Lattice Parameters Research Articles

Optimal synthetic route for obtaining Co/In layered double hydroxide

Cobalt-indium layered double hydroxides were successfully synthesized via coprecipitation and mechanochemical synthesis with subsequent soft hydrothermal treatment and additional crystallization. The latter method was shown to have advantages over coprecipitation and therefore the mechanochemical route was considered to be optimal for obtaining well-crystallized LDH samples, which do not contain extraneous crystalline phases within the detection limit of X-ray diffraction. The samples were characterized by FTIR spectroscopy, Raman spectroscopy, and transmission electron microscopy. The peroxidase-like activity of the samples was estimated, and the crystal lattice parameters were calculated. The possibility of obtaining cobalt-indium layered double hydroxides with a cationic ratio of Co2+: In3+ = 2 : 1 and 1.5 : 1 was shown. Increasing the aging temperature presumably led to the partial oxidation of cobalt in the samples into trivalent state resulted in the peroxidase-like activity of the samples.

Growth, structure and optical properties of Rb2CоCl4·2H2O crystals

Phase equilibria in the RbCl–CoCl2·2H2O–H2O system were investigated, single crystals of double rubidium–cobalt chloride dihydrate were obtained, and its structure and optical properties were studied. The regions of crystallization of compounds in the three-component system under study were delimited. Rb2CoCl4·2H2O crystals were grown by controlled decrease in the temperature of a saturated aqueous solution. Using X-ray diffraction analysis, the crystal lattice parameters of Rb2CoCl4·2H2O were obtained and the structure of the crystals was refined. The spectral characteristics of the obtained crystals and the corresponding aqueous solution were studied in the λ range 200–800 nm.

Unveiling the mechanism of the carbon ordering and martensite tetragonality in Fe–C alloys studied via deep-potential molecular dynamics simulations

The martensitic transformation plays a pivotal role in the strengthening and hardening of steels, yet an accurate interatomic potential for a comprehensive description of the martensitic phase formation in Fe–C alloys is lacking. Herein, we develop a deep learning-based interatomic potential to perform molecular dynamics (MD) simulations to study the martensitic phase transformation across a range of carbon (C) concentrations. The results reveal that an increased C concentration leads to a suppression of phase boundary movement and a deceleration of the phase transformation rate. To overcome the timescale limitations inherent in MD simulations, metadynamics sampling was employed to accelerate the simulations of C diffusion. We find that C atoms tend to cluster at distances equivalent to the lattice parameter of Fe with the same sublattice occupation, leading to local lattice tetragonality. Such C-ordered structures effectively inhibit dislocation movement and enhance strength. The stress field induced by dislocations facilitates a higher degree of ordering. The formation of C-ordered structures is identified as a potentially crucial strengthening mechanism for martensitic steels. The consistency between our simulation results and reported experimental observations underscores the effectiveness of the developed DP model in simulating martensitic phase transformation in Fe–C alloys, providing detailed insights into the mechanisms underlying this process.

A DFT-based computational study on a highly and lead-free inorganic new fluoroperovskite of Mg3PF3

Inorganic fluoroperovskite materials are increasingly important in solar technology due to their exceptional structural, optical, electronic, and mechanical properties. This study uses DFT calculations to investigate the properties of Mg3PF3 fluoroperovskite. Our results show a crystal structure and lattice parameter of (a = 4.64 Å) which align with previous theoretical and experimental findings, confirming the accuracy of our calculations. Mechanical analysis reveals that Mg3PF3 is naturally ductile, elastically anisotropic, and stable according to established criteria. The band structure and PDOS indicate that it is a semiconductor with direct bandgap of 3.88 eV at the Γ point, making it suitable for electronic applications. Electron charge density mapping suggests a predominantly ionic bonding nature. Optical property analysis shows significant dielectric constant peaks in the photon energy range favorable for solar cells. Overall, these findings position Mg3PF3 as a promising candidate for solar cell technology, highlighting its potential for enhancing renewable energy solutions.

