Spectroscopic measurements are detailed within this thesis, utilising incoherent neutron scattering to examine the dynamics of various condensed-matter systems, from nanosecond to sub-femtosecond timescales. The body of this work is divided into two distinct areas of research. I. Nuclear Momentum Measurements of Multiple Masses Deep inelastic neutron scattering (DINS) is used to probe the nuclear momentum distributions and kinetic energies of individual atomic species in sodium hydride (both in bulk and as nanoparticulates within a silica matrix), enriched lithium-7 fluoride and lithium tetra-ammoniate. Extension of DINS to examine heavier (M>4amu) nuclei is detailed, accomplished by the application of a simple stoichiometric fixing technique within the standard DINS theory and analysis protocols. The validity and accuracy of such simultaneous measurements are discussed. II. The Dynamics of Coordinated Ammonia in Zeolite A Inelastic neutron scattering (INS) and quasielastic neutron scattering (QENS) are utilised in the examination of vibrational and stochastic dynamics of the ammonia molecule, as coordinated to the internal surface of a zeolite host. Both sodium and copper-exchanged forms of zeolite-A are studied, with proton-weighted, low energy phonon-modes and rotational processes being observed and assigned.

This Thesis explores the role of structural defects and disorder and their relationship to experimental data, with a particular emphasis on molecular framework materials. The question of how we can build atomistic models of amorphous materials from experimental data without needing to make system-specific assumptions is addressed. The role of 'structural invariance', <i>i.e.</i> the limited range of distinct local atomic environments within a material, as a restraint within reverse Monte Carlo refinement (RMC) is investigated. The operation of these invariance restraints operate is shown to be system-dependent and the challenges associated with effective refinement, <i>e.g.</i> configurational 'jamming', are also investigated. A generalisation to the 'structural simplicity', <i>i.e.</i> the simplest model, holding all else constant, is most likely to be correct. Three new metrics of structural simplicity are proposed: two intrinsically three-dimensional measures of local geometric invariance and one measure of local symmetry. These metrics are shown to robustly quantify the configurational quality. The ability of these metrics to act as effective restraints for the RMC refinement of amorphous materials is demonstrated by the construction of the first data-driven tetrahedral models of amorphous silicon. The role of defects and disorder within metal–organic frameworks (MOFs) is investigated through the canonical MOF UiO-66(Hf). Through a combination of techniques, including X-ray diffuse scattering, anomalous diffraction, total scattering and electron diffraction measurements, the existence of correlated metal-cluster absences in UiO-66(Hf) is demonstrated. Furthermore the ability to synthetically tune both the interactions and concentration of defects is shown. The thermomechanical properties of defective UiO-66(Hf) are also examined. UiO-66(Hf) is shown to rapidly densify by up to 5% (ΔV/V ) on ligand elimination. The resultant densified phase exhibits colossal (≥100MK^-1) volumetric negative thermal expansion (NTE); the largest reported value for any MOF. Finally, the capability to tune the physical properties of MOFs through defect incorporation is demonstrated through the defect-dependence of both the densification and the NTE.

Un pont de dihidrogen (dihydrogen bond,DHB) és un tipus de pont d'hidrogen atípic que s'estableix entre un hidrur metàl·lic i un donador de protons com un grup OH o NH. Els ponts de dihidrogen són claus en les característiques geomètriques i altres propietats de compostos que en presenten tan de molècules petites com el dímer de NH3BH3, com d'estructures superiors més complicades com complexes metàl·lics o sòlids. Poden ser útils aplicats a certes molècules o síntesis moleculars per a obtenir nous materials amb propietats o característiques fetes a mida. El treball d'aquesta tesi està orientat a millorar la comprensió dels ponts de dihidrogen, aprofundint en certs aspectes de la seva naturalesa atòmica/molecular utilitzant mètodes teòrics basats en la química física quàntica. / A dihydrogen bond (or DHB) is a kind of unconventional hydrogen bond, established between a metal hydride bond and a proton donor like OH or NH. They are the key to important structure features and properties in compounds which have them. They can be responsible for the specific geometry not only of small molecules like the NH3 BH3 dimer, but also of higher structures like metallic complexes or solids. It is in this fashion that dihydrogen bonds can be profitable, up to a plausible extent, when they can be used in certain molecules or certain syntheses to obtain a new material with particular or even tailored properties or geometries. The work developed in this thesis is aimed to have a deeper understanding of dihydorgen bonds, deepening on certain aspects using theoretical methods.

