The dependence of the polarization P in Hf1-xZrxO2 nanoparticles on electric field, dopant concentration x, size and temperature are studied using the transverse Ising model and the Green’s function method. Pure ZrO2...The dependence of the polarization P in Hf1-xZrxO2 nanoparticles on electric field, dopant concentration x, size and temperature are studied using the transverse Ising model and the Green’s function method. Pure ZrO2 shows at high electric fields an antiferroelectric behavior. Pure HfO2 is a linear dielectric in the monoclinic phase. With increasing ZrO2 content the of HZO shows a ferroelectric behavior. The composition dependence x of the remanent polarization Pr(x)?has a maximum for x = 0.5. For x = 0, pure HfO2, and x = 1, pure ZrO2, Pr=0.?P increases with decreasing HZO nanoparticle size. The influence of Al and La doping on Pr?in HfO2 nanoparticles is also studied. The exhibiting of the ferroelectricity in ion doped HfO2 is due to a phase transformation and to an internal strain effect. The observed results are in good qualitative agreement with the experimental data.展开更多
In order to in situ measure chemical parameters of deep-sea water and hydrothermal fluids at midocean ridge(MOR),it is necessary to use high temperature and high pressure chemical sensors.Developing new sensors is ess...In order to in situ measure chemical parameters of deep-sea water and hydrothermal fluids at midocean ridge(MOR),it is necessary to use high temperature and high pressure chemical sensors.Developing new sensors is essential to measure in-situ pH and other chemical parameters(dissolved H2,dissolved H2S)of deep-sea water and hydrothermal fluids in a wide temperature range(2℃―400℃)at MOR vents.The YSZ(Yttria Stabilized Zirconia,9%Y2O3)ceramic-based(HgO/Hg)chemical sensors possess excellent electrochemical properties at high temperatures,which have been used to measure chemical parameters of hydrothermal fluids above 200℃.A novel Zr/ZrO2 oxidation/reduction electrode was constructed by oxidation of Zr wire in Na2CO3 melt.This Zr/ZrO2 electrode has good chemical stability while measuring pH of high-temperature aqueous solutions,combined with a Ag/AgCl reference electrode.Potentials of the Zr/ZrO2 sensor in association with a Ag/AgCl reference electrode vary linearly with pH over a wide pH range,as tested by various NaCl-HCl-H2O solutions(NaOH-NaCl-H2O for basic solutions),at temperatures in the range of 20℃―200℃.Thus,the Zr/ZrO2 sensors can be utilized in monitoring the fluids over the temperature range of 2℃―200℃.The Zr/ZrO2 electrode combined with Ag/AgCl,Ag/Ag2S,and Au electrodes has been used to measure pH and other chemical parameters(dissolved H2,dissolved H2S)of aqueous fluids from low to high temperatures and high pressures in the laboratory and to monitor those parameters of deep-sea water in South China Sea.展开更多
文摘The dependence of the polarization P in Hf1-xZrxO2 nanoparticles on electric field, dopant concentration x, size and temperature are studied using the transverse Ising model and the Green’s function method. Pure ZrO2 shows at high electric fields an antiferroelectric behavior. Pure HfO2 is a linear dielectric in the monoclinic phase. With increasing ZrO2 content the of HZO shows a ferroelectric behavior. The composition dependence x of the remanent polarization Pr(x)?has a maximum for x = 0.5. For x = 0, pure HfO2, and x = 1, pure ZrO2, Pr=0.?P increases with decreasing HZO nanoparticle size. The influence of Al and La doping on Pr?in HfO2 nanoparticles is also studied. The exhibiting of the ferroelectricity in ion doped HfO2 is due to a phase transformation and to an internal strain effect. The observed results are in good qualitative agreement with the experimental data.
基金Supported by the"863"Project of the Ministry of Science and Technology of China(Grant Nos.2001AA612020-3,2003AA612020-3,2001DEA30041,2002DEA30084,2003DEA2C021,2001DEA20023B,DY105-03-01,K2007-1-13)the National Natural Science Foundation of China(Grant Nos.20373064,50602042)
文摘In order to in situ measure chemical parameters of deep-sea water and hydrothermal fluids at midocean ridge(MOR),it is necessary to use high temperature and high pressure chemical sensors.Developing new sensors is essential to measure in-situ pH and other chemical parameters(dissolved H2,dissolved H2S)of deep-sea water and hydrothermal fluids in a wide temperature range(2℃―400℃)at MOR vents.The YSZ(Yttria Stabilized Zirconia,9%Y2O3)ceramic-based(HgO/Hg)chemical sensors possess excellent electrochemical properties at high temperatures,which have been used to measure chemical parameters of hydrothermal fluids above 200℃.A novel Zr/ZrO2 oxidation/reduction electrode was constructed by oxidation of Zr wire in Na2CO3 melt.This Zr/ZrO2 electrode has good chemical stability while measuring pH of high-temperature aqueous solutions,combined with a Ag/AgCl reference electrode.Potentials of the Zr/ZrO2 sensor in association with a Ag/AgCl reference electrode vary linearly with pH over a wide pH range,as tested by various NaCl-HCl-H2O solutions(NaOH-NaCl-H2O for basic solutions),at temperatures in the range of 20℃―200℃.Thus,the Zr/ZrO2 sensors can be utilized in monitoring the fluids over the temperature range of 2℃―200℃.The Zr/ZrO2 electrode combined with Ag/AgCl,Ag/Ag2S,and Au electrodes has been used to measure pH and other chemical parameters(dissolved H2,dissolved H2S)of aqueous fluids from low to high temperatures and high pressures in the laboratory and to monitor those parameters of deep-sea water in South China Sea.
