| Tetragonal Mn-doped Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-Pb Ti O3(Mn-PIMNT)r elaxor ferroelectric single crystal with high pyroelectric,ferroelectric and dielectric pr operties,high Curie temperature and thermal stability,is a powerful candidate material for preparing infrared detectors.Compared with relaxor ferroelectric single crystals,f erroelectric thin films have the advantages of higher integration,lower heat capacity,f aster response and lower relative cost.Therefore,the tetragonal Mn-PIMNT relaxor fe rroelectric single crystal thin film is proposed.The purpose of this paper is to prepare high Curie point relaxor ferroelectric films with high pyroelectric coefficient,excellen t value and wide temperature range by adjusting the film preparation and post-treatme nt process,the main research contents and results are as follows:Firstly,the solid-phase reaction method was used to prepare the tetragonal 1%Mn-0.29Pb(In1/2Nb1/2)O3-0.29Pb(Mg1/3Nb2/3)O3-0.42Pb Ti O3[Mn-PIMNT(0.29/0.29/0.42)]ceramics.The effects of sintering temperature on the phase structure,shrinkage rat e,strain behavior,pyroelectric and other electrical properties of ceramic samples were studied,and the optimal sintering temperature of the ceramic samples was determined.The research showed that the ceramic samples prepared at a sintering temperature of 1255?had good ferroelectric and pyroelectric properties,a high Curie temperature of271?,coercive field of 20 k V cm-1,a low dielectric loss of 0.006,and a piezoelectric coefficient of 139 p C N-1,a pyroelectric coefficient of 1.5×10-4 C m-2 K-1 at room tem perature,a figure of merit for detection of 0.76×10-5 Pa-1/2.The high Curie temperature and large coercive field will make the tetragonal Mn-PIMNT ceramics applicable to d evices with a wide operating temperature range and high power.At the same time,this study also laid a good foundation for the preparation of subsequent films.Tetragonal Mn-PIMNT(0.29/0.29/0.42)thin films were prepared on Pt/Ti/Si O2/S i substrates with La0.6Sr0.4Co O3(LSCO)buffer layer by the Pulsed Laser Deposition(P LD).The effects of oxygen pressure,substrate temperature and film thickness on the p hase structure,microstructure,pyroelectric and other properties of the films were deep ly studied.Under the optimized deposition conditions of oxygen pressure of 15 Pa and substrate temperature of 500?,the prepared Mn-PIMNT(0.29/0.29/0.42)films had a pure tetragonal perovskite structure,a flat and dense surface.On the basis,Mn-PIM NT(0.29/0.29/0.42)films with different thicknesses were prepared.With the increase of thickness from 200 nm to 500 nm,the dielectric constant of the films increased fro m 136.4 to 2939;the dielectric loss was reduced from 2.06 to 0.07,and the coercive fi eld was correspondingly reduced from 5.5 k V mm-1 to 4 k V mm-1.The film with a thickness of 500 nm prepared in this work had excellent dielectri c,ferroelectric and pyroelectric properties.Under the action of an in-situ DC electric f ield,a 180°domain inversion and butterfly-shaped piezoelectric response of the film w as observed,the leakage current density was 2.5×10-8 A cm-2,and the Curie temperatur e was 270°C,which was 90°C higher than that of the trigonal Mn-PIMNT(36/26/28)thin film(its Curie temperature was 185°C).The coercive field was 4 k V mm-1,remn ant polarization was 20?C cm-2.The pyroelectric coefficient at room temperature was2.23×10-4 C m-2 K-1,which was better than that of commercial PZT films(pyroelectri c coefficient was 1.55),the dielectric loss was 0.07,the figure of merit for detection wa s 2.35×10-5 Pa-1/2.These results show that the film has a good application prospect in p yroelectric detector devices,and broaden the working temperature range of the device s. |
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