Valoriser l'énergie perdue sous forme de chaleur par les moteurs thermiques en électricité via desgénérateurs thermoélectriques permettrai de diminuer l'empreinte carbone des transports routiers. Unesélection des matériaux basée sur des critères de performance, de coût et de développement durable aconduit au choix du siliciure de manganèse MnSi (semi-conducteur de type p). En s'appuyant sur uneapproche couplant la métallurgie et la chimie du solide, ce travail revisite l'état de l'art sur ces alliageset révèle les relations entre la structure (inco/commensurabilité), la microstructure et le procédé. Unemeilleure compréhension de ces liens a permis d'acquérir un contrôle plus précis des microstructures,et par conséquent d'optimiser les propriétés thermoélectriques, et a conduit à la mise au point d'unenouvelle voie de synthèse pour MnSi. De plus, la production de matériaux purs et texturés a permisde mettre en évidence l'isotropie des propriétés de transport de la phase MnSi. Enfin, cette étudesuggère une relation entre la texture des joints de grains et la ségrégation dans des alliages dopés,ouvrant de nouvelles perspectives pour améliorer les propriétés thermoélectriques. / Generating electricity from waste heat by means of thermoelectric generators may represent a very interestingopportunity to significantly reduce the impact of road transportation. In this context, HigherManganese Silicide (HMS) based alloys are studied as p-type semiconductors to achieve a sustainablescale-up of this technology. Through a strategy coupling metallurgy and solid state chemistry, thiswork revisits the knowledge on HMS and reveals the relationship between the phases, the microstructureand the manufacturing process. This systematic study has lead to the establishment of designguidance to maximize the performance and thus, to a new synthesis route. In addition, the productionof grain oriented and highly pure HMS materials evidences the isotropy of the transport properties ofHMS. Finally, this study suggests a relationship between grain boundary texture and segregation indoped-HMS, opening new directions for enhancing thermoelectric properties.

Crystal engineering is widely applied in the design of new solids with desired physical and chemical properties based on an understanding of intermolecular interactions in terms of crystal packing. The understanding of such structure-property correlations increased my interest in the modulation of macroscopic properties of solid compounds. Establishing connections between structure and macroscopic properties is a classical aspect of materials science and engineering. With the advent of the nanoindentation technique, it is now possible to make such a link between micro-level structures with mechanical properties of molecular solids - in other words, between chemistry and engineering. Nanoindentation is a quantitative probe for the assessment of mechanical behavior of small volume materials. In this technique, applied load and indenter depth penetration are measured simultaneously for a molecular crystal specimen, with high precision and resolution. From this data, one can obtain the elastic modulus and hardness of molecular crystals. Being able to accordingly assess the relative strengths of intermolecular interactions, such a technique has become relevant to the subject of crystal engineering. We have used nanoindentation to study the packing anisotropy of molecular crystals and to establish structure-property relationships. This thesis demonstrates that nanoindentation is a state-of-the-art technique to probe the mechanical properties of molecular crystals and assists the development of the subject of crystal engineering towards property design. Chapter 1 gives an overview of the development of crystal engineering from solid state organic chemistry and a brief introduction of the nanoindentation technique which has become relevant to the subject of crystal engineering to establish structure-property relationships. The study of the mechanical properties of molecular solids as a function of their crystal structures is a very active branch of crystal engineering. Chapter 2 explores the insights of well-known odd-even alternative mechanical, physical and thermal properties of α,ω-alkanedicarboxylic acids such as elastic modulus, hardness and melting temperature through nanoindentation technique. These properties are well correlated with their crystal structure packing. The odd acids were found to be softer and lower melting temperature as compared to the even ones, possibly due to the strained molecular conformations in the odd acids in easier plastic deformation. Shear sliding of molecular layers past each other during indentation is a key to the mechanism for plastic deformation in the molecular crystals. Relationships between structural features such as interplanar spacing, interlayer separation distance, molecular chain length and signatures of the nanoindentation responses, discrete displacement bursts have also been discussed in this chapter. Chapter 3 explores the use of the nanoindentation measurement as a signature response to study the microstructure that exists in a single crystal of organic solids. The analysis of microstructure through X-ray crystallography can be misleading. This is because crystal structures as determined from the single-crystal diffractometer data represent only space- and time-averaged structures. Thus, due to higher spatial resolution of the nanoindentation technique compared to X-ray diffraction (XRD) it become a local probe, which allows for discrimination between different microstructure or domains in the single crystal. Chapter 4 attempts to explore an understanding of the underlying relationship between crystal structure and the mechanical properties of molecular