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 fo...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.展开更多
The modification of the structure lanthanum orthoferrites(LaFeO_(3))to obtain ceramic materials with enhanced structural,optical,and electrical properties constitutes an active area of research.The preparation of La_(...The modification of the structure lanthanum orthoferrites(LaFeO_(3))to obtain ceramic materials with enhanced structural,optical,and electrical properties constitutes an active area of research.The preparation of La_(0.8)Pb_(0.2)(Fe,Ti)_(0.5)O_(3)(LPFTO)ceramic nanoparticles by following a cation substitution approach from LaFeO_(3)using sol–gel and sintering methods is described.The electrical and dielectric properties of the obtained material are investigated.The contribution of grain and grain boundary in the conduction mechanism is demonstrated by complex impedance analysis.The LPFTO ceramic nanoparticles exhibit a giant dielectric constant of the order of 108.The conductivity analysis suggests the occurrence of thermally activated semiconductor behavior.Moreover,the ferromagnetic–paramagnetic semiconductor transition temperature is observed at 385 K.The ac conductivity behavior satisfies the nonoverlapping small-polaron tunneling(NSPT)model.展开更多
文摘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.
基金support from the University of Indonesia under Grants No.NKB-0024/UN2.R3.1/HKP.05.00/2019.
文摘The modification of the structure lanthanum orthoferrites(LaFeO_(3))to obtain ceramic materials with enhanced structural,optical,and electrical properties constitutes an active area of research.The preparation of La_(0.8)Pb_(0.2)(Fe,Ti)_(0.5)O_(3)(LPFTO)ceramic nanoparticles by following a cation substitution approach from LaFeO_(3)using sol–gel and sintering methods is described.The electrical and dielectric properties of the obtained material are investigated.The contribution of grain and grain boundary in the conduction mechanism is demonstrated by complex impedance analysis.The LPFTO ceramic nanoparticles exhibit a giant dielectric constant of the order of 108.The conductivity analysis suggests the occurrence of thermally activated semiconductor behavior.Moreover,the ferromagnetic–paramagnetic semiconductor transition temperature is observed at 385 K.The ac conductivity behavior satisfies the nonoverlapping small-polaron tunneling(NSPT)model.
