CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Zhiyuan Zhang,Jinwu Chen,Ying Tang,Huaicheng Xiang,Jie Li,Liang Fang,Junqi Chen
Two novel low- ε r CaRECeV 3 O 12 (RE = Nd, Sm) microwave dielectric ceramics were prepared to utilize the solid-state method. According to XRD and Raman spectroscopy data, the CaRECeV 3 O 12 (RE = Nd, Sm) ceramics had a tetragonal zircon-type with an I 4 1 / amd space group. Dense CaNdCeV 3 O 12 and CaSmCeV 3 O 12 ceramics sintered at 1225 °C and 1200 °C showed ε r ∼11.85 ± 0.1 and 11.33 ± 0.1, Q × f ∼40,100 ± 500 GHz and 43,290 ± 500 GHz, τ f ∼ −27.2 ± 0.5 ppm/°C and −22.4 ± 0.5 ppm/°C, along with α L of 9.4 ppm/°C and 8.5 ppm/°C, respectively. The measured ε r and corrected ε r (corr) values were larger than ε r (C-M) (9.41 and 9.47) in CaNdCeV 3 O 12 and CaSmCeV 3 O 12 due to the cations being, on average, under-bonded and the overall structures being in a slightly expanded state. The slightly higher | < d > | value of CaNdCeV 3 O 12 led to its higher ε r (corr) value, even though it had a lower α D /V m value. The sign and magnitude of τ f values for CaNdCeV 3 O 12 and CaSmCeV 3 O 12 were mainly determined by their positive temperature coefficients of dielectric polarizability τ αm of +36.2 ppm/°C and +32.1 ppm/°C, respectively. The inherent dielectric constant and dielectric loss were examined using far-infrared reflectivity spectra, Raman spectra, and the packing fraction.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Shimeng Zhang,Zeyu He,Zhiguo Wang,Zhenggang Rao,Yunlong Hu,Chunchun Li,Longlong Shu
The diopside-structured CaZnGe 2 O 6 ceramics were synthesized using the conventional solid-state reaction method in this study, and their crystal structure, microstructural evolution, and microwave dielectric properties were systematically investigated. The XRD and Rietveld refinement analyses confirmed that CaZnGe 2 O 6 crystallizes in the monoclinic crystal system with a C 2/ c space group. The intrinsic microwave dielectric properties of the ceramics were evaluated using far-infrared spectroscopy. The ceramic structure exhibits high density and microstructural homogeneity after sintering at 1130 °C, resulting in exceptional microwave dielectric properties achieved at this optimal temperature ( ε r = 8.78 Q×f = 63,782 GHz, τ f = −66.4 ppm/°C). These findings highlight the potential application of CaZnGe 2 O 6 ceramics as low-permittivity materials suitable for microwave devices.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2018
·
IF 3.794
Y.H. Zhang,J.J. Sun,N. Dai,Z.C. Wu,H.T. Wu,C.H. Yang
A new kind of low-temperature fired Eu 2 Zr 3 (MoO 4 ) 9 ceramic was fabricated by conventional solid-state reaction method. The mixed powders was calcined at 600 ℃ and the samples were sintered at 500 ℃ –700 ℃ for 4 h. X-ray diffraction analysis and Rietveld refinement indicated that Eu 2 Zr 3 (MoO 4 ) 9 belonged to a trigonal system with space group R-3c. Bond ionicity, lattice energy and bond energy of the ceramic were calculated by the complex chemical bond theory. Microwave dielectric properties were determined at microwave frequencies of 9.7–14.7 GHz by a network analyzer. Far infrared spectra indicated the main contribution to polarization for Eu 2 Zr 3 (MoO 4 ) 9 ceramics was the absorption of structural phonon oscillation. The ceramic sintered at 600 ℃ for 4 h exhibited the best dielectric properties with a relative permittivity ( ε r ) of 10.75, a quality factor ( Q·f ) of 74,900 GHz and a temperature coefficient of resonance frequency ( τ f ) of -8.88 ppm/℃.
研究领域:
材料科学
·
无机化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Chengzhi Xu,Hongyu Yang,Linzhuang Xing,Yuan Wang,Guorui Zhao,Li Chen,Zhimin Li
The Al 2 Mo 3 O 12 ceramic with monoclinic type is prepared at the sintering temperature as low as 750 °C, which exhibits excellent microwave dielectric properties of ε r = 4.99, Q × f = 49,579 GHz ( f = 14.8 GHz), and τ f = −26 ppm/°C. The relationship between structure and characteristics is analyzed through the P–V–L chemical bond theory in depth, and the dielectric properties are investigated in combination with far-infrared spectroscopy. Results show that it is Mo–O bond that is responsible mainly for bond ionicity and dielectric polarizability, and structural stability as well. Based on the far-infrared reflectivity spectra and complicated dielectric function analysis, the calculated and measured results are in relative agreement using the classical damped oscillation mode, indicating that the mode at 80.23 cm −1 is dominant for the contribution to dielectric properties. This study gives an insight into the structural characteristic and provides a guide to further improve the microwave dielectric performance of Al 2 Mo 3 O 12 ceramic.
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
·
2022
·
IF 5.532
Yucheng Cao,Liangbin Zhang,Hongrong Mei,Zhenggang Rao,Tingfang Tian,Chunchun Li
The monoclinic diopside structured CaMgGe 2 O 6 dielectric ceramics were synthesized by the traditional solid-phase reaction method, and their microwave dielectric properties were characterized. X-ray diffraction (XRD) and Rietveld refinement revealed that CaMgGe 2 O 6 belongs to the monoclinic system of space group C2/c. SEM images showed that dense CaMgGe 2 O 6 ceramics could be formed at the optimum sintering temperature of 1300 °C. Typically, ceramic sintered at 1300 °C for 6 h possessed outstanding microwave dielectric properties with ε r ∼7.96, Q × f ∼41,280 GHz, and τ f ∼ −46.6 ppm/°C. Far-infrared spectra analysis revealed the intrinsic microwave dielectric properties of CaMgGe 2 O 6 ceramics. These findings demonstrate promising application prospects of CaMgGe 2 O 6 in microwave substrate materials.