crystals which are relevant for the systematic design of organic solids with a desired combination of mechanical properties such as elasticity and hardness through crystal engineering. Elastic properties in molecular solids are largely determined by the isotropy of crystal packing. By using the techniques of crystal engineering, seven halogenated N-benzylideneanilines (Schiff bases) crystals have been systematically designed and observed common underlying structural features which lead to high flexibility and elasticity. Elasticity in those crystals arises from a criss-cross packing of molecular tapes in isotropic structures with energetically comparable halogen bonds (Cl···Cl or Cl···Br). The chapter also demonstrates that the solid solution strengthening can be effectively employed to engineer hardness of organic solids. High hardness can be attained by increasing lattice resistance to shear sliding of molecular layers during plastic deformation. Chapter 5 demonstrates the broad applications of mechanical properties of molecular solids in the context of the pharmaceutical industry, which can be understood through nanoindentation. Crystal engineering is applied in designing active pharmaceutical ingredients (APIs) so as to obtain materials that exhibit optimum combinations of important physicochemical properties such as solubility, dissolution rate, and bioavailability. In the context of industrial-scale pharmaceutical manufacturing, it can also be used to tune mechanical properties such as grindability and tabletability, which often determine the processing steps that are adopted. Hence, there is always interest in the crystal structure−mechanical property correlations of APIs. The study of the mechanical properties of polymorphic drugs is an important for developing an understanding of their stability in the solid state. Overall, the main aim of this thesis is to explore an understanding for establishing structure-mechanical properties correlations of molecular crystals with recent advances in the nanoindentation technique and to gain knowledge for the design and synthesis of new materials using the crystal engineering approach. Nanoindentation of molecular crystals provides insights related to crystal packing, interaction characteristics, polymorphism and topochemistry.

One third of world’s total energy is used in production of electricity and one fifth of the total electricity produced in the world is used in lighting. Hence, the materials that have high potential in the field of photovoltaic’s and photoluminescence have recently drawn special attention to meet the ever increasing energy demands. In this thesis, we have studied a few materials that hold tremendous promises in fabricating photovoltaics and photoluminescent devices. Any ferroelectric material is an efficient solar energy converter as it contains an the intrinsic dipolar field which can effectively separate the photo excited electron and hole. We have developed a few materials which possess inherent polarization efficiently absorb over a wide portion of the solar spectrum and hence can find application in the field of photovoltaics. Secondly, we also dealt with semiconductor nonmaterial’s which are technologically very important owing to their improved photoluminescence properties. We tried to improve their light emitting efficiency by engineering crystal structure in nanometer length scales. The thesis deals with such advanced energy materials and is divided in seven chapters. Chapter 1 provides a brief introduction to the fundamental concepts that are relevant in the subsequent chapters. The chapter is started with a brief scenario of current status of energy production and its usage. Next, we have discussed the prospects of ferroelectric materials in photovoltaic devices. This is followed by a brief background on ferroelectricity and related properties which we have studied subsequently. At the end of this chapter a brief overview of photoluminescence properties in semiconductor nonmaterial’s is presented. In this section we have addressed the particular issues that need to be taken care of in order to improve their light emission properties. Chapter 2 describes different experimental and theoretical methods that have been employed to carry out different studies presented in the thesis. Chapter 3 addresses the possibility of employing BaTiO3 (BTO) based composite perovskite oxides as a potent photovoltaic material. It is known that BTO can produce photocurrent upon excitation with suitable light source. However, inability of BTO to absorb sufficient sunlight owing to its near UV band gap prevents to make use of this material in photovoltaic devices. In order to reduce the band gap we have tried to tune the electronic structure at the band edge by doping non-d0 transition metal ions at Ti site. As it is known in the literature an isovalent substitution of Ti4+ stabilizes non-polar phase of BTO we employed a co-doping strategy to substitute tetravalent Ti with equal percentage of a trivalent and a pentavalent metal ion. Keeping in mind off-centering of Ti4+ is primary reason behind the large ferroelectric polarization of BTO, a judicious choice of co-dopant was necessary to minimize reduction of polarization due to replacement of Ti. We have found at least two pairs of co-dopants, namely Mn3+-Nb5+ and Fe3+-Nb5+ which at low doping concentration ( < 10%) effectively reduces the band gap of BTO without affecting its polarization to a large extent. We systematically increase the doping concentration of both the pair of dopants and found Mn3+-Nb5+ pair is more efficient over Fe3+-Nb5+ both in terms of reducing band gap and retaining the polarization of BTO. We have characterized the ferroelectric nature of all the doped compositions with the help of