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Ali NA, Idris NH, Din MFM, Mustafa NS, Sazelee NA, Halim Yap FA, Sulaiman NN, Yahya MS, Ismail M. Nanolayer-like-shaped MgFe2O4 synthesised via a simple hydrothermal method and its catalytic effect on the hydrogen storage properties of MgH2. RSC Adv 2018; 8:15667-15674. [PMID: 35559118 PMCID: PMC9088278 DOI: 10.1039/c8ra02168f] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 04/18/2018] [Indexed: 12/12/2022] Open
Abstract
The nanolayer-like-shaped MgFe2O4-added MgH2 composite showed an improvement in de/absorption properties compared to that of un-doped MgH2.
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Affiliation(s)
- N. A. Ali
- School of Ocean Engineering
- Universiti Malaysia Terengganu
- 21030 Kuala Terengganu
- Malaysia
| | - Nurul Hayati Idris
- School of Ocean Engineering
- Universiti Malaysia Terengganu
- 21030 Kuala Terengganu
- Malaysia
| | - M. F. Md Din
- Department of Electrical and Electronic Engineering
- Faculty of Engineering
- National Defence University of Malaysia
- Kuala Lumpur
- Malaysia
| | - N. S. Mustafa
- School of Ocean Engineering
- Universiti Malaysia Terengganu
- 21030 Kuala Terengganu
- Malaysia
| | - N. A. Sazelee
- School of Ocean Engineering
- Universiti Malaysia Terengganu
- 21030 Kuala Terengganu
- Malaysia
| | - F. A. Halim Yap
- School of Ocean Engineering
- Universiti Malaysia Terengganu
- 21030 Kuala Terengganu
- Malaysia
| | - N. N. Sulaiman
- School of Ocean Engineering
- Universiti Malaysia Terengganu
- 21030 Kuala Terengganu
- Malaysia
| | - M. S. Yahya
- School of Ocean Engineering
- Universiti Malaysia Terengganu
- 21030 Kuala Terengganu
- Malaysia
| | - M. Ismail
- School of Ocean Engineering
- Universiti Malaysia Terengganu
- 21030 Kuala Terengganu
- Malaysia
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Md Din MF, Wang JL, Cheng ZX, Dou SX, Kennedy SJ, Avdeev M, Campbell SJ. Tuneable Magnetic Phase Transitions in Layered CeMn2Ge(2-x)Six Compounds. Sci Rep 2015; 5:11288. [PMID: 26090940 PMCID: PMC4650650 DOI: 10.1038/srep11288] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 05/12/2015] [Indexed: 11/20/2022] Open
Abstract
The structural and magnetic properties of seven CeMn2Ge(2-x)Six compounds with x = 0.0-2.0 have been investigated in detail. Substitution of Ge with Si leads to a monotonic decrease of both a and c along with concomitant contraction of the unit cell volume and significant modifications of the magnetic states - a crossover from ferromagnetism at room temperature for Ge-rich compounds to antiferromagnetism for Si-rich compounds. The magnetic phase diagram has been constructed over the full range of CeMn2Ge(2-x)Six compositions and co-existence of ferromagnetism and antiferromagnetism has been observed in CeMn2Ge1.2Si0.8, CeMn2Ge1.0Si1.0 and CeMn2Ge0.8Si1.2 with novel insight provided by high resolution neutron and X-ray synchrotron radiation studies. CeMn2Ge(2-x)Six compounds (x = 0, 0.4 and 0.8) exhibit moderate isothermal magnetic entropy accompanied with a second-order phase transition around room temperature. Analysis of critical behaviour in the vicinity of TC(inter) for CeMn2Ge2 compound indicates behaviour consistent with three-dimensional Heisenberg model predictions.
