Synthesis of γ-MnOOH nanorods and their isomorphous transformation into β-MnO<Subscript>2</Subscript> and α-Mn<Subscript>2</Subscript>O<Subscript>3</Subscript> nanorods

γ-MnOOH nanorods with different diameters were synthesized by a simple one-step polymer-assisted hydrothermal method using 50% (wt.%) Mn(NO₃)₂ solution and PEG-10000 as reagents. The diameters of as-synthesized γ-MnOOH nanorods were well controlled by simply varying the volume of the 50% Mn(NO₃)₂ solution. The calcination behavior of the as-synthesized γ-MnOOH nanorods was studied. Nanorods of β-MnO₂ and α-Mn₂O₃ were synthesized by calcination at 350 and 600 °C for 1 h respectively.     

Characterization of TeO<Subscript>2</Subscript> based glass frits and morphology to their silver films

Novel Pb-free Ag paste with a TeO₂ based glass frit for front contact electrodes of crystalline silicon solar cells were prepared. The influence of TeO₂ content (44–80 mol%) on thermal properties, structure and chemical durability of TeO₂ based glass was investigated. The thermal expansion coefficient decreased firstly when the TeO₂ content reached 60 mol%, then increased with further increasing TeO₂ content. The glass transition temperatures are 400–450 °C and melting temperature was as low as 800 °C. The weight loss of Te-3 glass specimen value is 0.28?×?10^?3 mg/cm², improving the chemical durability of the TeO₂ based glass system. In addition, morphology of TeO₂ based Ag films sintering at various temperatures were also investigated. The grain size of the Ag film increased when the content of glass frit increased, and grain boundaries for sintering TeO₂ based Ag pastes was obvious. The host elements of Ag, Te, Bi, and O in AT-3 specimens were almost homogeneously distributed. The amounts of SiO₂ formed when the Ag films were firing at 750 °C, indicating the etching of SiN _x layer by TeO₂ based glass frit. The specific resistivity of silver conducting films with 3 and 5 wt% glass materials of silver component were 3.1 and 3.7 µΩ cm, respectively.     

A facile template-free preparation of porous manganese oxides by thermal decomposition method

Porous Manganese oxides with large surface area were prepared by a facile template-free method. Highly crystallized MnCO₃ precursors with micron size in high dispersivity were prepared in water first. Thermal treatment was carried out with the obtained composite at different temperatures to produce porous manganese oxides. Thermogravimetry and differential thermal analysis (TG-DTA), X-ray powder diffraction (XRD), Scanning electron microscopy (SEM) and N₂ adsorption-desorption measurements were applied to characterize the porous manganese oxides. Amorphous MnO₂ obtained at 400°C shows a mesoporous structure and has a large specific surface area of 135.1 m²/g. Well crystallized α-Mn₂O₃ crystal with surface area of 18.51 m²/g macroporous framework was obtained at 600°C.     

Improvement of hydrothermally synthesized MnO2 electrodes on Ni foams via facile annealing for supercapacitor applications

Nanostructured manganese dioxide (MnO₂) is deposited on nickel foams by a hydrothermal synthesis route. As-deposited MnO₂ thin films are largely amorphous. Facile post-deposition annealing significantly improves the electrochemical performance of the MnO₂ thin films via changing their morphology, phase, and crystallinity. The specific capacitance of the MnO₂ electrode increases with the annealing temperature and reaches an optimal value of 244 F g^?1 (at the current density of 1 A g^?1) in a neutral 1 M Na₂SO₄ electrolyte for a specimen annealed at 500 °C. Furthermore, when an alkaline 5 M KOH electrolyte is used, an exceptionally high capacitance of 950 F g^?1 is achieved at the current density of 2 A g^?1. The cost-effective facile synthesis, high specific capacitance, and good cycle stability of these MnO₂-based electrodes enable their applications in high-performance supercapacitors.     

