vacancies through hopping mechanism.
