A5008044614- Crystal Structures and Properties
- Solid-state spectroscopy and crystallography
- Nonlinear Optical Materials Research
- Perovskite Materials and Applications
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Multiferroics and related materials
- Chalcogenide Semiconductor Thin Films
- X-ray Diffraction in Crystallography
- Heusler alloys: electronic and magnetic properties
- Optical properties and cooling technologies in crystalline materials
- Catalytic Processes in Materials Science
- Advanced Thermoelectric Materials and Devices
- Crystallization and Solubility Studies
- Solid State Laser Technologies
- Electronic and Structural Properties of Oxides
- Phase-change materials and chalcogenides
- Chemical and Physical Properties of Materials
- Photonic and Optical Devices
- Nonlinear Optical Materials Studies
- Spectroscopy and Laser Applications
- Iron-based superconductors research
- Zeolite Catalysis and Synthesis
- Organometallic Compounds Synthesis and Characterization
- Transition Metal Oxide Nanomaterials
Kaimosi Friends University College
2018-2024
Binghamton University
2013-2017
Northwest University
2015-2016
State University of New York
2014
Abstract Reducing the dimensionality of three-dimensional hybrid metal halide perovskites can improve their optoelectronic properties. Here, we show that third-order optical nonlinearity, n 2 , lead iodide is enhanced in two-dimensional Ruddlesden-Popper series, (CH 3 ) NH -1 Pb I +1 ( = 1–4), where layer number engineered for bandgap tuning from E g 1.60 eV ∞; bulk) to 2.40 1). Despite unfavorable relation, $${n_2} \propto E_{\rm{g}}^{ - 4}$$ <mml:math...
Hybrid organic–inorganic lead halide perovskites have recorded unprecedented improvement in efficiency as fourth-generation photovoltaic materials. Recently, they attracted enormous interest nonlinear optics stemming basically from their excellent optoelectronic properties. Here, we investigate multiphoton absorption (MPA) high-quality MAPbX3 (MA = CH3NH3 and X Cl, Br, I) bulk single crystals synthesized by an inverse-temperature crystallization (ITC) method. The two-photon (2PA)...
The pressure-induced structural evolution of formamidinium-based perovskite FAPbI3 was investigated using in situ synchrotron X-ray diffraction and laser-excited photoluminescence methods. Cubic α-FAPbI3 (Pm3̅m) partially irreversibly transformed to hexagonal δ-FAPbI3 (P63mc) at a pressure less than 0.1 GPa. Structural transitions followed the sequence Pm3̅m → P4/mbm Im3̅ partial amorphous during compression 6.59 GPa, whereas δ-phase converted an orthorhombic Cmc21 structure between 1.26...
We report on highly polarization-selective three-photon absorption (3PA) in a Bridgman-grown single crystal of ${\mathrm{CsPbBr}}_{3}$ oriented along the (112) direction, which is an inorganic counterpart to emerging organic-inorganic hybrid halide perovskites for solar-cell and optoelectronic applications. The exhibits strong photoluminescence (PL) at room temperature as direct consequence 3PA fundamental radiation. Interestingly, disappears when input polarization parallel...
It is established that the multiferroics RMn(2)O(5) crystallize in centrosymmetric Pbam space group and magnetically induced electric polarization appearing at low temperature accompanied by a symmetry breaking. However, both our present x-ray study-performed on compounds with R=Pr,Nd,Gd,Tb, Dy-and first-principles calculations unambiguously rule out this picture. Based structural refinements, geometry optimization, physical arguments, we demonstrate Letter actual likely to be Pm. This turns...
The APSe6 (A = K, K(1–x)Csx, Cs) family of one-dimensional (1D) materials was studied to examine the effects cation size on nonlinear optical (NLO) response. has high-performing NLO properties with noncentrosymmetric parent material, KPSe6, having infinite 1D chains 1/∞[PSe6–]. This structure been successfully substituted cesium up K0.6Cs0.4PSe6 while retaining polar character. All compounds crystallize in space group Pca21 and have band gaps 2.1 eV. In situ powder X-ray diffraction...
Mn2+2Fe2+W6+O6, a new polar magnetic phase, adopts the corundum-derived Ni3TeO6-type structure with large spontaneous polarization (PS) of 67.8 μC cm−2, complex antiferromagnetic order below ≈75 K, and field-induced first-order transition to ferrimagnetic phase ≈30 K. First-principles calculations predict (udu) ground state, optimal switching path along c-axis, lower energy udu–udd double cell.
CsPbBr3 is a direct-gap semiconductor where optical absorption takes place across the fundamental bandgap, but this all-inorganic halide perovskite typically exhibits above-bandgap emission when excited over an energy level, lying above conduction-band minimum. We probe bandgap anomaly using wavelength-dependent multiphoton spectroscopy and find that gap strictly two-photon forbidden, rendering it three-photon (3PA) active. Instead, (2PA) commences resonant with gap, associated level causing...
