Dipole relaxation process and giant dielectric permittivity in Eu3þdoped CdMoO_(4) single crystal  

作　　者：B.Sawicki E.Tomaszewicz T.Gron M.Berkowski M.Głowacki M.Oboz J.Kusz S.Pawlus 

机构地区：[1]A.Chełkowski Institute of Physics,University of Silesia in Katowice,40-007,Katowice,Poland [2]Faculty of Chemical Technology and Engineering,Department of Inorganic and Analytical Chemistry,West Pomeranian University of Technology in Szczecin,71-065,Szczecin,Poland [3]Institute of Physics,Polish Academy of Sciences,02-668,Warszawa,Poland

出　　处：《Journal of Materiomics》2021年第4期845-857,共13页无机材料学学报（英文）

基　　金：the Institute of Physics(University of Silesia)for providing practical and technical assistance.

摘　　要：Single crystal of Eu3þ-doped cadmium molybdate(Cd0.9268M0.0244Eu0.0488MoO_(4),where M denotes cationic vacancies)has been successfully grown by the Czochralski method in air and under 1 MPa.X-ray diffraction analysis indicates that as-grown single crystal exhibits tetragonal scheelite-type structure(a=b=5.16188(14)Å;c=11.2080(5)Å;space group I41/a).Eu^(3+) þions do not show long-range order and they are randomly distributed in CdMoO_(4) framework substituting Cd^(2+ )þones.UVevis diffuse reflectance measurements revealed very close optical band gap(Eg)values,i.e.-1.74 eV along[100]and[001]crystallographic directions that are twice smaller than Eg of microcrystalline pure CdMoO_(4) as well as powder Eu3þ-doped single crystal.Magnetic and electrical studies of Eu3þ-doped cadmium molybdate single crystal showed a paramagnetic and n-type semiconducting behaviour with the metal-insulator transition above 350 K along both crystallographic directions.Dielectric results analysis using the Cole-Cole fit function revealed that the dipole relaxation process has different time scale depending on the crystallographic direction and exhibits Arrhenius temperature dependence for both studied directions.This fact is accompanied by the colossal dielectric permittivity withεr>8,103.The above results are considered in the framework of narrow europium multiplets of energy comparable to thermal energy.

关 键 词：SCHEELITE Single crystal Solid solution Paramagnetic behaviour Relaxation process Giant dielectric permittivity 

分 类 号：O61[理学—无机化学]