Metal-ion doping can effectively regulate the metal-insulator transition temperature in $\mathrm{VO}_2$. Experiments found that the pentavalent and hexavalent ion doping dramatically reduces the transition temperature while the trivalent ion doping increases the transition temperature and induces intermediate phases. Based on the phase-field model of the metal-insulator transition in $\mathrm{VO}_2$ we developed previously, we formulate a Landau potential of the metal-ion-doped $\mathrm{VO}_2$ taking account of the effects of doping on the electron correlation and lattice structure. The effect of metal-ion doping on the lattice structure is accounted for in a phenomenological way. Using the Landau potential, we calculate the temperature-dopant-concentration phase diagrams of $\mathrm{VO}_2$ doped with various metal ions consistent with the experiments and provide explanation to the different behaviors of different metal-ion doping. The phenomenological theory can provide estimations of phase diagrams of $\mathrm{VO}_2$ doped with other metal ions.
Theoretical investigation of the more suitable rare earth to achieve high gain in waveguide based on silica containing silicon nanograins doped with either Nd3+ or Er3+ ions
Modeling of optical amplifier waveguide based on silicon nanostructures and rare earth ions doped silica matrix gain media by a finite-difference time-domain method: comparison of achievable gain with Er3+ or Nd3+ ions dopants
Mn2+-doped semiconductor nanocrystals with tuned location and concentration of Mn2+ ions can yield diverse coupling regimes, which can highly influence their optical properties such as emission wavelength and photoluminescence (PL) lifetime. However, investigation on the relationship between the Mn2+ concentration and the optical properties is still challenging because of the complex interactions of Mn2+ ions and the host and between the Mn2+ ions. Here, atomically flat ZnS nanoplatelets (NPLs) with uniform thickness were chosen as matrixes for Mn2+ doping. Using time-resolved (TR) PL spectros…
We report depth-resolved photoluminescence measurements of nitrogen-vacancy (NV$^-$) centers formed along the tracks of swift heavy ions (SHIs) in type Ib synthetic single crystal diamonds that had been doped with 100 ppm nitrogen during crystal growth. Analysis of the spectra shows that NV$^-$ centers are formed preferentially within regions where electronic stopping processes dominate and not at the end of the ion range where elastic collisions lead to formation of vacancies and defects. Thermal annealing further increases NV yields after irradiation with SHIs preferentially in regions with …
The possibility of using mixed crystals highly doped with rare earth ions (REIs) as physical systems for creating fast quantum computers with a sampling time of nanoseconds is discussed. The electronic 4f states of rare earth ions with small values of the diagonal elements of the Judd-Ofelt matrix U(2) are proposed as optical frequency qubit levels. CNOT and other conditional gate operations are performed by exciting the rare earth ion into the 4f state with a large diagonal element of U(2), causing a Stark blockade. It is found that the main interaction responsible for this blockade is the qu…
Photoluminescence, thermally stimulated luminescence (TSL) and EPR characteristics of the Ce3+ doped single crystals of multicomponent Y1Lu2GaxAl5-xO12 and Lu3GaxAl5-xO12 garnets with different Ga contents (x = 0, 1, 2, 3, 4, 5) excited in the Ce3+ - related absorption bands are investigated in the 9 - 500 K temperature range. The distribution of Ga3+ and Al3+ ions in the crystal lattice is determined by the NMR method. The relative number of Ga3+ ions in the tetrahedral crystal lattice sites, the maxima positions of the TSL glow curve peaks and the corresponding trap depths are found to decre…
The current work studies the effect of sintering conditions on the densification behavior, microstructure, and electrochemical performance of 6 mol% Sc2O3, 1 mol% CeO2 co-doped ZrO2 (6Sc1CeZr) for solid-state electrolyte applications. The specimen's physical properties and electrochemical performance sintered at different temperatures ranging from 1000 °C to 1700 °C for 6 hours are examined through diffraction, microscopy, and Raman and electrochemical impedance spectroscopy. The activation energy and pre-exponential conductivity factor of the oxygen ions are calculated using a linear fit to t…
Manganese (Mn)-doped ZnS nanocrystals (NCs) have been extensively explored for optical applications with the advantages of low toxicity, large Stokes shifts, and enhanced thermal and environmental stability. Although numerous studies on Mn-doped ZnS dots, rods, and wires have been reported, the literature related to Mn-doped ZnS nanoplatelets (ZnS:Mn NPLs) is scarce. Here, we present the first example of direct doping of Mn2+ ions into ZnS NPLs via the nucleation-doping strategy. The resulting ZnS:Mn NPLs exhibit Mn luminescence, indicative for successful doping of the host ZnS NPLs with Mn2+ …
Synthesis of Homogeneous Manganese-Doped Titanium Oxide Nanotubes from Titanate Precursors
