Anhydrous Phosphates of Molybdenum and Rhenium Synthesis, Crystallization, Crystal structures, and Spectroscopic investigations

In this thesis, the crystal chemistry of anhydrous transition metal phosphates have been extended by the syntheses of a large number of molybdenum and rhenium phosphates, (MoVO)4(P2O7)3, Phase X1 (a new polymorph of (MoVO)4(P2O7)3), βI-MoVO(PO4), ReV2O3(P2O7), ReVI2O3(PO4)2, ReVIIO2(PO4), NaReIV2(PO4)3, ReIV3[Sit2O(PO4)6], and (ReVII2O5)Sio2[Sit2O(PO4)6].Crystal structures and the bonding phenomena of these new phosphates have been studied by X-ray single-crystal and spectroscopic investigations. (MoVO)4(P2O7)3, Phase X1 and βI-MoVO(PO4) were synthesized reducing MoVI2P2O11 by red phosphorus followed by chemical vapour transport (CVT) using I2 as transport agent. The formations of these molybdenyl(V) phosphates are rather sensitive to the choice of starting solids and other experimental conditions. The crystal structure of (MoVO)4(P2O7)3 can be derived from the SiP2O7 structure type according to the scheme (MoVO)4(P2O7)3 = 4MIVP2O7 - “P2O3”. Pyrophosphates MP2O7 are structurally related to the rock salt type via the pyrite structure type. Thus, a very complicated structure can be derived from a rather simple one according to the relationship NaCl → FeS2 → MIVP2O7 (Z = 4, a ≈ 8 Å) → (MoVO)4(P2O7)3 (Z = 36, a ≈ 24, b ≈ 24, c ≈ 32 Å). As a consequence, the crystal structure of (MoO)4(P2O7)3 is considered as a hybrid of non-defect like MIVP2O7 layer (A) and P2O3 deficient layer (B), built up by alternating stacking forming ABA΄B΄AB…. along the crystallographic c-axis. The crystal structure of βI-MoVO(PO4) is isotypic to β-VVO(PO4). α-(MoVIO2)2P2O7, one of the four polymorphs, was crystallized by CVT using H2O as transport agent. Its structure has been solved from X-ray single-crystal data that showed improved precision in bond-lengths and -angles in compare to that of Lister et al. obtained from X-ray powder diffraction. The ternary phase diagram of Re / P / O has been developed at 800 and 500oC. It shows that the redox behaviour of rhenium phosphates is considerably different from higher to lower temperatures. Our study shows that CVT are particularly suitable for the crystallization of rhenium phosphates. High volatility of Re2O7(g) and ReO3X(g) (X = Cl, I, OH) allows crystallization of rhenium phosphates by CVT. Under perfectly dry conditions, dissociative sublimation of ReVIIO2(PO4) in a temperature gradient 400 → 300°C is possible. In addition to the long known ReIVP2O7, formation of the further tetravalent rhenium phosphates, NaReIV2(PO4)3 and ReIV3[Sit2O(PO4)6] evidently show the significant thermal stability of this oxidation state of rhenium. NaReIV2(PO4)3 is isotypic to NASICON NaZr2IV(PO4)3 and ReIV3[Sit2O(PO4)6] is isotypic to SioIV3[Sit2O(PO4)6]. Single-crystal UV/Vis/NIR spectra for rhenium(IV) phosphates evidently show their similarity. The first spin allowed transition 4A2g → 4T2g is observed at ∆o ~ 25000 cm-1. At about 8000-11000 cm-1 and around 16500 cm-1 spin-forbidden transitions 4A2g → 2T1g, 4A2g → 2Eg, and 4A2g → 2T2g are observed. According to AOM, B ~ 550 cm-1 and ξ~ 2500 cm-1 are found. AOM calculations show that for rhenium(IV)-phosphates d-p π-interactions between the Re4+ and O2- ions are present. The effective magnetic moment for ReIVP2O7 is 3.22 μB which is close to the value 3.28 μB calculated within AOM. ReV2O3(P2O7) is isostructural to WV2O3(P2O7). Its crystal structure consists of octahedra [ReO3/1O3/2] which are linked via three oxygen atoms to form chain-ladder type ribbons undulating along the crystallographic c-axis. In another approach to the crystal structure these ribbons might be considered as sections from a ReO3-type lattice which are linked via pyrophosphate groups to give rather wide octagonal tunnels. The crystal structure of ReVI2O3(PO4)2 consists of [ReVI2O11] groups with two terminal (Re=O) bonds as building units besides phosphate tetrahedra. Despite the same space group and very similar lattice parameters the orthorhombic modification of WVI2O3(PO4)2 is not immediately structurally related to ReVI2O3(PO4)2. In contrast to molybdenyl(V) phosphates, rather low magnetic moment for Re6+ in ReVI2O3(PO4)2(0.07 ≤ µexp /µB≤ 0.38; 1.4 K ≤ T ≤ 300 K) and its strong temperature dependence are indicative for a very strong spin-orbit interaction. The electronic absorption spectra of d1 systems in molybdenyl(V)- and rhenyl(VI)- phosphates are similar. ReVIIO2(PO4) and (ReVII2O5)Sio2[Sit2O(PO4)6] are the first anhydrous phosphates containing a heptavalent metal. These phosphates are stable up to 400°C. The crystal structure of ReVIIO2(PO4) might be regarded as superstructure of the ReO3 structure type, however, phosphorus is in tetragonal environment. The crystal structure of the silicophosphate, (ReVII2O5)Sio2[Sit2O(PO4)6] consists of distorted [Re2O11] dioctahedra, [SiIVO6] octahedra and [Sit2O(PO4)6]12- heteropolyanions. It is quite remarkable that the observed range of distances 1.66 ≤ d(ReVII-O) ≤ 2.10 Å in the phosphates is very similar to that found in many other oxide compounds containing rhenium in oxidation states 4+, 5+, 6+ and 7+. Therefore, assignment of oxidation states for rhenium on the basis of distances d(Re-O) has to be treated with great care. As in several coordination compounds of Re7+ the formation of the perrhenyl cations (ReO2)3+ and (Re2O5)4+ are observed in the phosphate and the silico-phosphate, respectively. The presence of two distinctly different types of oxygen atoms (terminal in the perrhenyl-groups and bridging between Re and P) is comparable to oxides and in particular phosphates of V4+, V5+, and Mo6+, which are all active catalysts for selective oxidation of hydrocarbons. These observations might emphasize the catalytic activity of rhenium phosphates. Chemically and crystal chemically ReVIIO2(PO4) is very similar to oxide compounds of V4+, V5+ and Mo6+, thus providing support for the diagonal relation among V5+, Mo6+, and Re7+. This relation is further expressed by the closely related crystal structures of ReVIIO2(PO4) and MoVIO2(SO4). There is even evidence for polymorphism in ReVIIO2(PO4) as it was observed for MoVIO2(SO4). Phosphates of rhenium in the lower oxidation states +IV, +V, and +VI (ReIVP2O7, ReV2O3(P2O7), ReVI2O3(PO4)2) are closely related to the corresponding tungsten compounds WIVP2O7, WV2O3(P2O7), and WVI2O3(PO4)2. Finally, it might be concluded that with the syntheses of anhydrous rhenium phosphates at +IV, +V, +VI, and +VII oxidation states of rhenium, the crystal chemistry of anhydrous transition metal phosphates have been considerably extended. Our study shows that the redox behaviour of rhenium is comparable to that of its neighbour elements; i. e. molybdenum, vanadium. In addition to formation of a large number of ternary phosphates of these elements, up to now a plethora of quaternary phosphates have been synthesized and characterized. The main reason for the formation of such a large number of phosphates is the existence of various oxidation states and their stability in a phosphate matrix. Therefore, it is evident that an enormous research field for polynary rhenium phosphates have been opened by the present work

