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enhanced optical conductivity nonlinear optical and semiconducting properties of mgxcuo1-x/pmma nanocomposite abstract mg1-xcuxo /pmma nanocomposite films where x 0.05 0.1 0.15 and 0.2 samples were prepared using solid state reaction technique. the values of both of dispersion energy ed and oscillating energy eo were determined optically and these values decreased with increasing cu content. the calculated values of free carrier concentration/effective mass n/m* decreased with increasing cu content. on the other hand the values of first order of moment m-1 the third order of moment m-3 and static refractive index no were determined.
the both of dielectric loss and dielectric tangent loss for these films increased with photon energy and cu ratio affected on both of and the determined values of real part of optical conductivity 1 and imaginary part of optical conductivity 2 increase with cu content. the linear optical susceptibility 1 increases with hЅ for all samples. the nonlinear optical parameters such as nonlinear refractive index n2 the third-order nonlinear optical susceptibility 3 non-linear absorption coefficient Іc were determined theoritically.
both of the electrical susceptibility e and relative permittivity µr increase with hЅ the semiconducting results such as density of conduction band/electron effective mass nc/ m*e cm-3 density of valence band/ hole effective mass nv/m*h cm-3 were calculated. 1 introduction a nanocomposite is a composite material in which one of the components has at least one dimension that is nano size [1]. inorganic/organic composite materials had attracted attention because of their excellent properties such as high mechanical strength magnetic and thermal flexibility dielectric ductility and processibility [2 3]. these composite is a promising materials as a result of their applications [4″12]. such as super capacitors rechargeable batteries and antistatic textiles [10-12]. poly methyl methacrylate pmma is an imperative material which achieve excellent optical electrical properties and high thermal stability [13″16]. many scientists concentrate their attention to synthesis of the nanoparticles of transition conducting metal oxides tcmos [17″20]. tcmos were synthesized using different technique such as :direct mixing of nanoparticles in the polymer [21] sol gel methods [22] in-situ techniques [23] and deposition method [24].the ii”vi semiconductor nanocrystals achieve an excellent physico-chemical properties to get a new optoelectronics and nano-electronics [25″27]. synthesis and characterization of cuo”mgo nanocrystal was studied by different techniques [28″30]. the influence of doping on optical properties of pmma had been studied by many authors[31-35]. it was found that the fluorescence branch ratios for is evaluated. for nd dbm 3phen-doped pmma[32] that absorption in pmma films with nd dopant is due to intratransition within the 4f shell of the nd3+ ion[33] the energy band decreases with access of cds in pmma matrix[34] zno dopant decreased energy gap in pmma/pvdf-zno nano composites[35]. while the nonlinear optical properties of doped pmma were studied[36-39] it was noticed that nonlinear absorption decreased with increase the filler [37] pmma doped with ag enhanced a negative nonlinear refractive index[39] on the other hand the structure and optical properties of mg1-xcuxo/pmma nanocomposite films were studied in pervious work[40] it was found that the energy gap decreased with increasing cu content. in this paper we study the influence of cu content on the optical conductivity linear optical susceptibility nonlinear optical results and density of both valence and conduction states for the mg1-xcuxo /pmma nanocomposite films. 3. results and discussion 3.1. optical conductivity vel/sel linear optical susceptibility results the influence of cu content on optical transmittance t and reflectance r for these samples were measured and discussed in previous work [40]. the single oscillator theory was expressed by the wemple”didomenico relationship [41]: 1 where n is the refractive index values of these samples which is determined in previous work [40] e is the photon energy hЅ the values of eo and ed with different cu content values are shown in table 1. the ratio values of carrier concentration /effective mass n/m* using the following equation [42]: 2 where µl is the lattice dielectric constant µo is the permittivity of free space e is the charge of electron n k are the linear refractive index and the absorption index of these films respectively which were determined in previous work [40] n is the free carrier concentration for these films and c is the speed of light so the values of n/m* are determined by plotting n2 vs. wave length 2 “2 as shown in fig.1. it is known that the refractive index depends on the density of the material so when an additive increases in material then the refractive index increases but in figure 1 we can observe that the refractive index of mg1-xcuxo /pmma composites decreases and then increases. the reason of this behavior can be explained depending on ewald-oseen extinction theorem [43] when an electromagnetic wave incident on the material the atoms and electrons excited so they will oscillate and emit an electromagnetic waves in the same frequency of the original electromagnetic wave but with different phase which interface with the original wave because of that the phase velocity of the new electromagnetic will change. the values of n/m* is shown in table 1. from this table it was noticed that n/m* increases with cu content as a result of increasing carrier concentration with cu. the moments m-1 and m-3 are the measure of interband transition strengths for these thin films. the values of m-1 and m-3 derived from the relations [42]: 3 4 table 1 shows the values of the m-1 and m-3 for these thin films. the oscillator strength f which was calculated as follow [43]: 5 the values of the f are shown in table 1. another important parameter depending on both of eo and ed is that static refractive index no which was determined as follow [44]: 6 the values of no for all these samples are shown in table 1. it is noticed that no increases as cu content increases this may be attributed to the difference in covalent radius of mg 130pm and cu 138pm the dependence of n2-1 -1 on hЅ is shown in fig.2. it is shown that the refractive index depends on the cu