The chemical ordering, electrical, optical, and magnetic properties of $Na_{0.5}Bi_{0.5}TiO_{3}$ (NBT) and 25$\%$ dysprosium doped NBT (DyNBT) were investigated in the framework of first-principles calculations using the full potential linearized augmented plane wave (FP-LAPW) method based on spin-polarized density functional theory implemented in the WIEN2k code. We demonstrated that NBT structure is stable in the 001 A-site configuration, while DyNBT presents an A-site disorder perceived by the minimal energy difference between the different A-site configurations. A significant magnetic moment of $5μB$ emerges in DyNBT system, while NBT is known to be non-magnetic. Dysprosium in NBT matrix seems to form an ionic bonding with oxygen atoms whereas Bi-O forms covalent bonding which is responsible for the decrease of the polarization value from 42.3 $μC/cm^{2}$ for NBT to 22.08 $μC/cm^{2}$ for the doped compound. In the second part, the transition temperature and the hysteresis loops of $Na_{0.5}(Bi_{1-x}Dy_{x})_{0.5}TiO_{3}$ system x = 0 - $25\%$ were investigated using the Monte Carlo simulation. We observed a decrease in the transition temperature as a function of dysprosium introduction. We pointed out from the hysteresis loops, an apparent decrease of the coercive field together with the remanent polarization as a function of doping and also as a function of temperature. Our proposed model was seen to approach the values of experimental studies.
DFT+U simulation of the Ti${}_4$O${}_7$-TiO${}_2$ interface
Ti ${}_4$ O ${}_7$在基于TiO ${}_2$的忆阻器内的导电通道的形成被认为是这些器件的电阻率变化的起源。虽然块体材料的性质是合理的已知的，但它们之间的界面迄今为止还没有被研究，主要是由于它们不同的晶体结构。在这项工作中，我们提出了一种方法来匹配TiO ${}_2$和Ti ${}_4$ O ${}_7$之间的界面，随后这些材料之间的能带偏移是从基于密度泛函理论的计算。结果表明，当价带位于Ti ${}_4$ O ${}_7$结构时，导带位于TiO ${}_2$结构，形成II型界面.在这种情况下，Ti ${}_4$ O ${}_7$将作为TiO ${}_2$基质的供体。
First-principles Hubbard U and Hund's J corrected approximate density-functional theory predicts an accurate fundamental gap in rutile and anatase TiO2
Complex impedance and Raman spectroscopy of Na$_{0.5}$(Bi$_{1-x}$Dy$_x$)$_{0.5}$TiO$_3$ ceramics
本工作研究了Na $_{0.5}$（Bi $_{1-x}$ Dy $_x$）$_{0.5}$ TiO $_3$（xDyNBT）陶瓷体系的结构细化、复阻抗谱和拉曼光谱。纯NBT、2DyNBT和5DyNBT化合物以菱形结构结晶，而15DyNBT组合物以正交Pnma结构结晶。我们报道了镝的添加影响相变温度以及介电损耗。在高温下的电输运进行了研究，使用CIS在很宽的频率范围内。所研究的样品显示出非德拜型过程，与纯NBT的短程弛豫和共存的局域和长程弛豫的2DyNBT和5DyNBT化合物的载流子。对于高浓度，15DyNBT，观察到短程弛豫。此外，使用砖层模型，我们讨论了在我们的样品中的不同贡献者（晶粒和晶界）的电阻和电容。高温拉曼光谱研究是为了跟踪铁电化合物结构转变的温度演化。振动模式的温度演化中的异常被认为与从介电测量观察到的温度转变很好地相关。
Electronic and magnetic properties of V-doped anatase TiO$_{2}$ from first principles
采用第一性原理研究了钒掺杂的二氧化钛$_{2}$的几何、电子和磁性。DFT+U（Hubbard系数）方法预测了Ti $_{1-x}$ V $_{x}$ O $_{2}$（x=6.25和12.5%）的半导体能带结构，与样品的低电导率很好地吻合，而广义梯度近似内的标准计算失败。理论结果表明，钒原子倾向于保持接近，并通过超交换相互作用产生强铁磁性。氧空位诱导的磁极化子能使大范围分离的磁性杂质之间产生长程铁磁相互作用。实验观察到的室温下V掺杂的TiO_2 $_{2}$的铁磁性可能源于短程超交换耦合和长程束缚磁极化子逾渗的结合。
Insulating titanium oxynitride for visible light photocatalysis
我们提出了一种系统的方法来获得各种形式的绝缘氮氧化钛Ti $_{n}$ N $_{2}$ O $_{2n-3}$，我们进行了详细的研究，它的$n=2$情况下，Ti $_{2}$ N $_{2}$ O。在密度泛函理论（DFT）和GW近似的框架下，我们研究了Ti $_{2}$ N $_{2}$ O的能量学和电子结构，并将这些结果与原始的和氮掺杂的TiO $_{2}$进行了比较.我们发现，Ti $_{2}$ N $_{2}$ O是半导体的计算带隙为1.81 eV，这是显着小于原始TiO $_{2}$金红石（3.14 eV）或金红石（3.55 eV）。此外，Ti $_{2}$ N $_{2}$ O的带隙的减小不是通过降低导带最小值而是通过升高价带最大值来实现的。因此，所提出的Ti $_{2}$ N $_{2}$ O具有用于水裂解的合适的带边对准。最后，总能量计算表明Ti $_{2}$ N $_{2}$ O比氮掺杂TiO $_{2}$更容易合成。基于这些结果，我们提出Ti $_{2}$ N $_{2}$ O是一种很有前途的可见光催化材料。
Accelerated Dopant Screening in Oxide Semiconductors via Multi-Fidelity Contextual Bandits and a Three-Tier DFT Validation Funnel
National Institute of Electronics and Information Technology (NIELIT), India（印度国家电子与信息技术研究院（NIELIT））；Indian Institute of Information Technology, Allahabad (IIITA), Prayagraj, India（印度阿拉哈巴德信息技术学院（IIITA），普拉亚格拉杰，印度）
Computational Design of Metal-Free Porphyrin Dyes for Sustainable Dye-Sensitized Solar Cells Informing Energy Informatics and Decision Support
Dinajpur Government College（迪纳杰布尔政府学院）；UiT The Arctic University of Norway（挪威北极大学）；Hajee Mohammad Danesh Science and Technology University（哈吉·穆罕默德·达内什科学与技术大学）；Daffodil International University（达芬奇国际大学）
