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Presented at ASETSDefense 2014: Sustainable Surface Engineering for Aerospace and Defense held at Fort Myer, VA on 18-20 Nov 2014.

Various domain patterns in 0.94Pb(Fe(1/2,Nb(1 /2))(O3)-0.06PbTiO3 single crystals have been observed in a transmission electron microscopy investigation. At room temperature the observed morphology includes mesoscopic cross-hatched two-variant tweed domains, single-variant tweeds, and mesoscopic needle-shape domains. They are all accommodated with elastic strains. There is also contrast on boundaries between two types of single-variant tweeds that have parallel and opposite displacements respectively. Upon variation of temperature, the single-variant tweeds and their associated needles appear unstable. Transformation between needles and single-variant tweeds occurred when decreasing temperature below -30DGC or increasing temperature above 50DGC. Above 150DGC, a new type of domains were formed and dominant. It disappeared at 200DGC. All transitions in domain structure at different temperature are reversible.

Various domain patterns in 0.94Pb(Fe(1/2,Nb(1 /2))(O3)-0.06PbTiO3 single crystals have been observed in a transmission electron microscopy investigation. At room temperature the observed morphology includes mesoscopic cross-hatched two-variant tweed domains, single-variant tweeds, and mesoscopic needle-shape domains. They are all accommodated with elastic strains. There is also contrast on boundaries between two types of single-variant tweeds that have parallel and opposite displacements respectively. Upon variation of temperature, the single-variant tweeds and their associated needles appear unstable. Transformation between needles and single-variant tweeds occurred when decreasing temperature below -30DGC or increasing temperature above 50DGC. Above 150DGC, a new type of domains were formed and dominant. It disappeared at 200DGC. All transitions in domain structure at different temperature are reversible.

Various domain patterns in 0.94Pb(Fe(1/2,Nb(1 /2))(O3)-0.06PbTiO3 single crystals have been observed in a transmission electron microscopy investigation. At room temperature the observed morphology includes mesoscopic cross-hatched two-variant tweed domains, single-variant tweeds, and mesoscopic needle-shape domains. They are all accommodated with elastic strains. There is also contrast on boundaries between two types of single-variant tweeds that have parallel and opposite displacements respectively. Upon variation of temperature, the single-variant tweeds and their associated needles appear unstable. Transformation between needles and single-variant tweeds occurred when decreasing temperature below -30DGC or increasing temperature above 50DGC. Above 150DGC, a new type of domains were formed and dominant. It disappeared at 200DGC. All transitions in domain structure at different temperature are reversible.

The reactions to prepare the complex hydride FeH6(4-) have been surveyed and it has been determined that the high pressure sintering method is the most efficient. The complex hydride Mg2FeH6 has little tendency to release hydrogen under ordinary conditions. Electrophilic species were not successful in producing a "reversible" form of hydrogen-storage, in situ. Reactions of soluble complex species prepared by solution synthetic techniques have some fascinating properties. These species are formulated as FeH6?MgY(THF)n!4, Y = halide or alkoxide. The more important findings include: (1) The position of hydride in the spectrochemical series has been unambiguously determined for the first time; (2) The thermodynamic (i.e. equilibrium constant) and kinetic parameters for the ion pairing in these species, where X = halide, have been characterized; (3) Highly soluble species have been prepared, where Y = alkoxide, and their solvatochromism has been characterized; (4) Catalysis of hydrogen-transfer reactions in hydrocarbons has been observed in solutions of FeH6(4-).

This report covers work accomplished on the second year of contract No. N00014-82-K0339 for the study of 'Piezoelectric and Electrostrictive Materials for Transducer Applications. The work accomplished covers a rather wide range of topics and for convenience, it is divided into four major sub-topics. (1) Composite materials, (2) Electrostriction, (3) Conventional Piezoelectrics, and (4) Preparative Studies.

