Structure and Electronic Effects from Mn and Nb Co-doping for Low Band Gap BaTiO₃ Ferroelectrics

Abstract

We have investigated the doping-induced local structural and electronic effects in the recently developed low band gap room temperature ferroelectric Mn–Nb co-doped BaTiO3. Experimental and theoretical Raman spectroscopies are utilized to quantify the Ti off-centering, identified to be the intrinsic origin of ferroelectricity in these systems. Mn and Nb exhibit contrasting doping behaviors that have remarkable effects on BaTiO3 functionality. Jahn–Teller distorted Mn3+ is primarily associated with lowering of the bulk band gap, while charge-compensating Nb5+ off-centers within the O6 octahedra, creating a polar mode that stabilizes the ferroelectric ground state. The charge neutral aliovalent Mn3+–Nb5+ pair effectively couples to the inherent ferroelectric instability of the BaTiO3 lattice, restoring some spontaneous polarization lost by doping Mn3+ (d4) ions at Ti4+ (d0) sites.

Charge Transfer-Triggered Bi3+Near-Infrared Emission in Y2Ti2O7for Dual-Mode Temperature Sensing

“…We confirmed the attribution of Bi luminescence in the YTOB phosphors to Bi 3+ by X-ray absorption spectroscopy (XAS). Specifically, to correlate the Bi local structure and the luminescent properties of the YTOB phosphors, we probed the oxidation state and the nearest surroundings of Bi in this YTO pyrochlore lattice by EXAFS spectroscopy with Bi 2 O 3 (Bi 3+ ) and NaBiO 3 (Bi 5+ ) as reference materials. ,− We examined Bi L 3 edge structures of the YTOB0.5, YTOB2.5, and YTOB3.5 phosphors with maximized accuracy. The nearly identical spectra (Figure a) indicate that the oxidation state and local environment of Bi do not vary with increasing Bi doping concentration in the YTO host.…”

Lead-Free Perovskite Cs3Bi2I9-Derived Electroactive PVDF Composite-Based Piezoelectric Nanogenerators for Physiological Signal Monitoring and Piezo-Phototronic-Aided Strain Modulated Photodetectors

“…In the development of better lead-free perovskite materials, there are well-established lead-free materials, e.g., barium titanate, barium calcium titanate, barium strontium titanate, potassium sodium niobate, bismuth sodium titanate, and bismuth ferrite, but they did not acquire much popularity in photovoltaic applications due to the large energy band gap and high recombination rate of charge carriers. − On the other hand, all-inorganic bismuth-based halide perovskite materials, with a typical formula of A 3 Bi 2 X 9 (A: Cs, X: I, Br, Cl), have attracted great attention due to their superior power conversion efficiency. , Recently, the bismuth-based perovskite Cs 3 Bi 2 I 9 has been synthesized and widely reported in photodetection and solar cell applications. ,,, However, it is still a difficult task to make it a very promising candidate with lots of potential for long-term optoelectronic applications considering its chemical instability in a harsh ambient environment. To extend the lifetime of Cs 3 Bi 2 I 9 -based devices, extensive research is being done to improve their water resistance, functioning, and encapsulation …”

Entrapped Molecule‐Like Europium‐Oxide Clusters in Zinc Oxide with Nearly Unaffected Host Structure

“…This may to a great degree be related to differences in crystal quality, grain boundaries, and perhaps most importantly, the doping structure, i.e., the spatial distribution and local coordination of the dopant ions in the host structure. [38][39][40][41] In spite of this, there are few studies that describe the dopant structure in sufficient detail to connect the properties with the actual structure. As a further complication, the structure and chemical contents vary with synthesis technique and heat-treatment, which thus have a profound effect on the optical and magnetic properties, as well as on the electronic band-structure.…”