Effects of cobalt and sintering temperature on electrical properties of Ba0.98Ca0.02Zr0.02Ti0.98O3 lead-free ceramics

Lead-free (Ba_0.98Ca_0.02)(Zr_0.02Ti_0.98)O₃-xmol% (x = 0–1.6) cobalt ceramics (BCZT-xCo) have been fabricated by the traditional solid-state reaction technique and the effects of Co and sintering temperature on ferroelectric, dielectric and piezoelectric properties of (Ba_0.98Ca_0.02)(Zr_0.02Ti_0.98)O₃ lead-free ceramics have been studied systematically. The orthorhombic–tetragonal (T _O–T) transition shift towards lower temperature with increasing Co addition, while Curie temperature (T _c) remained at relatively high value of 107 °C. And the Main piezoelectric parameters are optimized at x = 0.8 mol% with a high piezoelectric coefficient (d ₃₃ = 330 pC/N), a planar mode electromechanical coupling factor (k _p = 46.7 %), a high dielectric constant (ε _r = 2,675) and a low dielectric loss (tanδ = 0.90 %) at 1kHZ. Besides these, high remnant polarization (P _r) and low coercive field (E _c) of 11.5 μC/cm², 0.31 kV/cm are also obtained at (Ba_0.98Ca_0.02)(Zr_0.02Ti_0.98)O₃-0.8 mol%Co lead-free ceramics. Furthermore, greatly enhanced temperature stability of the piezoelectric properties was obtained in the temperature range from 20 to 90 °C. The above results indicate that BCZT-Co ceramics are promising lead-free materials for practical applications.     

O Plasma Treatment Enhanced Room Temperature Ferromagnetism in MoS2

Journal of Superconductivity and Novel Magnetism - MoS2 is a typical two-dimensional material with promising optical and electrical properties. The realization of ferromagnetism in MoS2 is...     

La0.4Ca0.6Mn0.98Ru0.02O3中的电致电阻效应研究

单相多晶锰氧化物样品La_0.4Ca_0.6Mn_0.98Ru_0.02O₃具有典型的电子相分离基态, 即低温下铁磁金属相与电荷有序绝缘相共存并竞争, 这为我们研究电致电阻效应提供了很好的模型。本论文基于此目的, 采用固相合成法制备了La_0.4Ca_0.6Mn_0.98Ru_0.02O₃的多晶陶瓷样品, 用X射线衍射证明了样品是单相, 并详细测量了样品的电致电阻效应。实验结果表明, 该体系的电阻率能够在大范围内被输入电流调控, 获得的电致电阻效应高达80%以上。此外, 低温下该样品的电阻态可以通过改变电流输入强度进行连续转换, 反映了样品基态在电流的激发下发生了改变。通过讨论, 我们认为这些观测到的物理效应起源于输入电流提升了样品中的铁磁金属相的稳定性。     

Si-based Multielement Thin Film Prepared by r.f. Reactive Sputtering at Room Temperature

Hydrogenatedam0rphousSi-basedthinfilmsareofinterestfortheapplicationsinelectr0nicdevicesin-cludinglightemittingdiodes,photodetect0rsandsolarenergycollectors.Theycanals0beusedasprotectivelayerspreventingcorrosionandpassivationc0atings.Silicon,carb0nnitridehydrogenatedamorph0usthinfilm(aSi:C:N:H)isoneofSi-basedfilms.Itsphysi-calandchemicalpropertiesprobablyintegratingtheexcellentcharacteristicsofa-SiC:Handa-SiN:Hfilmsareinterestingtoresearchw0rkers.Inthepresentwork,aSi:C:N:Hthinfilmswered…     

强磁靶共溅射法制备具有室温磁电阻特性的Co-TiO2纳米复合薄膜

Co-TiO₂纳米复合薄膜作为一种新型自旋电子材料, 由于具有良好的生物相容性, 近年来受到广泛关注。但在制备过程中, 磁性金属Co处于氧化气氛, 容易部分氧化, 从而影响薄膜的隧道磁电阻性能。为了抑制磁性金属的氧化, 提高金属态含量, 本研究通过强磁靶共溅射法制备了Co-TiO₂纳米复合薄膜。该方法采用的强磁靶头, 磁场强度高、分布均匀, 可以提高溅射粒子的能量和溅射速率, 降低因高能粒子碰撞而发生氧化的概率。因此强磁靶共溅射法能明显抑制金属Co的氧化, 提高纳米复合薄膜的自旋极化率。所制备的Co-TiO₂纳米复合薄膜主要由非晶态的TiO₂基体和分散其中的Co颗粒组成。通过调节金属Co颗粒尺寸和分布状态, 在电学上实现了金属态向绝缘态转变, 在磁学上实现了铁磁性向超顺磁性转变。Co含量为51.3at%时, Co-TiO₂纳米复合薄膜表现为高金属态和高电阻率, 并且实现了高达8.25%的室温隧道磁电阻。强磁靶共溅射法使Co-TiO₂纳米复合薄膜的室温磁电阻性能得到了进一步提高, 这对于磁性金属—氧化物纳米复合薄膜的研究有着重要的意义。     

