Synthesis And Characterization Of Strontium Ferrite Environmental Sciences Essay

atomic number 38 ferrite is a ferro attractorized kibosh and describe as keeping hexagonal magnetoplum slite eventcast ( M-type ) whirl. It is the most widely apply pertinacious magnets d matchlessout the universe, which account for slightly 90wt % of the yearly production of durable magnets. In this check over, the emerituserferrite is synthesized utilizing sol-colloidal gel methods and the magnetised belongingss were analyzed.Chapter 1 gave de that about the construction of M-type hexagonal olderferrite. Besides, some ordinary charismatic belongingss will be discussed. Commercial applications of Sr ferrite would be discussed every(prenominal)(a)(prenominal) bit strong.Chapter 2 is alto look ather about the experimental within informations, including the synthetical proficiencys utilize for Sr ferrite, description of instrument utilise and processs carried out.Chapter 3 severe on the consequences on charismatic susceptibility of hexagonal Sr ferrite. analogy between Sr ferrite and cation-substituted Sr ferrite was made.Chapter 4 concluded the whole probe of this survey. Suggestions for future surveies were at any rate discussed. Better apprehension of the belongingss and practical applications of Sr ferrite stop be achieved through this survey.AbstractionThe belongingss of magnetoplumbite type ( M-type ) hexangular Sr ferrite has been investigated. The effort of heterotaxy of Co ( II ) oxide and Ti ( IV ) oxide in magnitude to perplex forward a quaternate system of the type SrO-Fe2O3-XO where hug drug-spot pay offs the dopant cation was made. The implication is based on sol-gel method where ethene ethylene glycol is the gel precursor. This technique was use because it was found to be able to bring forth nanoparticles of cation substituted Sr ferrite. Furthermore, sol-gel method eject bring forth steep outputs of Sr ferrite atoms.Over each, the magnetized belongingss were observed to be alteproportionn aft(preno minal) the cation switching. Co ( II ) -Ti ( IV ) substitution in SrFe12O19 with different ratios were made in this survey to looking at into the consequence of cation exchange in magnetised belongingss of Sr ferrite. Co ( II ) -Ti ( IV ) surrogate in Sr ferrite with bulwark ratio of 0.4 showed the dress hat charismatic belongingss that we desired for. The host susceptibleness where X = 0.4 was found to be increase aggressively comp bed to the unsubstituted 1. Except the Co Ti permutation with groine ratio of 0.4, some other cation permutation ratios showed less(prenominal)ening in bunch susceptibleness which is non desirable. thence the cobalt-titanium permutation for SrCoxTixFe12-2xO19 with X = 0.4 is the beat out to better magnetized belongingss of Sr ferrite for assorted commercial applications.ReappraisalStrontium ferrite has been a topic of continual involvement and in exsive survey for several decennaries due to the fact that this fuse has been the the m ost widely utilize lasting magnets, which account for approximately 90wt % of the one-year production of lasting magnets since shortly later its find in the fiftiess. Strontium hexaferrite, SrFe12O19, is a ferrimagnet and is likewise known as ceramic lasting magnet. When comp ard with alnico-magnets, Sr ferrite has undecomposed(prenominal) coercivity, moderate remenance, corrosion opposition and first-class chemical constancy 5 . agitate ( leash ) oxide ( Fe2O3 ) is the chief constituents in SrFe12O19 which portrays turn out to its magnetised belongingss. Within the five different cryst entirelyizinglisationlo interpretic sites of Sr ferrite, the Fe ions atomic number 18 pair antiferro magnetizedally. Due to its naughty magneto perspicuous anisotropy field in its construction, SrFe12O19 let ons full(prenominal) saturation magnetized in cardinalsity and lofty coercivity 1 . The mellow magnetized permeableness in Sr ferrite enables it to hive absent strong magnetized Fieldss, which is stronger than Fe. Strontium ferrite is frequently produced as nanoscale size pulverization, which can be sintered into solidity nucleuss.Strontium ferrite has been use for several of import industrial applications, much(prenominal) as lasting magnets, microwave devices and advanced parsimony upright incoming media, with proper doping in put in to better belongingss of Sr ferrite 1 . SrFe12O19 has besides been investigated as a fair for magnetized recording and magneto-optical recording and for long ( millimeter ) -wave devices 2 . Attempts labor a trend made to the development of fresh man-made methods which facilitate the production of all business hexangular ferrite atoms and to possible commissions of cut toss off their high intrinsic magnetocrystalline anisotropy.The aim in this survey was to try the tax write-off of cation substituted M-type hexangular ferrite SrCoxTixFe12-2xO19 utilizing the sol-gel method. The sol-gel method h as been used widely to bring forth all right atoms of a assortment of oxides. The consequence of doping Sr ferrite with Co ( II ) and Ti ( IV ) oxides to bring forth quaternate systems of SrO-Fe2O3-XO, where Ten represents the dopant cation would be tested. The all right atoms of cation substituted ferrite produced by utilizing sol-gel technique is desirable because the particle size of the deflects used in magnetic recording is the chief factor finding the