Preparation And Electrical Properties Of Orientated Lead Zirconate-barium Thin Films

The lead zirconate-based anti-ferroelectric thin films applied in energy storage,phase shifter and refrigeration field are kinds of perovskite structure material which are expected to obtain excellent energy storage,dielectric and electrocaloric peoperties due to large energy release near the phase transition of AFE-FE.At present,the influences of doping elements,electric field andt temperature on the anti ferroelestric-ferroelectric phase transition and electrical properties have been studyed.However,it is not clear that the influence of membrane orientation on the behavior of anti ferroelectric-ferroelectric phase transition and its electrical properties.In this paper,the composition and orientation dependence of dielectric,ferroelectric and electrocaloric properties was studied.The main research contents and conclusions are as follows:(1)(100),(110)and(111)-oriented lanthanum nickel oxide bottom electrodes with excellent conductive have been prepared on the same orientation lanthanum aluminate single crystals substrates by Sol-gel method;Then,the high quality zirconium-barium zirconate film materials have been prepared with the same orientation as the bottom electrode.The degree of orientation is 97.06%,96.82%and 97.08%respectively.It is found that the orientation growth of the film can be achieved by controling the thermal decomposition temperature of lead zirconate-barium film.(100)-oriented growth requires the lowest thermal decomposition temperature,approaching 400?.The thermal decomposition temperature of the(111)-orientated film is the highest,reaching to 500?.And it is easy to obtain(110)-orientated film chosing the thermal decomposition temperature in between.The orientation of films is closely related to interfacial energy.(2)The dielectric properties of different components and different orientations of lead zirconate-barium thin films have been studied.It is found that the Curie temperature,the phase transition electric field and the electrocaloric performance are related to the composition and orientation of the film.The results show that the Curie temperature of the(001),(011)and(111)-oriented Pb0.95Ba0.05ZrO3 film is 210 ?,184? and 192? respectively.The Tc of(001),(011)and(111)-oriented Pb0.8Ba0.2ZrO3 is 92?,94? and 78? respectively.The dielectric constant change rate of(110)-oriented Pb0.8Ba0.2ZrO3 thin film under bias electric field is the largest,and its value is 73.7%.The phase transition of Pb0.95Ba0.05ZrO3 film growing along(001),(011)and(111)is 133kV/cm,129kV/cm and 121 kV/cm respectively.The corresponding phase transition electric fields of Pb0.8Ba0.2ZrO3 films is 33.6kV/cm,24.0kV/cm and 32.0kV/cm respectively.(3)The electrocaloric performance of lead zirconate-barium films with different compositions and orientations were studied.It is found that the performance of the films growing along(111)orientation is the best.The maximum adiabatic temperature change ?T of Pb0.95Ba0.05ZrO3 with(100),(110)and(111)-oriented is 13.51K(253K),20.47K(257K)and 45.96K(246K)under 725kv/cm electric field in the 200-300K temperature range.The maximum adiabatic temperature change ?T of the Pb0.8Ba0.2ZrO3 film in the direction of(100),(110)and(111)is 27.78K(253K),28.5K(250K)and 31.8K(249K)in order under 670kV/cm electric field in the same temperature condition.