Search

Four enantiopure imines in solid state with different functional groups added in the para-position of the aromatic ring in the chiral moiety were analysed. The molecular packing was investigated with the aim of correlating this fact with the surface morphology, structural and optical changes of these imines. By applying Scanning Electron Microscopy (SEM) the morphology showed dense plates and smooth surface. X-ray diffraction studies exhibited a Monoclinic→Orthorhombic variation. The absorbance of these organic materials showed absorption bands associated with the π→π* and n→π* electronic transitions located in the UV-region, typical of organic molecules. By applying the Tauc model, the band gap energy was quantified. An electronic transition located at ∼2.5 eV and another well-defined band situated at ∼3.3 eV can be observed. Photoluminescence (PL) spectroscopy performed at room temperature with the 450 nm laser line showed green, yellow and red emission bands located in the ∼450–700 nm range of the Vis-region with different intensities. The experimental results indicated that the photoluminescence properties of the crystals strongly depend on molecular stacking in the crystal arrays and this optical behavior can be associated with different crystalline effects. The Raman spectra was examined to identify the vibrational modes in a qualitative way and the experimental results were confirmed with the reported values obtained through theoretical-experimental models.

Undoped cadmium selenide nanoparticles (CdSe-NP's) were grown on glass substrates by chemical bath synthesis (CBS). The particle size was controlled by means of the bath temperature (Tb), which was chosen within the interval 0–80 °C. X ray diffraction patterns indicate that CdSe-NP's grow in the hexagonal wurtzite (WZ) crystalline phase for low Tb values and in the cubic zinc-blende (ZB) structure for higher ones. The WZ → ZB transitions occurs at the critical temperature Tbc ≅ 40 °C. Considering the CdSe-NP's like spheres as an approximation, the average size, calculated by using the Scherrer formula, is in the range 7.0–12.2 nm. The Arrhenius plot of the natural logarithm of the diameter versus the inverse of the absolute temperature (Tb + 273.6 K) reveals two slopes which were identified as activation energies related with two thermally activated processes of the growing NP's phases. The photoluminescence spectra show, in general, three type of emissions, which were associated with the more probable electronic transitions: a) near band edge emission, b) donor or acceptor level-band, c) donor-acceptor (DAP). The spectrum when Tb = 40 °C shows more PL bands, that is because the DAP band splits in two bands. This splitting has been associated to the presence of tetrahedral and octahedral Cd-interstitial donor levels in ZB and WZ CdS, respectively, when mixed phases are present in the material at the critical temperature of phase transition.

The morphological, structural and optical properties of the new enantiopure (S)-(-)-1-[(1-phenyl)-N-(biphen-2-yl)methylidene]ethylamine in the solid state are reported. The molecular packing displayed a compact and dense three-dimensional arrangement associated with the biphenyl group as well as a significant distortion induced by the effect of the stereogenic carbon atom, contributing to the molecular torsion in a nonplanar angular-shaped small molecule. The morphology of this organic material showed dense crystalline surfaces. By X-ray diffraction (XRD) studies, an orthorhombic crystal system and a P212121 spacial group was established. The optical part was analysed by recording the coefficient of absorption which presented the behavior of an oxide and by the Tauc law a direct band gap can be seen, allowing to quantify the band gap at Eg ˜3.45 eV. The photoluminescence analysis performed at room temperature exhibited two emission bands located in the Vis-region which were identified as blue and green emission bands situated at ˜415 nm (˜2.98 eV) and ˜556 nm (˜2.23 eV), respectively. Finally, by Raman spectroscopy analysis, some vibrational modes were identified.

The structural, morphological and optical properties of an enantiopure Schiff base, namely [(S)-(+)-[(1-naphthyl)-N-(1-benzo[b]tiophen-2-yl)methylidene]ethylamine] (Bt-Naph) are reported. By using Scanning Electron Microscopy (SEM), tubular crystals of different sizes can be seen. X-ray diffraction studies showed an orthorhombic phase, which has been confirmed by powder X-ray diffraction (XRD) analysis applying Bragg's law. The absorbance results showed typical bands of organic molecules located in the UV region for π→π* and n→π* electronic transitions. Considering the behavior of this organic crystal as similar to other crystalline materials, the Tauc law was applied to investigate the band gap energy (Eg). Two electronic transitions were experimentally evaluated: Eg ∼3.5 eV and Eg ∼4.7 eV. The photoluminescence spectroscopy showed a broad emission band located in the visible region at ∼575 nm, identified as a green emission (GE) band. Deconvolution of the spectra displayed two emission bands located at ∼558 nm and ∼672 nm, and the latter was assigned to a yellow emission band. Finally, the Raman spectroscopy exhibited peaks associated with different vibrational modes, typical of molecules containing aromatic rings.

The morphological, structural and optical properties of a new chiral imine, namely (S)-(+)-[(1-phenyl)-N-(1-benzo [b]tiofen-2-yl)methylidene]ethylamine (Bt), are reported. Photoluminescence showed a band of intense green emission located at ∼525 nm. The absorbance spectra displayed bands associated with π→π* and n→π* electronic transitions. The band gap was quantified by two electronic transitions at ∼3.5 and ∼4.7 eV, confirming those observed by absorbance. XRD studies showed a monoclinic phase. Additionally, by using Time Depending-Density Functional Theory (TD-DFT), the electronic and optical properties were examined.

CdCO 3 →CdO transitions by thermal treatment (TT) at ∼400 °C in an air atmosphere are reported. The CdCO 3 was grown at room temperature by using the green chemical bath (CB) approach, and the morphological, structural and optical analysis. Thus, the morphological analysis performed by SEM in CdCO 3 showed crystals with a cubic geometry, long linear stacks, as well as circular regions. After TT, the morphology is retained and the sample exhibited a spongy appearance, the typical morphology of TT materials. FTIR spectra revealed absorption bands associated with C O 3 2 - and OH − ions, which disappeared after TT. XRD showed a crystalline phase of CdCO 3 with rhombohedral structure, and after the CdCO 3 →CdO transition, CdO was identified in the cubic zincblende phase. The OA studies showed a running in the band gap from ∼4.1 eV for CdCO 3 to ∼2.3 eV for CdO. A brief mechanism by calculating the Gibbs free energy changes is shown.

