RARE METALS
·
2024
·
IF 9.6
Zeng Jin-Quan,Qi Jun-Lei,Yang Yue-Yang,Zhang Min-Hao,Lin Yuan-Hua
The practical application of CaSmAlO 4 microwave dielectric ceramics is limited by its low quality factor ( Q × f ) value and non-zero temperature coefficient resonant frequency ( τ f ) value. In this study, we introduced Mg 2+ –Ti 4+ ionic pairs into CaSmAlO 4 , along with an excess of 9% Sm 2 O 3 . The Mg 2+ –Ti 4+ ionic pairs substituted Al 3+ , and two phases simultaneously coexisted in the ceramics: CaSmAlO 4 and Sm 2 O 3 . As the doping concentration of Mg 2+ –Ti 4+ ionic pairs increased, the relative permittivity exhibited an upward trend, while the quality factor and resonant frequency temperature coefficient first rose and then descended. Remarkably, 0.09Sm 2 O 3 –0.91CaSmAl 0.7 Mg 0.15 –Ti 0.15 O 4 sintered at 1450 °C yielded excellent dielectric properties: ε r = 19.72, Q × f = 72,936 GHz, and τ f = –0.044 ppm·°C − 1 . The factors influencing the microwave dielectric properties of 0.09Sm 2 O 3 –0.91CaSmAlO 4 ceramics were further examined by considering the crystal structure, grain size, Lichtenecker logarithmic rule, tolerance factor and packing fraction. Graphic abstract
研究领域:
材料科学
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电子工程
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产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2024
·Vol. 35
·期 34
·1-9
·
IF 2.8
Gao Dawei,Ma Juncheng,Zhang Jiafen,Shi Qingang,Xiong Zhe,Zhang Xing,Tang Bin
The occurrence of "dark holes" is a common phenomenon in TiO 2 -based ceramics, resulting from the reduction of Ti 4+ under high-temperature and low-oxygen partial pressure sintering conditions. To achieve low dielectric loss, Ca 0.61 Nd 0.26 Ti 1- x Cu x O 3 ceramics were designed and prepared in this work. The results indicate that moderate doping of CuO not only enhances insulation resistivity and Q × f value but also reduces the positive τ f value. The Ca 0.61 Nd 0.26 Ti 0.98 Cu 0.02 O 3 sample exhibited the highest Q × f value of 16,895 GHz, contributing to the miniaturization and insertion loss of microwave devices.
研究领域:
材料科学
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电子工程
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DOI
高影响因子
Journal of Materials Chemistry C
·
2020
·Vol. 8
·期 13
·4518-4533
·
IF 7.059
Guo-Hui Pan,Liangliang Zhang,Huajun Wu,Xuesong Qu,Hao Wu,Zhendong Hao,Ligong Zhang,Xia Zhang,Jiahua Zhang
Monoclinic ZrO2 (m-ZrO2) is an attractive material for photonic applications due to its low site symmetry and phonon energy. In this paper, we present detailed studies on the luminescence properties of Ti4+ and Eu3+ in m-ZrO2. In view of the continuing controversy over the origin of “intrinsic” white-blue luminescence in pristine m-ZrO2, more spectroscopic information obtained by characterizing m-ZrO2 intentionally doped with Ti4+, Ti3+ and other metal ions and extensive discussions on the general characteristics of different luminescence processes were provided to evidence the luminescence as the Ti3+ → O− charge transfer transition in the [Ti(IV)O7]10− complex due to the trace amount of Ti4+ impurity in ZrO2 reagent. Competitive absorption was observed between host exciton and oxygen–metal charge transfer processes (O2−–Ti4+, O2−–Eu3+), and even between the two types of charge transfer process because of the sharing of electrons at the top of the valence band, which greatly influenced the absorption and excitation processes. The spectral components comprising the broad excitation band of O2−–Ti4+ white-blue or Eu3+ red emissions in different phosphors were identified, and their evolutions with doping concentration were explained. The energy state locations of oxygen defects produced by intrinsic charge compensation in m-ZrO2:Eu3+ were proposed to be ∼2.41 eV above the top of the valence band by using Eu3+ for the luminescent probe. Efficient energy transfer from the [Ti(IV)O7]10− complex to Eu3+ was first observed in m-ZrO2:Ti4+,Eu3+ phosphors, which were demonstrated to be high performance ratiometric self-referencing optical thermometric materials based on the dual-emitting combination strategy, with the relative sensitivity amounting to ∼3.84% K−1. Optical thermometry not only covering the physiological temperature range but also with high relative sensitivity could be achieved upon appropriate doping.