The synthesis and characterization of Cu<Subscript>2</Subscript>ZnSnS<Subscript>4</Subscript> thin films from melt reactions using xanthate precursors

Kesterite, Cu₂ZnSnS₄ (CZTS), is a promising absorber layer for use in photovoltaic cells. We report the use of copper, zinc and tin xanthates in melt reactions to produce Cu₂ZnSnS₄ (CZTS) thin films. The phase of the as-produced CZTS is dependent on decomposition temperature. X-ray diffraction patterns and Raman spectra show that films annealed between 375 and 475 °C are tetragonal, while at temperatures <375 °C hexagonal material was obtained. The electrical parameters of the CZTS films have also been determined. The conduction of all films was p-type, while the other parameters differ for the hexagonal and tetragonal materials: resistivity (27.1 vs 1.23 Ω cm), carrier concentration (2.65 × 10⁺¹⁵ vs 4.55 × 10⁺¹⁷ cm^?3) and mobility (87.1 vs 11.1 cm² V^?1 s^?1). The Hall coefficients were 2.36 × 10³ versus 13.7 cm³ C^?1.     

Growth and properties of Cu<Subscript>2</Subscript>ZnSnS<Subscript>4</Subscript> thin films prepared by multiple metallic layer stacks as a function of sulfurization time

In this paper, we report the two stage growth of Cu₂ZnSnS₄ (CZTS) thin films as a function of sulfurization time. First, magnetron sputtered metallic precursors were deposited sequentially (Zn/Cu/Sn/Cu) over rotating glass substrates held at 230?°C. Later, the sputtered precursors were heat treated at 500?°C in the ambiance of sulfur for various time durations in the range, 10–120 min. The sulfur treated samples were examined using various analytical tools to understand the role of sulfurization time on the CZTS growth and properties. From composition and structural analysis, Zn/Cu/Sn/Cu precursors sulfurized for shorter duration (10 and 20 min) revealed severe deficiency of sulfur that resulted in several metallic, bi-metallic and metal sulfide phases. With the increase of sulfurization time to 30 min, sulfur incorporation was enhanced and reached stoichiometric ratio (~50% S) for CZTS growth, however, samples were poorly crystalline in nature and consisted of prominent Cu_2?xS phase as well. The Zn/Cu/Sn/Cu precursors sulfurized for 60 min exhibited prominent CZTS phase without Cu_2?xS phase. Further, rise in sulfurization time to 120 min enabled drastic improvement in crystallinity of CZTS phase. Raman mapping over 60 µm × 60 µm for these films confirmed the homogeneous phase growth of CZTS. XPS study revealed the oxidation states of Cu¹⁺, Zn²⁺, Sn⁴⁺ and S^2? in CZTS films. The optimized films showed high absorption coefficient of 10⁵ cm^?1 with an optical band gap of 1.51 eV. These films showed leaf like grain morphology with high mobility and low resistivity of 18.2 cm²/V-s and 0.7 Ω-cm, respectively.     

Effect of Mn doping on the dielectric properties of BaTi<Subscript>0.9</Subscript>Sn<Subscript>0.1</Subscript>O<Subscript>3</Subscript> ceramics

Pure and Mn-doped BaTi_0.9Sn_0.1O₃ ceramics are prepared via the conventional solid state reaction method. The microstructures, dielectric properties, and diffuse transition of BaTi_0.9Sn_0.1O₃ ceramics with 0, 0.2, 1 and 2 at.% Mn have been investigated. The results indicate that manganese ions enter the unit cell maintaining the perovskite structure of solid solution. Grain size of BaTi_0.9Sn_0.1O₃ ceramics sharply decreases after doping MnO₂. However, once MnO₂ content is more than 0.2 at.%, the average grain size of Mn-doped BaTi_0.9Sn_0.1O₃ ceramics increases with the increasing of MnO₂ content. The addition of manganese leads to the increase of the Curie temperature. The diffuseness of the phase transition of Mn-doped BTS ceramics decreases with the increase of Mn content, which may be due to grain size effect.     

MOF-derived,CeO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>-modified CoP/carbon composites for oxygen evolution and hydrogen evolution reactions

Development of low-cost, highly efficient catalysts for water splitting is required to replace precious metal catalysts. CeO _x -modified CoP@carbon composites are prepared via Ce-doped metal–organic frameworks. The as-prepared CeO _x -modified CoP@carbon composites have excellent electrocatalytic activity with respect to the oxygen evolution reaction, for which an overpotential (η) up to?~?313 mV is achieved at the current density of 10 mA cm^?2. In addition, CeO _x -modified CoP@carbon composites show an overpotential of up to 127 mV at the current density of 10 mA cm^?2 for the hydrogen evolution reaction, showing excellent catalytic activity for water splitting.     