Effect of B4C nanoparticles addition on the refinement of Fe-rich phase in ZL108 alloy

Refining effect of B4C nanoparticles in ZL108 alloy on Fe-rich phase was studied in this work. It was observed that B4C nanoparticles apparently refines the size of the Fe-rich phases and partially transforms Fe-rich phases morphology from hollow polyhedron to petal-like shape. The DSC results show that B4C nanoparticles does not affect the initial nucleation temperature of the Fe-rich phase. However, the addition of B4C nanoparticles to ZL108 alloy inhibits the growth of Fe-rich phase. The TEM results confirm that the addition of B4C nanoparticles alters the lattice parameter of Fe-rich phase due to incorporation of C atoms, thereby suppressing the growth of the Fe-rich phase and ultimately leading to its refinement. From the perspective of fracture behavior, the addition of B4C nanoparticles remarkably reduces the stress concentration of Fe-rich phase, and the elongation of the alloy increases by 25.3%. These findings provide a new perspective for further research and development to refine Fe-rich phase.

Novel Tl2SnX6 (X=Cl,Br) Double Perovskites for Photovoltaic Applications: A DFT Insight

New double perovskites Tl2SnCl6 and Tl2SnBr6 have been computationally investigated for the first time to determine their structural, mechanical, and optoelectronic properties. The calculations were carried out using Density Functional Theory (DFT), implemented in the Quantum Espresso and Thermo_pw codes. DFT is a theoretical framework used to accurately predict the ground state properties of quantum many-body systems ranging from atoms to condensed matter systems. The results indicated that Tl2SnCl6 and Tl2SnBr6 possess equilibrium lattice parameters of 10.28 Å and 10.77 Å, respectively. Their negative formation energy ensures chemical stability while their positive elastic tensors imply mechanical stability, which is also confirmed by the fulfillment of the Born-Huang stability criteria. Analysis of their Poisson’s and Pugh’s ratio suggested that the materials are brittle but Tl2SnCl6 was estimated to be ductile in some directions. The materials were found to possess semiconducting behavior with bandgap of 1.19 eV (1.48 eV) and 2.48 eV (2.84 eV) for Tl2SnBr6 and Tl2SnCl6, respectively, using the PBE (SCAN) functionals. The calculated optical characteristics indicated that both Tl2SnCl6 and Tl2SnBr6 exhibit remarkable optical properties including significantly high absorption coefficient and low reflectivity, rendering their potential as light absorbers. In particular, with an ideal band gap of 1.48 eV and strong absorption in the visible region of the solar spectra, Tl2SnBr6 is predicted to be an excellent absorber for perovskite solar cells.

Origin of the distinct site occupations of H atom in hcp Ti and Zr/Hf

The location of the H atoms in Ti, Zr, and Hf is crucial to the formation of the hydrides in these metals as it influences the crystal lattice transformation and the hydrogen diffusion involved in the hydride formation process. Although Ti, Zr, and Hf are all of hexagonal close-packed structure with similar lattice parameters, the solute H atom occupies the octahedral interstice in Ti but the tetragonal interstice in Zr and Hf, of which the origin is still mysterious. In the present work, the origin of the distinct site occupation behavior of H atom in Ti and Zr/Hf is investigated through first principles calculations. The calculated solution energies confirm that H prefers the octahedral interstice in Ti but the tetrahedral interstice in Zr and Hf. We ascribe the distinct site occupations of H in Ti and Zr/Hf to the varying Coulomb repulsion between the H (as a screened proton in the metals) and the matrix atoms against the interstitial size. The competition between the H-induced electron accumulation effect and the matrix atom debonding effect might matter as well. We propose that, as a general rule, a H atom prefers the site with a trade-off between a large space and a high electron density in metals.

Electronic structure modulation of yttrium sites with heteroanions coordination enhances the bidirectional catalytic performance of lithium-sulfur batteries

Oxyfluorides exhibit unique properties, including catalytic activity and electrical conductivity. However, to date, there has been minimal application of oxyfluorides in the field of lithium-sulfur (Li-S) batteries. This study synthesizes yttrium oxyfluoride-doped semi-encapsulated porous carbon nanofibers (YOF@PCNFs) using through electrospinning strategy for the separator coating in Li-S batteries. The precisely engineered OF heteroanionic environment surrounding the Y cation can adjust the lattice spacing and electronic density of the catalyst. This enhancement improves interactions between the active sites and the reactants, intermediates, and products, reduces the energy barrier for polysulfide (LiPSs) conversion, and enhances the bidirectional catalytic conversion capability of LiPSs. Furthermore, the semi-encapsulated structure helps inhibit polysulfide shuttle and ensures uniform Li-ion deposition. Improved catalysts and the interconnected special structure can establish a series of polysulfides conversion factories which operate efficiently over the long term through a “confinement-adsorption-catalysis-desorption” process, thereby enhancing battery cycling stability. The assembled Li-S full cell exhibits a high initial capacity of 1013.2 mAh/g at 1 mA cm−2 and maintains steady operation over 1500 cycles, with a minimal capacity decay rate of only 0.039 % per cycle. Even at a high current density of 4 mA cm−2, it operates for 200 cycles with an exceptionally low decay rate of 0.081 % per cycle. The study provides an anion hybrid strategy for typical metal catalysts, offering design guidelines for tailored advanced Li-S catalysts.