In this report, we investigate the fabrication of solar cells obtained by chemical bath technique, based on CdS as window layer and PbS and PbS-Li+-doped as the active layer. We report open-circuit-voltage Voc values of ∼ 392 meV for PbS and ∼630 meV for PbSLi+-doped, a remarkable enhanced in the open circuit voltage is shown for solar cells with doped active layer. Li+ ion passivate the dangling bonds in PbS-metal layer interface in consequence reducing the recombination centers.

PbS nanocrystals co-doped simultaneously in Er 3+ and Bi 3+ solutions were grown and the modification of morphological, structural and some optical properties was investigated. The thicknesses of the undoped and doped PbS films were in the ∼560–400 nm range. The morphological changes of the nanocrystals were analyzed using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) techniques. Fourier transform infrared spectroscopy ((FT-IR)) spectra showed a broad absorption band located at ∼3500 cm −1 attributed to stretching of the –OH groups and a sharp band at ∼1384 cm -1 owing to stretching vibrations mode of C O 3 2 - ions. X-ray diffraction displayed a cubic phase in all films and grain size (GS) of the undoped and doped samples were ∼33 and ∼21–17 nm, respectively. The films showed stress, a typical behavior of doped nanocrystals displaying residual strain. The absorbance spectra of PbS film exhibited four absorption bands located at ∼251 nm (∼4.9 eV), ∼610 nm (∼2.0 eV), ∼668 nm (∼1.8 eV) and ∼830 nm (∼1.4 eV) due to strong confinement effect and ∼446 nm (∼2.7 eV), ∼478 nm (∼2.5 eV) corresponding to 4 F 7/2 → 4 I 5/2 , 4 F 3/2 → 4 I 15/2 ( f → f ) transitions of Er 3+ ions. Sharp bands were found at ∼287 nm (∼4.3 eV) and 366 nm (∼3.38 eV), corresponding to transitions of Bi 3+ ions. The band gap energy of films showed a shift in the ∼0.9–1.2 eV range. Raman spectra showed two bands located at ∼450 cm −1 due to the first overtone of the longitudinal optical (LO) phonon (2LO) and a band observed at ∼200 cm −1 which was attributed to the LO (Γ) phonon. A kinetic mechanism using the free energy changes Gibbs is proposed.

ZnO films prepared on glass substrates at T = 80 °C ± 3 °C using the chemical bath deposition technical. The precursor solutions was KOH (0.5 M), NH4NO3 (1.5 M) using three different Zn(NO3)2 (0.2 M, 0.3 M, 0.4 M) concentration. The morphology is investigated by Scanning Electron Microscopy (SEM) and images shows porous matrix with cavities of different size, javelin and tretrap. According to the XRD diffractograms, all the nanocrystals present hexagonal crystalline phase with grain size of ∼33.4 nm, ∼36.5 nm and ∼34.2 nm. The samples present typical stress in these films. Absorbance spectrum exhibits a characteristic band of the nanocrystals, band gap energy shows a shift in the range ∼3.7–3.8 eV associated with decreasing grain size, as well as the quantum confinement effect in this case of nanocrystalline material. Photoluminescence shows bands, associated with the existence of interstices and vacancies of oxygen and Zinc respectively. Analysis of chemical reactions is performed using the Nernst equation to quantify changes ΔG° to predict the spontaneity of the reactions.

CdS, CdS-CdCO3 and CdCO3 thin films grown by chemical bath at ∼80, ∼60 and ∼40 °C temperature range were prepared. Morphology and size showed changes as a variety of truncated cube-shaped structures, wires and circles. Energy band gap was ∼2.4 eV (CdS) and ∼4.0 eV (CdCO3), respectively. XRD showed wurtzite crystalline phase for CdS films and a rhombohedral phase for CdCO3. Raman spectra in CdS exhibited a peak for A1(TO) phonon corresponding to wurzite and CdCO3 film showed internal vibrations of C O 3 2 − group: v1-symmetric stretching (∼1090 cm−1) v3-asymmetric C O stretching (∼1401 cm−1); v4-in-plane band of the C O 3 2 − ions and two bands assigned to translations and release of the C O 3 2 − group relative to the Cd atoms: v13 (∼274 cm−1), v14 (∼169 cm−1). Lattice modes v13 (∼274 cm−1), v3- asymmetric C O stretching (∼1401 cm−1), v1-symmetric C O stretching ∼1090 cm−1 were also noted. Finally, a simple thermodynamic analysis is presented to understand the formation of the compounds by calculations of Gibbs free energy and data associated with the corresponding ions of the CdS and CdCO3 materials in our working conditions.

The growth of Er 3+ -doped PbS thin films and the changes of structural, morphological, electrical and some optical properties were examined. The thicknesses of these films were found in the ∼200–120 nm range. The morphological properties of the nanocrystals were analyzed using Atomic Force Microscopy (AFM). FTIR spectra showed strong sharp absorption located at ∼1447 cm −1 associated with the asymmetric stretching vibrations assigned to the bending out-plane vibrations of C O 3 2 − ions. X-ray diffraction displayed a cubic phase in all films and grain size (GS) was ∼6.5 nm for PbS, whereas for doped nanocrystals was ∼5.1 nm. Absorption bands located at ∼371 nm (∼3.3 eV), ∼385 nm (∼3.2 eV), 406 nm (∼3.0 eV), ∼608 nm (∼2.0 eV), ∼619 nm (∼2.03 eV), ∼640 nm (∼1.9 eV), and another intense band located at ∼682 nm (∼1.8 eV) were observed. An optical absorption band located at ∼371 nm (∼3.3 eV) was observed in doped films, corresponding to 4 f → 4 f transitions of Er 3+ ions. The band gap energy of films showed a shift in the ∼1.49 eV for PbS and ∼2.25–2.58 eV for doped samples, respectively. The resistivity increased from ∼0.65 to 8.57 × 10 3 (Ω cm) −1 , and the electrical conductivity decreases from ∼1.52 to 0.001 Ω m, mobility decreased from ∼29.6 to 0.13 cm 2 /Vs, and carrier increases from ∼1.9 × 10 15 to 7.0 × 10 15 cm −3 , while increasing V [Er3+] . As expected, doped samples showed better photosensitivity.