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Affiliation(s)
- M. F. Md Din
- Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522, Australia
- Department of Electrical & Electronic Engineering, Faculty of Engineering, National Defence University of Malaysia, Kem Sungai Besi, 57000 Kuala Lumpur, Malaysia
| | - J. L. Wang
- Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522, Australia
- Bragg Institute, Australian Nuclear Science and Technology Organization, Lucas Heights, NSW 2234, Australia
| | - Z. X. Cheng
- Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522, Australia
| | - S. X. Dou
- Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522, Australia
| | - S. J. Kennedy
- Bragg Institute, Australian Nuclear Science and Technology Organization, Lucas Heights, NSW 2234, Australia
| | - M. Avdeev
- Bragg Institute, Australian Nuclear Science and Technology Organization, Lucas Heights, NSW 2234, Australia
| | - S. J. Campbell
- School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, Canberra, ACT 2600, Australia
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Wang JL, Campbell SJ, Hofmann M, Kennedy SJ, Zeng R, Md Din MF, Dou SX, Arulraj A, Stusser N. Magnetism and magnetic structures of PrMn2Ge2-xSix. J Phys Condens Matter 2013; 25:386003. [PMID: 23988490 DOI: 10.1088/0953-8984/25/38/386003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The structural and magnetic properties of seven PrMn2Ge2-xSix compounds with Si concentrations in the range x = 0.0-2.0 have been investigated by x-ray diffraction, magnetic (5-350 K), differential scanning calorimetry (300-500 K) and neutron diffraction (3-480 K) measurements. Replacement of Ge by Si leads to a contraction of the unit cell and significant modifications to the magnetic states--a crossover from ferromagnetism at room temperature for Ge-rich compounds to antiferromagnetism for Si-rich compounds. The compositional dependence of the room temperature lattice parameters exhibits non-linear behaviour around x = 1.2, reflecting the presence of magnetovolume effects. Re-entrant ferromagnetism has been observed in both PrMn2Ge1.0Si1.0 and PrMn2Ge0.8Si1.2 compounds with co-existence of canted ferromagnetism and canted antiferromagnetism detected, with both compounds exhibiting a larger unit cell volume in the canted Fmc state than in the canted AFmc. Combined with earlier studies of this system, the magnetic phase diagram has been constructed over the full range of PrMn2Ge2-xSix compositions (x = 0.0-2.0) and over the temperature range of interest (T = 3-480 K). In common with other systems in the RMn2X2 series, the overall magnetic behaviour of PrMn2Ge2-xSix compounds is governed by the strong dependence of the magnetic couplings on the Mn-Mn spacing within the ab-plane. Both total manganese moment µ(Mn)(tot) and in-plane manganese moment µ(Mn)(ab) at 5 K are found to decrease with increasing Si content, which can be ascribed to the reduction of Mn-Mn separation distance and stronger Si-Mn hybridization compared with Ge-Mn hybridization. Pr site ferromagnetic ordering occurs for x < 1.6 below T(Pr)(C).
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Affiliation(s)
- J L Wang
- Bragg Institute, ANSTO, Lucas Heights, NSW 2234, Australia
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Wang JL, Caron L, Campbell SJ, Kennedy SJ, Hofmann M, Cheng ZX, Din MFM, Studer AJ, Brück E, Dou SX. Driving magnetostructural transitions in layered intermetallic compounds. Phys Rev Lett 2013; 110:217211. [PMID: 23745927 DOI: 10.1103/physrevlett.110.217211] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Indexed: 06/02/2023]
Abstract
We report the dramatic effect of applied pressure and magnetic field on the layered intermetallic compound Pr(0.5)Y(0.5)Mn(2)Ge(2). In the absence of pressure or magnetic field this compound displays interplanar ferromagnetism at room temperature and undergoes an isostructural first order magnetic transition (FOMT) to an antiferromagnetic state below 158 K, followed by another FOMT at 50 K due to the reemergence of ferromagnetism as praseodymium orders (T(C)(Pr)). The application of a magnetic field drives these two transitions towards each other, whereas the application of pressure drives them apart. Pressure also produces a giant magnetocaloric effect such that a threefold increase of the entropy change associated with the lower FOMT (at T(C)(Pr)) is seen under a pressure of 7.5 kbar. First principles calculations, using density functional theory, show that this remarkable magnetic behavior derives from the strong magnetoelastic coupling of the manganese layers in this compound.
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Affiliation(s)
- J L Wang
- Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, New South Wales 2522, Australia.
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Shamba P, Wang JL, Debnath JC, Kennedy SJ, Zeng R, Din MFM, Hong F, Cheng ZX, Studer AJ, Dou SX. The magnetocaloric effect and critical behaviour of the Mn(0.94)Ti(0.06)CoGe alloy. J Phys Condens Matter 2013; 25:056001. [PMID: 23262456 DOI: 10.1088/0953-8984/25/5/056001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Structural, magnetic and magnetocaloric properties of the Mn(0.94)Ti(0.06)CoGe alloy have been investigated using x-ray diffraction, DC magnetization and neutron diffraction measurements. Two phase transitions have been detected, at T(str) = 235 K and T(C) = 270 K. A giant magnetocaloric effect has been obtained at around T(str) associated with a structural phase transition from the low temperature orthorhombic TiNiSi-type structure to the high temperature hexagonal Ni(2)In-type structure, which is confirmed by neutron study. In the vicinity of the structural transition, at T(str), the magnetic entropy change, -ΔS(M) reached a maximum value of 14.8 J kg(-1) K(-1) under a magnetic field of 5 T, which is much higher than that previously reported for the parent compound MnCoGe. To investigate the nature of the magnetic phase transition around T(C) = 270 K from the ferromagnetic to the paramagnetic state, we performed a detailed critical exponent study. The critical components γ, β and δ determined using the Kouvel-Fisher method, the modified Arrott plot and the critical isotherm analysis agree well. The values deduced for the critical exponents are close to the theoretical prediction from the mean-field model, indicating that the magnetic interactions are long range. On the basis of these critical exponents, the magnetization, field and temperature data around T(C) collapse onto two curves obeying the single scaling equation M(H,ε) = ε(β)f ± (H/ε(β+γ)).