Visible light photocatalytic reduction of Toxic Chemical Organophosphate Monocrotophos using reduced Graphene Oxide derived from bamboo leaves

In this study, graphene oxide (GO) was synthesized from waste bamboo leaves using a pyrolysis and ultra-sonication technique. UV-visible spectroscopy revealed a prominent absorption peak at 230nm, while Raman spectroscopy confirmed the presence of characteristic D-band (1340cm⁻¹) and G-band (1596cm⁻¹). XRD analysis showed a peak at 11.5°, corresponding to a lattice spacing of 3nm, and SEM/TEM imaging demonstrated the formation of multi-layered graphene sheets. The synthesized GO was evaluated for the photocatalytic degradation of the organophosphate pesticide monocrotophos under visible light. At a concentration of 25mg/L, graphene exhibited a removal efficiency of 98% with a degradation rate of 0.036 ppm/min, following a Langmuir isotherm and pseudo-first-order kinetic model. The significance of this study lies in the potential environmental application, offering an economical and sustainable solution for the decontamination of pesticide-contaminated water sources. The method could contribute significantly for reducing environmental pollution and addressing global water safety challenges.

Thermal Expansion of Römerite under Low-Temperature Conditions Revision 2

Abstract Römerite, a triclinic hydrous sulfate in the P1 space group with the chemical formula Fe2+Fe3+2 (SO4)4 × 14(H2O), is of potential interest in studies of planetary environments, with particular relevance to Mars and the icy Jovian satellites. Past work has indicated the presence of hydrous sulfates on said bodies and the mixed-valence iron in the structure of römerite makes the mineral a worthwhile end-member composition in thermodynamic models. Such models should be constrained with measurements at the low temperatures relevant to the planetary environments in question. We characterized single crystals of römerite with time-domain Mössbauer spectroscopy, Raman spectroscopy, and X-ray diffraction methods. Through our X-ray diffraction experiment, we refined the unit–cell parameters of the crystal between 100 and 300 K. The resulting temperature-variant lattice parameters and volumes are reported and are fit by physical and empirical models of the thermal expansion coefficient. The physical model considered, a Debye model of thermal expansion, provides estimates of additional thermodynamic parameters: the ratio of the bulk modulus at 0 K and 1 bar to the thermodynamic Grüneisen parameter (K0,0K/γth), the volume at 0 K and 1 bar (V0,0K), and the Debye temperature (θD).

Investigating the photocatalytic efficacy of a porous cuprous gallate (CuGa2O4) thick film

Abstract The study aimed to investigate the photocatalytic activity of porous copper gallate (CuGa2O4) thick film with significant wall dimensions. The thick film was meticulously fabricated using tape casting systems, with CuGa2O4 nanoparticles synthesized by Sol–Gel technique and subsequently transformed into gels for the tape casting process. Rietveld refinements were employed to elucidate the crystal structure and lattice parameters of the CuGa2O4 spinel oxide lattice. Moreover, electronic energy configurations and optical transmittance measurements were acquired through UV-visible spectrophotometry. The correlations between the crystal structure, band gap change and formation of electronic energy levels in relation to the photocatalytic performance of CuGa2O4 were explored. The comprehensive examination provides valuable insights into the complex interaction between material properties and photocatalytic behavior, offering a nuanced understanding of the potential applications of porous CuGa2O4 thick films in various technological fields.

