Metal-Richal-Rich Phases (E.G

Programme: M.Sc.(Chemistry) Course: Advanced Inorganic Materials Semester: IV Code: MSCHE4003E04

Topic: CHALCOGENIDENIDEy Date- 07/04/2020 Only e Use

PPe Dr. Angad Kumar Singh F Department of Chemistry, Central University of South Bihar, Gaya (Bihar)

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia.

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Intercalation is the reversible inclusion or insertion of a molecule (or ion) into materials with layered structures. Examples are found in graphite and transition metal dichalcogenides. A chalcogenide is a chemical compoundund consistingcoy of at least one halogen anion and at least one moreoreOnlyO electropositive element. Although all group 16 elementsnts of thethe periodic table are defined Use as chalcogens (derived from the Greeal k word ‘chalcos' means ore and ‘genes' means former), The term chalcogenidehalcogehalcogersonalis more commonly reserved Pe for sulfides, selenides,es, telluridestelr and polonides rather than oxides.Many metal ores exist as chalcogenideschahaFor . Photoconductive chalcogenide glasses are used in xerography.

Themetltal dihldichalcogenid e MSMoS2 is a common solid lbilubricant .

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Transition metal chalcogenides occur with many stoichiometries and many structures. Most common and most important technologically, the chalcogenides of simple stoichiometries,chiomy such as 1:1 and 1:2. OnlyO e Extreme cases include metal-richal-rich phases (e.g. Ta2S), which exhibit extensive metal-metal bondinding, Useand chalco genide-rich materials al such as Re S , which features extensiveextens chalcogen-chalcogen bonding. 2 7 onal For the purpose of classifyingclascl these materials, the chalcogenide is often viewed as a diadianion,PersoPe i.e., S2,Se2,Te2,andPo2. In fact, transition metal chalcogenideschahaFor are highly covalent, not ionic, as indicated by their semiconducting properties.

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Monochalcogenides Transition metal monochalcogenides have the formula ME,where M = transition metal and E=S,Se,Te. They typically crystallize in one of two motifs, named after the corresponding forms of zincziny sulfide. In the zinc blende structure, the sulfideulfide atoms pack in a cubic OnlyO symmetry and the Zn2+ ions occupy hlfhalff of theetetrae hdhedra lhlholes.The result is a diamond like framework. Use The main alternative structureructuuctual for the monochalcogenides is the wurtzite structure whereinerein the atoms connectivity are similar (tetrahedral), but the crystaltalal symmetrysymmsym is hexagonal. A third motiftif fo forPersonaPe metal monochalcogenide is the nickel arsenide lattice, whereForF the metal and chalcogenide each have octahedral and trigonal prismatic coordination, respectively. This motif is commonly subject to nonstoichiometry.

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Transition metal dichalcogenides have the formula ME2, where M = transition metal and E = S, Se, Te. As usual, the most important members are the sulfides. They are always diamagnetic solids, insoluble in all solvents, and exhibiting semiconductinductinyg properties. In terms of their electronic structures,tures, these compounds are OnlyO usually viewed as derivatives of e M4+, where M4+ = Ti4+ (d0 configuration),Use V4+4 (d1 configuration), Mo4+ (d2 configuration). Titaniumaniumal disulfide was investigated in prototype cathodes for secondaryconda batteries, exploiting its ability to reversibly undergo intercalationcalatioPersonalPe by lithium. Molybdenumnum ddisulfide, is the main ore of molybdenum where it is called molybdenitedeForF .Itisused as a solid lubricant and catalyst for hydrodesulfurization. The corresponding diselenides and even

ditellurides are known, e.g., TiSe2,MoSe2,and WSe2.

