Proceedings of SerbiaTrib '13

The method of dilution of the studied sample inKBr at concentration 0.5 % was used.The diffuse reflectance UV–vis spectra weretaken with a Thermo Evolution 300 UV-VisSpectrophotometer equipped with a Praying Mantisdevice with Spectralon as the reference. Spectralonis a fluoropolymer, which has the highest diffusereflectance of any known material or coating overthe ultraviolet, visible, and near-infrared regions ofthe spectrum.As milling proceeds broadening of diffraction peaksis observed due to grain size reduction.3. RESULTS AND DISCUSSIONTextural properties of initial hematite andrutile and mechanochemically synthesized mixedoxides are presented in Table 1.Table 1. Samples composition and textural propertiesSamplecodeChemicalcomposition [%]Fe 2 O 3 ZnOSpecificsurface area,m 2 g -1PorevolumeZnO 0.0 100.0 5.5 0.004ZnO-MA 0.0 100.0 3.0 0.0020.3 FZ 0.3 99.7 5.3 0.0044.3 FZ 4.3 95.7 5.4 0.00414.3 FZn 14.3 85.7 5.3 0.00466 FZ 66.0 33.0 6.6 0.005The XRD patterns of the Fe 2 O 3 -ZnO mixedoxides with different iron content are presented inFig. 1.66 FZ14.3 FZ4.3 FZFigure 2. FTIR spectra of the Fe 2 O 3 -ZnO mixed oxidesFigure 2 shows the IFTR spectra themechanically activated Fe 2 O 3 -ZnO mixed oxides.All the samples show prominent absorption bandand shoulder at about 440 cm - 1 and 550 cm -1 ,respectively. Slight variation with increasing of ironcontent in the samples is due to grain size influencethe band position. The band at lower frequency of440 cm-1 corresponds to M-O stretching vibrationin octahedral site. This shift can be result of highercontent of oxygen vacancies present in the structureand created during mechanical activation [14].The diffuse reflectance of the ZnO and Fe 2 O 3 -ZnO mixed oxides are shown in Fig. 3. The spectraof the samples in UV region exhibit an absorptionpeak at about 220-250 nm attributable to isolated,tetrahedral coordinated species.0.3 FZZnO MA****ooo * o*o * oZnO+Fe 2O 310 20 30 40 50, degreeFigure 1. XRD patterns of the Fe 2 O 3 -ZnO sample. Themark (*) indicated the peaks corresponding to Fe 2 O 3 , andthe marks (o) – peaks corresponding to ZnO.The XRD diagram marks as ZnO+Fe 2 O 3corresponds to the starting mixture with molar ratioZnO:Fe 2 O 3 = 1:1 before milling. All the diffractionpeaks of mechanical activated zinc oxide and 0.3FZ sample can be well indexed to the hexagonalphase ZnO (JCPDS card no. 36-1451. A decrease inthe reflection intensity was observed during milling.Figure 3. UV-vis diffuse reflectance spectra of ZnO andFe 2 O 3 -ZnO mixed oxidesThe samples with larger iron content showintense absorption in wide wavelength range fromUV to visible light with absorption tail extendinginto infrared region. This means that Fe componentwas physically connected to the external surface ofZnO structure. The peak with maximum centred at56 13 th International Conference on Tribology – Serbiatrib’13