|
|
|
题名
|
作者
|
年代
|
出处
|
被引量
|
| 1 | First-order phase transition and unexpected rigid rotation mode in hybrid improper ferroelectric(La,Al)co-substituted Ca_(3)Ti_(2)O_(7) ceramics显示文摘Ca_(3)Ti_(2)O_(7) with Ruddlesden-Popper structure exhibits the largest polarization among the known hybrid improper ferroelectrics.However,the high Curie temperature impedes the thorough study of phase transition through dielectric characterization.According to the previous theoretical design rule,the Curie temperature can be suppressed by increasing the tolerance factor.So,in the present work,high-quality Ca_(3-x)LaxTi_(2-x)Al_(x)O_(7)(x=0.0,0.1,0.2,0.3)ceramics with increased tolerance factors were successfully prepared.The amplitude of oxygen octahedral tilt mode indeed decreases with increasing tolerance factors,leading to a degeneration of ferroelectric polarization.However,the unexpected rigid rotation mode causes the composition-invariable coercive fields.The Curie temperatures decrease linearly with increasing x and tolerance factors.The variable-temperature dielectric constant confirms first-order improper ferroelectric transitions in Ca_(3)Ti_(2)O_(7)-based ceramics.The results of variable temperature Xray diffraction reveal the coexistence of two-phases below Curie temperature.The present work confidently confirms the first-order improper ferroelectric transition in Ca_(3)Ti_(2)O_(7)-based ceramics by combining results of variable-temperature dielectric response and in-situ X-ray powder diffraction. | Z.Z.Hu J.J.Lu B.H.Chen T.T.Gao X.Q.Liu W.Wen X.M.Chen | 2019 | Journal of Materiomics2019，5，4： | 4 |
| 2 | EFFECT OF HEAT TREATMENT ON MECHANICAL PROPERTIES OF 0Cr12Mn5Ni4Mo3Al显示文摘In this work, the effect of solid soluble temperature, cold treating temperature and aging temperature on the mechanical properties of 0Crl2Mn5Ni4Mo3Al had been investigated systemically.The results show that under the optimal parameters (solid soluble treatment 1050℃×40min, cold treatment -78℃×4h, aging treatment 520℃×2h) the properties (stren.qth and tenacity) could be up to its maximum. | Y.L.Guo X.Q.Liu X.M. Zhang J.T.Niu Analyse-Tset Center of Harbin Institute of Technology,Harbin 150001,China | 2004 | Acta Metallurgica Sinica(English Letters)2004，17，2： | 2 |
| 3 | Role of extrusion rate on the microstructure and tensile properties evolution of ultrahigh-strength low-alloy Mg-1.0Al-1.0Ca-0.4Mn(wt.%)alloy显示文摘Mg-1.0Al-1.0Ca-0.4Mn(AXM1104, wt.%) low alloy was extruded at 200 ℃ with an extrusion ratio of 25 and different ram speeds from 1.0 to 7.0 mm/s. The influence of extrusion rate on microstructure and mechanical properties of the AXM1104 alloy was systematically studied. With the increasing of extrusion rate, the mean dynamically recrystallized(DRXed) grain size of the low alloy and average particles diameter of precipitate second phases were increased, while the degree of grain boundary segregation and the intensity of the basal fiber texture were decreased. With the rising of extrusion rate from 1.0 to 7.0 mm/s, the tensile yield strength(TYS) of the as-extruded AXM1104 alloy was decreased from 445 MPa to 249 MPa, while the elongation to failure(EL) was increased from 5.0% to 17.6%. The TYS, ultimate tensile strength(UTS) and EL of the AXM1104 alloy extruded at the ram speed of 1.5 mm/s was 412 MPa, 419 MPa and 12.0%, respectively,exhibiting comprehensive tensile mechanical properties with ultra-high strength and excellent plasticity. The ultra-high TYS of 412 MPa was mainly due to the strengthening from ultra-fine DRXed grains with segregation of solute atoms at grain boundaries. The strain hardening rate is increase slightly with increasing extrusion speed, which may be ascribed to the increasing mean DRXed grain size with rising extrusion speed. The higher strain hardening rate contributes to the higher EL of these AXM1104 samples extruded at higher ram speed. | X.Q.Liu X.G.Qiao R.S.Pei Y.Q.Chi L.Yuan M.Y.Zheng | 2023 | Journal of Magnesium and Alloys2023，11，2： | 2 |
| 4 | Gomplex-permittivity Measurement on High-Q Materials Via Combined Numerical Approaches显示文摘 | X.C.Fan X.M.Chen X.Q.Liu | | 0，，10： | 1 |
| 5 | Structure and Microwave Dielectric Characteristics of Ca1-x-xNd2x/3 TiO3 Ceramics显示文摘 | M.S.Fu X.Q.Liu X.M.Chen | | 0，，03： | 1 |
| 6 | New solutions of the 3+1 dimensional Jimbo-Miwa equation显示文摘 | X.Q.Liu S.Jiang | | 0，，： | 1 |
| 7 | Room-temperature ferroelectricity in A-site ordered Ruddlesden-Popper Li_(2)CaTa_(2)O_(7) ceramics显示文摘In the present work,the crystal structure,ferroelectric and dielectric properties of the dense single-phase Li_(2)CaTa_(2)O_(7) ceramics with A-site ordered double-layer Ruddlesden-Popper structures have been investigated by the experiments and first-principles calculations.A polar Pna21 phase was determined by the Rietveld refinement against the X-ray diffraction pattern at room temperature,and it was confirmed by its lowest calculated energy and rigid phonon modes.The ferroelectricity was found by observing the ferroelectric hysteresis loop at room temperature,and its remanent polarization was similar to the value calculated from the Berry phase and Born effective charge approaches.The ferroelectricity is a nonconventional proper one since its polarization is induced from the displacement of oxygen anions instead of tantalum cations based on the individual atomic polarization.A first-order transition from an antiferroelectric to paraelectric phase around 900 K was found by the DSC and variable-temperature dielectric measurements.From the present work,the room-temperature ferroelectricity is experimental confirmed in the present ceramics,inspiring the search for new ferroelectricity in the ceramics with A-site ordered Ruddlesden-Popper structures. | B.H.Zhang Z.Z.Hu B.H.Chen X.Q.Liu X.M.Chen | 2020 | Journal of Materiomics2020，6，3： | 0 |
您所在的机构暂未开通此部分的功能，请联系管理员