SCRIPTA MATERIALIA
·
2019
·
IF 4.539
Qingshuang Ma,Feng Lan,Xinhua Li,Zunfeng Du,Huijun Li,Zongqing Ma
In this work, the superconducting properties of FeSe 1−x S x with 0 ≤ x ≤ 0.5 were studied. With S doping, T c is enhanced and shows a dome shape in the studied composition range. XRD measurements demonstrate that S substituting Se sites introduces positive chemical pressure, which can suppress the orbital ordering, manifesting as the decrease of T s . Hall measurements demonstrate that S doping can effectively tune the charge carriers and make hole-type carriers predominant. However, no maxing T c is obtained as T s vanishes in FeSe 0.7 S 0.3 , indicating the nematic order has no universal influence on the superconductivity of FeSe system.
研究领域:
凝聚态物理
·
材料科学
·
低温物理学
·
强关联电子系统
✓ 已验证
DOI
高影响因子
POLYMER DEGRADATION AND STABILITY
·
2014
·
IF 2.633
Guang-Rui Xu,Miao-Jun Xu,Bin Li
The cyclotriphosphazene-based epoxy resin hexa-[4-(glycidyloxycarbonyl) phenoxy]cyclotriphosphazene defined as CTP-EP was successfully synthesized from hexachlorocyclotriphosphazene, p -hydroxybenzaldehyde and epichlorohydrin. Its chemical structure was characterized by Fourier transform infrared (FTIR) spectroscopy, 1 H NMR, 13 C NMR and 31 P NMR spectroscopy . The prepared compound was cured with diamino diphenyl methane (DDM), diamino diphenyl sulfone (DDS) and m -phenylenediamine (mPDA), respectively. The flame retardant properties, thermal degradation behavior and flame retardant mechanism of the cured CTP-EP were investigated. The LOI values of all cured CTP-EP samples increased from 19.9% for cured diglycidyl ether of bisphenol-A (DGEBA) to above 30% and successfully passed UL-94 V-0 rating, which demonstrated that the prepared CTP-EP thermoset exhibited excellent flame retardancy. The dynamic mechanical thermal analysis (DMA) test demonstrated that the glass transition temperature ( Tg ) enhanced from 155 °C for the cured DGEBA to 167 °C for CTP-EP thermoset . The results of thermogravimetric analysis/infrared spectrometry (TG-IR) tests suggested that the phosphazene group and high aromatic content in CTP-EP thermoset stimulated the dehydration of the matrix at earlier degradation process and the formation of char layer, which retarded the release of pyrolysis gas and enhanced the thermal stability of the cured CTP-EP at high temperature. The cone calorimeter tests (cone) test revealed that heat release rate (HRR), total heat release (THR), smoke production rate (SPR) and total heat production (TSP) of the cured CTP-EP decreased significantly compared with the cured DGEBA. The scanning electron microscopy (SEM) results showed that the phosphazene groups in CTP-EP obviously stimulated the formation of the intumescent, compact and stable char layer, which enhanced the flame retardancy of the matrix during combustion. Consequently, the underlying materials were protected from further degradation and combustion during a fire and result in the efficient flame retardancy of CTP-EP thermoset.
研究领域:
高分子化学
·
材料科学
·
热分析
·
阻燃材料
·
聚合物化学
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
·
IF 4.175
Liang Zheng,Wenjie Zhang,Qi Wang,Hong Zhang,Zhou Yu,Cuihua Cheng,Yong Zhang,Ming Lei,Yong Zhao
MgB 2 bulks with NaCl doping amount ranging from 0–30 at% have been prepared by hot pressed sintering process . With the increase of NaCl doping amount, the c axis lattice parameter of MgB 2 monotonously increases, indicating the substitution of Mg atoms by larger Na atoms. Meanwhile, the intensity of diffraction peaks of both NaCl and impurity phase of MgO increases. More compact morphology was found in the NaCl doped MgB 2 samples. The critical transition temperature ( T c ) decreases from 38.2 K to 36.8 K with the increase of NaCl doping amount from 0 to 30 at%, and the corresponding transition width of T c (Δ T c ) increases from 0.5 K to 1.8 K. When the doping amount of NaCl is not exceeding 10 at%, the J c value is about 10 6 A/cm 2 at 4.2 K, 3 T, and 5 × 10 5 A/cm 2 at 10 K, 3T. J c performance of the 5 at% NaCl doped MgB 2 sample (NC05) reaches 6.8 × 10 5 A/cm 2 at 20 K, 2T, which improves approximately 20% compared to the pure one, attributing to the better grain connectivity of MgB 2 and enhancement of flux pinning force by NaCl doping.
研究领域:
凝聚态物理
·
材料科学
·
超导材料
·
无机固体化学
·
功能陶瓷
✓ 已验证
DOI
高影响因子
POLYMER BULLETIN
·
2024
·Vol. 81
·期 11
·10175-10185
·
IF 3.1
Hu Jing,Wang Guoqiang
Polylactic acid (PLA) is a kind of polyester from biomass. To increase the ductility of PLA, melt blending was used to prepare the polylactic acid/poly(butylene diglycolate) blends in this study. The effect of poly(butylene diglycolate) (PBD) on the thermal, crystallization, tensile, and dynamic mechanical properties of PLA was investigated. The blend containing 30 wt% PBD has a substantially improved elongation at break (79%) due to the lower glass transition temperature of PBD compared to PLA. The results indicated that PLA and PBD exhibited partial compatibility, which was confirmed by dynamic mechanical analysis (DMA) and scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FTIR) analysis showed there is the interaction between PLA and PBD. In summary, the incorporation of PBD resulted in improved mechanical properties, indicating potential for applications requiring enhanced ductility.
研究领域:
高分子材料科学
·
生物医用材料
·
聚合物共混
·
材料力学性能
·
可降解高分子
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）