Trisodium pentacyanoferrate (TPF) forms derivatives with hydrazine, methylhydrazine, and unsym-dimethylhydrazine. Each of these derivatives are similar in color and each of the derivatives have similar visible spectra. Separation of these derivatives by HPLC could offer a rapid analytical method of determining the composition of mixtures of the hydrazines. The photoreduction of Zn-tetraphenylporphyrin (Zn-TPP) with hydrazine, methylhydrazine, and unsym-dimethylhydrazine in pyridine was investigated. Results indicate that the presence of hydrazine in mixture with methylhydrazine, and unsym-dimethylhydrazine can be confirmed due to the formation of a unique color that is not produced when Zn-TPP is photoreduced with methylhydrazine, and unsym-dimethylhydrazine. Organometallic compounds more sensitive to reduction by hydrazine and porphyrin derivatives that may possibly form hydrazone derivatives with hydrazine are currently being investigated. (Author)

This is the Final Report on this contract. Work involved the preparation and property measurements on a number of potential ionic conductors and mixed ionic-electronic conductors, as well as the investigation of a novel technique for the preparation of oxide solid electrolytes. Especially interesting were the results on several groups of new lithium ionic conductors. (Author)

The objectives undertaken in this work are as follows: The shock induced anisotropy effect in single crystal ferromagnetic material will be considered by a consistent application of the established tools of domain theory; the shock induced anisotropy effect in polycrystalline ferromagnetic material will be considered. Integral in this consideration is a critical analysis of the averaging process required to predict the random behavior of the polycrystalline structure. The contribution due to finite strain, a serious question in the region of large elastic strain, will be determined. Finally, the effect of porosity on the macroscopic magnetic response of material subject to this effect will be addressed. Further objectives of this work are the design and implementation of an experimental technique capable of measuring the magnetic state of the shocked ferromagnetic material during the few tenths of a microsecond within which this state exists. With this method data is accumulated in the region of large elastic strain in yttrium iron garnet. Favorable magnetic properties of yttrium iron garnet provide a critical comparison of experiment with theory.

SILICON DIOXIDE, INTEGRAL EQUATIONSYTTRIUM IRON GARNETS, *MAGNETIC BUBBLE DOMAINS, MAGNETIC DOMAINS, MAGNETIC FILMS, PERMALLOYS, FREDHOLM EQUATIONS, THIN FILMSThe first part of the report describes a two-dimensional mathematical model currently being used to describe field access bubble domain propagation. The model is based upon a continuous in-plane magnetization distribution in the permalloy which is determined by minimizing the system energy-assumed to consist of Zeeman and Magnetostatic energy contributions. The numerical techniques required to solve the resulting coupled Fredholm integral equations are described as well as the complete computer program used to analyze propagation in realistic permalloy patterns. Results are presented and discussed for bubble propagation along a 90 degree Chevron, a T-bar and a Y-bar. The second part of this report describes the design and construction of a high-frequency multiple-bar-Chevron shift register. Each of the individual components - generator, track, detector, annihilator - are described along with the experiments used to design them. (Modified author abstract), See also report dated Sep 72, AD-749 267.

A steady-state crystal growth system suitable for both homoepitaxial and heteroepitaxial growth of unixial magnetic rare earth compounds has been constructed and used for the growth of both YFeO3 and Eu2Er1Ga(0.7)Fe(4.3)O12. A very stable solvent, comprised of BaO-B2O3-BaF2 has been developed. This solvent is nonvolatile and nonreactive, and is well suited to the solution growth of magnetic oxides. Arrays of bubbles have been generated in YFeO3 and the coercivity and mobility of crystals grown from this solvent have been measured and found to be about 0.05 Oe and about 3500 cm/s-Oe, comparable to the values for crystals grown in the PbO-based solvents. Stable arrays of mobile bubbles have also been generated in heteroepitaxially grown Eu2Er1Ga(0.7)Fe(4.3)O12. Emission spectrographic analysis indicates that barium incorporation in the crystals grown from the BaO-based solvent is less than lead incorporated in those grown from the PbO-based solvent.