研究领域:
材料科学
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光物理学
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产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
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2021
·Vol. 32
·期 13
·18205-18211
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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
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电子工程
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DOI
高影响因子
Journal of Physical Chemistry C
·
2019
·
IF 4.309
Lina Lin,Yanling Ma,Jianbo Wu,Fei Pang,Jianping Ge,Song Sui,Yefeng Yao,Ruijuan Qi,Yan Cheng,Chun-gang Duan,Junhao Chu,Rong Huang
Colored titanium dioxide (TiO2) nanocrystals have been studied intensively in recent years due to their substantial solar-driven photocatalytic activities. Because of the scarcity of information correlated among atomic structure, electronic structure, and photocatalytic property from isolated nanoparticles, the origin of photocatalytic activity of colored TiO2 from microscopic and electronic level remains intensely debated. Here we demonstrated the origin of photocatalytic activity in Ti4+/Ti3+ core–shell TiO2 nanocrystals mainly by a combination of high-resolution transmission electron microscopy (HRTEM), electron energy-loss spectroscopy (EELS), and photo-Kelvin probe force microscopy (KPFM). The thickness of the Ti3+ shell layer increases with the annealing temperature, meanwhile the O/Ti atomic ratio of the outermost layer decrease. The differences in interplanar spacing between the surface and the subsurface generate strain effect, which increase carrier mobility and ultimately improve catalytic performance. Quantum size effect and specific surface area also have a big impact on catalytic performance. A prerequisite is to keep a good balance between the Ti4+/Ti3+ core–shell structure and the particle size to optimize its photocatalytic properties. By employing Au as a reference, we were able to estimate the Fermi levels of TiO2 before and after illumination. The amplitude of the Fermi level upshift unambiguously relates with the photocatalytic activity. The largest Fermi level upshift under illumination means generating the most efficient photoinduced carries to perform a highly catalytic reaction, carried out by optimizing the electronic structure with appropriate oxygen vacancies. But too many oxygen vacancies increase the recombination center and reduce the concentration of photoinduced electrons, which can also be observed from the photo-KPFM result.
研究领域:
材料科学
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纳米技术
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表面科学
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产品关联
DOI
高影响因子
Chemosensors
·
2024
·Vol. 12
·期 4
·62
·
IF 3.7
Lu Li,Xuesong Qu,Guo-Hui Pan,Jung Hyun Jeong
In this paper, we report on the solvothermal preparation and detailed characterization of pristine and intentionally doped zirconium dioxide (ZrO2) nanocrystals (NCs, ~5 nm) with Eu3+or Ti4+/Eu3+ions using alkoxide precursors. The results indicated that the ZrO2NCs were dominantly of a tetragonal phase (t-ZrO2) with a small proportion of monoclinic ZrO2(m-ZrO2). The high purity of t-ZrO2NCs could be synthesized with more Eu3+doping. It was found that the as-obtained ZrO2NCs contain some naturally present Ti4+ions originating from precursors, but were being overlooked commonly, and some carbon impurities produced during synthesis. These species showed distinct photoluminescence (PL) properties. At least two types of Eu3+, located at low- and high-symmetry sites (probably sevenfold and eightfold oxygen coordination), respectively, were demonstrated to build into the lattice structure of t-ZrO2NCs together. The cationic dopants were illustrated to be distributed non-randomly over the sites normally occupied by Zr, while Ti impurities preferentially occupied the sites near the low-symmetry site of Eu3+, yielding efficient energy transfer from the titanate groups to the neighboring Eu3+. Luminescence nanothermometry could measure temperature in a non-contact and remote way and could find great potentials in micro/nano-electronics, integrated photonics, and biomedicine. On the basis of the dual-emitting combination strategy involving the white broadband CT (Ti3+→O−) emissions of the titanate groups and red sharp Eu3+emissions, t-ZrO2:Eu3+nanophosphors were demonstrated to be ratiometric self-referencing optical thermometric materials, with a working range of 130–230 K and a maxima of relative sensitivity of ~1.9% K−1at 230 K.