diiodide(CdI2) or molybdenum

disulfide(MoS2) structures.Inthe

CdI2 motif, the metals exhibit octahedral

structures. In the MoS2 motif, which is notnootc observed for dihalides, the metals exhibitxhibitUs MoS2, the most common metal trigonal prismatic structures. al dichalcogenide, a layered structure The strong bondingng betweenbetw the metal and chalcogenide ligands, contrasts with the weak chalcogenide—chalcogenidehaPersonalPe bonding between the layers. ForF Owing to these contrasting bond strengths, these materials engage in intercalation by alkali metals. The intercalation process is accompanied by charge transfer, reducing the M(IV) centres to M(III).

formula TaS2. It is a layered compound with three-coordinate sulfide centres and trigonal prismatic metal centres. It is structurally similar to the more famousmousy material molybdenum disulfide, MoS2. 1 OnlyO TaS2 is a semiconductor with d electronelectroe configuration. TaS2 has been the subject of numerous studies becausese it isUse a versatile host for intercalation of electron donors, because it exhibitsibitsal unusual phase transitions at low temperatures.

Microporous Compound PersonPe A microporousousForFmaterialm is a material containing pores with diameters less than 2 nm. Examples of microporous materials include zeolites and metal- organic frameworks. Porous materials are classified into several kinds by their size. Mesoporous materials have pore diameters between 2 nm and 50 nm.

Topic: ZEOLITES y Date- 09/04/2020 Only e Use

PPe Dr. Angad Kumar Singh F Department of Chemistry, Central University of South Bihar, Gaya (Bihar)

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia.

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Zeolites are microporous, aluminosilicate minerals commonly used as commercial adsorbents and catalysts. The term zeolite was originally coined in 1756 by Swedish mineralogist Axel Fredrikdrr Cronstedt, observed that rapidly heating the material, believed too have beenb stilbite (a series Only of tectosilicate ("( framework silicates, " have a threetthe -dimensional framework of silicate tetrahedra with SiO . This groupp comprisescomp nearly 75% of the crust of 2 Use the Earth) minerals of the zeolite group)grouproupal , produced large amounts of steam from water that had been adsorbedrbed byb the material. Based on this, he called the material zeolite, fromm theth Greek word (zeo), meaning "to boil" and (líthos), meaning "stone"."stone"PersonalPe Zeolites occururrForFnaturally but are also produced industrially on a large scale. Around 245 unique zeolite frameworks have been identified, and over 40 naturally occurring zeolite frameworks are known.

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Zeolitic Materials Zeolites are crystalline alumino-silicates with a three dimensional framework structure that forms uniformly sized pores of molecular dimensions. Zeolites adsorb moleculesleculesy that fit inside the pores and exclude molecules that are too largeargeOnlyO, i.e. they act as sieves on a molecular scale. e Use

AiAluminophosphate (AlPO4) al A novel class of crystalline,cryst microporous, aluminophosphate phases has been discovereddiscoPersonalPe that represents the first family of framework oxidede molecularmolForF sieves synthesized without silica. The most widely known molecular sieves are the aluminosilicate zeolites and the microporous silica polymorphs.

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Aluminophosphate materials (AlPO4), the three-dimensional structures are structurally related to the zeolite family, has hexagonal symmetry and contains one-dimensional channels orientedorieny parallel to the c axis and bounded by 12- membered rings composedposed of alternating A1O and OnlyO 4 PO4 tetrahedra. The main two types of AlPOPO4 molecularmoe sieve are - Use

AOAlPO4-5 type molllecular sieveal ischidharacterized bya1-dimensi ona l system of channels parallel too [001][00sonal or c with circular 12-ring apertures, which could be presented byPersPe notationnot of [001] 12 AlPO -11type molecularm sieve is characterized by a 1-dimensional 4 ForF system of channels parallel to [001] or c with elliptic 10-ring apertures, which could be presented by a short notation of [001] 10.

aluminophosphates,suchasM(III)X(V)O4-type transition metal phosphates, aluminoborates, microporous oxides, sulfides, selenides,seley halides, etc. Microporous compounds with special structuress referrefOnlyO to molecular sieves and microporous crystals, whose structuress are threee dimensional (3-D) open Use frameworks. al Apart from a large varietyiety of AlPO4-n compounds, M(III)X(V)O4 — type microporous crystals have been prepared by hydrothermal reactions PersonalPe among the other elementsments ofo the third (III) and fifth (V) main groups in the peridiiodic tbltable, such as AlAForF, Ga, and In, and P and As.

