Liquid phase synthesis

Liquid phase synthesis  

            Laser ablation method is used in this technique. The pulsed laser ablative deposition is an important technique today because of the control size and stability of synthesized nanoparticles can be achieved at low concentration of impurities. The particles are obtained from the substance immersed in liquid and three steps are required to fabricate controlled nanomaterial (Masuda et al., 2012).

1.9.4. Controlled precipitation 

            Another method used for the fabrication of ZnO NPs with the repeated properties of the material. In this process zinc salt is reduced to get nanomaterial by using a reducing agent. The growth of particles is limited and precursor precipitation of ZnO from the treated solution is done. The precursor is treated thermally and the products are then subjected to the removal of impurities. The formed agglomerates are too much difficult to break and calcanei powder includes high value of the particles agglomerated. The pH scale and temperature are use to describe the precipitation process with the time. Some other materials can be used to fabricate the ZnO nanoparticles such as the aqueous solution of zinc acetate, zinc chloride and zinc sulphate. During the process the concentration of reagents, temperature and time of reaction cared throughout the process (Sadraei, 2016).

1.9.5 Microwave synthesis   

            This process is only related to the growth of the oxide nanomaterial. Microwave irradiations have uniquely synthesized the nanoparticles in a short while. This technique also eliminates the use of high temperature calcination to increase the time and make the reaction fast for the production of desired nanomaterial. By this method the total energy is focused on the sample and time duration is controlled making the reaction controlled and fine particles in the regime are found by this process (Kong et al., 2003).

1.10. Objectives

Following are some important aims of the present study.

  • To obtain and characterize ZnO nanoparticles by co-precipitation method.
  • To study the surface morphology of the nanoparticles.
  • Electrical conductivity measurement is to be carried out by four probe method.
  • To synthesize zinc oxide nanostructures with the most practical ways by using co-precipitation method and characterize the nanostructures.      

Chapter 02

LITERATURE REVIEW

            Those particles which have a size range of 1-100 nanometres are called nanoparticles.  Size includes the interfacial layer. This layer is also the part of nanoparticles. It affects the properties of the material. This layer mostly consist inorganic, organic molecules and ions. Typically due to three different layer elements of the layer three types of nanoparticles are proposed. The layers formed by the inorganic substances are called stabilizers or capping and passivating agents. In nanotechnology a single particles is considered with respect t to its transport and other properties as a small object. These particles are further divided into different categories depending upon their size and nature. The term nanoparticle is usually associated with the inorganic material rather than a single molecule (Batista et al., 2015).

            Elilarassi et al. (2010) reported that nanoparticles have been elucidated by sol-gel method. The sample used was Zn1-NixOx powder. The metallic nitrites are used including nickel, glycine and zinc. The nickel doped ZnO structures have been studied by using different characteristics. These characteristics were SEM, EDAX, XRD, UV and photoluminescence. It has been reported that these nanoparticles were hexagonal wurtzite in structure revealed by XRD (x-ray diffraction technique). After the increasing the concentration of nickel the secondary phase of NiO has been studied and confirmed with the help of XRD.

            Bhakat et al. (2012) reported that the nanoparticles and Nano sized material have attracted a unique importance and value in the field of basics and applied science. Due to this reason these nanoparticles have been enormously under considerations for last many decades. In the purpose, the zinc oxide Nano rods in form of hexagonal structures are fabricated by adopting the thermal composition method. Zinc chloride with sodium hydroxide in the ratio of 1:2 has been used as precursor by wet chemical method for the fabrication of ZnO NPs. The synthesized NPs were then subjected to different characteristics. The opted characteristics were UV-vis spectrophotometry, XRD and SEM. The nanoparticles of 100-200 diameters were reported with the average length of 1 micrometer. These were then used in the photocell.

            Kumar et al. (2013) reported that zinc oxide NPs have been prepared using sodium chloride and zinc sulphate by simple method. Calcination of prepared particles was done at different temperatures. SEM, EDX, XRD and x-ray emission analysis have been done in order to study the further properties and structure of synthesized nanoparticles. Change in the morphology has been reported as revealed by the images of SEM. Debye formula is used to calculate the particles domain size of nanoparticles with the help of peaks obtained by XRD characteristic. The domain size was found in range of nano size. The EDS results revealed that the obtained particles were totally pure. Optical properties and band gape were studied by using UV analysis were found in agreement with original values.

            Kulkarni et al. (2015) reported that zinc oxide is a semiconductor material with the energy gape of 3.37 eV has the unique properties and large excitation energy at almost room temperature enables is to be used in electronics and optoelectronics. Most importantly it is transparent, environment friendly and very much non-toxic. Due to above reasons the ZnO NPs were synthesized by sol-gel method using NaOH and zinc acetate as initial materials with distilled water as a solvent. The synthesized nanoparticles were subjected to the different characteristics to investigate the structure, morphology and other properties by using XRD, SEM and EDAX. The optical properties have been studies using UV visible spectrophotometer. FTIR analysis has been opted for the confirmation of ZnO NPs.

            Hasnidawani et al. (2016) reported that ZnO NPs have a vital role in the current industry due to its unique properties such as antibacterial property, low conductivity and resistant to heat. For this purpose the nanoparticles of ZnO were prepared by sol-gel method because this method is very simple and capable to control the size, structure and properties of the particles by the control of parameters during the whole process. For this purpose zinc acetate dehydrate is used as precursor. The solvents used were ethanol and sodium hydroxide with the dehydrated water. The synthesized nanoparticles were subjected to different characterizations for further analysis using XRD, FESEM, EDS and particle analyzer. A remarkable purity with 55.4% of zinc and 4.6% of oxygen has been proposed by the EDS results. The particles were crystalline in nature as revealed by the respective zinc and oxygen broad peaks of XRD. The images and results of FESEM revealed that the particles are in the form of Nano rods. Homogeneity of particles is confirmed with the XRD peaks showing the constant size of reduced nanoparticles. The range of the particles was reported from 80 to 85 nanometers.

            Al Abdullah et al. (2017) reported the synthesis of ZnO NPs by sol-gel method. The methanol is used as solution for this purpose and initially zinc acetate dehydrate is used with the addition of ammonia NH4OH to stabilize the pH value. The pH value has been adjusted from 9 to 11 and the fabricated nanoparticles are made a substrate material for ZnO Nano material. The synthesized nanoparticles were wurtzite hexagonal in structure explained by XRD analysis. The particle size range ws reported from 12-30 nanometers. The nanoparticles were further analyzed using atomic force microscope for the topographical information. The particles were distribute homogeneously and particles size was 22 nanometres which is exactly given out from the XRD results. The synthesized nanoparticles were analysed by magnetometer to study the current voltage characteristics. The temperature was selected was 1050 degree centigrade.

            Parihar et al. (2018) reported that nanotechnology deals with materials at Nano size. At this level surface to the volume ratio has large value. Due to this the intrinsic properties of materials vary. Due to large band width and high excitation potential the zinc oxide nanoparticles attracted the researcher today. This large band width and high potential capability it is used in the electronics and optoelectronics. The zinc oxide nanoparticles have different magnetic and structural properties from the bulk matter making it significantly important to be used in different fields. Our aim of study is to study comprehensively the properties of the ZnO nanoparticles.

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