dielectric, polarization and pyroelectric measurements. We have also performed first principle density functional theory (DFT) calculations for an equivalent doped composition and addressed the nature of modulations of electronic structure at the band edges which is responsible for such large reduction of band gap. Chapter 4 deals with composite perovskite materials which posses large tetragonal distortions with reduced optical band gaps. Here we have exploited Cu-Nb and Cu-Ta pair which upon complete substitution of Ti of BTO leads to composite perovskites with enhanced tetragonal distortion of the perovskite lattice. For two resultant compositions, namely BaCu1/3Nb2/3O3 and BaCu 1/3Ta2/3O3 we have characterized the optical and ferroelectric properties. We found though these material possess small band gap (∼ 2 eV), these are not ferroelectric in nature. Results of second harmonic generation measurements and refinement of powder X-ray diffraction both establish Centro symmetric nature of these materials. We infer from these results that presence of large tetragonal distortion is a result of symmetric Jahn-Teller type distortion of Cu2+ and not due to off-centering of any of the metal ions in their MO6 octahedral geometries. In Chapter 5, we have considered the material SrTiO3 (STO) which is stable in cubic paraelectric phase at room temperature. But at the same time this material is considered as an incipient ferroelectric due to presence of an active polar vibrational mode which does not become completely soft even at temperature close to 0 K. While this polar vibrational mode can easily be frozen by making substitution at Sr site, a similar attempt by making substitution at Ti site failed earlier. Keeping in mind Ti is easier to substitute than Sr we employed same co-doping strategy that we have considered in Chapter 3. We found Mn- Nb and Mn-Ta co-dopants at low doping concentration are extremely useful in transforming incipient ferroelectric STO into a dipolar glass. We have characterized the glassy dipolar property of doped STO with the help of tem-perature dependent dielectric response of these material. At the same time we found these co-doped STO possess enhanced static dielectric constant at room temperature with favourable dielectric loss values in comparison to pure STO. We have also ad-dressed the origin of a glassy dipolar state with the help of DFT calculation performed on equivalent doped composition that we have considered for our experiments. In Chapter 6, we have considered another incipient ferroelectric material TiO2 in rutile phase which also possess polar vibrational mode at temperature close to 0 K. A lattice strain along the polar vibrational mode make symmetric non-polar structure unstable with respect to the distorted polar structure. In this context, we found two particular compositions FeTiTaO6 and CrTiTaO6 that are also stable in rutile phases at room temperature but possess similar strain due to presence of larger Fe or Cr and Ta in rutile lattice. Considering the fact these two composite rutile oxides are relaxer ferroelectric in nature, we critically evaluated the effect of the particular kind of strain that these materials introduce in rutile lattice. We also characterized relaxor ferroelectric property and optical band gap of these materials and commented on the potential of these materials in exploiting them in photovoltaic devices. Chapter 7 presents a unique strategy of making use of crystal defects in improving photoluminescent properties of semiconductor nanocrystals. We have shown defects when introduced in nanocrystals in a controlled protected manner efficiently overcome the problem of self absorption which is known to reduce quantum efficiency of emit-ted light. Controlling synthesis conditions we separately prepared CdS nanocrystals with and without intergrowth defects. We characterized the presence of the intergrowth defect with the help of high resolution transmission electron microscope (HRTEM) image. We have also characterized Stokes’ shifted PL emission and ultrafast charge carrier dynamics of these NCs with intergrowth defects. To support these experimental findings we have computed the electronic structures of model nanoclusters possessing similar intergrowth defects that has been observed in HRTEM images. We find that the presence of defects in a nanocluster particularly affect the position of the band edge. However our joint density of state calculation shows that contribution of these defect states to an absorption spectra is negligible. Thus presence of defect states at band edge ensures a Stokes’ shifted emission without affecting the position of absorption. In a separate section of this chapter we have shown apart from intergrowth defects presence of twin boundary also provide similar mid-gap states that can alter its’ optical proper-ties to large extent. In summary, we have studied a few bulk and nano-materials which can show improved photovoltaic and photoluminescence property. We investigated effect of external dopant ions on a classical ferroelectric material BaTiO3 and two incipient ferroelectric materials SrTiO3 and rutile TiO2. We have also shown that efficient defect engineering could be extremely useful in improving photoluminescent property of CdS nanocrystals which is a prototype of II-VI semiconductor nanomaterials. In a separate Appendix Chapter, we have shown an easy and efficient way to suppress coffee ring effect which takes place universally when a drop of colloidal suspension is dried on a solid substrate. We have shown temporary modification of hydropho-bicity of a glass substrate not only can suppress the coffee ring effect but also leaves the particle in a highly ordered self-assembled phase after completion of drying process

No description available.

