23 research outputs found
Synthesis and characterization of LiMPO[4] (M=Mn, Ni and Fe) olivine materials / Azlin Sanusi
Get PDFLithium transition metal phosphate, LiMPO4 compounds with olivine structure namely LiMnPO4, LiNiPO4 and LiFePO4 were successfully synthesized in the present work. LiMnPO4 and LiNiPO4 were synthesized by the sol-gel method with tartaric acid as the chelating agent. LiFePO4 was synthesized via the chemical precipitation and low temperature sterilizer heating method. TGA was carried out on LiMnPO4 and LiNiPO4 samples to determine the firing temperature of the gel precursor and the thermal stability of the prepared samples. LiMnPO4 was heated for 15 hours at various temperatures and LiNiPO4 was formed at 1000 oC with firing time of 24 hours. Firing of samples in this work was carried out in air. The absence of inert gas and reducing agents made the synthesis simple and low cost which is one of the objectives of this work. Reactions mechanisms for both LiMnPO4 and LiNiPO4 were deduced from the TGA curves. The weight loss predicted by these reaction mechanisms agree with that obtained experimentally for the two samples. XRD reveals that both LiMnPO4 and LiNiPO4 samples are pure while LiFePO4 was formed with minor impurities. Crystallite size of samples were calculated from Scherrer equation and both methods have proven to produce nano-size crystallites. The crystallite size was found to be in the range of 31 nm to 46 nm for LiMnPO4 produced at sintering temperatures from 350 oC to 1000 oC for 15 hours, 66 nm for LiNiPO4 fired at 1000 oC for 24 hours and 58 nm for LiFePO4 produced at 121 oC for 5 hours. Thus, tartaric acid as chelating agent is successful in inhibiting the growth of the particle as expected since nanosized samples are obtained. Samples were also characterized by FTIR. All spectra show the presence of peaks at 1135-1138 cm-1,1088-1096 cm-1,1051-1071 cm-1 and 984-1040 cm-1 and in addition asymmetric PO bending bands in the region 550-700 cm-1 were also observed. These observations indicate the presence of PO43- ions in all samples
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prepared. EDX analysis confirmed the percentage composition of the samples and that Mn2+, Ni2+ and Fe2+ oxidation state remain unchanged although fired in air. Cyclic voltammetry measurements gave redox peaks for all samples prepared in this work indicating lithiation and delithiation of Li+ ion has taken place. Oxidation peak at ~ 4.4 V and reduction peak at ~ 4.0 V was observed for LiMnPO4 and as for LiNiPO4 anodic and cathodic peaks are observed at ~ 4.9V and ~ 4.8V respectively. Oxidation peak at ~3.8 V and reduction peak at ~3.2 V are observed in the cyclic voltammogram of LiFePO4. Diffusion coefficient calculated using CV and Randles-Sevcik equation are 3.50 x 10-11 cm2s-1 for LiNiPO4 and 3.09 x 10-13 cm2 s-1 for LiFePO4. The diffusion coefficient for LiMnPO4 are 9.37 x 10-13 cm2 s-1, 8.57 x 10-13cm2 s-1 and 2.97 x 10-14 cm2 s-1 for sample A3, A4 and A5 respectively indicating that smaller particles at lower heating temperature has shortened the path length and enhances intercalation
Synthesis and fourier transform infrared spectroscopic studies of C-O bond in the Nickel(II) benzoate derivatives substitued with electron-attracting groups / Zuraida Khusaimi and Azlin Sanusi
Get PDFMiniaturization of electronic devices increases the reliability and energy saving nature of electronic devices [8]. For the last 10 years or so scientists like Tour and Reed [5] has been enthusiastically studying, synthesizing and isolating molecules exhibiting conductive, semi-conductive and super-conductive ability. One of the major advantage in the manufacturing of molecular electronics is that they are self-assembled, by simply putting the right ingredients into a beaker, unlike time consuming microchip-producing technique. Computing speed can also be revolutionized to millions of times faster than of silicon material [5]. Nickel(II) benzoate is a metallomesogens, a potential low-dimensional electronic material. Its structure is assumed to follow the ligand-field theory [12]
Synthesis of nanocrystalline olivine LiNiPo4 powder prepared by sol-gel method: thermal analysis and XRD studies
No full textLiMPO4 have attracted much attention as potential cathode material as it does not liberate oxygen on decomposition unlike lithium transition metal oxides (LMO). In this work, LiNiPO4 powder was prepared by sol gel method using LiOH, Ni(CH3COO)2, NH4H2(PO4) and tartaric acid as chelating agent .The precursor powders were studied by thermogravimetric analysis (TGA). Based on the TGA results, the sample was calcined at 1000oC in air. The TGA/DTGA studies have been employed to analyse the reaction of raw materials during the formation of LiNiPO4 .The formation mechanism for the synthesis of LiNiPO4 and the overall decomposition equation for the precursor were proposed from the TGA/DTGA analysis. The calculated total weight loss from the overall proposed decomposition process which is 66.4% shows agreement with the percentage weight loss from the TGA curves which is 68%. The X-ray diffraction analysis was carried out to confirm the formation of LiNiPO4. The precursors and the calcined powders were characterized by X-ray diffraction (XRD). Analysis of the synthesized LiNiPO4 using XRD demonstrated the formation of a pure LiNiPO4 phase powder
