Materials
·
2023
·Vol. 16
·期 14
·5195
·
IF 3.4
Jun Yang,Jinbiao Pang,Xiaofang Luo,Laiyuan Ao,Qiang Xie,Xing Wang,Hongyu Yang,Xianzhong Tang
This work studied the phase constitution, bond characteristics, and microwave dielectric performances of Sr2TiO4ceramics. Based on XRD and Rietveld refinement analysis, pure tetragonal Ruddlesden–Popper type Sr2TiO4ceramic is synthesized at 1425~1525 °C. Meanwhile, the microstructure is dense and without porosity, indicating its high sinterability and densification. Great microwave dielectric performances can be obtained, namely anεrvalue of 39.41, and aQ × fvalue of 93,120 GHz, when sintered at 1475 °C. Under ideal sintering conditions, the extrinsic factors are minimized and can be ignored. Thus, the intrinsic factors are considered crucial in determining microwave dielectric performances. Based on the P–V–L complex chemical bond theory calculation, the largest bond ionicity, and proportions to the bond susceptibility from Sr–O bonds suggest that Sr–O bonds mainly determine the dielectric polarizability. However, the Ti–O bonds show lattice energy about three times larger than Sr–O bonds, emphasizing that the structural stability of Sr2TiO4ceramics is dominated by Ti–O bonds, and the Ti–O bonds are vital in determining the intrinsic dielectric loss. The thermal expansion coefficient value of the Sr2TiO4structure is also mainly decided by Ti–O bonds.Keywords:Sr2TiO4;microwave dielectric properties;P–V–L complex chemical bond theory
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2017
·
IF 3.454
Atta Ullah,Hanxing Liu,Hua Hao,Javed Iqbal,Zhonghua Yao,Minghe Cao
(1- x )Mg 0.90 Ni 0.1 SiO 3 - x TiO 2 ( x = 0, 0.01, 0.03, 0.05) ceramics were successfully formed by the conventional solid-state methods and characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS), and their microstructure and microwave dielectric properties systematically investigated. It was observed that when TiO 2 content increased from 0 to 5 wt%, the Q u f o of the sample decreased from 118,702 GHz to 101,307 GHz and increases the τ f value from −10 ppm/°C to +3.14 ppm/°C accompanied by a notable lowering in the sintering temperature (125 °C). A good combination of microwave dielectric properties (ε r ∼ 8.29, Q u f o ∼ 101,307 GHz and τ f ∼ −2.98 ppm/°C) were achieved for Mg 0.90 Ni 0.1 SiO 3 containing 3 wt% of TiO 2 sintered at 1300 °C for 9 h which make this material of possible interest for millimeter wave applications.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
Crystals
·
2022
·Vol. 12
·期 4
·512
·
IF 2.67
Zhijian Wang,Feng Pan,Lanlan Liu,Qifeng Du,Ruitao Tang,Jun Ai,Hong Zhang,Ying Chen
Mg2SiO4holds promise for its application in the microwave communication field due to its low dielectric constant and highQ×fvalue. However, its high negativeτfand high sintering temperature limit its application in low-temperature co-fired ceramic (LTCC) devices. In this work, Li2TiO3and CaTiO3were introduced to improve theτf, and LiF was chosen to decrease the sintering temperature. According to XRD patterns and SEM micrographs, the ceramic systems displayed a complex-phase structure, and the microstructure was densified when CaTiO3was added. All of the relative densities, dielectric constants, andQ×fvalues first increased and then decreased as the sintering temperature increased. The MLLC11.5 ceramics sintered at 800 °C could be obtained with the highestQ×fvalue of 54,581 GHz (at 8.06 GHz),εrof 14.13, andτfof + 5.81 ppm/°C. Furthermore, it was proven that the MLLC11.5 powders could be co-fired without any reaction with Ag powders at 800 °C, indicating its potential for LTCC application. The MLLC11.5 composition was used to prepare a GPS antenna and showed good prospects for its application in electronic communications.Keywords:Mg2SiO4-Li2TiO3-LiF-CaTiO3ceramics;structure;microwave dielectric property;LTCC;antenna