The report discusses the development of microwave S- and C-band lithium ferrites with substantially improved properties, comparable to those of the more expensive ferrimagnetic garnets currently in use. Although the development of these materials has been directed at applications for latching microwave devices, they are also useful for other microwave devices. The requirements for ferrite materials in latching phasers are reviewed, the compositional factors which result in useful properties are discussed, and performance in circulators and latching phasers is reported., Prepared in cooperation with Ampex Corp., Redwood City, Calif. Research and Advanced Technology Div. Rept. no. RR-71-13.

A procedure was developed for synthesizing a complete, solid equation of state and applied to iron. An experimental technique was developed for measuring shock induced magnetic anisotropy in YIG5 An improved procedure was developed for averaging magnetic moment in polycrystalline material. A theory of the asymptotic behavior of magnetization with field was developed for ferromagnetic materials. A code was written for 2-D elastic-plastic wave propagation in a bar. Analytic solutions for finite amplitude waves in lattices were developed.

The magnetically uniaxial rare earth garnets (Eu, Er)3(Ga, Fe)5O12 and (Gd,Y,Yb)3 (Ga,Fe)5O12 have been grown on (111), Gd3Ga5O12 substrates by the liquid phase epitaxial dipping technique in both PbO-B2O3 and BaO-B2O3-BaF2 solvents. The BaO-based solvent has been characterized with respect to solubility and suitable growth parameters of the magnetic garnets. The substrate and magnetic films have been characterized with respect to compositional uniformity, lattice parameters, impurities, surface morphology, thickness uniformity and magnetic properties., See also AD738537.

The goal of this program is to demonstrate the feasibility of a buffer memory using the controlled propagation of cylindrical magnetic (or bubble) domains. The bubble domain material investigation, directed toward preparing single crystal layers which exhibit useful device properties is being pursued with heteroepitaxial films of gallium-substituted yttrium iron garnet or related garnet compositions. The bubble domain device investigation is directed toward developing bubble manipulation techniques suitable for implementing the memory. The body of the report contains sections on material and device work. The material section is chiefly concerned with Czochralski-grown rare earth garnet crystals used as substrates for bubble domain films. This discussion covers observed imperfections in crystals, the effect substrate imperfections have on bubble domain behavior in epitaxial films and crystal growth parameters which influence the formation of these imperfections. The device sections of this report present advances in bubble domain device physics and hardware.

The work covered in this report deals mainly with experiments to study transient radiation induced information loss in magnetic bubble domain devices. Two shift registers of 96 and 84 bits each were tested. These devices consisted of T-bar propagation loops with a chevron stretcher and thick permalloy (4000 A) magnetoresistive detector on a glass overlay. This overlay was mounted on proton implanted (YGdTm)3(GaFe)5o(12) material. Stored information was read out electrically before and after exposure to electrons. Experiments were performed with the stored domain pattern both stationary and propagating during exposure. Radiation-induced changes usually involved only 1 or 2 bits (bubbles) and the probability of a failure (change of one or more bits) per shot averaged less than 40%. The output of the domain detector was monitored during e-beam exposure and indicates a threshold of >3 x 10 to the 11th power rads(Si)/sec in a 30 ns pulse for generation of false read signals., See also AD-782 015.

Research results are reported from a contract to develop improved electrochemical power sources. Topics discussed include: Apparatus for preparation of solid bismuth electrodes; characteristics of a mixed positive polarographic maximum; polarographic maxima of the first kind: specific suppressive effects of alkali-metal cations; potentiostatic anodic synthesis of ferrate (VI); conductance behavior of tetraalkylammonium salts in 3-tert-butyl-2-oxazolidone at 25C; conductance behavior of ammonium and mono-, di-, and tri-ethylammonium tetraphenylborates in 3-methyl-2-oxazolidone and 3-tert-butyl-2-oxazolidone at 25C; dielectric constants, viscosities, and related physical properties of five cyano- and halopyridines at several temperatures; dielectric constants, viscosities, and related physical properties of four liquid pyridine-N-oxides at several temperatures.