tier of background noise at low niggardness. magnetized belongingss of Sr ferrite would be focus in this survey. magnetized susceptibleness balance would be used to find the plentitude susceptibleness for dickens strontium ferrite and cation-substituted Sr ferrite produced utilizing the sol-gel method. The potbelly susceptiblenesss of the try ons were comp ard to find the optimal consorterness of cation infallible to dope to ferrite to give the outflank magnetic behavior.CRYSTAL STRUCTURE OF M-TYPE HEXAGONAL SrFe12O 19Harmonizing to crystalline construction, hexaferrite can be classify into four types, these include M, W, Y and Z types hexaferrites which correspond to ( SrO + MeO ) Fe2O3 ratios of 16, 38, 46 and 512 severally. SrFe12O19 is classified as M-type hexaferrite.The hexangular SrFe12O19 was foremost prepared by AdelskA?old in 1938 2 . He besides confirmed that the crystal construction of this compound to be iso-structural with the of itinerary happening ferrite mineral magnetoplumbite, and thence it has the M-type construction. Subsequently structural polishs for Sr hexaferrite imbibe confirmed his finding 2 . Strontium ferrite is classified as hexangular ferrite. It is denoted as holding the infinite group P63/mmc. Harmonizing to the research made by Kimura et Al, the lattice parametric quantities measured are found to be a = 0.588 36nm and c = 2.303 76nm at room temperature 2 .As shown for M-type hexaferrite BaFe12O19 in Fig. 1.1, the crystalline constructions of differen t types of hexaferrites are unusually complex. The social social whole cell contains 10 O bonks. A unit cell is consecutive constructed for four blocks, they are S ( spinel ) , R ( hexangular ) , S* and R* . The S and R blocks rich person tantamount atomic understandings and are rotated rough the c-axis at 180A with impress to S* and R* blocks. Roentgen or R* block consists of trey O2a?A beds art object S or S* block contains dickens O2a?A beds with one O site in the in-between bed substituted by a Ba2+A ion 16 . The construction of Sr ferrite is interchangeable to that of Ba ferrite, by that replacing the Ba ion with strontium ion.Fig.A 1.1 A Structure of Ba hexaferriteOccasionally, a unit cell is comprises of cardinal enactment units. The unit cell consists of 64 ions per hexangular unit cell, which are 2 strontium ions, 38 O ions and 24 ferrous ions. The construction of magnetoplumbite are made of a bed of hexangular close jammed agreement of O and Sr ions, which is sandwiched between ii spinal blocks incorporating a 3-dimensional close-packed agreement of O atoms with Fe atoms.The Fe atoms are positioned at five interstitial crystallographically different cation sites of the close-packed beds, viz. 4f1 ( tetrahedral site, A sites ) , 12k, 4f2, 2a ( octahedral sites, B sites ) and 2b ( rhombohedral bipyramidal site ) 15 . The tetrahedral Fe oxide is FeO4, octahedral Fe oxide consists of six O ions, which is FeO6, and the reflectivity for rhombohedral bipyramidal Fe oxide is FeO5. A conventional M-type structural model and the five Fe3+ sites are shown in Fig. 1.2 by Collomb et Al. 15 .Figure 1.2 The crystal construction study map of the hexangular M-type stage and the five Fe sites with their milieus are displayed.The 2b sites merely occur in the same bed with strontium ion. 12k site is the octahedral site of S and R blocks. There are two tetrahedral ( 4f1 ) sites and one octahedral ( 2a ) site in Centre of S block. The two octahedr al ( 4f2 ) sites are found in the R block, adjacent to the strontium-containing bed.The M-type construction of strontium ferrite gives rise to its magnetic belongingss. Cation permutation to strontium ferrite may give opportunities whereby changing the construction and in that respectfore act upon the magnetic belongingss.MAGNETIC PROPERTIES OF M-TYPE HEXAGONAL SrFe12O19Strontium hexaferrite is a ferrimagnetic stuff. Since the excess negatrons in SrFe12O19 are in close propinquity and remain seted even the external magnetic field hold up been removed, it is able to retain a lasting magnetic field and is recognized as ferrimagnetic stuff.In mid-fifties Gorter predicted that the Fe ions at the rhombohedral bipyramidal ( 2b ) and octahedral ( 2a, 12k ) sites down their spin orientation parallel to that of the Fe ions at the 4f sites 2 . The antiparallel 4f1 and 4f2 and parallel 2a, 12k and 2b sublattices form the ferrimagnetic construction. The magnetic ordination corresponding to the magnetoplumbite construction of hexangular Sr ferrite is good illustrated in Fig. 1.3.In S block, the bug out I-sublattice consists of four octahedral ions and the minority I?