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2011
·Vol. 95
·期 1
·37-40
·
IF 2.169
Songping Wu,Chan Jiang,Youxian Mei,Weiping Tu
The Sm 2 SiO 5 ceramics were synthesized and their microwave dielectric properties were investigated. The pure monoclinic Sm 2 SiO 5 phase could be obtained when the molar ratio of Sm 2 O 3 /SiO 2 was 1:1.05 at 1350°C. A small amount of hexagonal Sm 4 (SiO 4 ) 3 second phase occurred as temperature increased. The relative density of Sm 2 SiO 5 ceramics increased with increasing temperature. The Sm 2 SiO 5 ceramics sintered at 1500°C exhibited microwave dielectric properties: a dielectric constant (ε r ) of 8.44, a quality factor ( Q × f ) of 64 000 GHz, and a temperature coefficient of resonant frequency (τ f ) of −37 ppm/°C. The Sm 2 SiO 5 ceramics have a wide sintering temperature region and small negative τ f values. They are promising candidate materials for millimeter-wave devices.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2022
·Vol. 106
·期 1
·285-292
·
IF 4.186
Mengjiao Chi,Yahan Liu,Jianwei Zhao,Chao Dong,Xinjiang Luo,Dawei Wang,Bing Liu,Minmin Mao,Feng Shi,Kaixin Song
It is difficult to get pure-phase Mg 3 B 2 O 6 (abbreviated as MBO) ceramics by the traditional high-temperature solid-state reaction method. In this paper, pure-phase MBO ceramics were successfully densified and obtained by combining the cold sintering and post-annealing process. The relative density of MBO ceramics was ∼80% cold sintered at 150°C/90 min/800 MPa, which was further improved to ∼91% by post-annealing at 900°C, 400°C lower than that of the traditional high-temperature sintering process (∼1300°C). X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and Raman results demonstrated that the secondary phase of MgO was effectively eliminated, and dense microstructure was observed by the cold-sintering process plus post-annealing treatment. Finally, the microwave dielectric properties of MBO were evaluated with ε r : 5.15–6.37, Q×f : 5942–16 686 GHz, τ f : −48.45–69.72 ppm/°C.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2021
·Vol. 32
·期 13
·18205-18211
·
IF 2.478
Jin Ding Hao,Hu Cheng Chao,Liu Bing
CaAl 2 − 2 x Zn x Ti x O 4 ( x = 0.05, 0.10, 0.15) ceramics with low permittivity have been prepared via a standard solid-state reaction method. The partial co-substitution of (Zn 0.5 Ti 0.5 ) 3+ for Al 3+ can effectively lower the sintering temperature of CaAl 2 O 4 ceramics by approximately 200 °C. Meanwhile, the large negative temperature coefficient of resonant frequency ( τ f = − 55 ppm/°C) of CaAl 2 O 4 ceramics can be simultaneously modified toward zero. With increasing x , the quality factor ( Q f ) indicates a downward changing trend owing to the appearance of ZnAl 2 O 4 and CaTiO 3 secondary phases. The optimum microwave dielectric properties ( ε r = 11.9, Q f = 28,090 GHz, and τ f = − 1.2 ppm/°C) are achieved at x = 0.15. Moreover, a microstrip patch antenna is fabricated using the x = 0.15 ceramic as the dielectric substrate. The fabricated antenna demonstrates a S 11 value of − 17.8 dB at 4.9 GHz and a measured − 10 dB bandwidth of 86 MHz. The good antenna performances suggest that the present ceramics are good candidates for 5G antenna applications at the sub-6 GHz band.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Hongcheng Yang,Qingyu Wen,Enzhu Li