The first microporous gallophosphate (denoted as GaPO4-Cn) with open-framework structure was synthesized by Parise in 1985.

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Intercalation Reaction, ggyenerally reversible, that involves the penetration of a host material by guest species without causing a major structural modification of the host. y 1. Intercalation can refer to the insertionof a gueguest species into a one-, two- or three dimensional host structurecturtu OnlyO. 2. The guest species is not distributedbutedUse randomlyr but occupies positions predtdeterm ine dby thestttructureal o f the hthost matilterial. 3. Examples of intercalationation rreactions are the insertion of lithium into layered TiS [Li TiS (0 x 1)] and of potassium into the layers 2 x PersonalPe2 of graphite(C 8K). or ForF An insertion reaction is a chemical reaction where one chemical entity (a molecule or molecular fragment) interposes itself

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. into an existing bond of typically a second chemical entity e.g.: A + B–C B–A–C. The term only refers to the result of thee reactionreey and does not suggest a mechanism. OnlyO DiDuring iliintercalation reactions,s, thee acceptor compoundsare much more susceptible to exfoliationn orUse self-cleaving,se and are quite easy to cleave with tape (as is graphite)e) whereaswhal LiC is much harder to tape- nal 6 cleave. Layered compoundsoundsPersonPe of metal chalcogenides undergo topotactic intercalation reactionsions wiwith lithium, and these have offered great promise F for a new class of secondary batteries having high energy densities.

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Intercalation compounds of graphite are of interest, both scienfically and technologically because of unusual properties that diderive mailinly from hig h degree of crystal anisotropyropyy. This structure, composed of atomss tighttightly bonded in loosely OnlyO stacked planes, produces a two dimensionalitynsionae that yields a high in- plane strength and elastic modulus,duluusUse high electrical conductivity, selective catalytic and chemicalmicalal reactions and other interesting phenomena. Since a widerange of variables can control these effects. In graphite thehe two PersonalPe important bondings are associated with the carbon 2s and 2p electrons.electrForF The sp hybridized orbitals constituting the a bonds are formed into a planar hexagonal network. The remaining pz orbital, the -bond, loosely holds the planes together.

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. The in-plane closest approach of the carbon atoms is 1.35Å. The planes are stacked in an ABAB •.• sequence as shown in Figure 1 with half of the atoms in one plane directly over theone y bbelow at a spacing of 3.35 Å. The three atom unit cell that is shownnin inOnlyOFigureF 1 has dimensions a = 2. 46 Å and c = 6. 70 Å. The anisotropyotropye ofo properties results from this difference in bond strength parallel and normalUse to the hexagonal planes. al The fabricating syntheticynthet graphite by decomposing a hydrocarbon gas and hotot ppgressinress g the resulting ggpraphitic material. The product is called "highlyighlyPersonalPe oriented pyrolytic graphite" (HOPG) and is characterized crystallographicallyallolloFor by a and c axis spread of a few tenths of a degree and a random orientation of the a axis.

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Figure 1

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Graphite intercalation compounds (GICs) are complex materials

n+ n having a formula CXm where the ion X or X is inserted (itintercal ltdated) btbetween the opposite lychdharged carrbyono layers. TillTypically m is much less than 1. These materials aree deepldeeply colored solids that OnlyO exhibit a range of electrical and redoxedoxe properties of potential applications. Use al rsonal

Topic: Graphite intercalationon cocompoundsy Date- 11/04/2020 Only e Use

PPe Dr. Angad Kumar Singh F Department of Chemistry, Central University of South Bihar, Gaya (Bihar)

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia.