In a previous report, some morphological, structural, and optical properties of NdOHCO3 to Nd2O3 transition were presented. This paper continues investigating this interesting inorganic nanomaterial, proposing the creation of the coordination complex [Nd(NH3)6]3+ ion during crystalline growth as a crucial step for the growth of NdOHCO3 nanocrystals. A concise experimental-theoretical model is detailed in order to understand the spherical-like crystalline growth observed. The orthorhombic and cubic phases for NdOHCO3 and Nd2O3 nanocrystal samples were identified from the X-Ray diffraction results. In addition, the average grain size was estimated for each sample: NdOHCO3 ~15.31–18.82 nm and Nd2O3 ~45.10–59.01 nm. Other optical parameters like absorbance, transmittance, and reflectance are examined. The Urbach energy (Eu) model allows us to investigate the degree of absorption. The Maxwell-Boltzmann statistical (MBS) model results fit well with the experimental photoluminescence (PL) spectroscopy data registered, implying that native intrinsic crystalline defects behave as free particles and the emission bands overlap 4f4s2→4f4s2 electronic intra-transitions. The PL spectra show two emission bands: Yellow ~3.10–1.55 eV and Red > 1.99 eV. Finally, the trap densities of NdOHCO3 (~1.08 × 1014 cm−3) and Nd2O3 (~9.64 × 1013 cm−3) were estimated.

Cerium oxide (CeO2(s)) is prepared by Chemical Bath Deposition (green chemistry) at ~23.0 °C and subsequent thermal annealing treated (TAT) at ~1000 °C. This manuscript continues with previous research examining the spectra situated at UV-Vis-region to investigate the 4fds→4fds electronic intra-transitions of CeO2. The in-plane and out-of-plane strains are located at ec ~ 1.1 × 10-3, ~ -3.0 × 10-4 and ea ~ -1.2 × 10-3, ~4.0 × 10-4, dislocation density were ~3.87 × 10 14 lines/m2 and ~ 4.31 × 10 16 lines/m2 for the As-grown and the CeO2-TAT nanocrystals, respectively. As a first approximation, we consider that the inorganic nanomaterial has intrinsic native crystalline defects. It is supposed that the strain is caused by native point defects (vacancies and interstices). According to the d(DO)/dE equation, absorption band associated at Ce3+ + e- →Ce4+, assigned to 5d→4 f electronic intra-transitions (~2.48 eV) at Vis-region. Deconvolution of the observed absorbance spectra shows that the emissions bands originating from the F0 centers prevail over those of F+ centers of V0. For CeO2-TAT nanocrystals, the bandgap energy was at ~289 nm (~ 4.29 eV), whereas the As-grown was found at ~304 nm (~4.07 eV). In As-grown nanocrystals, three optical signals can be seen ~277 nm (~ 4.47 eV), ~330 nm (~3.75 eV), and ~393 nm (~ 3.15 eV). The absorption band at ~3.15 eV is relatively narrow and assigned to Ce3+ + e- → Ce4+ charge transfer. Calculations of Urbach energy were Eu ~ 1.54 eV for As-grown and Eu ~0.52 eV for CeO2-TAT nanocrystals, respectively.

Herein, we report the morphological, optical, and structural modifications induced by the change of different functional groups in the para-position of the benzene ring in a series of chiral imines. These organic compounds were examined using scanning electron microscopy (SEM), optical absorption, X-ray diffraction, and photoluminescence (PL) techniques. SEM images showed drastic morphological changes, and the absorbance results showed significant changes in the bands located in the ∼200–400 nm range, associated with π → π*, δ → δ*, and n → π* transitions. An optical behavior similar to that of semiconductors (in the UV region), with two transitions in the ∼3.3–4.3 eV range was observed for the compounds. The results obtained by PL spectra exhibited changes in intensity, with gradually shifting increases in the green band emission. However, it is more intense with the crystals of the imine bearing the -OCH3 functional group, considering that the aforementioned green band is associated with the different m...

We present preliminary theoretical-experimental results in the crystalline growth of Fe(OH)3 and CuS inorganic nanomaterials. These were obtained employing the Chemical Bath Deposition technique and thermally annealing treated at ~ 1000 °C in the air atmosphere. In each case, the proposed chemical kinetic model supports the obtained complex coordination [Fe(NH3)6]3+ and [Cu(NH3)4]2+ ions and then serves to investigate theoretical-experimental insights of the Fe(OH)3 and CuS products. Scanning Electron Microscopy (SEM) images show spongy crystals in Fe(OH)3(s) and CuS(s) that drastically change to dense plates in both inorganic materials due to thermal annealing treatment. The X-ray diffraction (XRD) studies identify Fe(OH)3→α-Fe2O3(s) phase transition to oxide (Rhombo.H.axes). Differential Scanning Calorimetric (DSC) studies show the loss of mass and the gradual transition of Fe(OH)3→α-Fe2O3(s). Likewise, the CuS(s) (Orthorhombic S8 cyclo-octasulfur) is identified. It is possibly interlaced and forming -S-Cu-S- chemical bonds, with small nanoparticles of CuS(s) trapped within the (zig-zag) cyclical chains of the S8. The GS ranges between ~ 23.2 and 27.8 nm for CuS8(s) and ~ 35.5 and 38.8 for CuO(s).

The Chemical Bath deposition method has been used to synthesize Samarium Oxide (Sm2O3) in previous research where the morphological, structural, and optical properties were studied after thermal annealing treatment at ~1000 °C in the air atmosphere. The present study continues the research on this interesting inorganic material. The average grain size is located at ranges ~22.10 nm to ~28.20 nm, and the optical absorption shows two bands located at ~277 nm (~4.47 eV) and ~408 nm (~3.03 eV) situated in the UV-Vis region. We apply the photoluminescence (PL) spectroscopic technique to examine the emission bands that overlap with the 4fd→4fd electronic transitions in the context of some optical properties at the UV-Vis region. The emission signals present peaks at ~2.52, ~2.55, ~2.56, ~2.60, ~2.63 and ~2.66 eV. Likewise, the Maxwell-Boltzmann statistical model (MBSM) is employed to correlate the native crystalline defects with the cited electronic transitions and emission bands. Finally, the MBSM theoretical curve wraps the emission signals associated with the 4fd→4fd electronic transitions linked with crystalline native defects confirmed by the calculated density of traps. A brief analysis of the chemical kinetics of crystal growth is proposed here.