Investigation of the behaviour of tunable chalcogenide-Bismuth based perovskite BiTl (SxSe1-x)3(X = 0, 0.33, 0.67, 1): first principles calculations

Density functional theory (DFT) driven by the quantum ESPRESSO code was used in this study to investigate the structural, opto-electronic, and thermoelectric properties of ternary perovskite chalcogenide compound. This is to examine their possible use in optoelectronics and reducing the dependency on silicon and fossil fuel. The Perovskite compounds crystalize in the cubic phase with a space group Pm-3m. The volume versus energy is fitted by the Birch-Murnaghan equation of state which yielded the equilibrium lattice constant of 8.353, 8.488, 8.629 and 8.806, bulk modulus of 255.8, 242.7, 233.5 and 222.4, for BiTlS3 , BiTlS2 Se1 , BiTlS1 Se2 and BiTlSe3 . Indirect band gaps of 2.6 eV, 2.7 eV, 2.9 eV, and 3.2 eV were obtained for BiTlS3 , BiTlS2 Se1 , BiTlS1 Se2 and BiTlSe3 compounds, respectively. Also, increment in the energy from 0 eV to 10 eV resulted in optical properties fluctuation within 0 cm-1 to 1.5 × 109 cm-1 for absorption coefficient in the compounds. However, a variation from 10 eV to 20 eV moved the absorption coefficient to 4.2 × 109 cm-1 for all the compounds from visible to the UV range. Furthermore, the observed properties show that the value of figure of merit obtained is 0.125 for BiTlS3 , 0.100 for BiTlS2 Se1 , 0.068 for BiTlS1 Se2 and 0.055 for BiTlSe3 at 300 K. By adjusting the chalcogen ratio, BiTlX3 (X = S, Se) possess the tunable band gap in the whole visible light range, which is of great significance for the development of new-type, high-efficient semiconductor material and optoelectronic devices, while the low thermoelectric values predict the compounds use as sensors. The proposed results may pave the way for further investigations into the use of the perovskite compounds for optoelectronic devices.

Aluminum matrix composites reinforced with high-entropy oxides and in situ formed Al2O3 and intermetallic compounds through aluminothermic reactions during spark plasma sintering

This work proposes a new strategy for producing aluminum matrix composites with strong interfaces by forming additional reinforcing particles in situ through an aluminothermic reaction between the system components. Sol-gel synthesized high-entropy spinel-type (Cr0.23Mn0.22Fe0.22Co0.19Ni0.13)3O4 oxides (HEO) were added to Al nanopowder and the resulting mixture was subjected to high-energy ball milling (HEBM) and then spark plasma sintering (SPS). As a result of the aluminothermic reaction during SPS, HEO are partially reduced, providing excess oxygen for the formation of reinforcing Al2O3 nanoparticles, and the reduced metals react with Al with the formation of various intermetallic compounds (Al9Me2, Al5Me2, and Al2Me), which, in addition to HEO, serve as secondary strengthening phases. A new hexagonal AlMex phase with lattice parameters of approximately a = c = 1.76 nm has been well documented. HEBM has been shown to be an important step not only for uniform HEO distribution, but also for the aluminothermic reaction to occur at a relatively low temperature by improving the interaction between activated Al and HEO nanopowders. The maximum increase in hardness with the addition of HEO is 198 %, tensile strength 90 % (25°C) and 97 % (500°C), and compressive strength 220 % (25°C) and 250 % (500°C). Excellent mechanical properties are achieved at 500°C: the ultimate tensile and compressive strength are 258 MPa and 410 MPa, respectively. The introduction of HEO also leads to a significant reduction in the coefficient of friction (from 0.7 (0 %) to 0.2 (3 %HEO)) and a noticeable reduction in dynamic wear (5.9–6.3 (3 %HEO) and 10.6–14.3 (5 %HEO) times depending on applied load). Thus, our research opens up exciting new possibilities for creating lightweight and high strength composites for use in the mid-temperature range.

Effect of Thermal Processing on the Structural and Magnetic Properties of Epitaxial Co2FeGe Films.

The structure and magnetic properties of epitaxial Heusler alloy films (Co2FeGe) deposited on MgO (100) substrates were investigated. Films of 60 nm thickness were prepared by magnetron co-sputtering at different substrate temperatures (TS), and those deposited at room temperature were later annealed at various temperatures (Ta). X-ray diffraction confirmed (001) [110] Co2FeGe || (001) [100] MgO epitaxial growth. A slight tetragonal distortion of the film cubic structure was found in all samples due to the tensile stress induced by the mismatch of the lattice parameters between Co2FeGe and the substrate. Improved quality of epitaxy and the formation of an atomically ordered L21 structure were observed for films processed at elevated temperatures. The values of magnetization increased with increasing TS and Ta. Ferromagnetic resonance (FMR) studies revealed 45° in-plane rotation of the easy anisotropy axis direction depending on the degree of the tetragonal distortion. The film annealed at Ta = 573 K possesses the minimal FMR linewidth and magnetic damping, while both these parameters increase for another TS and Ta. Overall, this study underscores the crucial role of thermal treatment in optimizing the magnetic properties of Co2FeGe films for potential spintronic and magnonic applications.