C + mX CXm y The reaction is reversible. OnlyO The host (graphite) and the guestuest (X)e interact by charge transfer. An analogous process is thethebaUse basis of commercial lithium-ion batteries. al In a graphite intercalationntercal compound not every layer is necessarily occupied byy guestsguestPersonalPe . In so-called stage 1 compounds, graphite layers and intercalatedalated layersl alternate and in stage 2 compounds, two graphite layers withhForF no guest material in between alternate with an intercalated layer. The actual composition may vary and therefore these compounds are an example of non-stoichiometric compounds.

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. One of the best studied graphite intercalation compounds,

KC8, is prepared by melting potassium over graphiteap powder. The potassium is absorbed into the graphite and the materialmate changes color Only from black to bronze. The resulting solid isie pyrophoric (A substance (from Greek: pyrophoros, 'fire-bearing')ng')Use isi a substance that ignites spontltaneously inairat or blbelow 54al°C (129 °F) or within 5 mitinutes after coming into contact withh air)). The compositionnise isPersonalPe explained by assuming that the potassium to potassium distanceance is twice the distance between hexagons in the carbon framework.FT The bond between anionic graphite layers and potassium cations is ionic. The electrical conductivity of the material is greater than that of -graphite.

0.14 K. Heating KC8 leads to the formation of a series of decomposition products as the K atoms are eliminated. y 3KC8 KC24 +2K

via the intermediates KC24 (blue inn colorcoloOnlyO ), KC36, KC48, ultimately the compound KC results. e 60 Use The stoichiometry MC is observeobs d for M=K, Rb and Cs.For 8 al smaller ions M=Li+,Sr2+,BaBa2+,Eu2+,Yb3+,andCa2+, the limiting

stoichiometry is MC6. PersonalPe Calcium graphite;aph te CaC6 is obtained by immersing highly oriented pyrol ytic ggpraaForFphitehi in liquid Li–Ca alloy for 10 days at 350 °C. The graphite interlayer distance increases upon Ca intercalation, and the carbon- carbon distance increases.

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Graphite bisulfate, perchlorate, hexafluoroarsenate: oxidized carbons The intercalation compounds graphitete bisulfateby and graphite perchlorate can be prepared by treating graphiteraphite with strong oxidizing OnlyO agents in the presence of strong acids. e In contrast to the potassiumiumanUse and calcium graphites, the carbon layers are oxidized in this process:ess:al

+ 48C + 0.25O2 + 3H2SO4 [C24] [HSO4] ·2H2SO4 + 0.5 H2O In graphitepperch perchlorate,PersonalPe planar layers of carbon atoms are 794 picometersapart, separated by ClO ions. Cathodic reduction of F 4 graphite perchlorate is analogous to heating KC8, which leads to a

sequential elimination of HClO4.

+ mechanism. Reaction of graphite with [O2] [AsF6] affords the salt + [C8] [AsF6] . y OnlyO Metal halide derivatives e Use A number of metal halides intercalateinteral into ggpraphite. The chloride derivatives have been most extensivelynsively studied. Examples include MCl2 (M = Zn, Ni, Cu, Mn), MCl (M = AlA , Fe, Ga), MCl (M = Zr, Pt), etc. 3 PersonalPe 4 The materialsals conconsists of layers of close-packed metal halide

layers between sheetstssForFof carbon. The derivative C8FeCl3 exhibits spin glass ( is a model of a certain type of magnet) behavior. It proved to be a partillicularly filfertile system on whic h to study phhase transiiitions.

Topic: Halogen- and oxide-graphite-grapy compounds Date- 13/04/2020 Only e Use

PPe Dr. Angad Kumar Singh F Department of Chemistry, Central University of South Bihar, Gaya (Bihar)

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia.