Applications of conjugated polymer (CPs) in optoelectronic devices are critically depend on nature of thin film morphology. In thin film of CPs, the distribution of conjugation length is highly heterogeneous because of conformational defects, distortions of polymer chain and aggregates. A greater understanding of the self-assembly properties of polymer in solution, in particular control over aggregation leads to richer description of electronic properties and hence reproducible fabrication of thin film devices. Recently, chiral CPs have attracted profound interest because of their promising chiroptical properties in thin films and easy control over the selective agglomeration process. In this thesis, we have investigated the role of chiral side-chains on a series of thiophene diketopyrrolopyrrole (TDPP)-benzodithiophene (BDT) based copolymers. Chiral 3,7-dimethyloctyl chain was introduced as an asymmetric chain to incorporate chirality on one of the repeating unit (TDPP) of copolymers. Two polymers with side-chains of identical chirality (S),(S)-PTDPP-BDT; (R),(R)-PTDPP-BDT and a third polymer with similar side-chains of opposite chirality (R),(S)-PTDPP-BDT were synthesized. The chiroptical properties were investigated by UV-visible and circular dichroism (CD) spectroscopy. Figure 1: The structure of the TDPP-BDT copolymers. The copolymers dissolved in a good solvent (e.g. chloroform, chlorobenzene) in which polymers adopts random coil conformation, no chiral response has been observed. However, a critical addition of non-solvent (methanol), the copolymers stack in a chiral fashion and leads to typical bisignate Cotton effects. It is noteworthy that the two polymers, (S),(S)-PTDPP-BDT and (R),(R)-PTDPP-BDT exhibiting a nearly ideal mirror-image relationship in CD spectra (Figure 2a) whereas the (R),(S)-PTDPP-BDT lacks chiropticity even with the addition of methanol. The aggregation induced CD phenomena are dependent on the temperature of solution and do not exhibit reversibility in a heating-cooling cycle. Figure 2: (a) The mirror image Cotton effects of (S),(S)-PTDPP-BDT and (R),(R)-PTDPP-BDT (b) No CD signal was observed for the (R),(S)-PTDPP-BDT polymer. Figure 3: The variation of (a) UV-vis and (b) CD spectra of (R),(R)-PTDPP-BDT polymer with thickness of the solid film. To investigate the role of thickness and annealing temperature on optical and chiroptical properties of polymer films, thin films were prepared using drop-casting method from a solution of chlorobenzene. Both the polymer showed gradual enhancement of CD signal with the increase of film thickness but we did not see any such order with temperature (Figure 3). Figure 4: The morphology observed for the film by (a) AFM; (b); (c) FESEM. The thin film morphology of polymers is characterized by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) (Figure 4). AFM studies show the polymer molecules self-assembled and formed interconnected nanofibers. Whereas FESEM images clearly revealed that, the nanofibers of polymers are predominantly stack in a chiral fashion and mimic a one-handed helix which leads to bisignate Cotton effects. The (S),(S)-PTDPP-BDT and (R),(R)-PTDPP-BDT form fibers with opposite handedness whereas (R),(S)-PTDPP-BDT do not have such preferred handedness. The research described in this thesis aims to explore the role of chiral side-chains to impose chiral stacking and hence resulting chiral expression. Chirality in this class of polymers may endows them promising optoelectronic properties. (For figures pl see the abstract pdf file)