-sublattice contains two tetrahedral ions whereas R block contributes three octahedral ions and one rhombohedral ion to the bulk sublattice and two octahedral ions to the minority sublattice.Figure 1.3 The conventional construction ( left ) of the SrFe12O19 with Gorter s magnetic ordination ( in-between ) along the c-axis. The big unfastened circles are oxygen ions, the big broken circles are Sr ions wee circles with a cross inside represent Fe ions at 12k, subaltern circles incorporating a filled circle inside represent Fe ions at 4f2, little unfilled circles represent Fe ions at 4f1, filled little circles represent Fe ions at 2a and little circles with a unfilled circle inside represent Fe ions at 2b. The magnetic construction suggested by Gorter is shown on the right, where the pointers represent the way of spin polarisation.From Fig. 1.3, we can snapper up the sites of Fe ( III ) ions matching to the spin way, as in turn off 1.1. putCoordinationOccupancyDirection of spin polarisation12kOctahedral12Up2aOctahedral2Up2bTrigonal Bypiramidal2Up4f1Tetrahedral4Down4f2Octahedral4DownTable 1.1 Fe ( III ) ion sites in M-type hexangular ferriteHysteresis LoopThe magnetic belongingss of Sr ferrite can be examined through hysteresis loop topologys. Hysteresis cringle can be measured utilizing instruments much(prenominal) as Vibrating Sample Magnetometer ( VSM ) and squid Magnetometry Measurements.When a magnetic stuff is placed in a magnetic field, the fluxion denseness ( B ) would dawdle behind the magnetising draw ( H ) that causes it, and this kind hysteresis cringle.From a hysteresis cringle, we can place the magnetic belongingss of the stuff, they are saturation magnetic field effect, remanence or besides known as residuum magnetic field strength, and coercivity. A typi cal hysteresis cringle is good illustrated in Fig. 1.4.Figure 1.4 Typical hysteresis cringle ( B-H curve )Initially, there is no utilise magnetic field and it is known as unmagnetized province. after(prenominal) magnetic field is use, it causes alignment. Until maximal magnetising force applied, maximal flux denseness achieved at the same clip and this phenomenon is known as saturation magnetic intensity. At this point, the maximal figure of spin has mobilized. Saturation magnetisation is defined as the maximal possible magnetization of a stuff. It is besides a pure tone of strongest magnetic field a magnet can bring forth. The unit of impregnation magnetisation is in angstroms per metre. Strontium ferrite is holding high impregnation magnetisation at which it can hive away high quantity of magnetising force. As the magnetizing force being slatternly removed, the alliance stays at the point where H = 0, this is known as remnant magnetisation. Remnant magnetisation is the mag netisation left in a lasting magnet after an external magnetic field is removed. When a magnet is magnetic , it has remanence. It is ordinarily measured in unit Tesla. Strong lasting magnet such as Sr ferrite has high leftover magnetisation which means the high sum of magnetic force remains in it even after the magnetizing force is removed. As form Fig. 1.4, ostracise magnetic field is applied to demagnetise the lasting magnet. When the flux denseness ( B ) = 0, there is no magnetising force remain in the magnet and the negative H needed to demagnetise the magnet is known as coercivity. Negative H is the magnetic field applied in opposite way. Coercivity is measured in unit amperes per metre. Due to its high uniaxial magnetocrystalline anisotropy with an easy axis of magnetisation along the hexangular c-axis in the construction, SrFe12O19 has high coercivity.Anisotropy is directional or orientational effects in crystal construction of stuffs which can return better magnetic pu blic monstrance along certain preferable axis. Therefore, we need to use high negative magnetising force to demagnetise Sr ferrite. Attempts have to be made to germinate down down the coercivity of Sr ferrite for use.whole of measurements in magneticsThe units used in magnetic attraction can be divided in general into two classs, SI system and c.g.s system. The transition table shown in Table 1.2 is to clear up the magnetic attraction observation in both(prenominal) SI and c.g.s systems and the transition factors between them.MeasureSymbolSI UnitSI Equationc.g.s Unitc.g.s EquationConversion FactorMagnetic InitiationBacillustesla ( T )B=Ao ( H+M )gauss ( G )B = H+4IM1 T = 104A GMagnetic Field StrengthHydrogenampere/meterA( A/m )H = NA-I/lcA( lc magneticAway, m )oersted ( Oe )H = 0.4INA-I/lc( lc magneticAway, centimeter )1 A/m =A4 IA-10-3A OeMagnetic FluxIWb ( Wb )I = BA-Ac( Ac country, m2A )Mx ( M )I = BA-Ac( Ac country, cm2A )1 Wb = 108A MMagnetizationMeterampere/meter ( A /m )M=m/V( m- sum magnetic heartbeat, AV- volume, m3A )emu/cm3M=m/V( m- sum magnetic minute, AV- volume, cm3A )1 A/m = 10-3Aelectromagnetic unit / cm3Magnetic Perme index of VaccumAonewton/ampere2Ao= 4IA-10-714IA-10-7InductionLiterHL=I?oI?N2Ac/lc( Ac- country, M2, Alc magnetic way, m )HL=0.4II?N2Ac/lcA-10-8( Ac-area, cm2, Alc magnetic way, centimeter )1Emf ( electromotive force )VoltVV=-NA-dI/dtVV=-10-8NA-dI/dt1Note In the above equations, I = catamenia ( in As ) , N = bendsTable 1.2 Magnetism expressions in SI and c.g.s systems and their transition factors for the magnetic units.1.4 PHOTOLUMINESCENCE PROPERTIES OF SrFe12O19Harmonizing to the survey of G. B. Teh et.al 3 on Sr ferrite, Sr ferrite was found to exhibit photoluminescence behaviour. When a attempt of Sr ferrite is excited at a certain wave distance, highest strength of photoluminescence emanation extremums was obtained. The ability of Sr ferrite to photoluminesce could be due to the O vacancies in their lattice co nstruction. The O vacancies are assumed to do the atoms to exhibit photoluminescence behaviour by move as traps for nomadic excitement. The O vacancies have effectual +2 charges, doing them herculean electron gaining control centres. Valence negatron would derive sufficient button to leap from the valency set to the conductivity set and go forthing a spread known as hole during excitement. F-centers, which is the