Crystal structure, spectra analysis and dielectric characteristics of Ba4M28/3Ti18O54 (M= La, Pr, Nd, and Sm) microwave ceramics

Wang, Geng; Fu, Qiuyun; Guo, Peng; Hu, Ming; Wang, Huanhuan; Yu, Shijin; Zheng, Zhiping; Luo, Wei

doi:10.1016/j.ceramint.2020.08.294

Cited by 22 publications

(17 citation statements)

References 55 publications

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“…As shown in Fig. 7, with the increase in z value, most of the Raman modes present a blue-shift, which indicates that the cell volume decreases [20,32,48,51,52], consistent with the XRD results. The relative intensities of the vibration modes in the region of 300~400 cm -1 increase slightly as z value increases, implying that the tilting vibration of the TiO 6 octahedra becomes stronger, and the decline of τ f is related to this phenomenon [47,50,52].…”

Section: Resultssupporting

confidence: 83%

“…The polarization mechanism of dielectrics in the microwave frequency band is mainly ion displacement polarization [45], which is closely related to the vibration of ions in the crystal lattice. Therefore, Raman spectroscopy is a powerful tool for studying the relationship between the structure and properties of microwave dielectric ceramics [20,32,[46][47][48][49][50][51][52]. The space group of the BLT superlattice with tungsten-bronze structure is Pbnm (No.…”

Section: Resultsmentioning

confidence: 99%

“…The vibration modes in the regions of 200~400 cm -1 and 400~600 cm -1 were attributed to the rotation and the internal vibration of the TiO 6 octahedra, respectively. The mode at 757 cm -1 might correspond to the second order scatter [20,32,[50][51][52]. Limited by the test conditions, vibration modes between 50 cm -1 and 100 cm -1 in BLT system have not been reported yet.…”

Section: Resultsmentioning

confidence: 99%

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Structure, Defects and Microwave Dielectric Properties of Al-doped and Al/Nd Co-doped Ba4Nd9.33Ti18O54 Ceramics

Guo¹,

Ma²,

Luo³

et al. 2021

Preprint

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Ba4Nd9.33Ti18-zAl4z/3O54 (BNT-A, 0 ≤ z ≤ 2) and Ba4Nd9.33+z/3Ti18-zAlzO54 (BNT-AN, 0 ≤ z ≤ 2) ceramics were prepared by solid state method, and the effects of the two doping methods on microwave dielectric properties were compared. As the doping amount z increased, the relative dielectric constant (εr) and the temperature coefficient of resonant frequency (τf) values of the ceramics decreased, and the quality factor (Q, usually expressed by Q×f, where f is the resonant frequency) of the ceramics obviously increased when z ≤ 1.5. With the same z value, the εr and Q×f values of Al/Nd co-doped ceramics are both higher than those of Al-doped ceramics. Rietveld refinement, Raman spectroscopy and thermally stimulated depolarization current (TSDC) technique were applied to clarify the relationship among the structure, defects and microwave dielectric properties. It is shown that the Q×f values of those ceramics were closely related to the strength of the A-site cation vibration and the concentration of oxygen vacancies (B). Excellent microwave dielectric properties of εr = 72.2, Q×f = 16480 GHz, and τf = +14.3 ppm/℃ were achieved in BNT-AN ceramics with z = 1.25.

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Section: Resultssupporting

confidence: 83%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Structure, Defects and Microwave Dielectric Properties of Al-doped and Al/Nd Co-doped Ba4Nd9.33Ti18O54 Ceramics

Guo¹,

Ma²,

Luo³

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…As shown in Fig. 7, with the increase in z value, most of the Raman modes present a blue-shift, which indicates that the cell volume decreases [20,32,46,49,52,53,60], consistent with the XRD results. The relative intensities of the vibration modes in the region of 300 ~ 400 cm − 1 increase slightly as z value increases, implying that the tilting vibration of the TiO 6 octahedra becomes stronger, and the decline of τ f is related to this phenomenon [48,51,53].…”

Section: Resultssupporting

confidence: 80%

“…The vibration modes in the regions of 200 ~ 400 cm − 1 and 400 ~ 600 cm − 1 were attributed to the rotation and the internal vibration of the TiO 6 octahedra, respectively. The mode at 757 cm − 1 might correspond to the second order scatter [20,32,[51][52][53]. Limited by the test conditions, vibration modes between 50 cm − 1 and 100 cm − 1 in BLT system have not been reported yet.…”

Section: Resultsmentioning

confidence: 99%

Structure, Defects and Microwave Dielectric Properties of Al-Doped and Al/Nd Co-doped Ba4Nd9.33Ti18O54 Ceramics

Guo

Luo

et al. 2021

Preprint

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Low-loss tungsten-bronze microwave dielectric ceramics are a kind of dielectric materials with potential application value for miniaturized dielectric filters and antennas in 5G communication technology. In this work, a novel Al/Nd co-doping method of Ba4Nd9.33Ti18O54 (BNT) ceramics with a chamical formula of Ba4Nd9.33+z/3Ti18-zAlzO54 (BNT-AN, 0 ≤ z ≤ 2) was proposed to improve the dielectric properties through structural and defect modulation. Together with Al-doped ceramics (Ba4Nd9.33Ti18-zAl4z/3O54, BNT-A, 0 ≤ z ≤ 2) for comparison, the ceramics were prepared by solid state method. It is found that Al/Nd co-doping method has a significant effect on improving the dielectric properties compared with Al doping. As the doping amount z increased, the relative dielectric constant (εr) and the temperature coefficient of resonant frequency (τf) of the ceramics decreased, and the Q×f values of the ceramics obviously increased when z ≤ 1.5. Excellent microwave dielectric properties of εr = 72.2, Q×f = 16480 GHz, and τf = +14.3 ppm/℃ were achieved in BNT-AN ceramics with z = 1.25. Raman spectroscopy and thermally stimulated depolarization current (TSDC) technique were firstly combined to analyze the structure and defects in the dielectric ceramics. It is shown that the improvement on Q×f values were origined from the decrease in the strength of the A-site cation vibration and the concentration of oxygen vacancies (Vö), demonstrating the effect and mechanism underlying for structural and defect modulation on the performance improvement of microwave dielectric ceramics.

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Microwave dielectric properties of α-CaSiO3/Al2O3-Li2CO3 ceramics sintered at low temperature

Liu

Sun

Wang

et al. 2021

J Mater Sci: Mater Electron

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Crystal structure, spectra analysis and dielectric characteristics of Ba4M28/3Ti18O54 (M= La, Pr, Nd, and Sm) microwave ceramics

Cited by 22 publications

References 55 publications

Structure, Defects and Microwave Dielectric Properties of Al-doped and Al/Nd Co-doped Ba4Nd9.33Ti18O54 Ceramics

Structure, Defects and Microwave Dielectric Properties of Al-doped and Al/Nd Co-doped Ba4Nd9.33Ti18O54 Ceramics

Structure, Defects and Microwave Dielectric Properties of Al-Doped and Al/Nd Co-doped Ba4Nd9.33Ti18O54 Ceramics

Microwave dielectric properties of α-CaSiO3/Al2O3-Li2CO3 ceramics sintered at low temperature

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