Microwave Dielectric Properties of Bi-Added Ba4Nd9+1/3Ti18O54 Solid Solutions

Okawa, Takashi; Imaeda, Masaki; Ohsato, Hitoshi

doi:10.1143/jjap.39.5645

Cited by 29 publications

(15 citation statements)

References 9 publications

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“…Though it was not the optimum sintering temperature, the grain size grew obviously versus substitution content with some abnormal grains for x C 0.15. All compositions had column grains which were always observed in Ba 6-3x Nd 8?2x Ti 18 O 54 ceramics [5,6,9]. Here element ratio data of the energy-dispersive X-ray analysis (EDS) of spots A and B were detected and are listed in Table 1 Fig.…”

Section: Resultsmentioning

confidence: 87%

“…Therefore, research on both sites' simultaneous replacement was an effective way to overcome the shortcomings of those separate substitution. Also due to the fact that many other studies has reported the positive effects of single Bi substituting (0.05 B x) at Nd site on the system, goals of the investigation were to study the impact of substitution in Al-replaced Ba 3.75 Nd 9.5 Ti 18 0 54 (0.05 B x B 0.2) ceramic on microwave dielectric properties and to find a proper x value range that would conduct good dielectric properties [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…In the present work, Ba 3.75 (Nd 1-x Bi x ) 9 The apparent densities of sintered samples were measured by the Archimedes method. The phase of the sintered samples was identified by X-ray diffraction (XRD) using Cu Ka radiation (Philips x'pert Pro MPD, PANalytical, the Netherlands).…”

Section: Introductionmentioning

confidence: 99%

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Microwave dielectric properties of bismuth-substituted Ba3.75Nd9.5Ti17Al4/3O54 ceramics

et al. 2015

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The impact of bismuth substitution at neodymium (Nd) site in aluminum-replaced Ba 3.75 Nd 9.5 Ti 18 O 54 ceramics on dielectric constant (e r ), quality factor (Qf), and temperature coefficient of resonant frequency (s f ) has been determined (0.05 B x B 0.2). With appropriate quality factor values (Qf [ 5000 GHz), the dielectric constant increased from 74.42 to a maximum of 90.8 and the temperature coefficient of resonant frequency was tailored from approximately ?20 ppm/°C to the vicinity of 0 ppm/°C . The X-ray diffraction patterns showed a single phase for all compositions, while the scanning electron microscopy and energy-dispersive spectrometer data confirmed XRD results. Factors, such as bulk density, average polarizability, microstructure, and tolerance factor which were caused by the substitution, were taken into consideration to discuss the microwave dielectric properties' variation. Within substituting limit, a series of controllable microwave dielectric properties (e r = 75.8, Qf = 8994 GHz, s f = 7.2 ppm/°C; e r = 79.1, Qf = 7282 GHz, s f = 2.3 ppm/°C; e r = 87.07, Qf = 5548 GHz, s f = -8.6 ppm/°C) could be obtained when sintered at 1350°C for 2 h for x = 0.05, 0.1, and 0.15, respectively.

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Section: Resultsmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

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Microwave dielectric properties of bismuth-substituted Ba3.75Nd9.5Ti17Al4/3O54 ceramics

et al. 2015

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“…Thus, thermally stable composites could be achieved by using HDPE and PS together. Herein, Bi substituted BNT in BaO-Nd 2 O 3 -TiO 2 system was chosen as the ceramic filler because it has a high dielectric constant of 88, a low dielectric loss of  0.0005, and a f  of 0±5 ppm/℃ [12,13]; while HDPE was selected as the basic matrix. Then, a coating route with the incorporation of polystyrene (PS) was designed to improve the thermal behaviors of the composites.…”

Section: Introductionmentioning

confidence: 99%

Thermally stable polymer–ceramic composites for microwave antenna applications

Zhang

Yue

et al. 2016

J Adv Ceram

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Polymer-ceramic composites were prepared by twin screw melt extrusion with high-density polyethylene (HDPE) as the matrix and polystyrene-coated BaO-Nd 2 O 3 -TiO 2 (BNT) ceramics as the filling material. Interestingly, the incorporation of polystyrene (PS) by the coating route could significantly improve the thermal behaviors of the composites (HDPE-PS/BNT), besides the temperature stability of dielectric properties and thermal displacement. The microwave dielectric properties of the composites were investigated systematically. The results indicated that, as the volume fraction of BNT ceramic particles increased from 10 to 50 vol% in the composites, the dielectric constant increased from 3.54 (9.23 GHz) to 13.14 (7.20 GHz), which can be beneficial for the miniaturization of microwave devices; the dielectric loss tangent was relatively low (0.0003-0.0012); more importantly, the ratio of PS to HDPE increased accordingly, making the composite containing 50 vol% BNT ceramics have a low value of temperature coefficient of resonant frequency ( f  = −11.2 ppm/℃) from −20 to 60 ℃. The GPS microstrip antennas were therefore designed and prepared from the HDPE-PS/BNT composites. They possessed good thermal stability ( f  = 23.6 ppm/℃) over a temperature range of −20 to 60 ℃, promising to meet the requirements of practical antenna applications.

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“…Tungsten-bronze type ceramics like BaO-Nd 2 O 3 -TiO 2 (BNT) are widely used in microwave devices due to their high permittivity and low losses [4][5][6]. The substitution of Bi for Nd (BNBT ceramics) can decrease the temperature coefficient of resonant frequency and increase the permittivity of BNT based ceramics [7,8].…”

Section: Introductionmentioning

confidence: 99%