| Multiferroic materials,which exhibit simultaneous ferroelectric and magnetic orders,have attracted a lot of interest in recent years due to their potential applications for developing novel storage media and spintronic devices.In addition,the magnetoelectric?ME?coupling between the two orderings provides an additional degree of freedom in device design.Although a number of materials exhibiting both ferroelectricity and magnetism were studied,unfortunately,single-phase multiferroic materials with ME effect at room temperature are very rare because not all the multiferroic materials possess ME effect.And it is the ME coupling that can in principle permit data to be written electrically and read magnetically,then provide an additional degree of freedom in the design of novel multifunctional devices and realize the multi-state data storage.Thus,the search for multiferroic materials having a large ME effect at or above room temperature is ongoing.In the field of ferroelectric photovoltaic,the main research direction of most scholars is the photovoltaic effect of ferroelectric thin films.In this paper,the magnetic and photovoltaic properties of a kind of layered perovskite material Bi4NdTi3Fe0.7Ni0.3O15 and a kind of simple perovskite structrue material Pb(Fe1/2Nb1/2)O3 magnetic are researched.For Pb(Fe1/2Nb1/2)O3 samples,we change the content of Fe and prepare the Pb(Fe1/3Nb2/3)O3 and Pb(Fe2/3Nb1/3)O3 samples.Using Co and Ni respectively to replace the content of Fe in Pb(Fe1/2Nb1/2)O3.Then we use W and Ta respectively to replace the content of Nb in Pb(Fe1/2Nb1/2)O3,research the ferromagnetic properties and photovoltaic properties of the perovskite ceramics with different orientations and different compositions.Bi4NdTi3Fe0.7Co0.3O15 polycrystalline samples were synthesized following a multicalcination procedure.X-ray analysis indicated a four-layer Aurivillius phase with an orthorhombic symmetry was obtained.The multiferroic properties of the sample at room temperature were demonstrated by the ferroelectric?2Pr=7.23?C/cm2,2Ec=35.72 kV/cm at applied electric field 70 kV/cm?and magnetic?2Mr=232 memu/g,2Hc=769 Oe at applied magnetic field 1.07 T?hysteresis loops.Obvious magnetodielectric effect which is dependent on frequency was observed at room temperature.It is found that the magnetodielectric effect exhibits a linear relation with M4 rather than M2 which may be due to the complicated spin-pair correlation interactions among next nearest neighbors.The present study suggests the possibility of magnetic ions doped Bi4NdTi3FeO15 as a potential candidate for novel multifunctional device application.In this paper,we prepared layered perovskite material Bi4NdTi3Fe0.7Ni0.3O15 with different orientation.The experimental results show that the c-axis orientation samples and non-c-axis orientation samples were prepared well.There is obvious difference between the c-axis orientation samples and the non-c-axis orientation samples.Comparing the photovoltaic properties of the samples with different orientations,it is found that the light absorption of the samples with orientation is better than that of the random oriented ceramic samples,and the absorption ability of the c-axis orientation samples are the best.The photovoltaic properties of c-axis orientation samples are Voc=0.1V,the short-circuit current density Jsc=11.2?A/cm2.The photovoltaic properties of non-c-axis orientation samples are Voc=0.4V,short-circuit current density Jsc=1.67?A/cm2.The results show that the energy conversion efficiency of the c-axis orientation sample is higher than non-c-axis orientation sample of the solar energy.Pb(AxB1-x)O3 series of simple perovskite samples were prepared by solid state method.The hysteresis loop at room temperature showed that Pb(Fe1/2Nb1/2)O3 remanent magnetization 2Mr and coercivity 2Hc were very small,indicating that the sample were antiferromagnet at room temperature.Pb(Fe1/3Nb2/3)O3,Pb(Fe2/3Nb1/3)O3 samples had room temperature ferromagnetism,which might be caused by the lattice distortion due to the change of Fe content.The 2Mr and the 2Hc of Pb(Fe2/3Nb1/3)O3 were larger than that of Pb(Fe1/3Nb2/3)O3,which might be related to the appearance of oxygen vacancies.The weak ferromagnetism of Pb(Ni1/2Nb1/2)O3 and Pb(Co1/2Nb1/2)O3 at room temperature might be due to lattice distortion.The remanent magnetization of Pb(Co1/2Nb1/2)O3 was about 3.8 times than that of Pb(Ni1/2Nb1/2)O3,which might be due to the different magnetic moments of Co and Ni.The weak ferromagnetism of Pb(Fe1/2W1/2)O3 and Pb(Fe1/2Ta1/2)O3 might be related to the lattice distortion and the incomplete reaction of Fe2O3 in the sample.According to the UV visible spectrophotometer?UV-vis?test of different series of powder sample,the samples with different Fe content had different optical band gap,which might be associated with the color of powder samples and sample components.The band gap of Pb(Fe1/2Nb1/2)O3,Pb(Ni1/2Nb1/2)O3,and Pb(Co1/2Nb1/2)O3 might be related to the color of the sample powder,the electronegativity of different doping elements and the lattice distortion.Pb(Fe1/2Nb1/2)O3,Pb(Fe1/2Ta1/2)O3,Pb(Fe1/2W1/2)O3 band gap might be related to the lattice structure and the number of oxygen vacancies.The volt ampere characteristic curve test to Pb(Fe1/2Nb1/2)O3,Pb(Ni1/2Nb1/2)O3,Pb(Co1/2Nb1/2)O3 series of samples showed that Pb(Fe1/2Nb1/2)O3 samples of the open circuit voltage Voc=0.11 V in a standard solar light irradiation,the short-circuit current density of Jsc=5.83?A/cm2.Pb(Ni1/2Nb1/2)O3,Pb(Fe1/2Nb1/2)O3,Pb(Co1/2Nb1/2)O3 samples in the light of open circuit voltage and short circuit currently increased,while the band gap of the samples decreased,indicating the size of the optical band gap was likely to affect the simple perovskite material Pb(AxB1-x)O3 photovoltaic performance.In addition to the band gap,the ferroelectric properties of the sample,the electrode material and other factors might have an impact on the photocurrent and voltage,which needed further experimental verification. |
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