A study of the structural,optical, and electrical properties of SnS<Subscript>2</Subscript>:Cu optical semiconductor thin films deposited by the spray pyrolysis technique

Cu-doped tin-sulfide thin films were deposited onto glass substrates at T = 400 °C through spray pyrolysis. The effects of Cu doping on the structural, optical, and electrical properties of the thin films were investigated. The precursor solution was prepared by dissolving tin chloride (SnCl₄·5H₂O) and thiourea (CS(NH₃)₂) in deionized water and then adding copper chloride (Cl₂Cu₂H₂O). SnS₂:Cu thin films were prepared with \(\frac{{\left[ {Cu} \right]}}{{\left[ {Sn} \right]}}\% = 0, 1, 2, 3, 4 \,{\text{at}}.\%\). X-ray diffraction analysis showed that the thin films had a preferred (001) orientation of the SnS₂ phase and that the intensity of the (001) peak decreased with increased doping concentration from 1–4 at.%. Scanning electron microscopy studies indicated that the thin films had spherical grains. Characterization results of thin films showed that single-crystal grains, average grain size, optical band gap, carrier concentration, Hall mobility, and electrical resistance varied within 5–14 nm, 46–104 nm, 2.81–2.99 eV, 2.42 × 10¹⁶–26.73 × 10¹⁶ cm^?3, 2.41 × 10^?3–20.04 × 10^?3 cm²/v.s, and 9.05–12.89 Ω cm, respectively. Hall effect studies further revealed that the films exhibited n-type conductivity.     

Facile synthesis and characterization of MnO<Subscript>2</Subscript> nanomaterials as supercapacitor electrode materials

MnO₂ nanomaterials are synthesized via calcinations in air at various temperatures. Amorphous MnO₂ masses appear between 100 and 300 °C and nanorods form above 400 °C. Transmission and scanning electron microscopy are used to observe the geometries of each material, with further structural analyses conducted using X-ray photoelectron spectroscopy, X-ray diffraction, and BET method. The electrochemical properties are investigated through galvanostatic charge/discharge cycling, electrochemical impedance spectra, and cyclic voltammetry within a three-electrode test cell filled with 1 mol L^?1 Na₂SO₄ solution. The slightly asymmetric galvanostatic cycling curves suggest that the reversibility of the Faradaic reactions are imperfect, requiring a larger time to charge than discharge. The specific capacitances of each sample are calculated and trends are identified, proving that the samples synthesized at higher temperatures exhibit poorer electrochemical behaviors. The highest calculated specific capacitance is 175 F g^?1 by the sample calcinated at 400 °C. However, the lower temperature samples exhibit more favorable geometric properties and higher overall average specific capacitances. For future research, it is suggested that surface modifications such as a carbon coating could be used in conjunction with the MnO₂ nanorods to reach the electrochemical properties required by contemporary industrial applications.     

Very high thermal stability with excellent dielectric,and non-ohmics properties of Mg-doped CaCu<Subscript>3</Subscript>Ti<Subscript>4.2</Subscript>O<Subscript>12</Subscript> ceramics

In this work, the nominal CaCu_3?xMg_xTi_4.2O₁₂ (0.00, 0.05 and 0.10) ceramics were prepared by sintering pellets of their precursor powders obtained by a polymer pyrolysis solution method at 1100 °C for different sintering time of 8 and 12 h. Very low loss tangent (tanδ)?<?0.009–0.014 and giant dielectric constant (ε′) ～?1.1?×?10⁴–1.8?×?10⁴ with excellent temperature coefficient (Δε′) less than ±?15% in a temperature range of ??60 to 210 °C were achieved. These excellent performances suggested a potent application of the ceramics for high temperature X8R and X9R capacitors. It was found that tanδ values decreased with increasing Mg²⁺ dopants due to the increase of grain boundary resistance (R_gb) caused by the very high density of grain, resulting from the substitution of small ionic radius Mg²⁺ dopants in the structure. In addition, CaCu_3?xMg_xTi_4.2O₁₂ ceramics displayed non-linear characteristics with the significant enhancements of a non-linear coefficient (α) and a breakdown field (E_b) due to Mg²⁺doping. The high values of ε′ (14012), α (13.64) and E_b (5977.02 V/cm) with very low tanδ value (0.009) were obtained in a CaCu_2.90Mg_0.10Ti_4.2O₁₂ ceramic sintered at 1100 °C for 8 h.     