Influence of annealing temperature on structural, optical and magnetic properties of Zn0.97Cu0.01V0.02O nanoparticles

Zn_0.97Cu_0.01V_0.02O nanoparticles have been successfully prepared by the sol–gel method and sintered in air at the different temperature. The effects of the annealing temperature on the structural, optical and magnetic properties of the obtained samples were studied. The X-ray diffraction (XRD) results showed that the Zn_0.97Cu_0.01V_0.02O nanoparticles was single phase with the ZnO-like wurtzite structure when the annealing temperature was <700 °C. The photoluminescence (PL) spectra revealed that as the annealing temperature increased, the intensity of the UV emission increased and the green emission enhanced significantly. Magnetic measurements indicated that the samples exhibited ferromagnetism at the room temperature. The results of XRD, transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) revealed that there was no ferromagnetic-related secondary phase in Zn_0.97Cu_0.01V_0.02O nanoparticles, the ferromagnetism of the Zn_0.97Cu_0.01V_0.02O samples was originated from the fact that the Cu and V ions doped into the ZnO lattice. In addition, the saturation magnetization (Ms) increased with the enhancement of the annealing temperature.     

沉积温度对化学气相沉积法制备铜薄膜性质的影响

以双(2,2,6,6-四甲基-3,5-庚二酮)化铜(Cu(DPM)₂)为前驱体,使用智能化学气相沉积设备在673 K至1173 K下于AlN多晶基板上制备Cu薄膜。研究了不同沉积温度对Cu薄膜的相组成、择优取向、宏观表面、微观结构、元素组成及电导的影响。在873 K至1173 K时制备了具有(111)择优取向的紫铜色铜薄膜,同时存在(200)和(220)取向,且铜晶粒呈岛状生长模式。随着沉积温度的升高,薄膜的导电性先增强后减弱。在1073 K时,制得了导电性最好且高度(111)择优取向的最纯紫铜色Cu薄膜,即1073 K为制备Cu薄膜的最佳沉积温度。     

Magnetic and Transport Properties of Mn()l)8Cr()()2Te Epitaxial Films Grown on A1,0、Substrates

The epitaxial Mno0.98Cr0.02Te films on single crystal Al2O3 （0001） substrates were prepared by pulsed laser deposition. The X-ray diffraction and scanning electron microscopy results showed that the good continuous epitaxial film was obtained with substrate temperature of 500 ℃. When the substrate temperature reached 700 ℃, the film was island growth and the manganese oxides phase appeared. The temperature dependence of both the magnetization and electrical resistance showed a sharp rise at around 60 K due to the magnetoelastic coupling. The temperature dependence of the electrical resistance of Mno0.98Cr0.02Te provided evidence for a transition from the metallic to semiconducting state at 305 K due to the spin disorder scattering with a large contribution from the influence of magnon drag.     

射频磁控室温溅射(Pb,La)TiO3薄膜退火前后的原子力显微镜分析

采用射频磁拉溅射技术在室温溅射（Ｐｂ,Ｌａ）ＴｉＯ３（ＰＬＴ）薄膜,在６００℃下退火２ｈ,通过对ＸＲＤ谱图和ＡＦＭ照片分析,发现薄膜结晶良好,已形成均匀、连续、致密、表面平滑的完全钙钛矿结构的ＰＬＴ铁电薄膜,退火对薄膜表面的粗糙度影响不大,薄膜的表面粗糙度主要由淀积过程决定。     

常温发黑磷化膜层结构与耐蚀性的探讨

介绍了在钢铁常温发黑膜上,形成完整致密磷化膜的工艺,提出了其膜层结构假设。并用该结构解释了生产中常温发黑磷化膜具有高耐蚀性能的现象。     

Effect of Annealing Temperature on Structural and Magnetic Properties of Zn0.94Co0.05Cu0.01O

The doped ZnO system Zn_0.94Co_0.05Cu_0.01O (ZCCO) was prepared as a nano-polycrystalline by a simple sol–gel process, then air annealed at different temperatures. Applying X-ray diffraction (XRD) and the Rietveld method, structural analysis showed that Co and Cu replace Zn substitutionally yielding ZCCO single phase. The refined u-fractional coordinate of Zn increases monotonically by an annealing temperature from 0.3546 at 500 °C reaching 0.3722 at 800 °C, very near from the ideal value 0.375. The Zn tetrahedrons become more symmetric and the distortion is gradually relieved by annealing up to 800 °C. Annealing at 900 °C introduces tetrahedron distortion in an opposite way. The zero field cooled (ZFC) and field cooled (FC) magnetization versus the temperature at different applied fields and the magnetization versus the applied field at different temperatures were carried out. The system exhibits a ferromagnetic behavior at room temperature. As the annealing temperature increases from 550 to 900 °C, the saturation magnetization at 300 K increases from 0.0507 to 0.1088 emu/g.     