Performance of dual-band infrared photodetectors based on M-structure superlattices

Abstract The mainstream dual-band photodetector structures are complex, requiring careful design of each absorption layer, making it difficult to customize according to specific requirements. We simplified the structure and proposed an alternative design, which based on the nBn barrier structure combined with the M-structure superlattice (M-SL). With the utmost consideration for lattice matching, we have enabled tailored design and arbitrary adjustment of the absorption coefficients for both detection bands and the overall absorption characteristics as needed. This manuscript presents a series of dual-band photodetectors. The performance of these devices was simulated at 77K, with quantum efficiency exceeding 22% in the MWIR band of the MWIR-LWIR detector, and normalized detectivity reaching 10^(11)cm·Hz^(1/2)/W. Quantum efficiency in the LWIR to VLWIR bands surpasses 19%, with normalized detectivity reaching 10^(11)cm·Hz^(1/2)/W.

Enhancing shielding efficiency of ordinary and barite concrete in radiation shielding utilizations

Concrete has been widely utilized as a radiation shielding material due to its properties and structural integrity. This study aims to evaluate the efficiency of ordinary concrete versus barite concrete as radiation shielding materials, focusing on the physical aspects and changes in crystal size lattice parameters after neutron irradiation. Specifically, the research investigates the shielding effectiveness of these materials across different grades (M15, M25, M35, and M45) against gamma-ray sources Cobalt-60 and Caesium-137. The methodology involves measuring the linear attenuation coefficient (μ), half value layer (HVL), tenth value layer (TVL), and mean free path (MFP). Additionally, X-ray diffraction (XRD) was employed to assess crystallite size and lattice parameter changes post-irradiation for neutron irradiation. Results indicate that incorporating barite as an aggregate significantly enhances the density and crystallite macroscopic properties of the concrete. Irradiation with Cobalt-60 and Cesium 137 revealed that ordinary concrete has a lower linear attenuation (μ) ranging from 0.172 to 0.195 cm−1, with consistent mass attenuation across all grades at 0.81 cm2/g. XRD analysis demonstrated a rightward shift in the SiO₂ and BaSO₄ peaks post-irradiation, signifying crystalline expansion. In terms of lattice parameters, the d-value showed a notable decrease of 0.10 after 48 h of irradiation in grade 25, while the most significant increase of 0.02 occurred after 24 h of irradiation in grades 15 and 45. In conclusion, barite concrete proves to be more effective for radiation shielding in nuclear facilities, whereas ordinary concrete is suitable for medical shielding, or facilities exposed to lower radiation doses.

Biaxial and Uniaxial Strain Effect on Structural and Electronic Properties of Anatase TiO<sub>2</sub>: A First-Principle Calculation

The effect of biaxial and uniaxial strains on the electronic structure of anatase is studied using Density Functional Theory (DFT) calculation with ultrasoft pseudopotential and a generalized gradient approximation (GGA) Perdew-Burke Ernzerhof (PBE) exchange-correlation. The lattice constant is optimized using the Birch-Murnaghan equation of states (BM-EOS) to get an optimized geometric structure of anatase TiO2. We apply biaxial and uniaxial strains to this optimized structure up to 16% and find that the applied strains change the band gap energy compared to a pure anatase with a different band gap energy up to 1.61 eV for biaxial strain and 0.35 eV for uniaxial strain. The biaxial strains increase gap energies except at +16% tensile strain, decreasing the gap energy to 0.04 eV. Uniaxial strains tend to increase as the strains increase except at-12 and-16%; their gap energy differences are 0.08 and 0.20 eV, respectively, smaller than that of the zero strain. The results also show that the applied 16% tensile strain significantly lengthens the atomic bonds; thus, we conclude that the maximum strain applied to anatase TiO2 is 16%.

