CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Junqing Ren,Pao Yang,Zhijian Peng,Xiuli Fu
Nowadays, microwave dielectric substrate materials have been extensively investigated to meet the requirements of rapid development in modern communications. Among them, the composites of ceramic powder filled polytetrafluoroethylene (PTFE) have been a hot topic. However, the compatibility and connectivity between the surface of ceramics and PTFE molecular chains in the samples are usually low. Herein novel PTFE based composites with different contents of Al 2 Mo 3 O 12 (20–60 wt%) modified by C 14 H 19 F 13 O 3 Si (F8261) coupling agent were designed and prepared. The coupling agent F8261 has been successfully grafted to the surface of Al 2 Mo 3 O 12 powders, effectively promoting the densification and dielectric properties of the composites. As the content of the modified Al 2 Mo 3 O 12 powders increases from 20 to 60 wt%, the ε r value increases from 3.4 to 4.2, and tanδ almost remains constant at the beginning and increases with much more Al 2 Mo 3 O 12 added. The Al 2 Mo 3 O 12 -PTFE composites filled with 30 wt% Al 2 Mo 3 O 12 present the optimal dielectric properties of ε r = 3.6 and tanδ = 0.0018 with a high density of 95.6%. In addition, the electromagnetic and multiphysic simulation of a 24 GHz substrate integrated waveguide filter on the basis of the 30 wt% Al 2 Mo 3 O 12 - 70 wt% PTFE composite was carried out. It was revealed that the filter presented high stability on the electrical parameters caused by self-heating and dimension deformation due to the good microwave dielectric , thermal and mechanical properties of the substrate. These results indicate that the as-prepared 30 wt% Al 2 Mo 3 O 12 - 70 wt% PTFE composite would be a promising candidate for high-performance microwave dielectric substrates.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
INORGANIC CHEMISTRY
·
2022
·
IF 5.436
Huocheng Lv,Laihui Luo,Weiping Li,Peng Du
To ameliorate the inherent thermal quenching behaviors of upconverting materials, a series of Ho3+/Yb3+-codoped Al2Mo3O12 (i.e., Al2Mo3O12:Ho3+/2xYb3+) microparticles were developed. Upon excitation at 980 nm, intense upconversion (i.e., UC) emissions arising from Ho3+ are observed, and their optimal states occur at x = 0.09. Besides, the UC mechanisms of these generated emissions from 5F4/5S2 and 5F5 levels all pertain to a two-photon absorption process. Furthermore, modified thermal quenching performances are realized in the resultant microparticles, in which the intensities of the UC emissions arising from 5F4/5S2 levels decrease as the temperature increases, while that of the UC emission from the 5F5 level increases and then decreases with the increase of temperature. The coexistence of nonradiative transition promoted crossrelaxation, and energy transfer routes can be responsible for the above phenomenon. By studying the diverse UC emission characteristics at high temperatures, we revealed the thermometric properties of Al2Mo3O12:Ho3+/2xYb3+ microparticles, where their sensitivities can be regulated by selecting the spectral mode and dopant contents. According to the intensity ratio of the UC emissions originating from 5F5 → 5I8 to (5F4,5S2) → 5I7 transitions at different temperatures, one obtains that the relative and absolute sensitivities of the developed compounds reach up to 0.464% and 0.1739 K–1, respectively. Additionally, by the analysis of the thermochromic performances of final products, their thermometric characteristics were also investigated. Note that the environmental temperature is able to be facilely read out by distinguishing the emitting color. These results verify that the Al2Mo3O12:Ho3+/2xYb3+ microparticles are promising luminescent materials for multimode visual optical thermometry.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2024
·Vol. 35
·期 18
·1-10
·
IF 2.8
Gao Dawei,Ma Juncheng,Zhang Jiafen,Shi Qingang,Yang Hongyu,Xiong Zhe,Zhang Xing,Tang Bin
In this work, reducing sintering temperature while synergistically improving temperature stability in Al 2 Mo 3 O 12 ceramic has been achieved with the assistance of the LiMoVO 6 phase. The LiMoVO 6 does not react with the Al 2 Mo 3 O 12 phase, showing excellent chemical compatibility. Both intrinsic and extrinsic factors contribute to the development of microwave dielectric properties of (1- x )Al 2 Mo 3 O 12 - x LiMoVO 6 ( x = 0.205) ceramic. Dielectric polarization, relative density, phase constitutions, and contents greatly influence the change of ε r value; while the Q × f value is more sensitive to the technological process for the solid-state method inevitably introducing grain growth and grain boundaries, resulting in grain boundary losses. Benefitting from the temperature compensation effect of the LiMoVO 6 phase, the τ f value can be effectively regulated based on the mixture rule. When sintered at 600 °C, the (1- x )Al 2 Mo 3 O 12 - x LiMoVO 6 ( x = 0.205) ceramic shows a low ε r value of 7.05, a Q × f value of about 8543 GHz (@13.4 GHz), and a τ f value of ca. − 14.2 ppm/ o C, which is suitable for applying in ULTCC technology.
研究领域:
材料科学
·
电子工程
✓ 已验证
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
JOURNAL OF LUMINESCENCE
·
2022
·
IF 4.171
Huocheng Lv,Long Liu,Dandan Wang,Zhihong Mai,Feng Yan,Guozhong Xing,Peng Du
To explore highly sensitive luminescent materials , a series of Er 3+ /Yb 3+ -codoped Al 2 Mo 3 O 12 microparticles were prepared through a high-temperature solid-state reaction method. The phase structure, light harvest ability, morphology, and upconversion (UC) emission characteristics of these synthesized microparticles were investigated systematically. Excited at 980 nm, glaring visible UC emissions are gained in the developed specimens, in which the optimal doping content for Yb 3+ is 7 mol% and the two-photon absorption process contributes to the UC emission mechanism. Based on the fluorescence intensity ratio technology, the thermometric properties of resultant microparticles are studied by analyzing the temperature-dependent green UC emissions of Er 3+ arising from the thermal coupling energy levels. The maximum absolute and relative sensitivities of final products are 0.011 K -1 and 1.09% K −1 , respectively, and they are barely influenced by Yb 3+ contents. Besides, via exploring the lifetimes of 2 H 11/2 and 4 S 3/2 levels of Er 3+ at various temperatures, the relative sensitivities of resultant microparticles are determined to be 0.27% and 0.26% K −1 , respectively. Furthermore, the newly developed microparticles can be adopted to fabricate fluorescent ink to realize optical anti-counterfeiting and visual temperature monitoring. Our studies demonstrate that Er 3+ /Yb 3+ -codoped Al 2 Mo 3 O 12 microparticles with strong UC emissions possess great potential for multimode visual optical thermometry applications.
研究领域:
材料科学
·
光学材料
·
发光学
·
传感器与仪器
·
纳米光子学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）