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Affiliation(s)
- P Shamba
- Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2522, Australia
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Ujang Z, Salim MR, Md Din MF, Ahmad MA. Intracellular biopolymer productions using mixed microbial cultures from fermented POME. Water Sci Technol 2007; 56:179-185. [PMID: 17978446 DOI: 10.2166/wst.2007.687] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
This study aimed to produce polyhydroxyalkanoates (PHAs) from organic wastes by mixed bacterial cultures using anaerobic-aerobic fermentation systems. Palm oil mill effluent (POME) was used as an organic source, which was cultivated in a two-step-process of acidogenesis and acid polymerization. POME was operated in a continuous flow anaerobic reactor to access volatile fatty acids (VFAs) for PHAs production. During fermentation, VFA concentration was produced in the range of 5 to 8 g/L and the COD concentration reduced up to 80% from 65 g/L. The VFA from anaerobic fermentation was then utilised for PHA production using a mixed culture in availability of aerobic bioreactor. Production of PHAs was recorded high when using a high volume of substrates because of the higher VFA concentration. Even though the maximum PHA content was observed at only 40% of the cell dried weight (CDW), their production and performance are significant in mixed microbial culture.
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Din MFM, Ujang Z, van Loosdrecht MCM, Ahmad A, Sairan MF. Optimization of nitrogen and phosphorus limitation for better biodegradable plastic production and organic removal using single fed-batch mixed cultures and renewable resources. Water Sci Technol 2006; 53:15-20. [PMID: 16749434 DOI: 10.2166/wst.2006.164] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The process for the production of biodegradable plastic material (polyhydroxyalkanoates, PHAs) from microbial cells by mixed-bacterial cultivation using readily available waste (renewable resources) is the main consideration nowadays. These observations have shown impressive results typically under high carbon fraction, COD/N and COD/P (usually described as nutrient-limiting conditions) and warmest temperature (moderate condition). Therefore, the aim of this work is predominantly to select mixed cultures under high storage responded by cultivation on a substrate - non limited in a single batch reactor with shortest period for feeding and to characterize their storage response by using specific and kinetics determination. In that case, the selected-fixed temperature is 30 degrees C to establish tropical conditions. During the accumulated steady-state period, the cell growth was inhibited by high PHA content within the cells because of the carbon reserve consumption. From the experiments, there is no doubt about the PHA accumulation even at high carbon fraction ratio. Apparently, the best accumulation occurred at carbon fraction, 160 +/- 7.97 g COD/g N (PHAmean, = 44.54% of dried cells). Unfortunately, the highest PHA productivity was achieved at the high carbon fraction, 560 +/- 1.62 g COD/g N (0.152 +/- 0.17 g/l. min). Overall results showed that with high carbon fraction induced to the cultivation, the PO4 and NO3 can remove up to 20% in single cultivation.
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Affiliation(s)
- M F M Din
- IPASA, Faculty of Civil Engineering, University Technology of Malaysia, 81310 Skudai Johor, Malaysia.
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Aris A, Din MFM, Salim MR, Yunus S, Abu Bakar WA. Influence of varying reacting conditions in the degradation of azo dye using immobilized TiO2 photocatalyst. Water Sci Technol 2002; 46:255-262. [PMID: 12448476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In Malaysia, most colored wastewater from dyeing factories is discharged to the environment causing serious problems. In this paper the influence of several reacting conditions, i.e. H2O2, pH, Ultraviolet (UV) intensity and dye concentration, on the performance of the immobilized system is discussed. The pH of the solution was varied from 3 to 11 while H2O2 concentration tested was from 10(-4) M to 5 x 10(-2) M. UV was tested at 365 nm and 254 nm, while dye concentration ranged from 2.5 x 10(-4) M to 10(-3) M. The influence of the reacting conditions was assessed based on absorbance. Using an OG concentration of 10(-3) M, the degradation increases from 17.8% to 49.7%. Optimum concentration of H2O2 was found to be 5 x 10(-3) M for degradation. Increasing the intensity of the UV light via shorter light wavelength also improves the performance of the system. Increasing the concentration of the dye reduces the overall performance of the system. Using the dye concentration of 2.5 x 10(-4) M (H2O2 = 10(-2) M, lambda = 254 nm, pH = 11), gives a degradation of 93.2%. At dye concentration of 10(-3) M, the performance was reduced to 53.1%.
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Affiliation(s)
- A Aris
- Department of Environmental Engineering, Faculty of Civil Engineering, Universiti Teknologi Malaysia, Skudai, Johore
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