content. the dielectric loss and dielectric tangent loss for these films were calculated as follow [45]: 7 8 figs. 3 a b show both of and versus hЅ for mg1-xcuxo /pmma nanocomposite films with different cu content values. from this fig. it was seen that both of and had the same behavior with hЅ for all samples and the cu content ratio affected strongly of both of and values this is due to the increasing of electron motilities with cu content. the optical conductivity was calculated from the following equations [46]: 9 10 figs 4 a b show the both of 1 and 2 dependence on hЅ for these films. the increasing of the optical conductivity 1 and 2 at high photon energies may be arising from the electron excited by photon energy and also may be attributed to the high absorbance of sample thin films. the behavior of both 1 and 2 for all these studied films is the same with hЅ and also 1 and 2 increase with cu content as a result of increasing free carrier concentration with cu which leads to increase of electron mobility and finally increase of both 1 and 2 the values of volume energy loss function velf and surface energy loss function self for these films were determined optically as follow [42]: 11 12 the relation between velf/self for these thin films is shown in fig. 5. linear optical susceptibility 1 describes the response of the material to an optical wave length 1 was determined using the following relation [47]: 13 the relation between 1 and hЅ for these investigates samples is shown in fig.6 from this fig. it was seen that the 1 increased with hЅ this means that there is a possibility of wide change in optical properties with change doping while the values of 1 increase with cu content due to the increase of free carrier concentration with cu which give the high possibility for a large number of electron to absorb light and go up to upper energy level for these samples. 3.2. nonlinear optical properties an important parameter of the non-linear optical parameters is that the nonlinear refractive index n2 which can be explained as when light with high intensity propagates through a medium this causes nonlinear effects[48] n2 was determined from the following simple equation [49-50]: 14 the dependence of n2 on for these samples is shown in fig. 7. the values of n2 decrease with for all these studied samples. 3 point to if the films are convenient for optical switching and photonic applications and assess the degree of nonlinearities which was determined as follow [51]: 15 where a is a quantity that is assumed to be frequency independent and nearly the same for all materials =1.7 x 10-10 e.s.u [50]. the dependance of 3 on and hЅ for these films is shown in fig.8. it was noticed that the behavior of 3 is the same for all the studied samples the values of 3 increses with cu content this is due to when cu content creases this leads to increase of both of carrier concentration and also the mobility of electrons which caused decrease of defliction of the incident ligth. on the other hand another important nonlinear parameter such was non-lnear absorption coefficient Іc which determined as follows [52]: 16 fig. 9 shows the the dependance of Іc on hЅ it is observed that the values of Іc increses with cu content for these samples as shown in fig. 8. because of the higher values of cu content the large number of excited electron which overcome the band gap. 3.3. electrical results electrical susceptibility e was determined using the following relation [53]: 17 fig. 10. shows the electrical susceptibility e dependence on hЅ of these investigated samples. from this figure it is clear that the values of e increase with hЅ and also the e increase with increase of cu content this is due to the electron mobility increases with cu ratio. the relative permittivity µr was calculated using the following relation [54] 18 the relation between relative permittivity µr and studied samples is shown in fig. 11. it is clear that the values of µr increase with hЅ for all these samples; this could be attributed to the electron mobility increases with hЅ 3.4. semiconducting and electronic results the density of states dos of a system describes the number of states per interval of energy at each energy level available to be occupied. the nv and nc play very important rule of examination the linear optical transition and non-linear optical properties. the nv and nc were calculated as follow [55]:- 19 20 where nv and nc were the density of states for both valence and conduction bands respectively. the determined values for both nv/m*h nc/m*e were shown in table 1. 4. conclusion the effect of cu content on optical conductivity nonlinear optical results and semiconductiong results of mg1-xcuxo /pmma nanocomposite films with 0.05‰¤ x‰¤ 0.2 were studied. the values of eo and ed increased slightly with cu ratio in these studied samples and also the determined values of both m-1 m-3 and f increased with cu content this is duo the increase of free electrons number and also electrons mobilitys with increasing cu ratio which affected also on the both values of and 1 slightly increases with hЅ for all samples this means that the optical response of these films to increase with hЅ while 3 increased with cu content this means cu content increase the ability for changing optical properties also the values of n2 increase with increasing cu content of these studied samples. the non-linear absorption coefficient Іc increased with cu ratio also both of the e and µr increase with cu content as a result of increasing the free carrier concentration and also the electron mobilitys which leads to the values of both of e and µr the cu ratio had affected on the values density of conduction band/electron effective on both of nc/ m*e cm-3 and nv/m*h cm-3 table 1: the influence of cu content on the determined values of pmma/mg1-x cuxo thin films such as µl eo ed m-1 m-3 f no n/m*e and nc/ m*e cm-3 and nv/m*h cm-3 nv//m*h nc/m*e n/m* no field strength f ev 2 m-3 ev m-1 ev dispersion energy ed ev oscillation energy eo ev lattice dielectric constant µl sample 9.5e+20 9.2e+20 1.3e+49 1.43 91.14 3.13 9.55 9.80 9.30 1.50 pmma 9.5e+20 9.2e+20 2.5e+49 1.44 81.78 3.07 9.04 9.40 8.70 1.20 pmma/mg0.95 cu0.05o 9.5e+20 9.2e+20 5.2e+49 1.44 79.12 3.03 8.89 9.20 8.60 1.90 pmma/mg0.90 cu0.10o 9.5e+20 9.2e+20 8.5e+49 1.44 75.60 3.00 8.69 9.00 8.40 1.30 pmma/mg0.85 cu0.15o 9.5e+20 9.2e+20 1.1e+50 1.45 72.09 2.98 8.49 8.90 8.10 1.95 pmma/mg0.80 cu0.20o