High-temperature oxidation behaviour of Ti<Subscript>3</Subscript>Si<Subscript>(1−<Emphasis Type="Italic">x</Emphasis>)</Subscript>Al<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>C<Subscript>2</Subscript> in air

The oxidation behaviours of bulk Ti₃Si_(1−x)Al _x C₂ prepared by hot pressing were investigated. The results showed that the isothermal oxidation behaviour of Ti₃SiC₂ obeyed a parabolic law between 900 and 1100°C, and followed a two-step parabolic rate law between 1200°C and 1300°C. The cyclic oxidation behaviour of material is assumed to obey a three-step parabolic rate law at 1100°C and 1200°C. The calculated activation energy of isothermal oxidation is 101·43 kJ·mol⁻¹. The oxide layers consisted of a mass of α-Al₂O₃ and little TiO₂ and SiO₂ are observed on Ti₃SiC₂ as a dense and adhesive protect scale. The oxidation mechanism varies with the additive aluminum that greatly improves the oxidation resistance of Ti₃SiC₂.     

Facial synthesis of MnO<Subscript>2</Subscript>/three dimensional graphene composite and its application in supercapacitors

MnO₂ nanoparticle/three dimensional graphene composite (MnO₂/3DG) was synthesized by a hydrothermal template-free method and subsequent ultrasonic treatment in KMnO₄ solution. The MnCO₃/3DG particles can be detected after the hydrothermal process, which may be produced through the reaction between Mn²⁺ and \({\text{C}}{{\text{O}}_{\text{3}}}^{{\text{2}} - }\) due to the decarboxylation of GO under the hydrothermal condition. The final product MnO₂/3DG displayed high specific capacitance (324 F g^??1 at 0.4 A g^?1) and good cycle stability (91.1% capacitance retention after 5000 cycles). Furthermore, the asymmetric supercapacitor assembled with MnO₂/3DG and activated carbon (AC) exhibits an energy density of 33.78 Wh kg^?1 at the powder density of 380 W kg^?1. The excellent supercapacitance of the MnO₂/3DG composite may be due to the high pseudocapacitance of the dispersed MnO₂ nanoparticles and the conductive graphene with three dimensional porous microstructure.     

Structure and electrical properties of MnO doped (Ba<Subscript>0.96</Subscript>Ca<Subscript>0.04</Subscript>)(Ti<Subscript>0.92</Subscript>Sn<Subscript>0.08</Subscript>)O<Subscript>3</Subscript> lead free ceramics

In this work, (Ba_0.96Ca_0.04)(Ti_0.92Sn_0.08)O₃–xmol MnO (BCTS–xMn) lead-free piezoelectric ceramics were fabricated by the conventional solid-state technique. The composition dependence (0 ≤ x ≤ 3.0 %) of the microstructure, phase structure, and electrical properties was systematically investigated. An O–T phase structure was obtained in all ceramics, and the sintering behavior of the BCTS ceramics was gradually improved by doping MnO content. In addition, the relationship between poling temperature and piezoelectric activity was discussed. The ceramics with x = 1.5 % sintering at temperature of 1330 °C demonstrated an optimum electrical behavior: d ₃₃ ~ 475 pC/N, k _p ~ 50 %, ε _r ~ 4060, tanδ ~ 0.4 %, P _r ~ 10.3 μC/cm², E _c ~ 1.35 kV/mm, T _C ~ 82 °C, strain ~0.114 % and \(d_{33}^{*}\) ~ 525 pm/V. As a result, we achieved a preferable electric performance in BaTiO₃-based ceramics with lower sintering temperature, suggesting that the BCTS–xMn material system is a promising candidate for lead-free piezoelectric ceramics.     

Urea combustion synthesis of nano-structure bimetallic perovskite FeMnO<Subscript>3</Subscript> and mixed monometallic iron manganese oxides: effects of preparation parameters on structural,opto-electronic and photocatalytic activity for photo-degradation of Basic Blue 12