In the patent magnetic manganese ferrite and manganese-magnesium ferrite films of high compositional purity can be made by a relatively short and simple technique. The technique involves the dissolving of ferric nitrate and either manganese nitrate, or manganese nitrate and magnesium nitrate, in alcohol at room temperature; immersing the surface of a substrate in the solution; preliminarily firing the coated substrate at 400C to 700C and successively cooling to room temperature between coats. After weighing on a balance to determine exact amounts of material deposited, the coated substrate is fired at 800C to 1000C in an inert atmosphere for one to four hours to align the oxides formed to the spinel structure of the ferrite.

This patent relates to a method for growing single crystals of compounds of chemical formula Ba2Me2Fe12O22, BaMe2Fe16O27 and Ba3Me2Fe24O41 wherein Me is at least one divalent metal cation selected from the group Mg, Zn, Co, Ni, or Fe(+2). An object of this invention is to grow single crystals of the above-identified compounds that can be recovered by a simple chemical treatment at a melting temperature sufficiently low to eliminate the problem of the reduction of Fe(+3), thus improving the electronic properties of the product.

This patent relates to a method of growing single crystals of the formula BaZn2Fe16O27 that are mechanically sound, have well developed crystalline faces and are relatively free of macroscopic pits and foreign inclusions for use in microwave and millimeter device applications as in isolators, rotators, filters, power limiters, and harmonic generators.

This report details a facility for the fabrication of europium-erbium garnet films for computer memory applications. Magnetic 'bubbles' produced by the dipping method, and the substrate material are included. Variations in the garnet formula and the extent of success are discussed. (Author)

Nb-Co-Al and Nb-Fe-Al base alloys have been studied to determine the effects of composition both elemental and constituent (i.e., intermetallic alloy compounds used to make alloys) on the oxides formed during 1200C oxidation in air. Alloys were formed by both pressing and sintering of intermetallic compounds and elemental powders and by arc melting alloy buttons from intermetallic compounds and elements in powder form. Oxidation kinetics have been measured, and the oxides formed have been examined by x-ray diffraction techniques. In addition, Y and Y2O3 additions were made to several alloys to evaluate the effects of rare earth additions on the oxide structure. In addition to the oxidation kinetics and oxide structure correlation, metallographic techniques were used to evaluate the depth of penetration of oxygen into the various alloys. This study confirmed that rutile type oxides such as NbAlO4, NbFeO4, and NbCrO4 are responsible for improved oxidation performance. Parabolic rate constants were measured for these alloys. (Modified author abstract), Continuation of Contracts N00019-71-C-0089, and N00019-72-C-0132. See also report dated Feb 73, AD-761 215.

The work described in this report is an extension of work performed on Contract no. F19628-72-C-0342. The present effort is primarily concerned with establishing failure thresholds and mechanisms of magnetic bubble domain devices. Four types of experiments were performed. A study was made of the effect of 60 KV x-rays on the hard bubble suppression properties of a neon implanted layer in (YSm)3(FeGa)5O12 material. Radiation burn-out of 300 A permalloy domain sensors was found to occur with 30 ns pulses of 1.5 MeV electrons at doses above 30,000 rads/pulse. The stability of stored information in a transient ionizing environment was investigated. Finally, measurements were made of the transient radiation response of domain sensors. (Modified author abstract)

The authors have built an experimental setup which enables them to view the magnetic domains in the film and measure the conversion efficiency simultaneously. Reasonable mode conversion efficiency is obtained, only when the stripe magnetic domains in the film are eliminated along the line of light propagation. The bias field (H(a)) required to annihilate the stripe domain is dependent on the direction of the bias field with respect to the axes of magnetic anisotropy. The annihilation field (H(a)) is found to be maxima, of the order of 50 Oe, at O, plus or minus 60, plus or minus 120 degrees from the easy axis, and minima of the order of 2 Oe at plus or minus 45 degrees from the hard axis. (Modified author abstract), See also report dated Jun 73, AD-763 792.

