Giant dielectrics from modified boundary layers in n-BaTiO3 ceramics involving selective melting reactions of silver/glass composites at the grain boundaries

Jayanthi, S.; Kutty, T.R.N.

doi:10.1007/s10854-005-0544-0

Cited by 8 publications

(8 citation statements)

References 15 publications

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“…These oxygens help in pinning the interface traps and [37] causes to decrease of barrier height. The permittivity value of order 10 5 is found in Bi and Cu doped BT [51]. The interfacial polarization is found in glass added BT.…”

Section: Brief Introduction To Ferroelectricsmentioning

confidence: 83%

Dielectric behavior of perovskite glass ceramics

Yadav

Gautam

2014

J Mater Sci: Mater Electron

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The recent developments of energy storage devices are concerned with larger energy storage ability, low loss and good temperature stability. It has a great technological importance in engineering science. The dielectric materials like ceramics and glass ceramics have great interest in electronic ceramic industry due to above concern. The ceramic dielectrics are used as a capacitive element in electronic circuits. The perovskite glass ceramics have very high dielectric constant and low dielectric loss. The high dielectric constant in glass ceramics is attributed to space charge polarization. In order to produce glass ceramics of high dielectric constant, barium titanate glass ceramics is the first discovered ferroelectric perovskite. In this review article, we are summarizing the dielectric behavior of perovskite glass ceramics such as

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Section: Brief Introduction To Ferroelectricsmentioning

confidence: 83%

Dielectric behavior of perovskite glass ceramics

Yadav

Gautam

2014

J Mater Sci: Mater Electron

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“…[3,4] The achievement of high permittivity values in this material was ascribed to interfacial polarization phenomena. Recently, giant permittivity values were reported in hexagonal barium titanate (h-BaTiO 3 ) single crystals.…”

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confidence: 95%

“…[2] Indeed, colossal permittivity values up to 200000 at room temperature were achieved in BaTiO 3 micronic grain size materials in which preparation included incorporation of metallic layers in a complex multi step process. [3,4] The achievement of high permittivity values in this material was ascribed to interfacial polarization phenomena. Recently, giant permittivity values were reported in hexagonal barium titanate (h-BaTiO 3 ) single crystals.…”

mentioning

confidence: 99%

Colossal Permittivity in Ultrafine Grain Size BaTiO_3–_x and Ba_0.95La_0.05TiO_3–_x Materials

et al. 2008

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Development of microelectronic devices is driven by a large demand for faster and smaller systems. In the near future, colossal permittivity in nanomaterials will play a key role in the advances of electronic devices. We report on "colossal" permittivity values achieved in dense ceramics displaying ultrafine grain size ranging from 70 nm to 300 nm. Relative permittivity values of ∼ 10 6 at 1 kHz (0.1 < tand < 0.7) were obtained for Ba 0.95 La 0.05 TiO 3-x ceramics. The colossal effective permittivity is related to an interfacial polarization and is achieved in nanomaterials by the activation of a high number of carriers and their trapping at the interfaces. Polarization carriers involving Ti 3+ polaron is proposed to be at the origin of the observed colossal permittivity. These results may have an important technological impact since these ceramics display ultrafine grain size opening a new route to the fabrication of very thin dielectric films.High permittivity values such as e r ∼ 10 000 were reported in polycrystalline BaTiO 3 , a well known ferroelectric material.[1] Decreasing the grain size below 0.7 lm of the BaTiO 3 ferroelectric ceramic was shown to yield unrelieved stresses resulting in smaller permittivity values.[2] Indeed, colossal permittivity values up to 200000 at room temperature were achieved in BaTiO 3 micronic grain size materials in which preparation included incorporation of metallic layers in a complex multi step process. [3,4] The achievement of high permittivity values in this material was ascribed to interfacial polarization phenomena. Recently, giant permittivity values were reported in hexagonal barium titanate (h-BaTiO 3 ) single crystals. [5,6] High permittivity values around 10 5 measured on the oxygen deficient materials were explained by a MaxwellWagner interfacial polarization effect due to the presence of interfacial boundaries consisting of crystal defects such as screw dislocations. Nevertheless, the internal interfaces as well as the nature of the polarization carriers in the h-BaTiO 3 single crystals were not fully identified. Within the last few years, a large class of dielectric materials displaying colossal permittivity was proposed [7][8][9] with colossal dielectric con- [10] The large permittivity values of this material being attributed to the well established IBLC effect.[11] According to the brick layer model, the effective permittivity e eff of the microstructure can be expressed as e eff = e gb t g /t gb where e gb is the grain boundary permittivity and t g and t gb are the thickness of the grain and grain boundary, respectively.[12]Thus the IBLC mechanism is usually associated with enhanced grain size. In this context, a decrease of the average grain size should not favor the IBLC effect and colossal permittivity in ultrafine ceramics, to our knowledge, has not been reported. In this communication, we discuss the "colossal" permittivity values achieved in BaTiO 3-x and Ba 0.95 La 0.05 TiO 3-x materials exhibiting very small grain size (< 300 nm). Dense dielectrics...