研究领域:
材料科学
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纳米技术
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光学
·
测温技术
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产品关联
DOI
高影响因子
LUMINESCENCE
·
2025
·Vol. 40
·期 7
·e70255
·
IF 3
Keyue Wu,Yi Yang,Zeya Wang
Near-infrared (NIR) phosphors activated by Cr 3+ ions hold significant potential for applications such as night vision and plant growth lighting due to their tunable emission properties governed by crystal field (CF) strength. In this study, Cr 3+ and Ti 4+ co-doped MgO phosphors were synthesized via a high-temperature solid-state reaction to modulate the NIR emission. Structural and optical characterizations revealed that Ti 4+ incorporation enhances the CF strength ( D q/ B ratio increases from 2.4 to 2.6), inducing a blue shift in the emission peak from 810 (MgO:Cr 3+ ) to 780 nm (Mg 0.8 Ti 0.2 O:Cr 3+ ) and with a strong sharp emission at 720 nm. The Ti 4+ doping also increases the fluorescence lifetime from 150.9 to 816.4 μs, attributed to altered Cr 3+ occupancy in octahedral sites and modified spin-allowed transitions. These findings demonstrate that Ti 4+ co-doping effectively tunes the NIR emission of MgO:Cr 3+ phosphors, offering a promising strategy for designing wavelength-adjustable NIR light sources.
研究领域:
材料科学
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光学材料
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固体物理
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光子学
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产品关联
DOI
PubMed
高影响因子
ChemSusChem
·
2023
·Vol. 16
·期 19
·e202300607
·
IF 8.4
Jinmei Wu,Jianwen Yang,Jiawei Zheng,Mengwen Wang,Shengxian Li,Bin Huang,Yanwei Li,Qing Zhu,Quanqi Chen,Shunhua Xiao,Botian Liu
Graphical Co - doping modification of LiNiO 2 : The replacement of Ni atoms with Al 3+ and Ti 4+ ions respectively can improve the charge/discharge cycling performance of LiNiO 2 cathode materials, and their co-doping can more efficiently suppress the Ni 2+ /Li + cation mixing, irreversible phase transition of H2 and H3. Thus, the electrochemical performances exhibit significant synergistic effects. LiNiO 2 cathode material for lithium-ion batteries has the advantages of high specific capacity, abundant resources, and low cost, but it suffers from difficulties in preparation, structural instability, and serious capacity decay. In this work, highly pure and layered structural LiNi 0.95 Al a Ti 0.05- a O 2 ( a =0, 0.025, 0.05) cathode materials were synthesized by a simply sol-gel method. The cation mixing of Ni 2+ and Li + , structural deterioration, irreversible conversion between H2 and H3 phases and unstable surface and CEI (Cathode-electrolyte interface) film can be effectively suppressed by co-doping with Al 3+ and Ti 4+ . A preferred LiNi 0.95 Al 0.025 Ti 0.025 O 2 sample provides a discharge specific capacity of 223 mAh g −1 at 0.1 C and 148.32 mAh g −1 at 5 C, a capacity retention of 72.7 % after 300 cycles at 1 C and a Li + diffusion coefficient of about 2.0×10 −9 cm 2 s −1 .
研究领域:
材料科学
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电化学
✓ 已验证
DOI
PubMed
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2024
·
IF 5.8
Bei Ren,Ziqian Meng,Bixian Zhang,Sihao Jian,Chufei Cheng,Jiadong Hou,Ruixin Hao,Bo Li,Yang Miao,Chao Ma,Weihua Ji
High-entropy fluorite oxide ceramics are promising candidates for spacecraft applications due to their excellent high-temperature thermal-mechanical properties. In this work, four kinds of high-entropy fluorite oxide ceramics ((ZrHfCeYEr) (1-x)/5 Ti x )O 2-δ (HEFOs, x = 0, 0.025, 0.05, 0.075) with different Ti 4+ contents were successfully synthesized through solid-state reaction method with conventional sintering. They all exhibited phase stability when annealed at 1500 ℃ for 20 h. When the content of Ti 4+ was increased to x = 0.075, the thermal conductivity reduced to1.34 W·m −1 ·K −1 at 1100 ℃, and the hardness and elastic modulus increased to 14.01 GPa and 205.70 GPa, respectively. Furthermore, the cyclic thermal shock resistance of HEFOs at different temperatures was investigated. The initial flexural strength reached 219.03 MPa when the content of Ti 4+ was increased to x = 0.075. After 60 thermal shock cycles at 1200 ℃ and 1500 ℃, the residual strength ratios were 97.56 % and 83.36 %, respectively. The results of this study establish the foundation for future applications of high-entropy fluorite oxide ceramics in spacecraft hot-end components.