Examining the factors that influence customers' decision to choose Islamic hire purchase facility : A study of muslim customers in Kedah

Islamic hire purchase (IHP) facility is widely used by Islamic banks for car financing in Malaysia. Thus, this research was carried out to determine the factors that influence the customers’ decision to choose Islamic hire purchase facility in Kedah. A total of 105 customers on Islamic hire purchase in Kedah was selected as respondents of the survey questionnaire which was randomly distributed. The obtained data were analyzed using Ttest, ANOVA, Pearson Correlation and Multiple Regressions. The finding shows that religious obligation, awareness, tenure and age significantly influence the customers’ choice for Islamic hire purchase. Since choosing Islamic hire purchase rests largely on these factors, Islamic banks must emphasis on religious values such as ethics and manners which are friendlier towards the customers. Islamic banks should expand their target market and increase the quality of performance through Islamic values in Islamic banking. Last but not least, Islamic banks need to transparent and disclose all information to their customers to avoid misconception about Islamic hire purchase

Photoluminescence quenching in gold - MoS2 hybrid nanoflakes

Achieving tunability of two dimensional (2D) transition metal dichalcogenides (TMDs) functions calls for the introduction of hybrid 2D materials by means of localized interactions with zero dimensional (0D) materials. A metal-semiconductor interface, as in gold (Au) - molybdenum disulfide (MoS2), is of great interest from the standpoint of fundamental science as it constitutes an outstanding platform to investigate plasmonic-exciton interactions and charge transfer. The applied aspects of such systems introduce new options for electronics, photovoltaics, detectors, gas sensing, catalysis, and biosensing. Here we consider pristine MoS2 and study its interaction with Au nanoislands, resulting in local variations of photoluminescence (PL) associated with various Au-MoS2 hybrid configurations. By controllably depositing monolayers of Au on MoS2 to form Au nanostructures of given size and thickness, we investigate the electronic structure of the resulting hybrid systems. We present strong evidence of PL quenching of MoS2 as a result of charge transfer from MoS2 to Au: p-doping of MoS2. The results suggest new avenues for 2D nanoelectronics, active control of transport or catalytic properties