part where contain high sum of negatrons would organize when the aroused negatrons being trapped in O vacancies. These rich negatron centres would take to emanation of luminescence when the holes and negatrons recombine.1.5 SYNTHESIS highway OF SrFe12O19The processing paths used for entailment of Sr ferrite affect its belongingss much. Traditionally, this ferrite pulverization is synthesized by a assorted oxide ceramic method, which involves the solid-state reaction between SrCO3 and Fe2O3 at a high calcination temperature ( about 1300AC ) . However, uncontrolled atom m orphology, big atom size and agglomerates would be the biggest disadvantages of this technique. Besides, taint would be introduced to the sample distribution while subsequent milling of the calcined ferrite pulverization and this would impact the magnetic belongingss belong less desirable. Therefore, the narrowed atom size distribution, refined atom size and minimum atom agglomeration has been the chief concern during the entailment of Sr ferrite.In order to better the magnetic belongingss, legion nonconventional soft man-made paths have been carried out, including sol-gel tax deduction 3 , hydrothermal reaction 6 , co-precipitation 7 , citric acid method 8 and microemulsion processing 10 .In this survey, the synthesis of Sr ferrite employed the sol-gel technique. It is a wet chemical path using ethylene ethanediol as gel precursor. Sol-gel technique is the technique of utilizing chemical substances which have high solubility in organic dissolvers to synthesize prec ursor compounds. The compounds are easy transformed into hydrated oxides on hydrolysis. The metal alkoxides formed can be removed easy utilizing hydrolysis and thermic intervention and therefore consequences in hydrous oxides which are extremely purify.Sol-gel method is used in this survey because of its numerous advantages. Sol-gel technique is able to bring forth homogenous nanosized crystallites. This method is escape to give breakwaterded stuffs straight from a solution without go throughing through the pulverization processing and the fact that the annealing temperature is very low compared with other conventional engineering. The crystalline size and belongingss of the ferrite produced are mostly affected by calcinations temperature 3 . Sol gel method has the advantage that the crystal developing of atoms is easier to command by changing the screw up intervention 11 . It was describe that at 500EsC it produced merely maghemite, I?-Fe2O3. A assorted merchandise of m agnetic I-Fe2O3 and M-type SrFe12O19 were obtained at 600EsC. As the calcination temperature accession to 800EsC and supra, there are merely M-type SrFe12O19 stage was observed. Sol-gel synthesis is able to bring forth high outputs of SrFe12O19 nanoparticles. It is besides able to bring forth nanocrystallite of cation substituted SrFe12O19. Nanoparticle size of Sr ferrite is desirable and aimed to synthesise because nanoparticles tend to give better magnetic belongingss. Nanoparticles give few magnetic studys, likely single field of view. integrity field tends to give higher magnetic initiation because there are no maintain magnetic sphere. whizz sphere aligns in one way merely. These belongingss are ideal for the fashioning of lasting magnet.1.6 CATION SUBSTITUTION IN SrFe12O19In order to better the magnetic belongingss of Sr ferrite, many surveies have been carried out. one and only(a) of them is cation permutation in Sr ferrite. ancient Earth and other metal cations are used for permutation for Sr and Fe severally 5 . The put forward doping of SrFe12O19 such as a La-Co brace to alternate a Sr-Fe brace has been tested 14 . The doping, or known as cation permutation, is aim to better the magnetic belongingss of Sr ferrite. Cation permutation consequences in structural alterations in Sr ferrite. As the physical belongingss of ferrite alteration, the magnetic belongingss would be affected due to the fact that magnetic belongingss are find by the agreement of Fe ions in crystal construction. In this survey, Co-Ti brace will be doped to the Sr ferrite. Cobalt Ti permutation will bring forth a quaternate system of the type SrO-Fe2O3-AO where A represents the dopant cation.The Co Ti permutation gives rise to the new expression, SrCoxTixFe12-2xO19 where Ten is the figure of gram moleculee of cation substituted in.1.7 Commercial ApplicationsStrontium ferrite is widely used as lasting magnet because it has way of easy magnetisation and the hexangula r c-axis which are perpendicular to the plane of the home base. The belongingss that are desirable in utilizing as lasting magnet include high impregnation magnetisation, high leftover magnetisation, high coercivity, high Curie temperature and high magnetocrystalline anisotropy.Besides, SrFe12O19 is besides normally used in high-density informations storage magnetic entering media. Nanoparticles of SrFe12O19 with individual sphere and low coercivity are of import in used for magnetic recording media. M-type Sr ferrite nanoparticles have attracted much attending due to their good frequence characteristic, low noise, high end product, in peculiar, first-class high frequence characteristic and unspecific dynamic frequence scope 4 . There are two types of entering medium, viz. particulates and thin movies. Tape and floppy is categorized in particulate and difficult thrust is belongs