Effects of corporate governance and financial performance on fraudulent financial statements: evidence from Indonesia’s property, real estate, and building construction sectors / Reni Yendrawati , Reny Lia Riantika, Firkhansya Zuhaira Kusumadewi , Nurul Azlin Azmi and Zuraidah Mohd Sanusi
Get PDFThis study aimed to examine the effects of managerial and institutional ownership, and financial performance on fraudulent financial statements. Companies with weak governance and poor financial performance have a high tendency to partake in fraudulent activities as these factors create pressure and opportunity (fraud triangle theory) to mask financial figures. Weak governance sectors were chosen from the Indonesia Stock Exchange property, real estate, and building construction sectors. This study used a purposive sampling technique with predetermined criteria and employed panel regression analysis. The final panel data set consisted of 96 company-year observations. Managerial and institutional ownership had a significant and negative effect on fraudulent financial statements. Company leverage had a positive and significant relationship with fraudulent financial statements. Nevertheless, company profitability had no association with fraudulent financial statements. Furthermore, the interaction of company profitability strengthened the positive effect of managerial ownership and fraudulent financial statements. This study contributes to the literature by examining the corporate governance effectiveness in curbing fraudulent financial statements in selected sectors in Indonesia. In addition, this study offers practitioners insights into enhancing the effectiveness of internal and external governance mechanisms as well as the internal control systems in the companies
How well does political connection affect firms’ performance? / Nurul Azlin Azmi ...[et al.]
Get PDFThe purpose of this study is to examine the influence of political connections on firms’ performance by controlling the effect of board attributes and firms characteristics. Specifically, it is argued that politically connected firms enjoy a lot of benefit from the government and said to provide greater chances for the firms to increase their wealth. By using 156 public listed firms between the
study period of 2012 to 2017, this study maps out political connection based on the 13th Malaysian general election. The results reveal that the appearance of political connections on board give significant and negative effect on Tobin Q, while significant and positive effect on Return on Asset (ROA) and Return on Equity (ROE). Board independence is also significant to firms’ performance. This
result implies that political connections are favour for a better firm’s performance and not to firm’s value. The findings have an important implication to investors as it suggest that firms with political connection on board perform better
Comparison of Dijkstra’s algorithm and dynamic programming method in finding shortest path for order picker in a warehouse
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Optimization of culture conditions for biohydrogen production from sago wastewater by enterobacter aerogenes using response surface methodology
Get PDFSago wastewater (SWW) causes pollution to the environment due to its high organic content. Annually, about 2.5 million tons of SWW is produced in Malaysia. In this study, the potential of SWW as a substrate for biohydrogen production by Enterobacter aerogenes (E. aerogenes) was evaluated. Response Surface Methodology (RSM) was employed to find the optimum conditions. From preliminary optimization, it was found that the most significant factors were yeast extract, temperature, and inoculum size. According to Face Centered Central Composite Design (FCCCD), the maximum hydrogen concentration and yield were 630.67 μmol/L and 7.42 mmol H2/mol glucose, respectively, which is obtained from the sample supplemented with 4.8 g/L yeast extract concentration, 5% inoculum, and incubated at the temperature of 31 °C. Cumulative hydrogen production curve fitted by the modified Gompertz equation suggested that Hmax, Rmax, and λ from this study were 15.10 mL, 2.18 mL/h, and 9.84 h, respectively
The Impact of User – Generated Content (UGC) on Product Reviews towards Online Purchasing – A Conceptual Framework
No full textAbstractSocial media is a virtual community that links people around the globe through many websites such as Friendster, MySpace, YouTube, Facebook and Twitter. In 2010, Instagram was introduced as a new addition to this social media family. Since then, many online retailers have started to conduct their businesses on Instagram as they see this new social media as a friendlier channel and easier to monitor compared to Facebook and Blogs. Many buyers would also prefer to purchase from Instagram as well due to less cluttered page, straightforward interface and easier to read feedbacks from other buyers. Feedbacks or also known as User – Generated Content (UGC) happens when previous buyers share their experiences online, which allows others including the potential buyers to read. Based on an extensive literature review, this paper proposes a framework to investigate the influence of UGC on consumer's online product purchase intention. Findings from this study are expected to extend the literature on UGC and give benefits to marketers and online business operators