我们报道了一种新的合成方法，可以在很宽的浓度范围内均匀地掺杂锰元素钛白纳米管。以水热法制备的涡旋型三钛酸盐（H2 Ti 3 O 7）纳米管为前驱体，研究了纳米管的结构和性能。通过离子交换法引入Mn ~（2+），得到Mn（x）H（2-x）Ti（3）O（7）。在随后的热处理中，它们转变为Mn（y）Ti（1-y）O（2），其中y=x/（3+x）。利用电子自旋共振（ESR）技术研究了Mn ~（2+）离子在前驱体和最终产物中的存在状态和局部环境。结果发现，Mn 2+离子占据两个位置：第一个具有几乎完美的立方对称性，而另一个是在一个强烈扭曲的八面体网站。两个Mn ~（2+）位置的比例与掺杂水平无关，在Mn（x）H（2-x）Ti（3）O（7）中为15：85，在Mn（y）Ti（1-y）O（2）中为5：95。SQUID磁强计没有显示在均匀Mn 2+掺杂的纳米管的长程磁序。
A Cluster-Based Model of the Spectrum of Erbium-Doped GdVO$_4$
Basic Research Laboratories, NTT, Inc.（NTT公司基础研究所）；Department of Physics, University of Otago（奥塔哥大学物理系）；Dodd-Walls Centre for Photonic and Quantum Technologies（多德-沃尔斯光子与量子技术中心）
Transition metal oxides such as \ce{BiVO4} are promising materials as photoelectrodes in solar-to-fuel conversion applications. However, their performance is limited by the low carrier mobility (especially electron mobility) due to the formation of small polarons. Recent experimental studies show improved carrier mobility and conductivity by atomic dopings. We studied the small polaron hopping mobility in pristine and doped \ce{BiVO4} by combining Landau-Zener theory and kinetic Monte Carlo (kMC) simulation fully from first-principles, and investigated the effect of dopant-polaron interactions…
The rare-earth (RE) elements [Holmium (Ho) and Ytterbium (Yb)] doped vanadium pentoxide (V2O5) with a series of doping concentrations (1 mol.%, 3 mol.%, and 5 mol.%) have been successfully synthesized using environment-friendly facile hydrothermal method. The effect of RE ions on the photocatalytic efficiency of doped V2O5 has also been analyzed. The stable orthorhombic crystal structure of doped V2O5 confirms by the X-ray diffraction with no secondary phase, and high-stressed conditions are generated for the 3 mol.%. The crystallite size, strain, and dislocation density are calculated to perc…
Erbium-doped crystals offer a versatile platform for hybrid quantum devices because they combine magnetically-sensitive electron-spin transitions with telecom-wavelength optical transitions. At the high doping concentrations necessary for many quantum applications, however, strong magnetic interactions of the electron-spin bath lead to excess spectral diffusion and rapid decoherence. Here we lithographically fabricate a 4.4 GHz superconducting planar micro-resonator on a $\text{CaWO}_{4}$ crystal doped with Er ions at a concentration of twenty parts per million relative to Ca. Using the microw…
In this paper we study a role of F-centers, hole centers and excitons in energy transfer in Eu-doped BaBrI crystals. Optical absorption spectra, thermally stimulated (TSL) and photostimulated (PSL) luminescence in wide temperature range 7-300 K are studied in undoped and doped with different concentrations of Eu ions BaBrI crystals. Based on experimental and calculated results two possible energy transfer processes from host to Eu$^{2+}$ ions are established.
We present experimental evidence for the simultaneous existence of the magnons and spin-state transition contributions to the heat capacity in ferromagnetic (FM) Cr-doped MnTe (Tc~280K), where the magnon heat capacity is attributed to the observed magnon-bipolar carrier-drag thermopower. The pristine antiferromagnetic (AFM) MnTe shows only a magnon-induced peak in the heat capacity near the Neel temperature, TN~307K. However, Cr-doped MnTe shows a magnon-contributed heat capacity peak at ~293K with an additional peak in the deep paramagnetic domain near 780K. Temperature-dependent magnetic sus…
Phase stability of cation-doped LiMnO$_{2}$]{Phase stability of cation-doped LiMnO$_{2}$ within the GGA+U approximation
对锂离子电池的候选阴极材料LiMn $_{1-x}$ M $_x$ O $_{2}$（其中（$x=0.25$，M=Ni，Fe，Co，Mg））进行GGA+U近似内的第一原理密度泛函理论计算，以研究掺杂对单斜结构相对于层状菱面体结构的不稳定性的影响。这项工作的主要动机是确定在何种程度上的预测电子更现实的GGA+U治疗将不同于GGA内获得的。发现了一些显著的质的变化：对于菱形结构的原始体系，Mn离子在GGA+U中表现出高自旋态，而不是GGA中的低自旋（金属）态。掺杂的菱面体结构在GGA+U中是不稳定的，而不是像在GGA中那样是亚稳定的。在单斜结构中，GGA+U和GGA中的掺杂剂氧化态相同（三价Fe，二价Co，Ni）。Co和Ni离子在GGA+U中的自旋态比在GGA中的自旋态高。二价掺杂剂在GGA+U内比三价掺杂剂更大程度上使单斜结构不稳定，如从先前GGA计算所预期。总的来说，我们的研究结果表明，GGA和GGA+U中计算的性质之间的相对接近的协议有时可能是误导，因为潜在的电子行为可能是深刻的不同。
We theoretically investigated the electronic, electrochemical and magnetic properties of Sb doped $Na_xCoO_2$ ($x = 1, 0.75$ and $0.50$). $Sb_{Co}$ dopants adopt +5 oxidation state in $Na_xCoO_2$ host lattice for all Na concentrations ($x$). Due to high oxidation states, $Sb^{5+}$ strongly repels Na ions and therefore it decreases the electrochemical potential (vs. Na/Na$^+$). The electrons introduced by $Sb^{5+}$ localize on nearby Co ions creating $Co^{2+}$ species which are absent in undoped $Na_xCoO_2$. $Co^{2+}$ ions reduce the spin entropy flow decreasing the Seebeck coefficient in the S…
Er-doped aluminum nitride films, containing different Er concentrations, were obtained at room temperature by reactive radio frequency magnetron sputtering. The prepared samples show a nano-columnar microstructure and the size of the columns is dependent on the magnetron power. The Er-related photoluminescence (PL) was studied in relation with the temperature, the Er content and the microstructure. Steady-state PL, PL excitation spectroscopy and time-resolved PL were performed. Both visible and near infrared PL were obtained at room temperature for the as-deposited samples. It is demonstrated …