Abstract Above‐room‐temperature polar magnets are of interest due to their practical applications in spintronics. Here we present a strategy design high‐temperature magnetic oxides the corundum‐derived A 2 BB′O 6 family, exemplified by non‐centrosymmetric ( R 3) Ni 3 TeO ‐type Mn 2+ Fe 3+ Mo 5+ O , which shows strong ferrimagnetic ordering with T C =337 K and demonstrates structural polarization without any ions n −1)d 10 s 0 d or stereoactive lone‐pair electrons. Density functional theory...
The new compounds ANb2PSe10, where A = K, Rb and Cs, form from polyselenophosphate flux reactions crystallize in the noncentrosymmetric space group Pc. They feature infinite one-dimensional 1/∞[Nb2PSe10–] chains separated by alkali cations. consist of [Nb2(Se2)2]4+ clusters bridged a diselenide [PSe4]3– group. pack differently depending on which cation is present lattice. As result, analogs are not isostructural with respect to each other, has different unit cell. reaction chemistry...
We present a nonlinear optical (NLO) probe technique, wavelength-dependent Z-scan spectroscopy (WDZNS), which can be utilized for assessing broadband NLO properties of materials. Unlike typical Z-scans, WDZNS spectrally monitor the frequency-doubled output as function wavelength λ well input intensity I. Based on we have investigated strong impact two-photon absorption (TPA) second-harmonic generation in CdTe over broad TPA range. This complicated effect is characterized by λ-dependent...
One-dimensional noncentrosymmetric KPSe6 is an excellent mid-infrared (mid-IR) nonlinear optical (NLO) material possessing reversible phase-change behavior. In this special issue we present a broadband NLO study on its crystalline and glassy phases as well fundamental characterizations. The compound has bandgap of ∼ 2.1 eV exhibits intrinsic second harmonic generation even in the phase. type-I phase-matchable shows strong second- third-order responses over broad wavelength range (1.0 – 3.0...
Abstract Cationic rearrangement is a compelling strategy for producing desirable physical properties by atomic‐scale manipulation. However, activating ionic diffusion typically requires high temperature, and in some cases also pressure bulk oxide materials. Herein, we present the cationic Mn 2 FeMoO 6 at unparalleled low temperatures of 150–300 o C. The irreversible motion ambient pressure, as evidenced real‐time powder synchrotron X‐ray neutron diffraction, second harmonic generation, leads...
The soluble molecular selenophosphate salts ACsP2Se8 (A = K, Rb, Cs) crystallize in the orthorhombic space group Ccce with a 14.982(3) Å, b 24.579(5) and c 13.065(3) Å for Cs salt 14.782(3) 23.954(5) 13.044(3) K analogue. is composed of 6-membered ring, [P2Se8]2−, twist conformation charge balanced by alkali metals. band gaps these compounds are 2.44 ± 0.2 eV Cs2P2Se8, 2.41 RbCsP2Se8, 2.36 KCsP2Se8. amorphous versions materials can be made water quenching melt have all 2.12 eV. Raman...
We present a structural and spectroscopic study of the compound $\mathrm{N}{\mathrm{i}}_{2}\mathrm{MnTe}{\mathrm{O}}_{6}$, closely related to polar antiferromagnet $\mathrm{N}{\mathrm{i}}_{3}\mathrm{Te}{\mathrm{O}}_{6}$ known show colossal magnetoelectric effect pronounced elementary excitations. prepared single crystals polycrystalline samples $\mathrm{N}{\mathrm{i}}_{2}\mathrm{MnTe}{\mathrm{O}}_{6}$ showing same structure as from room temperature down 4 K with $R3$ space-group symmetry....
Abstract Above‐room‐temperature polar magnets are of interest due to their practical applications in spintronics. Here we present a strategy design high‐temperature magnetic oxides the corundum‐derived A 2 BB′O 6 family, exemplified by non‐centrosymmetric ( R 3) Ni 3 TeO ‐type Mn 2+ Fe 3+ Mo 5+ O , which shows strong ferrimagnetic ordering with T C =337 K and demonstrates structural polarization without any ions n −1)d 10 s 0 d or stereoactive lone‐pair electrons. Density functional theory...
Abstract Cationic rearrangement is a compelling strategy for producing desirable physical properties by atomic‐scale manipulation. However, activating ionic diffusion typically requires high temperature, and in some cases also pressure bulk oxide materials. Herein, we present the cationic Mn 2 FeMoO 6 at unparalleled low temperatures of 150–300 o C. The irreversible motion ambient pressure, as evidenced real‐time powder synchrotron X‐ray neutron diffraction, second harmonic generation, leads...
In this study we have investigated the electronic , structural, elastic, optical and thermodynamic properties of copper-based ternary semiconductors, that is, KCuZ (Z= Te, Se). The these materials been precisely determined based on first-principle calculations. lattice constants, bulk modulus equilibrium total energies were obtained from Murnaghan equation state a good agreement with other theoretical experimental methods.The absorption spectra was analyzed to determine active window...
The grain size of the organometallic halide perovskite, methylammonium lead iodide (MAPbI <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) was modified through a solvent annealing technique. Dimethyl sulfoxide (DMSO) found to coalesce perovskite grains leading improved carrier lifetimes and solar device performance. Samples with three ratios (1.0, 1.1, 1.2) PbI xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> /(CH NH I) were used for...