We present the synthesis of erbium oxide (Er2O3) by chemical bath deposition technique at ~ 60 ± 2 °C for a prolonged period of 60 hr and subsequently thermally treated at ~1000 °C in an air atmosphere. The morphology of samples is analyzed by Scanning Electron Microscopy. The crystalline phase is explored by X-Ray Diffraction, identifying the cubic-bixyite phase of Er2O3 and grain size that ranges between ~7.9 nm to ~10.9 nm. The calculated bandgap energy is found of ~4.5 eV and ~3.8 eV when using the Tauc equation and the Effective mass approximation model, respectively. We consider that vacancies, interstices, grain boundaries, and stacking faults present a corpuscular behavior. In this regard, the Maxwell-Boltzmann statistics is applied as an original approach considering the crystalline native defects associated with vacancies and interstices. We discuss the photoluminescence dependence with the trap density and the surface recombination velocity in the light of the Maxwell-Boltzmann theoretical results associated with the electronic transitions related to the native intrinsic defects situated at the Vis-region. The photoluminescence spectrum shows two strong emission bands in Vis-region that correspond to 4S3/2 and 4I15/2 electronic transitions. Upconversion-emission consists of blue, green, and weak red bands originated from the 4 f→4 f intra-transitions.

The growth of PbS nanocrystals doped in situ simultaneously with Er3+-Cd2+-Bi3+ solutions at different proportions was examined with the aim of investigating the morphological, optical and structural changes of the nanocrystals obtained. A brief summary of the chemical equilibria plus the Gibbs free energy changes are presented. Fourier transform infrared spectroscopy (FTIR) spectra showed an absorption band located at ~ 3356 cm−1 attributed to stretching of -OH groups and a sharp stretching band at ~ 1932 cm−1 assigned to vibration mode of C O 3 2 − ions.This absorption bands are generally due to the decomposition of thiourea in alkaline medium. X-ray diffraction (XRD) patterns exhibited a cubic phase in all films and the grain size (GS) of the undoped samples was ~6.57 nm, whereas for doped films was ~ 6.40–4.16 nm. Transmission Electron Microscopy (TEM) confirmed the structural characteristics of the nanocrystals. Absorbance spectra of PbS films exhibited five absorption bands located at ~ 346, ~ 585, ~ 615, ~ 670 and ~ 775 nm due to strong confinement effect. This multiplex of bands presented in PbS is induced by the simultaneous incorporation of the ions. The shift of the band gap energy is associated with the decrease of crystalline size in PbS films. On the other hand, a small absorption band located at ~ 446 nm, corresponding to 4F7/2 → 4I5/2 (4f → 4f transitions of Er3+ ions) was also observed. A small blue emission band centered at ~ 446 nm was originated from the allowed 3P1 → 1S0 transition of Bi3+ ions. Band gap energy of nanocrystals showed a shift in the ~ 1.4–2.6 eV range. The structural experimental results are associated with the optical changes confirming the gradual incorporation of the dopant ions in the crystallites network. Raman spectra showed two bands located at ~ 450 cm−1 due to the first overtone of the LO phonon (2LO) and other band located at ~ 200 cm−1 which has been attributed to the LO (Γ) phonon,confirming the existence of doped-PbS nanocrystals.

A novel synthesis of CeO2 powder by using chemical bath (CB) as green method is presented. The process was completed by thermal annealing (TA) at 1000 °C during 2 h. CeO2 growth was confirmed by: X-ray diffraction (XRD), UV–vis spectra, Energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and Raman spectra. By FTIR, bands associated with C O 3 2 − and OH− ions were identified, disappearing with the TA process. The X-ray diffraction (XRD) patterns of the as grown and CeO2 TA samples showed the reflection characteristic of CeO2 structure with a cubic symmetric pattern. By XRD diffractograms the grain size calculated were ∼2.7 nm and ∼28.5 nm for as-grown and CeO2 TA samples, respectively. The grain size of ∼2.7 nm is the smallest among the reported values for CeO2. Absorbance of as-grown spectra showed three bands located at ∼382, ∼357 and ∼271 nm while the CeO2 TA sample displayed only two bands at ∼271 and ∼320 nm. Direct optical energy gap were Eg = 4.4 eV and Eg = 4.3 eV for as-grown and CeO2 TA samples, respectively, showing quantum size effect of CeO2 nanoparticles. Raman spectra indicated that the as-grown and CeO2 samples have the fluorite structure.

We investigate the influence of Li+ in the optical properties of PbS thin films. PbS and PbS:Li doped films were prepared by chemical bath deposition. Optical studies using the first derivative absorption spectra reveals the multiple exciton generation process associated to the excitonic transitions. The refractive index (n), extinction coefficient (k), and dielectric parameters (e1 and e2) were obtained. The analysis of current-temperature measurement in the 12–320 K range shows that the activation energy exhibits lower values with increasing Li+ concentration. The mechanism of current conduction in the films is discussed.

CdSe thin films were prepared by chemical bath and doped in situ with Er3+ ions. Three impurity levels were prepared by changing the relative volume of the salt solution containing Er3+ ions in the CdSe growing solution. Changes in the grain size (∼5.5–3.5 nm) and band gap energy (∼1.80–2.25 eV) were observed in the undoped and doped CdSe films, respectively. Photoluminescence studies displayed room temperature emission exhibiting NIR-to visible upconversion. The transition bands 4I13/2 → 4I15/2, 2I9/2 → 4I15/2 and 2F9/2 → 4F15/2 in the ∼700–850 nm region were investigated. Upconversion emissions were observed from the CdSeEr sample under light excitation (325 nm). The upconversion emission intensity ratio of these transitions is attributed to the variation of the local structure around Er3+ ions. These results confirm that visible upconversion emissions of Er3+ in the CdSeEr nanocrystals are mainly produced via two-photon excited-state absorption and energy transfer upconversion processes.