to thin movie. Information is stored by magnetising stuff. The entering caput can use magnetic field ( H ) and align spheres to magnetise the medium. It can besides observe a alteration in the magnetisation of the medium. Magnetic entering media prefers high impregnation magnetisation do it to hive away as much information. High appraise of remnant magnetisation is required in entering media to do certain that all stuffs stored in the difficult disc thus far remained even the power supply ( applied magnetic field ) is switched away. Low coercivity is of import in magnetic recording media. When the positive magnetic field is applied, this charging manages the medium to hive away informations. On the other manus, negative magnetic field applied to recuperate back the information, this is called discharges. Therefore, less current is needed to recover the information in the low coercivity medium. As a consequence, less heat generated and this saves the electricity.In general, Sr ferrite has high value of uniaxial anisotropy field, high coercive force and high impregnation magneti sation. The high coercivity of Sr ferrite has to be lowered down and impregnation magnetisation has to be at the same time increased if it is to be serviceable for magnetic recording intents. It has been reported that the permutation of cations such as Co ( II ) for the ion Fe ( III ) in Sr ferrite has lowered the coercive force. Therefore, many surveies were carried out to accomplish better magnetic belongingss of Sr ferrite for commercial applications.Chapter 2 EXPERIMENTALSample Preparation discount of M-type SrFe12O19Synthesis of Cation Substituted SrFe12O19Sample CharacterizationMagnetic Susceptibility residue MK12.1 Sample Preparation2.1.1 Synthesis of M-type SrFe12O19The sol-gel technique was used to synthesise M-type SrFe12O19 whereby the ethene ethanediol acts as gel precursor. The kickoff stuffs, Sr nitrate, Sr ( NO3 ) 2 and Fe ( III ) nitrate-9-hydrates, Fe ( NO3 ) 3A9H2O were used due to their high solubility in ethylene ethanediol. Calculation to a lower place was m ade to find the weight of stuffs needed to be used.Relative molecular(a) set of stuffsStrontium nitrate, Sr ( NO3 ) 2 = 211.63 g/molIron ( III ) nitrate-9-hydrates, Fe ( NO3 ) 3A9H2O = 404 g/mol( Note any replies have to be converted into 3 important figures. )No. of mol of 1 g Sr ( NO3 ) 2 = spile of Sr ( NO3 ) 2RMM of Sr ( NO3 ) 2= 1g211.63g/mol= 4.725210-3 molStrontium Fe = 1 12No. of mol of Fe ( NO3 ) 3A9H2O needed = 4.725210-3 mol x 12= 5.670210-2 molMass of Fe ( NO3 ) 3A9H2O needed = No. of mol of Fe ( NO3 ) 3A9H2O needed ten RMM ofFe ( NO3 ) 3A9H2O= 5.670210-2 mol x 404g/mol= 22.9 gFrom the computation, 1g of Sr nitrate and 22.9g of Fe ( III ) nitrate-9-hydrates were needed in the synthesis and were weighted. Strontium nitrate would supply 1 mol of Sr ions and Fe ( III ) nitrate-9-hydrates would supply 12 mol of Fe ions in the synthesis of Sr ferrite, which matched the molecular expression of SrFe12O19. The Sr nitrate and Fe ( III ) nitrate-9-hydrates were readily dissolve d in ethene ethanediol with little heat applied due to their high solubility in it. The mixture was heat somewhat and stirred with a magnetic saloon until the mixture was to the full dissolved. The attendant solution is in crystalline ruddy colour. The magnetic brainchild saloon was removed.The mixture was heated to 100AC and it would easy transform into a gel signifier. The gel was dried with uninterrupted heating at 100AC for 3 hours. The dried gel was so transferred to a crucible to take hints of organic precursor. A mixture of metal oxides in spread nanoclusters signifier was obtained. The dried gel was so annealed in a furnace at 800AC for 3 yearss with extended land with a stamp in a howitzer after annealed at legal separation of each twenty-four hours.2.1.2 Synthesis of Cation Substituted SrFe12O19Cation substituted strontium ferrite was synthesized by utilizing Co ( II ) ions and Ti ( IV ) ions to replace the Fe ions in M-type hexangular Sr ferrite. The permutation of Co ( II ) and Ti ( IV ) gives the compound a new molecular expression, which is SrCoxTixFe12-2xO19 where the x denoted different ratios. In the synthesis of cation substituted SrFe12O19, the ratios of cations used, x, is in between 0.2 to 6.0 ( 0.2 a x a 6.0 ) , where ten = 0.2, 0.4, 0.6, 0.8, 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0. The same method described in branch 2.1.1 was used for the synthesis, by merely adding two new get downing stuffs, which are the Co ( II ) nitrate and Ti ( IV ) ethoxide to give the Co2+ and Ti4+ cations.Calculation as described below was made to think the weight of stuffs needed severally.Relative Molecular Mass of stuffsStrontium nitrate, Sr ( NO3 ) 2 = 211.63 g/molIron ( III ) nitrate-9-hydrates, Fe ( NO3 ) 3A9H2O = 404 g/molCobalt ( II ) nitrate, Co ( NO3 ) 2.6H2O = 291.04 g/mol titanium ( IV ) ethoxide, Ti ( CC2H5 ) 4 = 228.11 g/mol( Note totally replies have to be converted into 3 important figures. )Examples used for the computation SrCo0.2Ti0.2Fe11.6O19 , x= 0.2No. of mol of 1 g Ti ( CC2H5 ) 4 = Mass of Ti ( CC2H5 ) 4RMM of Ti ( CC2H5 ) 4= 1g228.11g/mol= 4.383810-3 mol0.2 mol of Ti needed 1 mol of Sr.4.383810-3 mol of Ti needed ( 4.383810-3 mol x 1 ) mol of Sr.0.2Therefore, 0.021919 mol of Sr is needed.Mass of Sr ( NO3 ) 2 needed = 0.021919mol ten 211.63 g/mol= 4.64 