Tests performed on bubble domain materials indicate that they are resistant to mechanical stresses of 50g. In a study of FMR and bubble domain wall mobility, it was found that the mobility is quite temperature sensitive over the range of interest, that FMR gives an upper bound but not a true value of mobility and that the exchange constant is about 0.6 of the normally assumed value for bubble domain compositions. An investigation aimed at selecting a composition to meet Air Force computer memory goals indicates that lower wall energy materials will have to be employed to reach high data rates. (Author)

Lead zirconate titanate compositions with zirconia to titania ratios of 51/49 to 57/43 were studied. Lead substitutions with barium, cadmium and strontium were made plus doping with LaFeO3, NaSbO3, MnO2, Fe2O3, U2O8 and Cr2O3. Materials were prepared by hot pressing and atmosphere sintering and tested for aging, high field drive and axial stress sensitivity characteristics. Results of a pilot production run of standard ring specimens fabricated from the composition (Pb(.94)Sr(.06))(.980)(Zr(.51)Ti(.49))(.995) Cr(.015)Mn(.005)O3 are presented. (Author)

Two (Gd(.5)Y(2.5))(Fe(4)Ga(1))O(12) garnet films deposited on GGG substrates have been tested for possible use as modulators, switches and isolators. Their passive optical waveguiding properties have been characterized at a wavelength of 1.15 micrometer. Modulation of the output, passed through an analyzer, was observed by applying a longitudinal magnetic field. The mode conversion efficiency was shown to be limited primarily by the phase velocity mismatch between TE and TM modes. The possibility of phase modulation of TM modes by a transverse magnetic field is discussed in the light of data obtained in the mode conversion experiments.

A study was made primarily of nonreciprocal YIG filter preselectors for the purpose of providing a suitable front-end for frequency-selective communications receivers. It was shown that fixed-tuned miniaturized nonreciprocal YIG preselectors can be arranged in a YIG filter bank (multi-channel) configuration with narrow bandwidths, low insertion loss, high directivity, nanosecond switching, and frequency-hopping rates in the MHz range. Accurate mathematical models were developed for analyzing the YIG preselector and these were utilized in a computer design program for the reciprocal and tri-loop filter configurations. Feasibility of achieving bandwidths within the 0.1 to 50 MHz range with low insertion loss was demonstrated. (Modified author abstract)

Synthesis of new ferromagnetic semiconductors with given properties can be solved on the basis of detailed physical studies of the nature of magnetism and of the mechanism of the electronic conductivity of ferromagnetic semiconductors in connection with their chemical composition and crystalline structure. The basic groups of oxide compounds of 4f- and 3d-transition metals with maximum spin values were selected for the studies in this work. The oxide compounds of divalent europrium which were studied are new ferromagnetic semiconductors and dielectrics with different cyrstal structures. The ferrodielectrics which were synthesized and studies can apparently be applied in super-high frequency low-temperature and optical instruments, and also as memory elements. (Modified author abstract), Trans. of Akademiya Nauk SSSR. Uralskii Filial, Sverdlovsk. Institut Fiziki Metallov. Trudy, v27 p142-158 1968.

Single crystals of BaFe12O19 have been grown using the flux method. The initial weight composition from which the crystals were grown consists of 64.3 BaCO3, 15.5 B2O3, 34.5 Fe2O3 and 1 V2O3. This composition has been varied to add PbO instead of BaO and to increase or decrease the amount of V2O3, in order to change the fluidity of the melt and improve the grown crystals. (Author Modified Abstract)

The report consists of two parts. First the characteristics of magnetostatic surface waves in a transversely magnetized YIG film are described and the conditions required to observe the convolution of two countertraveling magnetostatic waves are discussed. In the second part the experiments that have been performed under the contract are described. Magnetostatic surface waves have been observed. The convolution experiments were inconclusive. (Author)

