Phase equilibria and dielectric properties of Bi3+(5/2)xMg2−xNb3–(3/2)xO14−x cubic pyrochlores

Tan, P. Y.; Tan, Kar Ban; Khaw, Chwin Chieh; Zainal, Zulkarnain; Chen, Soo Kien; Chon, Mun Ping

doi:10.1016/j.ceramint.2013.08.087

Cited by 36 publications

(25 citation statements)

References 31 publications

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“…Higher activation energy is required to facilitate the charge‐transfer transportation, that is, E a is found to increase from 0.40 to 1.40 eV in the sequence BCT > BCZT > BZT. The high E a values are comparable to those reported in BZN or bismuth magnesium niobate (BMN) pyrochlores with a hopping type of electronic transport mechanism …”

supporting

confidence: 76%

“…In attempts to search for new materials with a specific set of desired properties, chemical substitutions of Zn with several divalent metals including Co, Ni, Fe, Mn, Mg have been explored . It is believed that an understanding of the definite correlation between crystallo‐chemical and physical properties in these pyrochlores is of great relevance to the development of new phases.…”

Section: Introductionmentioning

confidence: 99%

“…Owing to the great flexibility of composition variables and structures, chemical substitution is performed primarily by varying ionic species at the A or B site of the pyrochlores; however, the overall charge neutrality should be maintained. These doped pyrochlores demonstrate a broad spectrum of interesting properties ranging from semiconducting, insulating to useful magnetic behavior . In our earlier works, phase relations for the system Bi 2 O 3 –CuO–Ta 2 O 5 have been determined over the temperature range 700–950°C in air.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and Electrical Properties of Zn‐substituted Bismuth Copper Tantalate Pyrochlores

Chon

Tan

Zainal

et al. 2016

Int J Applied Ceramic Tech

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A complete substitutional solid solution, Bi3.08Cu1.84−xZnxTa3.08O14.16: 0 ≤ x ≤ 1.84, was prepared by solid‐state reaction at temperature 950°C over 48 h. These thermally stable pyrochlores exhibited a remarkable transition from semiconducting to highly insulating behavior as their electrical conductivities varied by many orders of magnitude depending on the Zn concentration. The recorded activation energies increased from 0.40 to 1.40 eV, while the dielectric constants, ε′, and losses, tan δ, were in the range 50–70 and of order 10−3–10−2 at 1 MHz and ambient temperature, ~25°C, respectively.

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supporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis and Electrical Properties of Zn‐substituted Bismuth Copper Tantalate Pyrochlores

Chon

Tan

Zainal

et al. 2016

Int J Applied Ceramic Tech

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“…In most cases, doping leads to the permittivity decrease and to the tangent loss increase. However, electrical properties of several systems were investigated in the high temperature range (up to 700 °C) only in order to determine their conductivity mechanism [3,9,[19][20]27]. In our previous work [28][29] we have determined that the dielectric constant of the Bi 1.6 Cu x Mg 0.8-x Nb 1.6 O 7-δ pyrochlores behave unusually passing through a maximum (250-350 °C) with temperature increasing.…”

Section: Introductionmentioning

confidence: 99%

“…The most attention has been paid to the Zn-, Mg-containing bismuth niobates, which possess high dielectric constant (170-180) and low dielectric loss (~10 -4 ) at 1 MHz (at room temperature) [1][2][3][4][5][6][7][8][9]. To search for the same properties Fe- [10], Mn- [11][12], Co- [13], Ni- [12,[14][15], Cu- [12] and the mixed Zn-M (M -Sr [16], Ca [16][17], Mn [16,18], Ti [19][20][21][22], Sn [19,22], Zr [19,[21][22], Ce [19,22], Gd [21], Ta [23], La [24]), Mg-M (M -Sr [25], Nd [26], Cu [27]) bismuth niobates and other ones were synthesized.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, structure and electrical properties of Mg-, Ni-codoped bismuth niobates

Королева¹,

Пийр²,

Истомина³

2017

Chim.Tech.Acta

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Synthesis, structure and electrical properties of Mg-, Ni-codoped bismuth niobatesMg-, Ni-codoped bismuth niobates Bi 1.6 Mg 0.8-x Ni x Nb 1.6 O 7-δ (x = 0; 0.2; 0.4; 0.6; 0.8) were obtained by conventional solid-state reaction method. It was shown that the Mg atoms are distributed at the Nb sites while the Ni atoms are distributed over the Bi-and the Nb-sites, according to the results of comparison of pycnometric and X-ray density of the Bi 1.6 Mg 0.4 Ni 0.4 Nb 1.6 O 7-δ pyrochlore. In this case, about 15-20% of the vacancies are formed at the Bi sites. The obtained compounds are stable up to their melting point based on the DSC analysis data. Real dielectric permittivity ε' of the Bi 1.6 Mg 0.8-x Ni x Nb 1.6 O 7-δ samples decreases from 80 to 65 with the temperature decrease from 25 to 700 °C and practically does not depend on frequency in the range of 1-1000 kHz. Oxides Bi 1.6 Mg 0.8-x Ni x Nb 1.6 O 7-δ behave like insulators up to 280 °C, their conductivity increases with temperature (E a,dc ≈ 1.3 eV, dc) and with the Ni content at a given temperature.

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Doping mechanisms and impedance study of Ba-substituted bismuth magnesium niobate pyrochlores

et al. 2019

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Here we investigated the doping mechanisms and electrical properties of Ba-substituted Bi3.36Mg1.92-xBaxNb2.72O14.36 (BMBN) pyrochlores. Phase-pure BMBN pyrochlores prepared by solid-state reaction were found to crystallise in a cubic structure (Fd3m; No. 227) with their lattice parameters in the range 10.5968( 16) -10.5879(3) Å. The Scanning Electron Microscopy (SEM) analysis revealed that BMBN pyrochlores were composed of irregular shaped grains and their estimated crystallite sizes by both Williamson-Hall and Scherrer methods were in the range 50-75 nm and 60-70 nm, respectively. Neither thermal event nor significant weight loss was observed over the studied temperature range ~30-1000 °C, confirming that BMBN pyrochlores were thermally stable with negligible Bi2O3 loss. The high activation energies in the range 1.18-1.30 eV, as determined by the Arrhenius conductivity plots, showed BMBN pyrochlores to be highly insulating. The dielectric constants, ε' and dielectric losses, tan δ were found in the range 147-183 and 7.9 × 10−2 -9.6 × 10−2 at ~30 °C and 1 MHz. Negative temperature coefficient of capacitances, TCC, in the range (−478) -(−688) ppm/°C were recorded over ~30-300 °C at 1 MHz.

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Phase equilibria and dielectric properties of Bi3+(5/2)xMg2−xNb3–(3/2)xO14−x cubic pyrochlores

Cited by 36 publications

References 31 publications

Synthesis and Electrical Properties of Zn‐substituted Bismuth Copper Tantalate Pyrochlores

Synthesis and Electrical Properties of Zn‐substituted Bismuth Copper Tantalate Pyrochlores

Synthesis, structure and electrical properties of Mg-, Ni-codoped bismuth niobates

Doping mechanisms and impedance study of Ba-substituted bismuth magnesium niobate pyrochlores

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