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“…Beyond 100 kHz, ε r shows negligible frequency dependence while tan( δ ) decreases further to 0.2% at 1000 kHz. Such dielectric relaxation over the 1–1000 kHz range is a well‐known phenomenon in cubic perovskite‐type materials such as CaCu 3 Ti 4 O 12 and in BaTiO 3 ‐based ferroelectric boundary layer capacitors (BLC) 62–64 . The BLC phenomenon is customarily analyzed by the Maxwell–Wagner model 27 …”

Section: Resultsmentioning

confidence: 99%

“…Such dielectric relaxation over the 1-1000 kHz range is a well-known phenomenon in cubic perovskite-type materials such as CaCu 3 Ti 4 O 12 and in BaTiO 3 -based ferroelectric boundary layer capacitors (BLC). [62][63][64] The BLC phenomenon is customarily analyzed by the Maxwell-Wagner model. 27 In BLCs, the GBs act as capacitors of low capacitance that are in series with the capacitance of the grains, resulting in a very high effective capacitance for a given polycrystalline ferroelectric ceramic.…”

Section: Dielectric Properties Of Flash Sintered Knnmentioning

confidence: 99%

Flash sintering and dielectric properties of K_0.5Na_0.5NbO₃

2021

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K 0.5 Na 0.5 NbO 3 (KNN) of 4-μm average particle size was flash sintered in parallel plate capacitor configuration (PPCC) under 100 V/mm (0.8 mA/mm 2 cut-off) with 10 • C/min heating rate in air. Precipitous densification occurred from T f = 662-670 • C (T f -furnace temperature) in 60 s with 55 mW/mm 3 peak power absorption at T f = 667 • C, resulting in 98% dense ceramic of < 5-μm grains size. No grain growth was observed. A cubic grain morphology was inherited from the starting KNN powder. No sign of liquid phase formation on grain boundaries (GBs) was detected. A 147 • C rise above T f = 667 • C due to Joule heating is predicted. At 25 • C and 1 kHz, relative permittivity (ε r ) and dielectric loss (tan(δ)) are 4096 and 2.9%, respectively. From 0.1 to 100 kHz, ε r and tan(δ) undergo relaxation, reaching ε r = 577 and tan(δ) = 0.2% at 1000 kHz.Variation of ε r with temperature revealed Amm2 → P4mm and P4mm → Pm3m transitions at ∼204 • C and 409 • C, respectively. As per Curie-Weiss analysis, Curie temperature and Curie-Weiss constant are θ = 375 • C and C = 3.1 × 10 −5• C for the P4mm → Pm3m transition, respectively. The transition is first order as T tr > θ with a diffusiveness exponent γ = 1.04, indicating normal ferroelectric behavior. The low-frequency dielectric relaxation is attributed to the space charge in the vicinity of GBs, which is a remnant of flash sintering. Joule heating cannot alone account for the densification in 60 s, which we substantiate within the framework of phase equilibrium and diffusion kinetics. We conjecture that oxygen vacancies start ionizing at T f = 662 • C, couple with the applied electric field via the Lorentz force, and increase their electrochemical potential, causing ultrafast densification. The effects of sample shape, size, and PPCC contributing to high sintered density are also discussed.

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Giant dielectrics from modified boundary layers in n-BaTiO3 ceramics involving selective melting reactions of silver/glass composites at the grain boundaries

Cited by 8 publications

References 15 publications

Dielectric behavior of perovskite glass ceramics

Dielectric behavior of perovskite glass ceramics

Colossal Permittivity in Ultrafine Grain Size BaTiO_3–_x and Ba_0.95La_0.05TiO_3–_x Materials

Flash sintering and dielectric properties of K_0.5Na_0.5NbO₃

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Giant dielectrics from modified boundary layers in n-BaTiO3 ceramics involving selective melting reactions of silver/glass composites at the grain boundaries

Cited by 8 publications

References 15 publications

Dielectric behavior of perovskite glass ceramics

Dielectric behavior of perovskite glass ceramics

Colossal Permittivity in Ultrafine Grain Size BaTiO3–x and Ba0.95La0.05TiO3–x Materials

Flash sintering and dielectric properties of K0.5Na0.5NbO3

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Product

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Colossal Permittivity in Ultrafine Grain Size BaTiO_3–_x and Ba_0.95La_0.05TiO_3–_x Materials

Flash sintering and dielectric properties of K_0.5Na_0.5NbO₃