Lithium borosilicate (LBS) and lithium fluoride (LiF) are verified to be effective sintering aids for CaAl 2 B 2 O 7 microwave dielectric ceramic to reduce the sintering temperature and lower the activation energies . Benefiting from the liquid phase sintering , low-firing, low permittivity and low-loss CaAl 2 B 2 O 7 microwave dielectric composite has been successfully obtained. Typically, CaAl 2 B 2 O 7 assembled with 1 wt % LBS composite possesses desirable properties of ε r = 5.91, Q × f = 39,443 GHz, τ f = −23.51 ppm/°C (@16.53 GHz). For composite ceramics with 0.5 wt % LiF, the optimal microwave dielectric properties are ε r = 6.08, Q × f = 37,295 GHz, τ f = −22.39 ppm/°C (@15.78 GHz). The two kinds of composite are densified at 875 °C, with co-existed CaB 2 O 4 and liquid phase. The mechanism underlying the low temperature sintering is revealed by well-matched wettability and lower activation energy of composite ceramics with additions.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Yao-Dong Liu,Xiao-Qiang Song,Du Kang,Chang-Zhi Yin,Yi-Yang Cai,Jia-Qing Yang,Wen Lei,Wen-Zhong Lu
The Ba 1- x Sr x Cu 2 Ge 2 O 7 was successfully obtained through the solid-state reaction method, with single-phase BaCu 2 Ge 2 O 7 formed at 850 °C. Scanning electron microscopy analysis revealed the excellent chemical compatibility of Ba 1- x Sr x Cu 2 Ge 2 O 7 with silver. The properties of Ba 1- x Sr x Cu 2 Ge 2 O 7 ceramics were explained using the P-V-L theory. The ε r-corr decreased with the polarization rate (Σχ u * N b u ) and ion polarization of the unit cell. The Q×f increased with the chemical bond strength and lattice energy (U cal ), particularly the lattice energy of the Ge-O bond (U(Ge-O)). The τ f exhibited an opposite trend to the Q×f value and was influenced by the U(Cu-O) and susceptibility of the Cu-O bond (χ(Cu-O)). Sintering at 875 °C for 3 h yielded optimal microwave dielectric performance for Ba 1- x Sr x Cu 2 Ge 2 O 7 ceramics, with observed values of ε r = 9.26 ± 0.14, Q×f = 85,660 ± 4200 GHz, and τ f = −15.6 ± 1.1 ppm/°C at x = 0.10. These promising microwave dielectric properties make Ba 1- x Sr x Cu 2 Ge 2 O 7 a potential candidate for LTCC material applications.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2025
·
IF 8.2
Shuai Ma,Xiaohua Zhang,Jie Zhang,Xiaohui Zhang,Yu Liu,Chenglong Yu,Zhenxing Yue
Low-loss microwave dielectrics are of significant importance for the miniaturization and integration of microwave devices. In this paper, the ceramics of nominal composition Mgn+1TinO3n+1 (n = 3–6) are synthesized, and the correlations among their phase compositions, defect behaviors, and microwave dielectric properties are systematically investigated. The analyses indicate that the Mgn+1TinO3n+1 ceramics are a biphasic system consisting of hexagonal ilmenite-structured MgTiO3 and cubic spinel-structured Mg2TiO4. The Rietveld refinement results demonstrate that as the n value increases, the content of the MgTiO3 phase gradually increases, while that of the Mg2TiO4 phase decreases. The results of the thermally stimulated depolarization current (TSDC) indicate that the oxygen vacancy-related defects are considered to be the main types of defects in Mgn+1TinO3n+1. As the value of n increases, the increase of the MgTiO3 phases with a more stable crystal structure leads to a gradual decrease in the concentration of oxygen vacancies. The Mgn+1TinO3n+1 ceramics exhibit excellent microwave dielectric properties at n = 6: εr = 17.55, Q × f = 284,600 GHz, and τf = −46.39 ppm/°C. In addition, the relationship between the dielectric constant and the electric field distribution is solved utilizing high-frequency structure simulator (HFSS) software, and the Q × f values are also predicted. The low-frequency dielectric temperature spectra and direct current pulse charge/discharge tests show that the low-loss Mgn+1TinO3n+1 ceramics can be good candidates for microwave capacitors even when operated under high-temperature conditions.