Sm(OH)3 nanocrystals were prepared by the green chemical bath deposition (CBD) approach and further subjected to thermal annealing treatment (TAT) at 1000 °C in air atmosphere to obtain Sm2O3 nanocrystals. Scanning Electron Microscopy (SEM), Fourier transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Photoluminescence (PL) and Raman Spectroscopy techniques were employed to examine the nanocrystals. SEM micrographs showed little morphological changes after TAT. FTIR spectra displayed bands associated with Sm-OH and C O 3 2 − bonds and, after TAT, these bands disappeared completely. According to XRD results, Sm(OH)3 nanocrystals were obtained in hexagonal phase, and after TAT, the Sm2O3 cubic phase can be seen. Absorption bands associated with electronic transitions reported for Sm(OH)3 and Sm2O3 nanocrystals were registered. A shift at 4.5–4.7 eV in the band gap was obtained, presenting the quantum confinement effect. The emissions band observed by photoluminescence showed peaks associated with the magnetic moment and 4G5/2 → 6H5/2 electronic transition. Finally, the results of Raman spectra confirmed the synthesis of Sm(OH)3 nanocrystals and their transition to Sm2O3.

The optical absorption spectra in the UV-region of crystals of enantiopure imines (I, I-F, I-Cl and I-Br) derived from 2-naphthaldehyde is reported. Atomic Force Microscopy (AFM), XRD, absorbance and photoluminiscence (PL) were registered. Substantial differences can be seen in the surface morphology of crystals because of changing halogen atoms in the structure of the imines. Photoluminescence spectra displayed broad bands in the visible region for all the crystals. These bands are associated with molecular defects produced in the molecular packing related with an increase in size of the corresponding halogen atoms.

NdOHCO3 nanocrystals were prepared by chemical bath (CB) and subsequently subjected to thermal annealing treatment (TAT) at 1000 °C in an air atmosphere, observing the NdOHCO3 → Nd2O3 transformation. Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), optical absorption and photoluminescence (PL), examined morphological, structural and optical properties of these powders. Rod-like nanocrystalline structures were observed by SEM. FTIR spectra corresponding to NdOHCO3 exhibited three bands located at ∼3321 cm−1, ∼1634 cm−1 and ∼583 cm−1, corresponding to the characteristic vibration bands of C O 3 2 − anion , these bands disappear completely due to TAT. XRD patterns showed NdOHCO3 in orthorhombic phase and Nd2O3 in cubic phase, respectively. The band gap optical value was found to be 4.48 eV for NdOHCO3 and 4.54 eV for Nd2O3 respectively. PL results displayed bands associated with electronic transitions that have surface and volumetric defects, exhibiting emission bands at ∼421–485 nm (blue), ∼529–542 nm (green) and ∼622 nm (red), respectively.

The morphological, optical, and structural changes in crystalline chiral imines derived from 2-naphthaldehyde as a result of changing the &minus, F, &minus, Cl, and &minus, Br halogen (&minus, X) atoms are reported. Scanning electron microscopy (SEM), optical absorption, photoluminescence (PL), and powder X-ray diffraction (XRD) studies were performed. Theoretical results of optical and structural properties were calculated using the PBE1PBE hybrid functional and compared with the experimental results. Differences in surface morphology, absorbance, XRD, and PL of crystals were due to the change of halogen atoms in the chiral moiety of the imine. Absorption spectra exhibited the typical bands of the naphthalene chromophore located in the ~200&ndash, 350 nm range. Observed absorption bands in the UV region are associated with &pi, &rarr, &pi, * and n&rarr, * electronic transitions. The band gap energy was calculated using the Tauc model. It showed a shift in the ~3.5&ndash, 4.5 eV range and the crystals exhibited different electronic transitions associated with the results of absorbance in the UV region. XRD showed the monoclinic&rarr, orthorhombic crystalline phase transition. PL spectra displayed broad bands in the visible region and all the samples have an emission band (identified as a green emission band) in the ~400&ndash, 750 nm range. This was associated with defects produced in the morphology, molecular packing, inductive effect and polarizability, crystalline phase transition, and increase in size of the corresponding halogen atoms, i.e., changes presumably induced by &minus, C&minus, X&hellip, X&minus, &minus, N&minus, N&hellip, and &minus, interactions in these crystalline materials were associated with morphological, optical, and structural changes.

We present theoretical and experimental results in PbS nanocrystalline thin films systematically doped with Co2+ ions utilizing the green Chemical Bath Deposition technique at ∼90 °C. All growth parameters are kept constant by systematically adding different solution's volume containing the Co2+ ions. We apply the first-order chemical kinetic reaction model to investigate some physicochemical parameters. The crystalline phase is investigated by X-ray Diffraction, identifying the cubic phase in all samples. After dopping the PbS sample (PbSCo2+), the grain size decreases from ∼29.7 nm to ∼15.7 nm and dislocation density increases from ∼3.4 lines m−2 to ∼6.4 lines m−2. The absorbance and bandgap studies conducted in the Vis-UV region show the typical 1Se→1Sh and 1Se→1Ph electronic transitions and the excitonic bands located at ∼1.5 eV and ∼1.8 eV due to higher energy transitions from 1Dh→1De, and 1Fh→1Fe respectively in nanocrystals. Finally, we apply three theoretical models to elucidate the correlation associated with the crystal radius and the bandgap energy (Eg).