g0.2 mol of Ti needed 11.6 mol of Fe.4.383810-3 mol of Ti needed ( 4.383810-3 mol x 11.6 ) mol of Sr.0.2Therefore, 0.25426 mol of Fe is needed.Mass of Fe ( NO3 ) 3A9H2O needed = 0.25426mol ten 404g/mol= 103 gMass of Co ( NO3 ) 2.6H2O needed = 4.383810-3 mol x 291.04g/mol= 1.28 gThe computation above were used to cipher the weight of get downing stuffs needed for other cation ratios, ten for 0.4, 0.6, 0.8, 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 severally every bit good. The weight needed for each stuff was tabulated in Table 2.1.tenWeight of stuffs needed ( g )Sr ( NO3 ) 2Fe ( NO3 ) 3A9H2OCo ( NO3 ) 2.6H2O0.24.641031.280.42.3251.41.280.61.5531.91.280.81.1123.01.281.00.9317.71.2 82.00.467.081.283.00.313.541.284.00.231.771.285.00.190.711.286.00.150.001.28Table 2.1 Weight of stuffs needed for synthesis of Co ( II ) -Ti ( IV ) substituted Sr ferriteFor the series of different permutation ratios ( ten ) , the corresponding Sr nitrate, Fe ( III ) nitrate-9-hydrates, Co ( II ) nitrate and Ti ( IV ) ethoxide were weighed and dissolved in 100ml ethene ethanediol. The oxides obtained after ignition were so annealed in a furnace at 800AC for 3 yearss with extended land with a stamp in a howitzer after annealed at interval of each twenty-four hours. The readying for Sr ferrite and cation substituted strontium ferrite is shown in Fig. 2.1 in flow chart array.Figure 2.1 Conventional diagram of the process for synthesis of Sr ferrite and cobalt-titanium substituted SrFe12O19.Sample CharacterizationMagnetic Susceptibility Balance MK1The magnetic belongingss of Sr ferrite and cobalt-titanium substituted Sr ferrite produced by the method described above were examined utiliz ing the Magnetic Susceptibility Balance retire 1 ( MK1 ) by Sherwood scientific Ltd, England. The magnetic susceptibleness balance setup was shown in Fig. 2.2.Figure 2.2 Magnetic Susceptibility Balance MK1 by Sherwood Scientific Ltd, England.The basic invent rule of Magnetic Susceptibility Balance MK1 was shown in Figure 2.3. Magnetic Susceptibility Balance determines the magnetic belongingss by puting two twosome of traveling magnets with the beam in between where the stationary sample is ready to be measured. Basically, the possible warp in the beam and the drive being made of a peculiar sample either solid or liquid could be observed in a balance system which possesses a magnetic field. Meanwhile, the spiral within the instrument is conducted with current required in order to do compensation of the magnetic force produced by the sample. Either paramagnetic or diamagnetic could be terminate in a asset or minus comparatively on show with the assistance of the way that the beam Swift.Figure 2.3 Basic design rule of Magnetic Susceptibility Balance MK1 by Sherwood Scientific Ltd, England.Magnetic susceptibleness is defined as when the magnetising field is applied to the sample, how much is the ratio of the strength of magnetic attraction induce by the sample in response to the magnetising field which it is capable. In this experiment, mass susceptibleness was the chief concern. Mass susceptibleness, xg, is defines by the mathematical expression below??g= ?v/dWhere vitamin D = denseness of substance??v is the volume susceptibleness, calculated by utilizing the expression??v = I/HWhere I = strength of magnetic attraction produced in a substanceH = strength of applied magnetic fieldBased on the magnetic belongingss of magnetic substances, they can be classified into one of the three groups. Among them, there is paramagnetic stuff which would pull by a strong magnetic field, diamagnetic which repelled by magnetic field and ferromagnetic which is alone to retain their ain magnetic field. After the external magnetic field is removed, ferromagnetic stuffs are still able to retain a lasting magnetic field. This is happened due to their free negatrons are in close propinquity and remain aligned without the magnetic field. Strontium ferrite and cobalt-titanium substituted Sr ferrite were found to be ferromagnetic due to the overshooting value observed on the show when the samples were introduced. To get the better of this job, a non-magnetic stuff Na chloride, was used to dilute the big magnetic attraction generate by the samples.Procedure was carried out. First, the scope boss of Magnetic Susceptibility Balance MK1 was turned to the x1 graduated table and was allowed to warm up for 10 proceedingss in the lead usage. The nothing boss is adjusted until the show reads 000. An nullify sample render of known weight was placed into the tubing usher and the teaching, Ro was taken. 