Optical properties of photoluminescent polycrystalline CuLa0.98Eu0.02O2 thin film prepared by pulsed laser deposition at room temperature

Smooth CuLa_0.98Eu_0.02O₂ thin film has successfully been prepared by pulsed laser deposition method at room temperature. Crystal structure of the obtained film was almost same as that of CuLa_0.98Eu_0.02O₂ polycrystalline ceramic. Orange luminescence with high intensity due to ⁵D₀ – ⁷F_0,1 transitions of Eu³⁺, which was an evidence of Eu³⁺ substitution for La³⁺ site in LaO₆ octahedra with the inversion symmetry, was also observed in the obtained film. The optical band gap of CuLa_0.98Eu_0.02O₂ was measured to be 2.85 eV from absorption spectroscopy.     

Cu-doping effect on the structural, optical and photoluminescence properties of Sn0.98Cr0.02O2 nanoparticles by co-precipitation method

Sn_0.98-xCr_0.02Cu_xO₂ nanoparticles were prepared by co-precipitation method with different Cu concentrations from x = 0 to 0.05 and annealed at 600°C for 2 h in air atmosphere. The prepared particle were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectra, UV–visible spectrophotometer, and Fourier transform infrared spectroscopy. The XRD measurement reveals that the prepared nanoparticles have different microstructure without changing a tetragonal structure. The calculated average crystalline size decreased from 12.2 to 10.5 nm for x = 0–0.02 then gradually increased up to 16.8 nm for x = 0.05 which were confirmed by Scanning electron microscope. The optical studies were done by UV–visible spectrometer and the energy band gap values were calculated from absorption spectra. A small red shift from 3.52 eV (Cu = 0) to 3.49 eV (Cu = 0.02, ΔE_g = 0.03 eV) at lower Cu concentrations and a remarkable blue shift from 3.49 eV (Cu = 0.02) to 3.71 eV (Cu = 0.05, ΔE_g = 0.22 eV) at higher Cu concentrations is due to Cu-doping in Cr–SnO₂ matrix. The presence of functional groups and the chemical bonding is confirmed by Fourier transforms infrared spectra. PL spectra of Sn_0.98-xCr_0.02Cu_xO₂ nanoparticle described the shift in UV emission from 366 to 381 nm (red shift) and a shift in blue band emission from 458 to 482 nm (red shift) which confirms the Cu-doping in Cr–SnO₂ matrix. The doping of Cu in the present system is useful to tune the emission wavelength and hence is appreciable for the fabrication of nano-optoelectronic devices and photo-catalytic applications.     

(K0.45Na0.55)0.98Li0.02Nb0.77Ta0.18Sb0.05O3-Co0.85Cu0.15Fe2O4复合陶瓷的磁电性能研究

以压电体(K0.45Na0.55)0.98Li0.02Nb0.77Ta0.18Sb0.05O3和压磁体Co0.85Cu0.15Fe2O4为原料,通过传统的固相反应法制备了(1-x)[(K0.45Na0.55)0.98Li0.02Nb0.77Ta0.18Sb0.05O3]-xCo0.85Cu0.15Fe2O4多铁性复合陶瓷,并使用X射线衍射仪、扫描电子显微镜、压电测试仪、铁电测试仪和磁电耦合测试仪对物相、显微结构、压电、铁电、磁电耦合性能进行了分析。结果表明,复合陶瓷的相结构保持为(K0.45Na0.55)0.98Li0.02Nb0.77Ta0.18Sb0.05O3和Co0.85Cu0.15Fe2O4两种物相,但两者之间发生了轻微的化学反应。随着Co0.85Cu0.15Fe2O4压磁相含量的增加,复合陶瓷的压电系数从56pC/N减小到21pC/N,剩余极化强度略有降低。在压磁相含量为0.2时可获得4.3mV·cm-1·Oe-1的最佳磁电耦合系数。     

室温固相合成纳米ZnS及其气敏性能研究

以无机盐ZnSO₄·7H₂O和Na₂S·9H₂O为原料,用室温固相化学反应合成了ZnS;用XRD、TEM对产物的组成、大小、形貌进行了表征;用TG-DTA确定了ZnS的稳定温区.结果表明,产物为纳米颗粒,平均粒径为15nm左右,且610℃以下能在空气中稳定存在.另外还采用静态配气法测定了材料的气敏性能,发现ZnS对H₂S有很高的灵敏度,且抗干扰能力强,有很好的应用前景.