In this paper, we present preliminary experimental results in the synthesis of Pd mixed with PdO nanoparticles, grown by chemical bath deposition at ~80 °C. These samples were subjected to further thermal annealing treatment at ~1000 °C in air atmosphere. The properties of these compounds were investigated using the scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), X-ray diffraction (XRD), optical absorption and photoluminescence (PL) techniques. The SEM images for the grown sample show small dense and compact crystals. The FTIR spectra shows absorption bands associated with the OH− and CO32− ions. XRD diffractograms identified a face-centred cubic structure for metallic Pd, and traces of PdO in the tetragonal structure. The grain size ranges between ~33.91 nm and 86.92 nm, and ~33.96 nm–86.94 nm, respectively. The bandgap energy (~3.7 eV) showed a shift towards higher energy linked with the quantum confinement effect. PL spectrum displayed eight emission bands at the UV–Vis range (~363–524 nm). The time-resolved (delayed) PL spectra were achieved ~13.0 ns after excitation. PL signals presented two blue emission bands in the Vis region, and they were associated with native crystalline defects. These blue emission bands are explained by the vacancies and interstitial defects, mostly associated with surfaces or grain boundaries. Likewise, emission bands were investigated, applying the Maxwell–Boltzmann theoretical model and contrasting them with the experimentally registered signals. The PL dependence on trap density and the surface recombination velocity is discussed in the light of calculated lifetimes, PdA1 ~2.04 cm3 s−1 and PdA2 ~9.65 cm3 s−1.

Here we synthesized the Co3O4 and Co(OH)2 nanocrystals using Chemical Bath Deposition technique. We discuss the Fluorescence dependence with the trap density and surface recombination velocity to the light of the Maxwell-Boltzmann theoretical results obtained through the characterization by techniques: X-ray Diffraction (XRD), Absorbance, Raman spectroscopy, and Fluorescence. The XRD show hexagonal β-Co(OH)2 and Co3O4 cubic phase, grain sizes of ∼18.60 nm and ∼19.06 nm, respectively. The Co(OH)2 absorbance shows band at ∼569 nm and at ∼286 nm and ∼377 nm. The Co(OH)2 shows electronic transitions at ∼1.51 eV and ∼2.07 eV assigned to O2−→Co2+ and O2−→Co3+ charge transfer processes. The Co3O4 and Co3O4 have modes. Raman of Co(OH)2 shows active Raman modes. The Fluorescence spectrum of Co3O4 shows peaks at range∼470−573 nm. Co(OH)2 exhibited twelve emission bands in the UV–vis region at range ∼460−660 nm.

Doping of PbS nanocrystals with Fe 2+ ions leads to changes in properties that make them useful in technology of thin films devices. In this paper we present the growth of PbS doped systematically with the solution containing the Fe 2+ ions (V [Fe2+] ) using the green chemical bath approach, with the goal of studying the effects of such Fe 2+ -doping on the morphological, structural, electrical and some optical properties of the PbS thin films obtained. The morphological changes of the films were followed by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). X-ray diffraction showed growth of all films in the zinc blende phase. The grain size was found to be ∼29 and ∼21–17 nm, for the undoped and doped sample, respectively. The absorbance showed in doped films a weak shoulder located at ∼625 nm (1.98 eV), and this exciton peak was attributed to a 1 S e → 1 S h transition. A shift for the band gap energy was observed by optical absorption from ∼1.56 eV for the undoped sample to ∼2.20–2.25 eV range for the doped films. The resistivity increased from ∼26.13–295.7 (Ω cm), and with respect to the electrical conductivity, mobility decreased from ∼8.8 × 10 −4 –2.1 × 10 −7 (Ω cm) −1 , ∼720.1–2.1 cm 2 V −1 s −1 and carrier from ∼1.9 × 10 15 –4.2 × 10 12 cm −3 , while increasing V [Fe2+] .

Herein, the growth of PbS doped systematically with solutions containing In 3 + ions by using chemical bath as a green approach is reported, with the aim of studying the effects of such In 3 + -doping on the morphological, structural and some optical properties of the PbS thin films obtained. The morphological changes of the films were followed by Atomic Force Microscopy and Scanning Electron Microscopy. X-ray diffraction studies showed growth in all films of the zinc blende phase. The grain size was found to be ~ 32 nm and ~ 24–14 nm for the undoped and doped samples, respectively. The absorbance results in doped films showed excitonic peaks at ~ 1.6 eV, ~ 1.8 eV, ~ 2.2 eV, owing to higher energy transitions from 1 D h → 1 De, 2 S h → 2 S h and 2 P h → 2 P e , states, respectively. By optical absorption, a shift for the band gap energy was observed from ~ 1.45 eV to ~ 2.18–2.3 eV range for the undoped and doped films, respectively. Gibbs energy calculation for the In 3 + doping PbS process was also examined.

The structural, electrical and opto-electronic properties of PbS thin films doped with Li+ ion were investigated. The crystallite size showed a strong dependence on Li doping, the crystal size changed from 36 nm to 12 nm due to Li incorporation in PbS. Optical band gap showed a shift in the range ∼1.5–2.3 eV with Li incorporation. Urbach tailing in the band gap was observed and the Urbach energy has a dependence on the amount of incorporated Li. SEM images showed a notable change in grain size with Li doping, however the morphology changes from large grains to agglomerations of smaller grains when doped with Li. The electric conductivity of the films showed a dependence on Li doping, reached a maximum value and later decreased for higher Li containing films. The doped samples showed better photosensitivity.

Herein Se 2− -doped PbS thin films obtained by using the green chemical bath approach are reported. Morphological, optical and structural properties were investigated by atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and optical absorption. Three impurity levels were prepared by changing the relative volume of the solution containing Se 2− ions in the PbS growing solution. XRD showed growth of all films with the zinc-blende phase. Changes in the grain size (∼27–14 nm) and band gap energy (∼1.4–2.24 eV) were observed. The absorbance in doped films, showing excitonic peaks are due to higher energy transitions from 1 S e → 1 S h . Gibbs energy calculation for the Se 2− doping PbS process was also investigated.