0.0005g sample + 0.2820g NaCl ( sample length, fifty =3cm ) was packed into the sample column. The weight of samples and Na chloride were fixed for all measurings made. The jammed sample tubing was placed into tubing usher and the reading, R was taken. The stairss were repeated for all the 11 samples.The mass susceptibleness, ?g is calculated utilizing the expression??g= CBal* solid dm * ( R-Ro )109 * mWhere cubic dm = length of sample ( centimeter )m = mass of sample ( gm )R = balance reading for sample + tubingRo = balance reading for empty tubingCBal = the balance standardization changeless ( =1 )Chapter 3 second AND DISCUSSION3.1 Consequences of Mass Susceptibility3.1.1 Mass susceptibleness of M-type SrFe12O193.1.2 Mass susceptibleness of Cation Substituted SrFe12O193.1.3 Table of mass susceptibleness of SrFe12O19 and Co ( II ) -Ti ( IV )substituted SrFe12O193.1.4 graph of mass susceptibleness, ?g ( cgs ) against Co ( II ) -Ti ( IV ) ratio3.2 Findingss and Discussion3.1 RESULTS OF MASS SUSCEPTIBILITYMass susceptiblenesss of the samples we re calculated utilizing the expression??g= CBal* cubic decimeter * ( R-Ro )109 * mWhere cubic decimeter = sample length ( centimeter )m = sample mass ( gm )R = balance reading for sample in tubingRo = balance reading for empty tubingCBal = the balance standardization changeless ( =1 )* All the replies are adjusted to 4 important figures.3.1.1 Mass Susceptibility of M-type SrFe12O19??g = CBal* cubic decimeter * ( R-Ro )109 * m= 1 ten 3cm ten 936- ( -036 ) 109 x 0.0005= 1.94410-43.1.2 Mass Susceptibility of Cation Substituted SrFe12O19SrCo0.2Ti0.2Fe11.6O19??g = CBal* cubic decimeter * ( R-Ro )109 * m= 1 ten 3cm ten 798- ( -036 ) 109 x 0.0005= 1.66810-4SrCo0.4Ti0.4Fe11.2O19??g = CBal* cubic decimeter * ( R-Ro )109 * m= 1 ten 3cm ten 671- ( -036 ) 109 x 0.0005= 1.41410-4SrCo0.6Ti0.6Fe10.8O19??g = CBal* cubic decimeter * ( R-Ro )109 * m= 1 ten 3cm ten 654- ( -036 ) 109 x 0.0005= 1.38010-4SrCo0.8Ti0.8Fe10.4O19??g = CBal* cubic decimeter * ( R-Ro )109 * m= 1 ten 3cm ten 542- ( -036 ) 109 x 0.0005= 1.15610-4SrCo1.0Ti1.0Fe10O19??g = CBal* cubic decimeter * ( R-Ro )109 * m= 1 ten 3cm ten 441- ( -036 ) 109 x 0.0005= 0.95410-4SrCo2.0Ti2.0Fe8O19??g = CBal* cubic decimeter * ( R-Ro )109 * m= 1 ten 3cm ten 236- ( -036 ) 109 x 0.0005= 0.54410-4SrCo3.0Ti3.0Fe6O19??g = CBal* cubic decimeter * ( R-Ro )109 * m= 1 ten 3cm ten 162- ( -036 ) 109 x 0.0005= 0.39610-4SrCo4.0Ti4.0Fe4O19??g = CBal* cubic decimeter * ( R-Ro )109 * m= 1 ten 3cm ten 145- ( -036 ) 109 x 0.0005= 0.36210-4SrCo5.0Ti5.0Fe2O19??g = CBal* cubic decimeter * ( R-Ro )109 * m= 1 ten 3cm ten -006- ( -036 ) 109 x 0.0005= 0.06010-4SrCo6.0Ti6.0O19??g = CBal* cubic decimeter * ( R-Ro )109 * m= 1 ten 3cm ten -066- ( -036 ) 109 x 0.0005= -0.06010-43.1.3 Table of mass susceptibleness of SrFe12O19 and Co ( II ) -Ti ( IV ) substituted SrFe12O19The mass susceptiblenesss of the samples calculated were summarized in Table 1.SamplesSample length, cubic decimeter ( centimeter )Sample mass, m ( gm )Empty tubing reading, R0 Reading for tubing + sample, RMass susceptibleness, xgSrFe12O190.10.0005-0369361.94410-4SrCo0.2Ti0.2Fe11.6O190.10.0005-0367981.66810-4SrCo0.4Ti0.4Fe11.2O190.10.0005-0366711.41410-4SrCo0.6Ti0.6Fe10.8O190.10.0005-0366541.38010-4SrCo0.8Ti0.8Fe10.4O190.10.0005-0365421.15610-4SrCo1.0Ti1.0Fe10O190.10.0005-0364410.95410-4SrCo2.0Ti2.0Fe8O190.10.0005-0362360.54410-4SrCo3.0Ti3.0Fe6O190.10.0005-0361620.39610-4SrCo4.0Ti4.0Fe4O190.10.0005-0361450.36210-4SrCo5.0Ti5.0Fe2O190.10.0005-036-0060.06010-4SrCo6.0Ti6.0O190.10.0005-036-066-0.06010-4Table 3.1 Mass susceptibleness, xg of SrFe12O19 and Co ( II ) -Ti ( IV ) substituted SrFe12O193.1.4 chart of mass susceptibleness, ?g ( cgs ) against Co ( II ) -Ti ( IV ) ratioA graph of mass susceptibleness of SrFe12O19 and Co ( II ) -Ti ( IV ) substituted SrFe12O19 against Co ( II ) -Ti ( IV ) ratio was plotted and shown in Graph 3.1.Figure 3.1 Graph of mass susceptibleness, ?g ( cgs ) against Co ( II ) -Ti ( IV ) ratio3.2 FINDINGS AND DISCUSSIONMagnetic susc eptibleness is a step of response of negatrons in sample to an applied magnetic field. Electrons produce magnetic minutes at where the negatrons spin circularly around the karyon following right-thumb regulation. The net magmetic minute is the amount of minutes from all negatrons. There are three types of magnetic attraction they are ferromagnetic or ferrimagnetic, paramagnetic and diamagnetic. Strontium ferrite is a ferrimagnetic compound due to its high magnetic initiation, B when magnetic field, H is applied. The magnetic minutes of ferrimagnetic Sr ferrite is aligned parallel with applied magnetic field. It is a of course magnet because the magnetic minutes are point at one way even there is no magnetic field is applied. The magnetic minute of M-type hexangular ferrites strongly prefer the hexangular axis way, which is the c-axis.Within the grain boundaries of ferrimagnetic atoms, the spheres are aligned in two waies opposing when there is no magnetic field applied. As the magn etic field is applied and strength of applied field ( H ) increases, the magnetic minute of ferrimagnetic stuff become aligns with H. The magnetic spheres with aligned magnetic minute grow at disbursement of ill aligned 1s. In the terminal, the magnetic spheres become individual sphere when the applied magnetic field additions until a point. Single magnetic sphere is desirable as it is easy to revolve the atoms for use. Single sphere besides gives higher magnetic initiation because there are no oppose magnetic sphere, the individual sphere align in one way merely. These belongingss are ideal for doing of lasting magnet. To a higher opportunity of obtaining individual sphere in atoms of a compound, the compound frequently produced in nanoparticles. Nanoparticles tend to give few magnetic spheres, likely individual sphere. This is due to the really little size of atoms tend to give the smallest sum of grain boundary, hence the opportunity of acquiring magnetic spheres in opposite way is little comparison to the big size atoms which have more grain boundaries. Therefore in this survey, sol-gel technique which is able to bring forth nano-sized atoms was