Primary Teachers’ Understanding About Inclusive Education

To develop inclusive education system in Bangladesh primary level should be prioritized. The main objective of this study was to identify the knowledge and understanding about inclusive education of primary teachers’ in Bangladesh. Qualitative research approach had been used to conduct this study. The data was collected from primary teachers and various training manuals. The teachers had been selected from three districts by using purposive sampling strategy. Document analysis and open ended interview schedule was used as data collection tools. Through thematic analysis, it was found that most of the teachers did not have clear understanding about inclusive education. Inclusive education was not emphasized on the present primary teachers’ training manuals. In this regard inclusive education should be emphasized in professional training manuals and also should give importance in practice

Peran guru Pendidikan Agama Islam (PAI) dalam meningkatkan motivasi belajar siswa di Sekolah Menengah Pertama Negeri (SMPN) 1 Grati

ABSTRAK Kegiatan belajar mengajar pada dasarnya merupakan interaksi atau hubungan timbal balik antara guru dengan siswa dalam situasi pendidikan, yaitu ada unsur take and give (memberi dan menerima), baik bagi guru maupun bagi siswa itu sendiri. Proses interaksi belajar mengajar pada prinsipnya sangat bergantung pada guru dan siswa. Oleh karena itu, guru dalam mengajar dituntut kesabaran, keuletan dan sikap terbuka di samping kemampuan dalam situasi belajar mengajar yang lebih aktif. Adapun siswa dituntut untuk semangat dan ada dorongan untuk belajar. Namun siswa kadang dihadapkan dengan masalah kejenuhan dan kurangnya konsentrasi terhadap materi yang diajarkan. Sehingga motivasi belajar siswa kurang maksimal. Disini peran guru sebagai fasilitator sangat diperlukan untuk meningkatkan motivasi belajar siswa dalam menyerap dan memahami materi yang akan diajarkan. Berdasarkan latar belakang di atas, maka dalam penelitian ini rumusan masalahnya adalah 1) Bagaimana Motivasi Belajar Pendidikan Agama Islam dalam meningkatkan motivasi belajar siswa di SMPN 1 Grati? 2) Bagaiamana Peran Guru Pendidikan Agama Islam dalam meningkatkan Motivasi Belajar siswa di SMPN 1 Grati? 3) Faktor apa yang menimbulkan motivasi belajar di SMPN 1 Grati? 4) Faktor apa yang menghambat motivasi belajar siswa di SMPN 1 Grati? Hasil penelitian ini menunjukkan bahwa Motivasi belajar siswa terhadap Pendidikan Agama Islam di SMPN 1 Grati dapat dikatakan cukup baik. Hal ini terlihat dari kedisiplinan siswa tepat waktu ketika pelajaran Pendidikan Agama Islam dan siswa yang membolos ketika pelajaran Pendidikan agama Islam hampir tidak ada. Peran Guru Pendidikan Agama Islam (PAI) dalam meningkatkan motivasi belajar siswa dibagi menjadi dua yakni motivasi sedang dimana guru mengadakan ulangan, memberikan tugas dan memberikan angka. Bagi siswa yang motivasinya rendah diberikan ganjaran, menumbuhkan minat dan menjelaskan tujuan akhir pelajaran. Sedangkan usaha yang dilakukan oleh guru PAI dengan memberikan angka seperti nilai, adanya ganjaran, memberikan tugas, serta memberikan timbal balik bagi siswa yang motivasi belajarnya sedang. ABSTRACT Activity of learn teach on basic it is interaction or interrelationship between teacher with student in the situation of education, namely have give and take, good for the theacher as well as to it self student. The interaction proses of learn teach in the principle heavily dependent in teacher and student. Because of teacher in teach prosecuted bypatience, tenacity and attitude opened beside ability in the situation of learn teach that more active. It so happens student prosecuted for spirit and have encouragement to learn. However sometimes student confronted with problem of surfeit and its shortage cocentration to material taught. So the motivation of learn less maximal for the student. Here role of teachers as facilictators indispensable to improve motivation learn for the student in absorb and understand the material taught. Based on by background above, so in this research of the problem formula is 1) How the Motivation Learn Education the Religion of Islam in improving motivation learn student at SMPN 1 Grati? 2) How the Role of Teacher Education the Religion of Islam in Improving motivation learn student at SMPN 1 Grati? 3) Factor what generating motivation learn the student at SMPN 1 Grati? 4) Factor what the demotivating to learn of student at SMPN 1 Grati? The result of research indicate that Motivation Learns Student the Education Religion of Islam in SMPN 1 Grati can be said pretty good. This thing seen from discipline of the student just in time when the Education Religion of Islam and student that cut when the Education Religion of Islam next to nothing. The Education religion role of teachers Islam in improving motivation learn student at to become two namely motivation is where teacher conduct repeat, tasking and provide feed bake. For student that the motivation is low given by reward, grown interest and explain final destination learning. While effort conducted by PAI teacher by providing rate like value, existence reward, tasking, as well as provide mutual for student that motivation learn him is