Barium carbonate (BaCO3) nanocrystals were synthesized at ∼20 °C by Chemical Bath Deposition technique in the absence of additives. Chemical kinetic mechanism analysis is presented to understand the formation of the BaCO3 nanocrystal associated with the Ba2+ and C O 3 2 - ions. The BaCO3 nanocrystals were thermally annealing treated at ∼500 °C (BaCO3-TT) and the corresponding thermal effects on morphology, grain size, dislocation density (δ), and crystalline phase, were studied. We identified javelin-like, quasi-spherical, and rod-like complex nanostructures by Scanning Electron Microscopy (SEM). We found that the thermal annealing treatment produces a drastic change in morphology, presenting change to dendrite-like complex nanostructures. The FTIR spectra were recorded, both BaCO3 and BaCO3-TT exhibit the same frequency absorptions bands. Those bands at ∼855 cm−1, ∼693 cm−1, and ∼1090 cm-1 are assigned to out-of-plane bending vibrations of C O 3 2 - ion while the frequency absorption band at ∼1411 cm-1 is connected with the asymmetric stretching vibration of C O 3 2 - ion. BaCO3 powders have a rhombohedral crystalline phase, maintaining this crystalline phase even with thermal annealing treatment, confirming the thermal stability of this material. The calculated strain values ∼2.141 × 10-3 and ∼1.15 × 10-3, and the dislocation density ∼1.15 × 10-3 lines m-2 and ∼2.29 × 1015 lines m-2 justify the observed crystalline defects of BaCO3 and BaCO3-TT nanocrystals.

Holmium oxide (Ho2O3) nanocrystals were prepared through an uncomplicated precipitation technique applying Chemical Bath Deposition. The effect by the reaction temperature (∼20 °C and ∼90 °C samples) on the morphological, structural and some optical properties were investigated. Ho2O3 powder samples have been analyzed by applying SEM, FTIR, XRD and absorbance techniques. The crystalline morphology shows differences in grain boundaries as well as porosity and granular packaging. These crystalline materials have an acceptable stoichiometric balance. FTIR spectra show OH- and ions bands of different intensities, that are commonly incorporated in the surface and volume of these crystals. According to the XRD diffractograms, the crystalline cubic phase in both materials is identified. The grain size for each sample is located at range ∼4.06–21.35 nm and ∼21.15–35.35 nm respectively. The absorbance spectra investigated at UV–vis shows eleven absorption bands of different intensities located at ∼278, ∼287, ∼333, ∼345, ∼360, ∼415, ∼448, ∼472, ∼485, ∼535 and ∼645 cm−1 identified as Ho+3 electronic transitions occurring in the UV- Vis-region. The bandgap energies for each sample were Eg ∼4.95 eV, and Eg ∼4.85 eV respectively. The effect of the reaction temperature is manifested with the decrease in the grain size and carries with it the shifting of the Eg towards greater energy, which usually manifests itself in materials that have nanocrystals.

In this paper, we present preliminary results in the synthesis of copper sulfide (CuS) nanocrystals, applying the Chemical Bath Deposit technique and subsequent thermal treatment at 1000 °C in air atmosphere. The crystalline growth is systematically performed at two different reaction temperatures of 20 °C and 90 °C. The powders are investigated by applying the techniques of Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and differential scanning calorimetry (DSC). SEM images showed morphology with crystalline conglomerates on the surfaces, and energy dispersive spectrometry (EDX) spectra shows of Cu, S and O elements. The materials show surface morphological differences associated with the temperature of the crystalline growth and the effect of temperature thermal treatment on texture, grain size, and grain boundaries. XRD identifies a hexagonal phase in CuS20 and CuS90 samples, as well as the transition to CuS(s)→CuO(s). The grain for size for the 20 °C and 90 °C is ∼3.7-5.7 nm, and ∼14.2–35.2 nm respectively. The FTIR analysis shows bands identified with the C O 3 2 - and OH− ions located at range ∼1000−2000 cm-1 which was generated by thiourea hydrolysis. These bands decrease with thermal treatment up to disappear completely. The DSC plots show the changes associated with the structural transition of CuS(s)→ CuO(s). This structural behavior is associated with the thermal stability properties of the CuS and CuO.

Nanocrystalline monoliths of Er doped TiO2 were prepared by the sol–gel technique, by controlling the Er-doping levels into the TiO2 precursor solution. As-prepared and annealed in air samples showed the anatase TiO2 phase. The average diameter of the nanoparticles ranged from 19 to 2.6 nm as the nominal concentration of Er varies from 0% to 7%, as revealed by EDS analysis in an electron microscope. Photo Acoustic Spectroscopy (PAS) allowed calculate the forbidden band gap, evidencing an absorption edge at around 300 nm, attributed to TiO2 and evidence of electronic transitions or Er3+. The Raman spectra, corresponding to the anatase phase, show the main phonon mode Eg(1) band position at 144 cm−1 with a red shift for the annealing samples.

A general approach has been developed for the synthesis of Erbium-Oxide/Erbium Hydroxide (Er2O3–ErOOH) powder at 25 °C via chemical bath. The powder was annealed at 1000 °C in air atmosphere at normal pressure. The FTIR exhibits a characteristic stretching mode of Er–O, a typical FTIR structural band for such groups. The structure of the powders was characterized by means of Scanning Electron Microscopy and Energy Dispersive X-ray spectroscopy and the results displayed a rhombohedral phase. The band gap is 4.5 eV, and luminescence spectra were observed in six bands at 380–420, 530–580, and 640–690 nm.

The growth through the green chemical bath of PbS doped systematically with the biomolecule L-tryptophan led to growth of hybrid, inorganic-organic, nanocrystalline thin films onto glass slides at T~80°C. The thickness was found in the range of 230–140 nm. Morphological changes were analyzed using atomic force microscopy (AFM). FTIR (Fourier-transform infrared spectroscopy) spectra showed broad absorption bands located at ~3450 cm−1 attributed to stretching of the H2O molecules and two small absorption bands located at ~2285 cm−1 and ~2918 cm−1 along with a strong band at ~1385 cm−1 assigned to vibration modes corresponding to CO32− ions. In the patterns of X-ray diffraction (XRD), the cubic phase was identified in all the samples according to the angular positions 2θ~26.08°, 30.13°, 43.08°, 51.91°, 53.60°, 6251°, 68.98°, and 71.15°. Using the Scherrer formula on the XRD patterns, the grain size (GS) was determined; for the undoped sample, ~42 nm was found, whereas for the doped samples, ~42–22 nm was found. The electronic charge distribution of L-tryptophan was determined using the molecular electrostatic potential (MEP) to understand the decrease on the GS associated with the interaction of π electrons from conjugated rings and amino-acid functional groups. The absorbance spectra in doped films showed excitonic peaks at ~1.8–2.1 eV associated to a higher energy of the 1Sh → 1Sh and 1Ph → 1Pe electronic transitions. Through optical absorption, a shift for the band gap energy was observed from ~1.4 eV for the undoped sample and ~2.1–2.3 eV for the doped films, respectively. Such behaviour is generally associated with the GS decrease and the effect of quantum confinement; a simple model by calculating changes in Gibbs free energy (ΔG°) for growth of nanocrystals is presented.