Optimization of MBE-grown GaSb buffer on GaAs substrates for infrared detectors

The aim of this work was to improve the quality of the GaSb buffer layers on GaAs substrates using the molecular beam epitaxy (MBE) technology. The high quality of the GaSb buffer layers is one of the most important elements enabling the synthesis of good quality of type II superlattices (T2SL) structures for infrared applications. The main challenges in this regard are: compensation of the difference in lattice constants between GaAs and GaSb and obtaining the highest achievable surface quality of the final GaSb layer. In the literature, many authors describe different techniques to obtain the best quality of a GaSb buffer layer. In this work, we present the results of HRXRD, AFM, TOF-SIMS, SEM, and Nomarski optical microscope measurements obtained for 2 μm thick GaSb buffer layers. The GaSb layers are made according to different techniques and these results are compared with a GaSb buffer construction technique according to our own technology. During the processes, we also obtained an unintentional structure of one of the buffer layers, which allowed us to obtain very good results in terms of surface structure and crystallographic quality where FWHM in ωRC scan was equal to 138 arcsec and RMS 0.20 nm proving that there is still a lot of work to be done in this area.

Nanostructured spinel ferrites: A comprehensive study on the synthesis, characterization, and magnetic properties of Zn and Mn substituted magnetite nanoparticles produced through the co-precipitation method

Seven cubic spinel ferrite nanoparticles were successfully synthesized through the co-precipitation method. These nanoparticles include Fe3O4, Zn0.4Fe0.62+Fe23+O4, Mn0.4Fe0.62+Fe23+O4, Zn0.6Mn0.4Fe0.42+Fe1.63+O4, Zn0.4Mn0.6Fe0.42+Fe1.63+O4, Zn0.4Mn0.4Fe0.22+Fe23+O4, and Zn0.4Mn0.4Fe0.42+Fe1.83+O4. The Rietveld method was used to analyze X-ray diffraction data, confirming that all samples have a single-phase cubic spinel structure. The presence of zinc and manganese ions in magnetite lattice leads to changes in lattice parameters and crystallite size, resulting in a range of 7–12 nm crystallite sizes. Fourier transform infrared spectroscopy (FT-IR) analysis of nanoparticles reveals two significant adsorption peaks at 560-576 cm−1 and 437-449 cm−1, corresponding to metal ion stretching vibrations at tetrahedral and octahedral sites. The X-ray photoelectron spectroscopy (XPS) analysis revealed the presence of iron, zinc, and manganese in various oxidation states. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) images showed spherical, agglomerated nanoparticles. The study confirmed the elemental composition and mapping images of prepared samples using energy-dispersive X-ray spectroscopy (EDS). The magnetic properties of the synthesized nanoparticles were meticulously examined utilizing a vibrating sample magnetometer (VSM) at room temperature. A direct correlation is established between the structural alterations induced by Zn2+/Mn2+ and their subsequent effects on magnetic characteristics, specifically through the reallocation of cations and the mechanisms of electron hopping occurring at the B-sites. The structural modifications result in enhanced superparamagnetic behavior, exhibiting saturation magnetization values between 46.01 and 69.38 emu/g. The sustainable characteristics of these materials render them highly viable options for applications in environmental remediation and green technology.

Solar Light Elimination of Bacteria, Yeast and Organic Pollutants by Effective Photocatalysts Based on Ag/Cr-TiO2 and Pd/Cr-TiO2.

This study focused on searching for more effective nanomaterials for environmental remediation and health protection; thus, coliform bacteria, yeast and the organic food dye sunset yellow were selected as target pollutants to be eliminated under solar light by Ag/Cr-TiO2 and Pd/Cr-TiO2. Firstly, Cr3+ was in situ incorporated into the anatase crystalline lattice by the sol-gel method; then, Ag or Pd nanoparticles were deposited on Cr-TiO2 by chemical photoreduction. The scientific challenge addressed by the development of these composites was to analyse the recovery of Cr, to be employed in photocatalyst formulation and the enhancement of the TiO2 photocatalytic activity by addition of other noble metals. By extensive characterization, it was found that after TiO2 doping with chromium, the parameters of the crystal lattice slightly increased, due to the incorporation of Cr ions into the lattice. The TiO2 band gap decreased after Cr addition, but an increase in the optical absorptions towards the visible region after noble metals deposition was also observed, which was dependent of the Ag or Pd loading. Generally, it was observed that the noble metals type is a factor that strongly influenced the effectiveness of the photocatalysts concerning each substrate studied. Thus, by using Ag(0.1%)/Cr-TiO2, the complete elimination of E. coli from samples of water coming from a highly polluted river was achieved. Pd(0.5%)/Cr-TiO2 showed the highest efficiency in the elimination of S. cerevisiae from a lab prepared strain. On the other hand, the Pd(0.1%)/Cr-TiO2 sample shows the highest dye degradation rate, achieving 92% of TOC removal after 180 min.