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Impedance Analysis of K2Pb2X2W2Ti4Nb4O30 (X = Nd, Y) Tungsten Bronze Ceramics
R. Padhee,Piyush R. Das,B. N. Parida,R. N. P. Choudhary 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.7
This paper highlights the electrical properties of two new complex tungsten bonze ceramics(K2Pb2Nd2W2Ti4Nb4O30 and K2Pb2Y2W2Ti4Nb4O30) that were prepared by using the high -temperature mixed - oxide method. The variations of impedance parameters with temperature (27− 500 C) and frequency (1 − 5 MHz) showed the grain and the grain - boundary effects in thesamples. The variations of the dielectric parameters with frequency were also studied. The variationof the ac conductivity with temperature clearly showed that the materials exhibited thermally- activated transport properties of an Arrhenius type.
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Dielectric and electrical properties of a tungsten bronze tantalate ceramic
R. Padhee,Piyush R. Das,B. N. Parida,S. Behera,R. N. P. Choudhary 한국물리학회 2013 Current Applied Physics Vol.13 No.6
Using high temperature solid state reaction the polycrystalline sample of K2Pb2Dy2W2Ti4Ta4O30 was prepared. Single-phase compound formation was confirmed by preliminary X-ray structural analysis. The surface morphology recorded by scanning electron microscope at room temperature exhibits a dense uniform grain distribution on the surface of the sample. Ferroelectricity in the material is confirmed by the variation of polarization with temperature. The temperature and frequency dependence of electrical parameters (impedance, modulus, conductivity, etc.) of the material exhibits a strong correlation with its microstructure (i.e., bulk, grain boundary, etc.) and electrical properties. A typical Arrhenius behavior was observed in the temperature dependence of dc conductivity. The nature of frequency dependence of ac conductivity obeys Jonscher’s universal power law. The variation of current with temperature shows that the material has high pyroelectric coefficient and figure of merit, thus making it useful for pyroelectric sensors with working temperature upto 500 ℃.
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Ferroelectric, pyroelectric and electrical properties of new tungstenebronze tantalate
B.N. Parida,Piyush R. Das,R. Padhee,R.N.P. Choudhary 한국물리학회 2013 Current Applied Physics Vol.13 No.9
The polycrystalline sample of Li2Pb2Y2W2Ti4Ta4O30 was prepared by a high-temperature solid-state reaction technique. Room temperature X-ray structural analysis confirms the formation of a single-phase compound. The surface morphology of the sintered pellet sample recorded by SEM (scanning electron microscope) exhibits a uniform grain distribution with few voids. Detailed studies of dielectric constant,tangent loss and remanent and spontaneous polarization with temperature and frequency exhibit the existence of ferroelectricity in the material. The temperature and frequency dependence of impedance parameters (impedance, modulus, etc) of the material exhibits a strong correlation between these electrical parameters with its micro-structure (i.e., bulk, grain boundary, etc). The nature of variation of pyroelectric-coefficient and current with temperature suggests that material has good pyroelectric properties useful for fabrication of pyroelectric detector.
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Pati Dinesh Kumar,Das Piyush R.,Parida B. N.,Behera B.,Padhee R. 한국세라믹학회 2022 한국세라믹학회지 Vol.59 No.6
The research article reports the various functional properties of barium strontium titanate [(Ba 0.8Sr0.2)TiO 3]-modifi ed lead iron niobate [Pb(Fe 0.5Nb0.5)O3] ceramic oxide synthesized by the solid-state method. Rietveld and POWD studies proved that the composition crystallizes in tetragonal structure as the primary phase. Ti–O perovskite vibrations were studied by Fourier transform infrared (FTIR) analysis. The TiO 6 octahedral stretching, O–Ti–O vibrations and Nb–O–Fe stretching vibrations of PFN were studied by Raman spectroscopy. The broadening of Raman modes was analysed in the framework of Heisenberg’s uncertainty principle using phonon confi nement model. Field emission gun-scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDS) studies revealed the dense grain distributions, grain growth and purity. UV–visible analysis was done to study the narrow band gap and Urbach energy. The eff ect of structural distortions and electronegativity on band gap were analysed. The photocatalytic response was studied by estimating the band edge levels +/H 2 1 Introduction The search for room temperature multiferroic materials is one of the most vital aspects in the fi eld of material science because of its enormous applications in multi- functional devices. Lead iron niobate (PFN) belongs to the family of multiferroic electroceramics with perovskite structure having formulation ABO 3 or A(B′B″)O3, where B′ and B″ are, respectively, low and high valence cati- ons like Fe 3+ and Nb 5+. The 3d 5 electrons of Fe 3+ boosts magnetic orders and the 6s 2 electrons of Pb 2+ generate the ferroelectric orderings [ 1 ]. PFN ceramics are widely used in device applications [ 2 –4 ] such as multilayer capaci- tors, actuators, transducers and so on due to their large values of relative permittivity, diff use phase transition Vol.:(0123456789) 1 3 using Mulliken’s model. The evaluated conduction band minimum level is suffi ciently negative with respect to the H (0 eV) level, which strongly signifi es the possible occurrence of the photocatalytic hydrogen emission reaction. A detailed electrical analysis was done to study the dielectric properties, relaxation, negative temperature coeffi cient of resistance (NTCR)-type response and DC conductivity. AC conductivity studies revealed the presence of overlapping large polaron tun- nelling (OLPT) model. The eff ect of oxygen vacancies on relaxation and its correlation with activation energy were discussed. Multiferroic nature was confi rmed from room temperature studies of P–E and M–H hysteresis loops. Fe 3+ Fe 3+ (F centre) exchange and Fe 3+ Fe 2+ double exchange mechanisms were discussed. A magnetic improvement was noticed on reduction of temperature to 50 K. The simultaneous existence of weak ferroelectricity and ferromagnetism is one of the interesting outcomes of the present study, which may provide a new multiferroic material for advanced electro-optical applications.
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