PbS:Cu nanocrystalline films were prepared by chemical bath at temperature of 80 degrees C and deposited on glass substrates. Different Cu-doping levels were obtained changing the volume of the Cu-reagent-solution into the PbS growing solution. X-ray diffraction (XRD) and optical absorption (OA) measurements were carried out to characterize the semiconductor. The morphological changes of the layers were analyzed using an atomic force microscopy. Diffraction X-ray spectra displayed peaks at 2 theta = (26.00, 30.07, 43.10, 51.00 and 53.48), indicating growth on the zinc blende face. The grain size determined by X-rays diffraction of the undoped samples, was found -37 nm, whereas with the doped sample was - 32-25 nm. Raman spectra reports strong band in - 133-140 cm(-1) attributed to a combination of longitudinal and transversal acoustic modes. Optical absorption, forbidden band gap energy (E(g)) shift disclose a shift in the range 1.4-2.4 eV. Gibbs free energy calculation for the Cu doping PbS is also included heading.

Herein, the analysis of the (S)-(+)-1-(4-bromophenyl)-N-1-phenylethylmethanimine organic material in solid state is reported, i.e., the crystal structure, molecular packing, morphological and optical analysis, as well as the correlation of these parameters are presented. The crystalline phase and spatial group were established by X-ray Diffraction (XRD) studies. The surface morphology of the crystal was recorded by Scanning Electron Microscopy (SEM) technique. SEM images showed a packing with dense plates stacked and fragmented. The UV–Vis spectral analysis was registered in the ~350–700 nm (~4.13–1.77 eV) range. The band gap energy (Eg) was determined by the Tauc model and located at Eg ~3.45 eV. Two experimental emission bands were recorded by Photoluminescence (PL) at room temperature in the Vis-region located in the ~415 nm (~2.88 eV) and ~558 nm (~2.22 eV) ranges. These emission signals were identified as blue (BE) and green (GE) emission bands, respectively. By applying the theoretical Maxwell-Boltzmann model as a proxy to considering crystalline defects as fixed particles, the optical emission bands of PL were calculated suggesting that the crystalline defects (e.g., vacancies and molecular interstices) generated the GE and BE bands. The experimental-theoretical results have values very close to each other when comparing the relative maxima, as it is presumed that this optical phenomenon is generated by the crystalline defects. A Raman spectroscopy study was also performed.

Growth of doped CdCO 3 –Pb 2+ thin films was carried out by chemical bath. Changes of the level doping affect the structure and morphology. XRD peaks of CdCO 3 sample show rhombohedral crystalline structure. A-10 and A-20 doped films exhibit peaks that indicate co-existence of one solid solution of CdCO 3 –PbCO 3 Pb(OH) 2 which has rhombohedral crystalline and tetragonal phase respectively, and A-30 film indicate co-existence of CdS–Pb 3 O 2 (SO 4 )(OH) 2 –Pb 4 (CO 2 ) 3 (SO 4 )(OH) 2 compounds. FTIR spectra displayed the peaks at 1400, 850, 718 cm −1 , which are characteristic vibration bands of CO 3 2 − ion and also exhibit an absorption band at ∼670 cm −1 , which is characteristic of Pb–O stretching mode.

Nanocrystalline CdS:Cu thin films were prepared by chemical synthesis on glass at 70 °C. X-ray diffraction (XRD), optical absorption (OA) and Raman measurements were carried out in order to characterize the material. From the XRD patterns it is concluded that grains of Cu-doped CdS films grow mainly in the zincblende cubic phase. The average radius ( R ), calculated by employing the Scherrer’s formula, is located in the range 2.7–8.7 nm. The forbidden energy band gap ( E g ) was estimated from the optical absorbance spectra and by means of the maximum of their first derivative. As effect of the doping the unit cell volume of CdS:Cu undergoes a shrinkage due to the compressive stress introduced by Cu atoms. Two effects overlap to change the E g values: (a) the quantum confinement and (b) the internal stress (IS). IS is that which does not come from forces out to the volume of the material like the stress produced by substrates. Raman spectra indicate that the stress decreases when R decreases. On the other hand, the (1 1 1) interplanar distance and the unit cell volume (UCV) increases when R decreases, following the relationship UCV ∝ R −1 . In the CdS:Cu stressed lattices, UCV increases when R decreases because in smaller particles the relaxation of the induced IS is more effective than in larger particles.

The melt-quenching method was used to prepare two groups of samples using CdO and V2O5 as starting materials. Taking into account that a crystalline-amorphous phase transition would be expected for the CdO–V2O5 system, a first batch was prepared varying the proportions of CdO and V2O5 in the intervals 60–95 and 40–5 wt%, respectively. With the aim of investigating the effect of erbium in the phase transition and crystalline quality of the first group of samples, a second batch was fabricated with the same proportions of CdO and V2O5, with the addition of 5 wt% of Er(NO3)5H2O as source of Er3+ ions. It was found that crystalline or amorphous samples could be obtained depending on the relative concentrations of CdO and V2O5, and that the borderline between amorphous and crystalline samples was affected by the incorporation of Er. From X-ray diffraction, it was possible to identify the formation of the ternary compound Cd2V2O7 in the crystalline cases. The Raman and infrared bands in these samples were in agreement with the lattice modes of Cd2V2O7. Additionally, an improvement in the crystalline quality of Cd2V2O7 was obtained for the Er-doped samples. The effect of the local environment around the Er3+ ions on the room temperature photoluminescence was also investigated for the amorphous and crystalline samples.