Nano-structure bimetallic FeMnO₃ and mixed monometallic iron manganese oxides have been synthesized by a urea combustion method using iron (III) choloride, manganese (II) chloride tetrahydrate and urea and calcination at 400 and 650?°C. The structural, optoelectronic and morphological analysis of samples have been studied by XRD, FESEM, EDX, FTIR, and UV–vis DRS measurements. The effect of calcination temperature was examined and XRD results reveal that at 650?°C a pure nano-structure bimetallic FeMnO₃ with perovskite-type structure is formed while at calcination temperature of 400?°C mixed monometallic iron manganese oxides (Fe₂O₃ and Mn₂O₃) is produced. FT-IR spectrum of nano-structure bimetallic FeMnO₃ and mixed monometallic iron manganese oxides exhibited strong absorption band at 473, 523, 547 and 666 cm^?1 for Fe–O, Mn–O and Fe–O–Mn bond stretching vibrations. UV–vis DRS absorption spectrum exhibited absorption peaks at 211, 262, 384 and 520 nm located at UV and visible region of the solar light. FESEM results showed that the pure nano-structure bimetallic FeMnO₃ appears as nano-structure with an average diameter 29 nm. Elemental analysis results of EDX spectrum demonstrated the presence of iron, manganese and oxygen. The photo-catalytic properties of the nano-structure bimetallic FeMnO₃ and mixed monometallic iron manganese oxides coated on glass were evaluated via degradation of Basic Blue 12 (BB12) an oxazine class dyes under irradiation. The results showed the best photocatalytic performance, which achieved as high as 99% for BB12 degradation exposed 1.5 h irradiation which is due to UV and visible absorption, an efficient electron–hole separation and high surface area of nano size particle with an average size of 29 nm. The results showed that nano-structure bimetallic FeMnO₃ and mixed monometallic iron manganese oxides coated on glass is a promising photo-catalyst for the removal of Basic Blue 12 (BB12) an oxazine class dyes from wastewater.     

Rietveld analysis of CaCu<Subscript>3</Subscript>Ti<Subscript>4</Subscript>O<Subscript>12</Subscript> thin films obtained by RF-sputtering

Calcium copper titanate, CaCu₃Ti₄O₁₂, CCTO, thin films with polycrystalline nature have been deposited by RF sputtering on Pt/Ti/SiO₂/Si (100) substrates at a room temperature followed by annealing at 600 °C for 2 h in a conventional furnace. The crystalline structure and the surface morphology of the films were markedly affected by the growth conditions. Rietveld analysis reveal a CCTO film with 100 % pure perovskite belonging to a space group Im3 and pseudo-cubic structure. The XPS spectroscopy reveal that the in a reducing N₂ atmosphere a lower Cu/Ca and Ti/Ca ratio were detected, while the O₂ treatment led to an excess of Cu, due to Cu segregation of the surface forming copper oxide crystals. The film present frequency -independent dielectric properties in the temperature range evaluated, which is similar to those properties obtained in single-crystal or epitaxial thin films. The room temperature dielectric constant of the 600-nm-thick CCTO films annealed at 600 °C at 1 kHz was found to be 70. The leakage current of the MFS capacitor structure was governed by the Schottky barrier conduction mechanism and the leakage current density was lower than 10^?7 A/cm² at a 1.0 V. The current–voltage measurements on MFS capacitors established good switching characteristics.     

Effect of manganese doping on conduction in olivine LiFePO<Subscript>4</Subscript>

Lithium ion batteries play a crucial role in terms of good rechargeability, long cycles and higher shelf life. For the fabrication of such a Li ion battery, properties of cathode material can be engineered keeping anode and electrolyte fixed. In the present work, lithium iron phosphate (LiFePO₄) has been utilized as cathode material and the properties of LiFePO₄ have been tuned by doping manganese (Mn). LiFePO₄ and different concentrations of Mn doped LiFePO₄ were prepared by solid state route. X-Ray diffraction and Raman studies were performed to confirm the formation of LiFePO₄ and Mn doped LiFePO₄ in olivine structure. Cyclic voltammetry studies revealed maximum peak oxidation current (2.96 mA) and largest surface coverage (0.066 nanoMoles/cm²) for the LiFePO₄ doped with 15% Mn (LiMn_0.15Fe_0.85PO₄). AC-conductivity study was carried out for different frequencies at room temperature. The conductivity parameters estimated using Almond and West formalism support the cyclic voltammetry results. Ion-hopping rate (ω _p ) and charge carrier concentration (K) maximize for 15% Mn doping (ω _p : 582974.48719 Hz; K: 2.62447?×?10^?6) and drop on either increasing (ω _p : 167134.73521 Hz; K: 1.25647?×?10^?7) or decreasing (ω _p : 130726.49084 Hz; K: 2.52435?×?10^?6) the Mn doping. The increase till 15% Mn doping has been attributed to the increase in unit cell volume with Mn doping while the sudden decrease at 20% Mn doping is due to dominance of back-hopping mechanism. The results clearly indicate that 15% Mn doped LiFePO₄ is the most appropriate for the realization of a cathode for Li-ion battery.     