研究领域:
材料科学
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航天工程
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产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2020
·
IF 4.65
Ziqing Li,Pengfei Zhu,Jimin Ding,Yang Chen,Zhenyan Wang,Nianjing Ji,Xiulan Duan,Huaidong Jiang
Inorganic upconversion materials show significant importance in both basic research and applied area, and searching for suitable host material and understanding of fundamental photophysical process are particularly worth studying in upconversion application. Herein, a heavily Yb 3+ -substituted langbeinite-type Rb 2 Ti 0.80 Yb 1.20 (PO 4 ) 3 (RTYP) millimeter-sized single crystal, which has been successfully grown by high temperature solution method, exhibits efficient dual-color upconversion photoluminescence under 980 nm excitation. The lifetimes of two-photon blue emission and one-photon red emission are 4.1 μs and 17.1 μs, respectively. X-ray structural analyses reveal that the dual-color emissions are ascribed to disordered Yb 3+ -Ti 4+ pairs and crystal defect, and the higher intensity of red emission is attributed to Yb 3+ -defect energy transfer activated by Ti 4+ . Notably, the blue emission originates from cooperative luminescence of Yb 3+ dimer, and the red emission originates dominantly from the cooperative sensitization of the intrinsic defect caused by excited Yb 3+ dimer. Moreover, RTYP with disordered structure shows high thermal stability up to 1,150 °C. This work not only demonstrates the promising potential of langbeinite-type materials in multicolor upconversion application, but also sheds light on the photophysical process associated with disordered crystal structure.
研究领域:
无机材料科学
·
光学
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产品关联
DOI
高影响因子
Advanced Science
·
2023
·Vol. 10
·期 32
·2304067
·
IF 15.1
Lin-Rong Wu,Yu-Han Zhang,Zhen Wu,Jinlv Tian,Haorui Wang,Haijun Zhao,Shoudong Xu,Liang Chen,Xiaochuan Duan,Ding Zhang,Huijuan Guo,Ya You,Zhi Zhu
High-capacity O3-type layered sodium oxides are considered one of the most promising cathode materials for the next generation of Na-ion batteries (NIBs). However, these cathodes usually suffer from low high-rate capacity and poor cycling stability due to structure deformation, native air sensitivity, and interfacial side reactions. Herein, a multi-site substituted strategy is employed to enhance the stability of O3-type NaNi 0.5 Mn 0.5 O 2 . Simulations indicate that the Ti substitution decreases the charge density of Ni ions and improves the antioxidative capability of the material. In addition, the synergistic effect of K + and Ti 4+ significantly reduces the formation energy of Na + vacancy and delivers an ultra-low lattice strain during the repeated Na + extraction/insertion. In situ characterizations verify that the complicated phase transformation is mitigated during the charge/discharge process, resulting in greatly improved structure stability. The co-substituted cathode delivers a high-rate capacity of 97 mAh g −1 at 5 C and excellent capacity retention of 81% after 400 cycles at 0.5 C. The full cell paired with commercial hard carbon anode also exhibits high capacity and long cycling life. This dual-ion substitution strategy will provide a universal approach for the new rational design of high-capacity cathode materials for NIBs.
研究领域:
材料科学
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电化学
·
电池技术
✓ 已验证
DOI
高影响因子
ANALYTICAL AND BIOANALYTICAL CHEMISTRY
·
2024
·Vol. 416
·期 29
·7151-7159
·
IF 3.8
Chen Jiakai,Zhou Xinyue,Cao Zhenzhen,Wang Bing,Ding Chuan-Fan,Yan Yinghua
When it comes to the early detection of colorectal cancer (CRC), the study of protein phosphorylation is crucial. This work used magnetic covalent organic framework (COF) materials as substrates. The magCOF@PM-Ti 4+ composites were obtained by constructing the three-dimensional cross-linked structures and chelating them with Ti 4+ in a green and economical way, which was utilized to identify the phosphopeptides. This material possesses magnetic properties that facilitate simplified experimental manipulation, has superior sensitivity (0.2 fmol), excellent selectivity (1000:1), and good reusability (10 cycles), and achieves outstanding recovery rates (103.4 ± 1.2%). In addition, magCOF@PM-Ti 4+ was utilized to identify phosphopeptides in human serum. One hundred phosphopeptides were identified from three normal control serums, whereas 98 phosphopeptides were identified from three CRC serums. The results demonstrated that magCOF@PM-Ti 4+ has great potential in efficiently identifying low-abundance phosphopeptides.
研究领域:
生物化学
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癌症研究
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）