A new route for the preparation of CoAl2O4 nanoblue pigments with high uniformity and its optical properties

Gao, Huajing; Yang, Hua; Wang, Shifa; Li, Danming; Wang, Fei; Fang, Leiming; Li, Lei; Xiao, Yuhua; Yang, Guixia

doi:10.1007/s10971-018-4609-y

Cited by 45 publications

(8 citation statements)

References 53 publications

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“…Additionally, metals are not Raman active . Second, the blue pad consists of mixed metal oxides and phosphates, including CoAl 2 O 4 and Fe 3 (PO 4 ) 2 , which are versatile blue pigments , or an organic polyphosphate film . To confirm such hypotheses, two specimens to be sectioned by the FIB from each region were prepared.…”

Section: Resultsmentioning

confidence: 99%

Comprehensive Investigation of Various Organophosphate Intercalated CoAl-LDHs As Additives in Polyalphaolefin

Dao,

Tieu,

Tran

2024

ACS Appl. Eng. Mater.

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This study focuses on the synthesis and investigation of four organophosphate-intercalated CoAl-LDHs as additives for oil lubricants. Phosphate esters have been wellknown for their excellent antiwear properties in automobile applications. On the other hand, layered double hydroxide (LDH) has a unique lamellar structure that can contain anionic species that can be released under certain conditions. The successful intercalations of various organophosphates, including methyl phosphate (C1P), isopropyl phosphate (C3P), phenyl phosphate (C6P), and dodecyl phosphate (C12P), into CoAl-LDH were achieved. Ultimately, the C6P-LDH demonstrated exceptional antiwear performance, reducing friction and wear loss by 25% and 69%, respectively, compared to PAO-4 base oil. Interestingly, the C6P tribofilm shows two distinct regions with different colors under an optical microscope. Thorough characterizations of the two regions of interest were conducted via Raman spectroscopy, scanning transmission electron microscopy, energy dispersive X-ray spectroscopy, and cryo-electron energy loss spectroscopy techniques and demonstrated that the blue tribofilm pads consisted of mixed metallic oxides and phosphates, while the gray pads were rich in metallic cobalt, which was unexpected for tribofilm formed in situ during lubrication under ambient atmosphere. The thick oxide-phosphate layer is crucial for preventing wear loss. Additionally, a thin iron oxide layer at the steel interface strengthens the tribofilm adhesion to the steel base. The tribofilm formation mechanism was discussed and proposed. The influence of LDH dispersibility on the tribological behaviors was also discussed.

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Section: Resultsmentioning

confidence: 99%

Comprehensive Investigation of Various Organophosphate Intercalated CoAl-LDHs As Additives in Polyalphaolefin

Dao,

Tieu,

Tran

2024

ACS Appl. Eng. Mater.

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“…Both emission peaks, in UV and at around 455 nm, are split, indicating the presence of two closer energy levels. Previous reports from the literature assign the UV and 455 nm emissions to the presence of M 2+ in tetrahedral voids in the crystalline lattice [40] but also to the presence of surface defects induced by the manufacturing process.…”

Section: Photoluminescence Spectramentioning

confidence: 93%

Structural, Morphological, and Optical Properties of Single and Mixed Ni-Co Aluminates Nanoparticles

Gingasu,

Oprea,

Marinescu

et al. 2023

Inorganics

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A series including single and mixed Ni-Co aluminates was obtained using the precursor method, with malic acid as a ligand. The malate precursors (polynuclear coordination compounds) were isolated and characterized by Fourier Transform Infrared (FTIR), Ultraviolet/Visible/Near Infrared (UV–Vis–NIR) spectroscopy, and thermal analysis. The UV–Vis–NIR spectra of the synthesized complex compounds highlighted the presence of Co2+ and Ni2+ in an octahedral environment. The thermal decomposition of these precursors led to Co1−xNixAl2O4 (x = 0, 0.1, 0.25, 0.5, 0.75, 0.9, and 1) spinels. The effect of Ni2+ substitution on the structure, morphology, and optical properties of the obtained oxides was studied with the help of different characterization tools. XRD, FTIR, and Raman spectra evidenced the formation of the spinel phase. The size of the crystallites and the agglomeration degree of the particles decrease when the nickel content increases. The band gap (BG) value is not significantly influenced by the Ni substitution. The fluorescence spectra recorded for all samples show a similar pattern, but different intensities of the emission bands.

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“…Spinel aluminate is a wide-gap semiconductor, such as BeAl 2 O 4 (6.450 eV) (Ching et al, 2001), MgAl 2 O 4 (3.923 eV) (Wang et al, 2019a), CaAl 2 O 4 (7.400 eV) (Moirangthem et al, 2019), SrAl 2 O 4 (3.984 eV) (Shifa , BaAl 2 O 4 (3.910 eV) (Nair and Pillai, 2021), MnAl 2 O 4 (4.030 eV) (Bhavani et al, 2018), FeAl 2 O 4 (1.780 eV) (Mu et al, 2017), CoAl 2 O 4 (1.948 eV) (Gao et al, 2018), NiAl 2 O 4 (3.000 eV) (Chellammal Gayathri et al, 2021), CuAl 2 O 4 (2.920 eV) (Potbhare et al, 2019), and ZnAl 2 O 4 (3.800 eV) (Shang-Pan et al, 2020). Based on the obtained optical band gap value and band theory, the conduction band potential and valence band potential of MAl 2 O 4 were calculated.…”

Section: Synthesis Of Mal 2 O 4 (M = Mg Sr and Ba) Photocatalystsmentioning

confidence: 99%

Progress in Synthesis and Photocatalytic Activity of MAl2O4(M=Mg, Sr, Ba) Based Photocatalysts

et al. 2022

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Photocatalysis is regarded as a green technology to degrade organic dyes driven by light energy. The selection of photocatalyst restricts the development of photocatalytic technology. Aluminate is a kind of potential broad-gap semiconductor photocatalyst and also an excellent phosphor substrate materials. The physical and chemical properties of aluminate are strongly dependent on the preparation method. Insight into the influence of synthesis methods on photocatalytic activity of aluminate based photocatalysts is helpful for the development of novel aluminate based photocatalysts. In this paper, the typical synthesis methods of aluminate photocatalysts, ion-doped aluminate based photocatalysts and heterojunction type aluminate photocatalysts, and their photocatalytic activities are reviewed. Based on the energy band theory, the photocatalytic mechanisms of single component aluminate photocatalyst, ion-doped aluminate based photocatalyst, and heterojunction type aluminate photocatalyst were reviewed. The future development of aluminate based photocatalyst will give priority to the salinization of aluminate modified by silver and other metal particles and the photocatalytic application of activated ion modified aluminate based phosphors.

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A new route for the preparation of CoAl2O4 nanoblue pigments with high uniformity and its optical properties

Cited by 45 publications

References 53 publications

Comprehensive Investigation of Various Organophosphate Intercalated CoAl-LDHs As Additives in Polyalphaolefin

Comprehensive Investigation of Various Organophosphate Intercalated CoAl-LDHs As Additives in Polyalphaolefin

Structural, Morphological, and Optical Properties of Single and Mixed Ni-Co Aluminates Nanoparticles

Progress in Synthesis and Photocatalytic Activity of MAl2O4(M=Mg, Sr, Ba) Based Photocatalysts

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