The refinement of XRD patterns only
provides the average structure
parameters for the alloying materials because of the symmetric protection.
Raman vibrational modes can append the detailed information about
the bond length and structure. The refinements of XRD patterns for
Bi alloying Cs2AgInCl6 revealed the strong structure
distortion with the enlarged octahedron of In(Bi)Cl6 and
the contracted octahedron of AgCl6 with the increasing
Bi. Raman spectra supported the expanded octahedron of InCl6 and the reduced octahedron of AgCl6 but identified the
anomalous shortening bond length of Bi–Cl with the increasing
Bi. These distorting octahedrons break parity forbidden transition,
modify Huang–Rhys factor, and result in the maximum values
at 30% Bi alloying and the same variation trend for both photoluminescence
and Huang–Rhys factor with the increasing Bi alloying.
In this work, Ag@CdS nanowires (NWs) were fabricated via a facile hydrothermal route and magnetron sputtering. The structure and morphology of the Ag@CdS NWs were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photon spectroscopy. The synthesized Ag@CdS NWs exhibit an enhanced light sensitizing ability due to plasmon-enhanced absorption at the Ag and CdS interface. The Ag@CdS NW photoanode exhibits superior light harvesting and photoelectrochemical performance with an optimal photocurrent density of about 6.15 mA/ cm 2 at a 0.18 V bias versus the saturated calomel electrode (SCE) and a photocurrent density of about 4.7 times compared to that of the pure CdS NW photoanode. The photochemical conversion efficiency calculated for Ag(45 s)@CdS NWs is found to be 6.6% (potential vs SCE at 0.12 V) compared to 1.28% for CdS NWs at the same potential. The H 2 generation obtained from the Ag(45 s) @CdS NW photoanode is 1.8 times higher than that from the pure CdS NW photoanode.
The emission properties of Mn 2+ ions with direct and indirect excitation in MnS/ZnS core/shell quantum dots are investigated under high pressure. A transition from the zincblende to rock salt phase is observed at 16.1 GPa. The intensity of the Mn 2+ emission peak attenuates significantly from 7.5 to 9.6 GPa due to the crossing of 2 T 2 ( 2 I) and 4 T 1 ( 4 G) energy levels and subsequent enhancement of nonradiative relaxation. Pressure-induced anomalous emission behaviors are observed and explained by the competition between two types of Mn 2+ emissions: a major one from coupled Mn 2+ ions and a minor one from isolated Mn 2+ ions. The corresponding mechanism is discussed. These findings can provide insights into the fundamental physics and better design/applications of this kind of material.
Raman scattering investigations based on density functional theory (DFT) calculations were performed to explore the vibrational modes of a cadmium hexathiohypodiphosphate CdPS 3 single crystal. The calculations were performed to obtain the Raman spectra for the cadmium hexathiohypodiphosphate atoms to study the size dependence. Several vibrational modes indicating stretching and bending features related to Cd, S and P atoms were observed. Modifications of the frequency and intensity of different Raman modes with an increase in the number of atoms in CdPS 3 were discussed in detail. Hydrogen atoms were added in order to make the closed shell configuration and saturate the CdPS 3 as per the requisite for calculating the Raman spectra. This produced some additional modes of vibration related to hydrogen atoms. Band gap and formation energy were also calculated. The results generated are found to be in close agreement with the experimental values.
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