Dielectric relaxation and conduction mechanism of NaMgPO_(4)compound  

作　　者：L.Miladi A.Oueslati M.Ben Gzaiel M.Gargouri 

机构地区：[1]Laboratory of Spectroscopic Characterization and Optical Materials,Faculty of Sciences University of Sfax B.P.1171,3000 Sfax,Tunisia

出　　处：《Journal of Advanced Dielectrics》2022年第3期1-10,共10页先进电介质学报（英文）

摘　　要：The polycrystalline NaMgPO_(4)ceramic,synthesized via a high-temperature solid-state reaction route,has been characterized by using different experimental procedures.The X-ray powder diffraction confirmed the phase formation of the synthesized com-pound in the orthorhombic phase.It assumed an olivine-type structure made up of corners linked between tetrahedral PO_(4)and octahedral NaO_(6)and MgO_(6)groups.Infrared and Raman spectroscopies confirmed the presence of PO_(4)^(3−)groups.Local structure and chemical bonding between MgO_(6)octahedral and PO_(4)3−tetrahedral groups investigated by diffusion Raman is the feature in the phase transition at T=693 K.The temperature dependences of the realε′and imaginaryε″parts of dielectric permittivity show a distribution of relaxation times.From Nyquist plots,the presence of grain and grain boundary effect in the material is noticed.The impedance spectroscopy measurement showed a non-Debye-type process.From the impedance data,the determined grain resistance reduces with increment of temperature showing negative temperature coefficient of resistance(NTCR)-type nature of the material which also confirmed from conductivity analysis.The temperature dependence ofσdc reveals an Arrhenius-type behavior with two activation energies,0.98 eV in region I and 0.67 eV in region II.Studied sample’s conduction is assured by Na+ions’hopping in tunnels and its mechanism was discussed.

关 键 词：Sodium-magnesium orthophosphate RAMAN phase transition NSPT model sodium-ion conductivity 

分 类 号：TQ174[化学工程—陶瓷工业]