Hydrothermal-induced growth of Ca10V6O25 crystals with various morphologies in a strong basic medium at different temperatures

Template-Free Synthesis of Alkaline Earth Vanadate Nanomaterials from Leaching Solutions of Oil Refinery Waste

“…The XRD characterization (Figure a) shows that the calcium vanadate product can be ascribed to the hexagonal Ca 10 V 6 O 25 phase (JCPDS card no. 52-0649). , Three different interplanar spacing of the crystals (0.350, 0.319, and 0.291 nm) are measured in a high-resolution TEM (HRTEM) image (Figure d), which can be assigned to (002), (210), and (211) crystal planes, respectively. The angle between the (002) and (211) planes is 65°, matching well with the hexagonal crystal structure.…”

Computational Chemistry Meets Experiments for Explaining the Geometry, Electronic Structure, and Optical Properties of Ca10V6O25

“…Synthesis. The synthesis of the Ca 10 V 6 O 25 crystals follows the procedure proposed by Hojamberdiev et al: 10 2 mmol of NH 4 VO 3 (≥99.9%, Sigma−Aldrich) was dissolved in 25 mL of distilled water, and heated thereafter at 50 °C under magnetic stirring until the reagent was dissolved completely. Separately, 1.6 mmol of CaCl 2 •2H 2 O (99.0%−105.0%, synth) was dissolved in 25 mL of distilled water at room temperature.…”

“…These distortions in clusters generate defects as quantum dots, which favor the different PL properties of the material. 10 According to the Wood−Tauc function, 60 αhν = C 1 (hν − E gap ) n , where n = 1 / 2 , α is the absorption coefficient, hν is the photon energy, C 1 is a proportionality constant, and n is the type of electronic transition. Thus, we have (αhν) 2 , which can be related to the Kubelka−Munk function (K−M), 61 and we obtain the band-gap energy (E gap ) values of the samples using the graph [F(R)hν] 2 vs hν (Figure S3 in the Supporting Information), where F(R) is the K−M function.…”

“…The members of the calcium vanadate family, such as Ca 0.5 V 3 O 8 , 1 CaV 4 O 9 , CaV 3 O 7 and CaV 2 O 5 , 2 CaV 2 O 6 , 3 CaVO 3 , 4 CaV 6 O 16 , 5 Ca 2 V 2 O 7 , 6 Ca 3 V 2 O 8 , 7 Ca 4 V 4 O 14 , 8 Ca 7 V 4 O 17 , 9 and Ca 10 V 6 O 25 5,10,11 have attracted increasing interest, because of their structure, compositional diversity, and physical and chemical properties, which facilitate a wide range of technological applications in the fields of magnetism, electrochemistry, catalysis, and optical devices. 1,2,10−16 In particular, Ca 10 V 6 O 25 has drawn attention, because of its geometric structure, in which both Ca and V cations adopt different local coordinations, 5,10 with a promising potential in electronic, biomedical, and semiconductor applications. 10,17 Moreover, Pei et al 11 observed that the Ca 10 V 6 O 25 nanorod modified glassy carbon electrode, which presents good performance in the electrochemical detection of tartaric acid, is promising for the development of electrochemical sensors for tartaric acid: However, information about its structure and related materials is scarce and incomplete.…”

“…Frost et al 21 assigned the vibrational modes to vanadinite [Pb 5 (VO 4 ) 3 Cl]; meanwhile, Bartholomai and Klee 22 resolved the vibrational modes for the apatites pyromorphite [Pb 5 (PO 4 For the synthesis of Ca 10 V 6 O 25 crystals, different authors reported the use of precipitation and hydrothermal methods to obtain crystals with diverse morphologies. 5,10,11 In particular, Hojamberdiev et al 10 synthesized Ca 10 V 6 O 25 via hydrothermal processing in a basic medium under the pH range of 12.0−13.5, the temperature range of 120−180 °C, and reaction times of 12, 24, and 48 h. These authors concluded that the above reaction parameters have a strong influence on the morphology of the assynthesized Ca 10 V 6 O 25 crystals, and they obtained various morphologies, such as rods and spherical, ricelike, and bundled particles. However, these methods require high temperatures, long processing times (from a few hours to a few days), and expensive equipment.…”