Effect of Al<Subscript>2</Subscript>O<Subscript>3</Subscript> addition on the microstructure and electrical properties of LaMnO<Subscript>3</Subscript>-based NTC thermistors

A study to develop a new system of negative temperature coefficient thermistors for wide temperature range, A series of Mn-based perovskite-structured ceramics of composition (LaMn_1?x Al _x O₃)_0.9(Al₂O₃)_0.1 has been synthesized by conventional solid state reaction at 1350?°C. The X-ray diffraction patterns showed that for all the samples, the substitution of manganese by aluminum up to x?=?0.1 preserved the rhombohedral perovskite LaMnO₃-like phase. For x?=?0.2, apart from the LaMnO₃-like structure, a second perovskite phase based on the cubic LaAlO₃ structure was formed. For x?=?0.3 and 0.4, the phase present was LaAlO₃ -type structure. The grain sizes of the sintered body detected by scanning electron microscope were decreased with increasing Al₂O₃ content. The resistivity increases with increasing the Al content. The obtained values of ρ _25?°C and B _25/50 and E _a are in the range of 10–13103 Ω cm, 1813–2794 K, 0.156–0.241 eV, respectively. The resistance variation (ΔR/R) was <0.241% and the minimum value (0.0483%) was obtained for aging at 125?°C at 500 h. The aim of this work was explored new composite ceramics materials, which could be used as potential candidates for wide temperature range from ?100 to 500?°C thermistors applications.     

Low temperature sintering and microwave dielectric properties of Zn<Subscript>3</Subscript>Mo<Subscript>2</Subscript>O<Subscript>9</Subscript> ceramic

Crystal structure and dielectric properties of Zn₃Mo₂O₉ ceramics prepared through a conventional solid-state reaction method were characterized. XRD and Raman analysis revealed that the Zn₃Mo₂O₉ crystallized in a monoclinic crystal structure and reminded stable up to1020 °C. Dense ceramics with high relative density (~ 92.3%) were obtained when sintered at 1000 °C and possessed good microwave dielectric properties with a relative permittivity (ε _r ) of 8.7, a quality factor (Q?×?f) of 23,400 GHz, and a negative temperature coefficient of resonance frequency (τ _f ) of around ??79 ppm/°C. With 5 wt% B₂O₃ addition, the sintering temperature of Zn₃Mo₂O₉ ceramic was successfully lowered to 900 °C and microwave dielectric properties with ε _r ?=?11.8, Q?×?f?=?20,000 GHz, and τ _f = ??79.5 ppm/°C were achieved.     

Structural,optical and magnetic properties of Cr doped In<Subscript>2</Subscript>O<Subscript>3</Subscript> powders and thin films

The (In_1?xCr_x)₂O₃ powders as well as thin films of x = 0.03, 0.05 and 0.07 were synthesized using a solid state reaction and an electron beam evaporation technique (on glass substrate), respectively. The influence of Cr doping concentration on structural, optical and magnetic properties of the In₂O₃ samples was systematically studied. The X-ray diffraction results confirmed that all the Cr doped In₂O₃ samples exist cubic structure of In₂O₃ without any secondary phases presence. The chemical composition analyses showed that all the Cr doped In₂O₃ compounds were nearly stoichiometric. The X-ray photoelectron spectroscopy analysis of the Cr doped In₂O₃ thin films showed an increase of oxygen vacancies with Cr concentration and the existence of Cr as Cr³⁺ state in the host In₂O₃ lattice. A small blue shift in the optical band gap was observed in the powder compounds, when the dopant concentration increased from x = 0.03 to x = 0.07. In thin films, the band gap found to increase from 3.63 to 3.74 eV, with an increase of Cr concentration. The magnetic measurements show that the undoped In₂O₃ bulk powder sample has the diamagnetic property at room temperature. And a trace of paramagnetism was observed in Cr doped In₂O₃ powders. However (In_1?xCr_x)₂O₃ thin films (x = 0.00, 0.03, 0.05 and 0.07) samples shows soft ferromagnetism. The observed ferromagnetism in thin films are attributed to oxygen vacancies created during film prepared in vacuum conditions. The ferromagnetic exchange interactions are established between metal cations via free electrons trapped in oxygen vacancies (F-centers).