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Halogen- and oxide-graphite compounds Chlorine and bromine reversibly intercalate into graphite. Iodine does not. Fluorine reacts irreversibly. In the case of bromine, the following

stoichiometries are known: CnBr for n = 8, 12, 14,4, 16,16y 20, and 28. Monofluoride monofluoride OnlyO Because it forms irreversibly,y, carboncarbe monofluoride is often not

classified as an intercalation compound.mpoundUse It has the formula (CF)x.Itis prepared by reaction of gaseousous fluorineflual with graphitic carbon at 215– 230 °C. The color is greyish,yish, white, or yellow. The bond between the carbon and fluorine atomsmsPersonalPe is covalent. Tetracarbon monofluoridenofluor (C F) ForF 4 Tetracarbon monofluoride (C4F) is prepared by treating graphite with a mixture of fluorine and hydrogen fluoride at room temperature. The compound has a blackish-blue color.

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Carbon monofluoride is not electrically conductive. It has been studied as a cathode material in one type of primary (non- rechargeable) lithium batteries. Graphite oxide is an unstable yellow y solid. OnlyO Properties and applications e Superconductivity Use Among the superconconaldtiduc ting graphite itintercal ltiation

compounds, CaC6 exhibits thehe highesthig critical temperature Tc =11.5K, which further increasesasesPersonalPe under applied pressure (15.1 K at 8 GPa). Superconductivitynductivi in these compounds is thought to be related to the role of an interlayerForF state, a free electron like band lying roughly 2 eV (0.32 aJ) above the Fermi level; superconductivity only occurs if the interlayer state is occupied.

The bronze-colored material KC8 is one of the strongest reducing agents known. It has also been used as a catalyst in polymerizations and as a coupling reagent for aryl halides to biphenyls. y In one study, freshly prepared KC was treated with 1- OnlyO8 iodododecane delivering a modification (micrometre(microe scale carbon platelets with long alkyl chains sticking outpprovi providingUse solubility) that is soluble inchloroform. al

Another potassium graphiteraphit compound, KC24, has been used as a neutron monochromator..A APersonalPe new essentilial applicati on for potassium graphite was introduceduced by the invention of the potassium-ion battery. Like the lit hium-ion battery,ryForF the potassium-ion battery shldhould use a carbon- based anode instead of a metallic anode. In this circumstance, the stable structure of potassium graphite isanimportant advantage.

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. An important reaction of layered compounds is intercalation.In intercalation reactions, guest molecules and ions enter the galleries that separate the sheets, usually with expansion of the latticett along the stacking axis. This reaction is typically reversible if it does notno perturb the bonding OnlyO within the sheets. e Often the driving force for intercalationntercaUse is a redox reaction, i.e., eltlectron tftransfer btbetween the hthost anald guest. For example, lithium metltal

reacts with TiS2,MoS2, andgraph graphite to produce LiTiS2,LixMoS2 (x < 1), and LiC . In these compounds,ounds lithium is ionized to Li+ and the sheets are 6 PersonalPe negatively charged.Oxidiz Oxidizing agents such as Br2,FeCl3,andAsF5 also react with graphite. In theForF resulting intercalation compounds, the sheets are positively charged and the intercalated species are anionic.

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia. Intercalation reactions are esppyecially important for electrochemical energy storage in secondary batteries,suchaslithium ion batteries, nickel-metal hydride batteries,err and nickel- cadmium batteries. The reversible natureof the inintercalation reaction allows the electrodes to be charged and dischargedschach Onlyup to several thousand times without losing their mechanical integrity.integriUse In lithium ion batteries, the negative eltdlectrodematilterial is tilltypicallalygrapy hite, whic h is itintercal ltdated by

lithium to make LiC6. Severalal diffdifferent oxides and phosphates containing redox active transition metaletalPersonalPe ionsio (Mn, Fe, Co, Ni) are used as the positive electrode materials. For

Note: These materials are only for classroom teaching purpose at Central University of South Bihar. All the data taken from several books, research articles including Wikipedia.