<p>Thermoelectric (TE) materials are able to convert heat directly into electricity and vice versa. This special property makes them valuable for a variety of applications involving power generation and refrigeration. In the search for potential high-performance TE materials, a number of rare-earth (<em>RE</em>) antimonide suboxide phases have been investigated.This presentation will focus on two classes of rare-earth antimonide suboxides: the <em>RE</em>₃Sb₃O₃ and <em>RE</em>₈Sb_3-<em>_d</em>O₈ phases (<em>C</em>2/<em>m</em> space group) based on the <em>RE</em>–O frameworks and the <em>anti</em>-ThCr₂Si₂ type <em>RE</em>₂SbO₂ compounds (<em>I</em>4/<em>mmm</em> space group). The physical property measurements on the high-purity bulk samples revealed unexpected semiconducting properties in the non-charge-balanced systems, i.e.<em> RE</em>₈Sb_3-<em>_d</em>O₈ and <em>RE</em>₂SbO₂. Since the electronic structure calculations suggest that the anionic Sb states dominate the valence band at the vicinity of the Fermi level, the local structure of the Sb atomic site is believed to dictate the observed physical properties. The charge transport properties are explained within the framework of Anderson/Mott-type localizations. Ultimately, systematic investigation of the <em>RE</em>₂SbO₂ and Ho₂Sb_1-<em>x</em>Bi<em>_x</em>O₂ series reveal the large variability of the electrical properties caused by the local structural perturbations.</p> / Doctor of Philosophy (PhD)

Highly selective and sensitive phosphate sensors have been fabricated by constructing a solid membrane disk consisting of variable mixtures of aluminium powder (Al), aluminium phosphate (AlPO4) and powdered copper (Cu). Both binary and ternary electrode systems are produced depending on their composition. The ternary membranes exhibit greater selectivity over a wide range of concentrations. The ternary electrode with the composition 25% AlPO4, 25% Cu and 50% Al was selected as our preferred electrode. The newly fabricated ternary membrane phosphate selective electrodes exhibited linear potential response in the concentration range of 1.0 × 10−6 to 1.0 × 10−1 mol L−1. The electrodes also exhibit a fast response time of <60 s. Their detection limit is 1.0 × 10−6 mol L−1. The unique feature of the described electrodes is their ability to maintain a steady and reproducible response in the absence of an ionic strength control. The electrodes have a long lifetime and can be stored in air when not in use. The selectivity of the new phosphate selective electrodes with respect to other common ions is excellent. The results obtained provide further insight into the working principles of the newly fabricated phosphate selective electrodes. Dephosphorylation and phosphorylation reactions were monitored using the preferred phosphate selective electrode. The following reactions were studied and inferences drawn; (a) the reactions between *[{CoN4(OH)(OH2)}]2+ and *[OH(PO2O)]2- for 1:1, 2:1 and 3:1 *[{CoN4(OH)(OH2)}]2+ to *[OH(PO2O)]2- ratios.(b) the reactions between *[{CoN4(OH)(OH2)}]2+ and *[O2NC6H4PO2(O)(OH)]- for 1:1, 2:1 and 3:1 *[{CoN4(OH)(OH2)}]2+ to *[O2NC6H4PO2(O)(OH)]- ratios. (c) the reactions between *[{CoN4(OH)(OH2)}]2+ and *[(OH)2(PO2)2O]2- for 1:1, 2:1 and 3:1 [{CoN4(OH)(OH2)}]2+ to *[(OH)2(PO2)2O]2- ratios, and (d) the reactions between *[{CoN4(OH)(OH2)}]2+ and *[(OH)2(PO2)3O2]3- for the 1:1, 2:1 and 3:1 [{CoN4(OH)(OH2)}]2+ to *[(OH)2(PO2)3O2]3- ratios. Further insight into dephosphorylation and phosphorylation reactions is unravelled by the novel phosphate selective electrode monitoring. *For clarity of the complexes utilized, see chapter 4, table 4.1. KEY WORDS; Dephosphorylation, phosphorylation, ion selective electrodes, phosphate ion selective electrode, decontamination, electromotive force, potential difference, activity, concentration, selectivity coefficient, calibration, ionic strength, hydrolysis, inorganic phosphates, nitrophenylphosphate, pyrophosphate, tripolyphosphate, organophosphate esters. / Chemistry / D.Phil (Chemistry)