研究领域:
材料科学
·
陶瓷
·
微波工程
·
介电材料
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2018
·Vol. 102
·期 7
·4092-4102
·
IF 2.956
Yunhui Zhang,Haitao Wu
La 2 (Zr 1− x Ti x ) 3 (MoO 4 ) 9 (0 ≤ x ≤ 0.1) ceramics were prepared by the traditional solid-state reaction method. XRD analysis showed that La 2 (Zr 1− x Ti x ) 3 (MoO 4 ) 9 (0 ≤ x ≤ 0.1) ceramics belonged to a trigonal system. Based on the chemical bond theory, the consequences of bond energy, bond ionicity, lattice energy, and thermal expansion coefficient of ceramics on microwave dielectric properties were discussed. As Ti 4+ addition was increased, the reduction in dielectric constant was ascribed to the fact that the polarizability of Ti 4+ is smaller than Zr 4+ , and the downward trend was related to the bond ionicity. Besides, the tendency of Q·f value depended on the packing fraction and the lattice energy. The improvement in τ f value, the increase in bond energy, and the decrease in the coefficient of thermal expansion were all correlated. The far-infrared spectra implied that the absorptions of structural phonon oscillation were the main reason for the maximum polarization contribution. La 2 (Zr 0.92 Ti 0.08 ) 3 (MoO 4 ) 9 ceramics sintered at 750°C for 4 hours exhibited the best dielectric properties ( ε r = 10.33, Q·f = 80 658 GHz, and τ f = 3.48 ppm/°C).
研究领域:
材料科学
·
陶瓷工程
·
电气工程
✓ 已验证
DOI
高影响因子
Nature Communications
·
2019
·Vol. 10
·期 1
·1-8
·
IF 11.878
Liu Kairui,Hou Guangjin,Mao Jingbo,Xu Zhanwei,Yan Peifang,Li Huixiang,Guo Xinwen,Bai Shi,Zhang Z. Conrad
While numerous single atoms stabilized by support surfaces have been reported, the synthesis of in-situ reduced discrete metal atoms weakly coordinated and stabilized in liquid media is a more challenging goal. We report the genesis of mononuclear electron deficient Pt 1 (0) by reducing H 2 PtCl 6 in liquid polydimethylsiloxane-polyethylene glycol (PDMS-PEG) (Pt 1 @PDMS-PEG). UV–Vis, far-IR, and X-ray photoelectron spectroscopies evidence the reduction of H 2 PtCl 6 . CO infrared, and 195 Pt and 13 C NMR spectroscopies provide strong evidence of Pt 1 (0), existing as a pseudo-octahedral structure of (R 1 OR 2 ) 2 Pt(0)Cl 2 H 2 (R 1 and R 2 are H, C, or Si groups accordingly). The weakly coordinated (R 1 OR 2 ) 2 Pt(0)Cl 2 H 2 structure and electron deficient Pt 1 (0) have been validated by comparing experimental and DFT calculated 195 Pt NMR spectra. The H + in protic state and the Cl − together resemble HCl as the weak coordination. Neutralization by a base causes the formation of Pt nanoparticles. The Pt 1 @PDMS-PEG shows ultrahigh activity in olefin hydrosilylation with excellent terminal adducts selectivity.
研究领域:
材料科学
·
化学工程
·
光谱学
·
催化
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Hailong Pan,Shijie Yan,Yiyun Zhang,Jialun Du,Xiaoyu Zhang,Pijun Gong,Haitao Wu,Huanrong Tian,Michael Wübbenhorst
A series of Ce 2 [Zr 1- x (A) x ] 3 (MoO 4 ) 9 (A = Sr 1/3 Ta 2/3 , Sr 1/3 Sb 2/3 ; x = 0.02, 0.04, 0.06, 0.08 and 0.10) (abbreviated as CZ 1- x T x and CZ 1- x S x ) microwave dielectric ceramics were studied systematically with respect to microstructures, sintering behaviors, crystal structures, microwave dielectric properties and infrared vibrational modes. Density measurements and scanning electron microscopy (SEM) reveal the dense and homogeneous microstructures. X-ray diffraction (XRD) results confirm the formation of solid solutions belonging to the hexagonal system with a R 3 ‾ c space group, and the lattice volume increases with raising the doping content. Furthermore, the complex chemical bond theory was used to calculate the intrinsic bond parameters, and the correlations between the microwave dielectric properties and intrinsic bond parameters were established. Finally, far infrared (FIR) spectra reveal that the main polarization contribution stems from the absorptions of the phonon oscillations in these two groups of ceramics. Typically, the optimum microwave dielectric properties are achieved for CZ 0.9 T 0.1 and CZ 0.94 S 0.06 ceramics with ε r = 10.24, Q × f = 92,009 GHz (at 9.70 GHz), τ f = −8.84 ppm °C −1 and ε r = 10.40, Q × f = 82,696 GHz (at 9.69 GHz) and τ f = −8.04 ppm °C −1 , respectively. Interestingly, the CZ 0.9 T 0.1 ceramic exhibits the maximum Q × f value in the ion doped Ce 2 Zr 3 (MoO 4 ) 9 ceramics while retaining a good τ f = −8.84 ppm °C −1 .
研究领域:
材料科学
·
陶瓷
·
介电材料
·
固体化学
·
微波工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）