employed.The magnetic belongingss of the hexangular Sr ferrites are strongly dependent upon the synthesis conditions and the site sense of taste of the substituted cations among the five different Fe3+ sublattices viz. , tetrahedral ( 4f1 ) , rhombohedral bipyramidal ( 2b ) and octahedral ( 12k, 2a and 4f2 ) of hexangular construction 13 .Mass susceptibleness is the ratio of the strength of magnetic attraction induced in the sample to the magnetizing field applied in response to the denseness of the substance. In commercial application, the mass susceptibleness is desirable as holding high value, for the use of strong lasting magnet and entering media.For the compose where x = 0.2, the substituted Sr ferrite recorded change magnitude in mass susceptibleness. The magnetic belongingss were non every bit desirab le as the value of susceptibleness demands to be comparatively high.In the specimen with x = 0.4, a dramatically addition in mass susceptibleness was measured. The addition in susceptibleness indicated that the permutation of Co ( II ) -Ti ( IV ) had filled up the minor I?-sublattice ( spin-down ) of the magnetoplumbite construction and therefore enhanced the measured magnetization along the I-sublattice ( spin-up ) axis.In the specimen with x = 0.6, the mass susceptibleness decreased. The big fall of susceptibleness indicated that at this ratio, the Co ( II ) -Ti ( IV ) cations may good hold occupied the cation sites which were in the I-sublattice ( spin-up ) .For x = 0.8 to 5.0, it was found that both specimens recorded similar values of susceptibleness. As the permutation of Co ( II ) -Ti ( IV ) increased, the susceptibleness showed a rapid lessening. It might hence be expected that farther permutation will later bring forth a superparamagnetic-like Sr ferrite. Superparamagnetis m is a phenomenon by which magnetic stuffs may exhibit a behaviour similar to paramagnetism at temperatures below the Curie temperature.For x = 6.0 shows negative value of mass susceptibleness, indicates the formation of Co oxide and Ti dioxide which are diamagnetic. There are no Fe oxides which gives ferromagnetic belongingss.From the old promulgated survey, the partial permutation of Fe3+ ions with a Co2+ + Ti4+ brace was attempted 4 . However, the coercive force reduces and at the same time impregnation magnetisation besides reduces. Therefore, the ratio of substituted cations is really of import in modifying the magnetic belongingss of ferrite.Single sphere atoms of Ti-Co substituted M-type hexaferrite posses attractive belongingss for the recording media applications 13 . Such permutations at Fe site are effectual in cut downing the coercivity and magnetocrystalline anisotropy but require higher annealing temperature for the individual stage formation. It has besides been r eported that when synthesising Ti-Co substituted hexaferrites, it is hard to avoid the formation of Co ferrite. Although the coercivity lessening by the permutation of Co-Ni but at the same clip the impregnation magnetisation of the stuffs lessening which limit their applications in the high denseness entering media.Chapter 4 Decisions4.1 Decisions4.2 incoming Work4.1 DecisionThe consequence of cation permutation on magnetic belongingss of Sr ferrite is discussed in the old chapter. The magnetic belongingss are differing matching to the different cation permutation ratios. There existed important tendency which corresponded to the alterations in permutation ratio in Sr ferrite. The mass susceptibleness is the highest at x = 0.4 in SrCoxTixFe12-2xO19. This indicates that this cation permutation ratio gives best magnetic behavior where the magnetisation is the highest. This phenomenon is favorable for commercial application such as doing of lasting magnet and magnetic recording media .4.2 FUTURE WORKIn this survey, the magnetic belongingss of M-type hexangular SrFe12O19 and cation substituted SrFe12O19 was studied. One of the magnetic belongingss, mass susceptibleness of the ferrites was determined in this survey, by utilizing magnetic susceptibleness balance. Besides magnetic susceptibleness balance, the survey on magnetic belongingss can be improved by utilizing SQUID gaussmeter or vibrating sample gaussmeter ( VSM ) 12 to look into the impregnation magnetization, remnant magnetization and coercivity. These three magnetic belongingss are the indispensable one to find their magnetic behavior for assorted applications. However, these two instruments are non functional in our research lab.The cobalt-titanium permutation is replacing the Fe sites alternatively of Sr sites. The Sr site could be substituted with other passage elements or rarified body politic elements with the similar atomic radii, illustration for Bi and rare earth.In future, farther survey co uld be carried out by substituted rare earth wholly to replace strontium ferrite to look into whether the M-type hexangular construction remains.One of the ways to heighten magnetic belongingss is to bring forth individual sphere atoms by partner offing the divalent-tetravalent permutation in Sr ferrite with get hold of man-made methods. Besides cation permutation by Co2+-Ti4+ brace, sol gel derived strontium ferrite with Fe substituted by Zn2+ , Ti4+ and Ir4+ have been carried out 9 . They are Zn2+-Ti4+ brace and Zn2+-Ir4+ brace. If this is true, it will hold a great impact on the engineering of tomorrow.