Hydrothermal synthesis and metal ions doping effects of single-crystal Mn3O4

Structural, Topography, and Optical Properties of Ba‐Doped Mn3O4 Thin Films for Ammonia Gas Sensing Application

“…The peak position shifts toward high (2 θ ) angle this shift may be caused by the nonuniform strain developed due to the influence of different ionic radii Mn 2+ ( r = 0.93 ) and Ba 2+ ( r = 1.38 ), whereas the interplanar spacing shifts to lower values due to the increase in lattice parameters as Ba concentration increases. The lattice parameters, unit cell volume and bond length are calculated using VESTA software and are summarized in Table , the values are in good agreement with the work reported in literature, the crystallite size is calculated using Debye–Scherrer formula, where D , λ , and β are the crystallite size, the wavelength of the X‐ray (0.154056 nm) and the full width half maximum; respectively, it is clearly seen that the crystallite size varies with Ba concentration in Mn 3 O 4 lattice (see Table ).…”

“…The band gap of the sprayed films is calculated using Tauc's relation using the following equation: where α , B , and Eg are the absorption coefficient, proportionality constant, and optical band gap; respectively, the absorption coefficient is calculated by the following equation: where A and t are the absorbance and thickness, respectively, Figure shows the band gap of pure and Ba‐doped Mn 3 O 4 thin films, the values fairly agree with the work reported in literature . It is found that band gap varies as Ba concentration increases reaching a minimum value 2.85 eV in Mn 3 O 4 :Ba1% thin films, the reduction in band gap may be due to the increase in RMS roughness and crystallite size as reported earlier, it is also observed band gap decreases with the increase in unit cell volume as well as bond lengths of (Mn 2+ O) and (Mn 3+ O) in tetrahedral and octahedral sites; respectively (see Table ) as Ba concentration increases, this behavior agrees with the findings reported in literature …”

Nickel‐Doping Effect on Mn3O4 Nanoparticles for Electrochemical Water Oxidation under Neutral Condition

“…The broad shoulders assigned to satellites for Ni 2p 1/2 and Ni 2p 3/2 were also observed at around 880 and 862 eV (Figure S2, Supporting Information). The Ni 3/2 spectra were fitted to two components for Ni 2+ (854.8 eV) and Ni 3+ (856.7 eV) . In Ni 2p 3/2 spectra of 5 at% Ni doped Mn 3 O 4 NPs, the ratio of Ni(II) was 1.5 times larger than Ni(III).…”

“…While a and b axes did not change considerably, c axis lattice parameters decreased with increasing Ni‐doping ratio, resulting in decrease of unit cell volume. The lattice distortion for Mn 3 O 4 NPs was in agreement with previous study on Mn 3 O 4 doped with various transition metal elements . It was attributed that Ni(II) (0.69 Å) and Ni(III) (0.74 Å) with smaller ionic radius were substituted for Mn(II) (0.80 Å) and Mn(III) (0.79 Å) sites for Mn 3 O 4 structure .…”

Nickel content effect on the microstructural, optical and electrical properties of p-type Mn3O4 sprayed thin films

“…Typically, nickel is one of the dopants needed for improving many properties for a wide range of applications of TMO oxides [14,15]. So, p-type Ni-doped Mn 3 O 4 thin film appears to be an interesting layer, given to its adjustable electronics property and to its application in electrocatalysts [16,17]. AC conductivity, dielectric properties and relaxation model of the transition metal oxide have been widely performed wherein the real part of the AC conductivity obey universal Jonscher law [18,19] The resulting solution was sprayed at a rate flow of 6 mL.min -1 using nitrogen gas.…”