研究领域:
材料科学
·
电子工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Yajie Wang,Ziyi Zhang,Jie Li,Ying Tang,Liang Fang
Excellent spinel microwave dielectric ceramics (1- x )Zn 2 TiO 4 - x Li 2 MgTi 3 O 8 (ZTLMT x , x = 1/3 and 2/3) were prepared at relatively low densification temperatures of 1100 °C and 1080 °C, respectively. A disordered cubic phase with space group Fd -3 m was formed at x = 1/3, whereas an ordered cubic phase with space group P 4 3 32 was formed at x = 2/3. The ceramics at x = 1/3 and 2/3 exhibited promising microwave dielectric properties of ɛ r = 18.27 and 22.96, Q × f = 91,877 GHz and 75,186 GHz, and τ f = −42.3 ppm/°C and −21.05 ppm/°C, respectively. The large deviation between the experimental ԑ r and theoretical ε th of 1/3 and 2/3 ceramics were 18.3 % and 57 %, respectively, due to the underestimation of the ionic polarizability of Ti 4+ . The difference in their ɛ r , Q × f , and τ f were discussed by the structure, FWHM of A 1g , lattice energy and bond energy in detail.
研究领域:
材料科学
·
陶瓷学
·
物理学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2018
·
IF 3.057
Y.K. Yang,H.L. Pan,H.T. Wu
Li 2 Mg 3 Ti 1-X (Mg 1/3 Nb 2/3 ) X O 6 (0 ≤x ≤ 0.25) ceramics were prepared by a conventional solid-state reaction process. Their crystal structures, sintering characteristics, Raman spectra and microwave dielectric properties were then investigated. XRD patterns of the sintered samples indicated that all compositions showed a single phase and the rock-salt structure. As the (Mg 1/3 Nb 2/3 ) 4+ contents increase, the variations of ε r values showed a downward trend, which could be explained by the changes of polarizabilities and the shift of Raman vibration modes. Q·f values initially increased to a maximum value and then decreased with increasing of x values. In addition, τ f values decreased almost linearly with the x values, which significantly correlated with the thermal expansion coefficient. Excellent combined microwave dielectric properties with ε r = 14.79, Q·f = 204,900 GHz and τ f = −18.43 ppm/°C were obtained for Li 2 Mg 3 Ti .95 (Mg 1/3 Nb 2/3 ) .05 O 6 ceramic sintered at 1550 °C.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2024
·Vol. 35
·期 13
·1-8
·
IF 2.8
Cai Chenxi,Tao Zhenli,Zuo Jianan
Within the scope of this research, Li 2 Mg 6 TiO 9 -based ceramics were prepared by a traditional solid-state sintering technique. The research analyzed the influence of lithium (Li) volatilization during the sintering process, on the phase composition, and resultant microwave dielectric performances (MIDP) of the Li 2 Mg 6 TiO 9 -based ceramics, employing advanced analytical techniques. X-ray diffraction and Raman spectroscopy analyses indicated the emergence of a second phase Mg 2 TiO 4 within the sample when the sintering temperature attained 1550 °C due to Li volatilization. The generated Mg 2 TiO 4 could effectively tune the MIDP of the ceramics. Optimal MIDP of Li 2 Mg 6 TiO 9 -based ceramics were derived from a sintering temperature of 1650 °C: dielectric constant ( ε r ) = 12.78, quality factor ( Q × f ) = 129,010 GHz, temperature coefficient of resonant frequency ( τ f ) = − 46.2 ppm/°C. Low ε r and ultrahigh Q × f indicate that the current ceramics have potential application prospects in millimeter wave communication as substrate materials.
研究领域:
材料科学
·
陶瓷工程
·
电子材料
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）