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There are three objectives to be achieved in this research which include to synthesis high purity ZnO pellets with different sintering time and green body pressure by using powder metallurgy process, the growth of ZnO crystal on ceramic bar by applying different current when conducting electric current heating (ECH) method and the characterization of ZnO crystal growth. In this research, high purity of ZnO powder is grinded and compressed at 3.5 tons, 4.5 tons and 5.5 tons to fabricate ZnO green pellets. Then, the ZnO green pellets are sintered for 3 hours and 5 hours. Next, the pellets are cut into bars and apply ECH method. The amount of current applied for the crystal growth are 2A and 3A. Finally, the crystal grown on the ZnO ceramic bar is characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Ultraviolet-visible Spectroscopy (UV-Vis) and Photoluminescence Spectroscopy (PL). High purity ceramic pellets are successfully synthesis by powder metallurgy process. By conducting ECH method, crystal are grown on the surface of ceramic bar. Most crystal structure found in ZnO ceramic bar is needle-liked rod structure which is hexagonally formed by many nanorod. The crystal grown in (100) orientation with the crystalline size of from 57.80 nm to 100.31 nm. The band gap energy obtained from UV-Vis were found between 3.2 eV to 3.4 eV which is nearly similar to the theoretical value of 3.37 eV. Lastly, PL emission measurement give the peak that range between 579 nm to 587 nm which indicate that the sample exhibit yellow colour. Among three different pressure applied, 4.5 tons gives the lowest emission energy. It is considered as the critical pressure in the synthesis of ZnO crystal. The intensity of PL is considered inversely proportional to intensity of XRD in [100] direction. Pressing pressure doesn’t show significant effect on the crystal growth of ZnO but current applied during ECH method and sintering time do give effect on UV-Vis absorption spectra and XRD result respectively.

Abstract. In this study, we reported the effect of applied compaction pressure on green body and electric current heating on ceramic bar on the ZnO crystal growth and its photoluminescence characteristic. Crystals grown on ZnO bar sintered by 1100 o C were mostly on (1 0 1) orientation. Sample with 3.0 ton and 3.0 A for applied pressure and current, respectively revealed the shortest photoluminescence (PL) wavelength of 409.5 nm with highest emission energy of 3.03 eV. IntroductionZnO has gained substantial interest in the research community because of its large exciton binding energy (60 meV) and wide direct band gap (Eg ∼ 3.37 eV) at room temperature (R.T.). This large exciton binding energy paves the way for an intense near-band-edge excitonic emission such as lasing action at R.T. and higher temperatures, because this value is 2.4 times larger than that of the room temperature thermal energy (kBT = 25 meV). In addition, the interest in ZnO is fueled and fanned by its prospects in electronics and photonics applications, viz. transparent electrodes in solar cells, flat display devices and novel solid-state ultraviolet (UV) lasers owing to its direct wide band gap [1][2][3][4][5][6][7].Many works have been done on the fabrication of ZnO micro/nanostructures with high aspect ratios using metalorganic chemical vapor deposition [8], thermal evaporation and thermal decomposition [9]. But these techniques appear to be involved process with many complex steps, require sophisticated equipment and rigorous experimental conditions. However, some of them have drawbacks like long reaction time, toxic templets and exotic metal catalysts, and low purity or poor crystallite quality of products, which may influence the quality and applications of ZnO. So there is still the need for developing a method that can produce the ZnO micro/nanostructures in laboratory environment with high quality, high repeatability and low cost process for a wide range of applications. Hence, a novel technique called ECH for the preparation of ZnO micro/nanocrystals [10][11][12].When a certain direct current flowed through a sample of ZnO ceramic bar, the sample was Jouleheated, and the crystal growth occurred. ZnO is a key technological material. The lack of a centre of symmetry in wurtzite, combined with large electromechanical coupling, results in strong piezoelectric

This reports about the synthesis of Mg doped ZnO thin film using spin-coating techniques through sol-gel method. For studying piezoelectric properties, optical properties and morphology, the prepared Mg doped ZnO thin film samples were characterized using Ultraviolet-Visible Spectroscopy (UV-Vis), Photoluminescence Spectroscopy (PL), X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FESEM) and Ultrasonic Vibrator. The particle size was evaluated using Scherrer’s formula from XRD patterns. The results show the crystallite size decreased with increasing Mg concentrations. The optical properties showed that sample exhibit a blue shift in absorption in UV spectra indicating good optical properties. The morphology of grain size microstructure was observed from FESEM with results the grain size of the samples decreased with increasing Mg doping. The piezoelectric properties were evaluated using ultrasonic vibrator and multimeter to obtain potential difference for each sample. The results obtained that potential difference increase with increasing Mg contents and higher rotation of spin speed was used.

The fabrication technique applied in this research to grow ZnO crystal is known as ECH method. It is a preferred method due to its low cost, simplicity in operating and low growth temperature. However the condition of ECH method to produce the optimum crystal growth has not been studied further. The objectives of this research are to synthesize ZnO ceramic pellets, to produce ZnO micro/nanostrcutures on ZnO ceramics bar by ECH method, as well as to characterize and analyze structural, morphological, and optical properties of ZnO crystals grown. ZnO pellets were formed by pressed at 3, 4, 5 tons and sintered at 1,100 °C in air for 4 and 72 hours. ZnO ceramic bar was joule heated by direct current of 2 A and 3 A. The result is the grain size of ZnO pellets increased with increasing sintering time and pressing pressure. XRD results indicated mostly crystal prefer to grow along (100) orientation. SEM images showed crystals grown was in a variety of shapes and sizes. PL measurements at room temperature revealed high intensity peak of in visible region in which yellow-level emission was observed from ZnO crystals grown.