The program's objective is to improve the compatibility between substrates and films of epitaxially grown magnetic bubble domain materials. The introductory section of this report contains a discussion of the means by which the requirements for the existence of cylindrical magnetic domains may be met in epitaxial films grown by chemical vapor deposition. The experimental section deals with substrate crystal growth and wafer preparation; chemical vapor deposition and heat treatment of epitaxial films. Techniques for characterizing magnetic bubble domain films are reviewed and properties of gallium-substituted erbium iron garnet films are discussed. Preparation and properties of polycrystalline ceramic samples of substituted ytterbium iron garnet are presented. (Author)

Procedures and results of Rochelle Salt, a ferroelectric crystal, growth in electric, magnetic and vibrational fields are presented and discussed. Evidence is given that experiences do not warrant continued effort. Preliminary results on the flux growth of barium ferrite are detailed in order to demonstrate that continued effort could lead to dislocation-free regions. The conclusion is made that highly perfect crystals for microwave applications could be produced. (Author)

Magnetostatic modes of resonance were studied in a rectangular slab of single-crystal yttrium iron garnet (YIG). Two moveable fine-wire transducers on opposite faces of the normally-magnetized slab allowed excitation and detection of spatially localized resonances at S-band frequencies. The strength of the detected signal was found to be dependent on the lateral displacement of the sample relative to the transducers. Multiple transmission peaks (corresponding to multiple modes of resonance) exhibited symmetry about the middle of the crystal. The distance of these peaks from the middle of the crystal increased as the excitation frequency was increased, or as the magnetic field was decreased., See also report dated 21 Nov 1971, AD0739993.

The magnetically uniaxial rare earth iron garnet (Gd,Y,Yb)3(Ga,Fe) 5O12 has been grown on (111) Gd3Ga5O12 substrates. The liquid phase expitaxial dipping technique with horizontal substrate rotation has been employed in conjunction with PbO-B2O3 and BaO-B2O3-BaF2 solvents in the temperature range of 900C-1050C. Growth parameters in the BaO-based solvent, such as growth temperature, undercooling, and rotation rate have been correlated with changes in growth rate and properties of the films. The films have been characterized with respect to composition, impurity content, lattice parameter, optical properties and magnetic properties

A method is described for the determination of the energy distribution curves of photoelectrons emitted by solutions of sufficiently low vapor pressure. Results are reported and analyzed qualitatively for emission by lithium ferrocyanide in glycerol. The method allows the study of energy transfer during the motion of quasi-free electrons in polar liquids of low vapor pressure, and generation of quasi-free electrons by optical excitation. (Author)

The habits of single crystals of the synthetic garnets, when grown from a SiO2 contaminated PbO-PbF2 flux, are dependent on the concentration of SiO2 in the melt. Y3Ga5O12 and Y3Fe5O12 crystals have a pure (211) habit when grown from an undoped melt. The crystal habit changes smoothly from (211) to (110) to (110) approximately to (100) for Y3Ga5O12, and from (211) to (110) for Y3Fe5O12 with increasing SiO2 in the melt. Y3Al5O12 crystals change from (211) > (110) to (211) or from (110) > (211) to (110) with increasing SiO2 in the melt. Analysis and comparison of the variation in oxygen positions in garnets of various composition indicate a tetrahedral site distortion for doped crystals that leads to surface energy conditions favoring a (110) habit for Si4+ doped crystals of Y3Fe5O12 and Y3Ga5O12. On the other hand, the habit change of Y3Al5O12 is believed to be dependent on a surface-contamination mechanism. (Author)

The report discusses the properties of Xenon 3.5 micrometer superradiant radiation sources with emphasis on frequency and intensity stability, in order to determine the feasibility of their use as a path-monitoring reference for Fourier spectroscopy. Irregular intensity fluctuations due to the interaction of radiation reflected from an interferometer were eliminated by means of an infrared isolator using the Faraday rotation in Yttrium Iron Garnet. A few important aspects of superradiant radiation courses and their applications, which are desireable for future research, are described. (Author)

It is shown explicity that the frequencies of small k, infinitefilm spin waves follows guide curves, which are simply the dispersion relations for pure magnetostatic modes (exchange constant D = O) with the internal field (H sub i replaced by (H sub i) + D(k squared). A previous result, that the magnetostatic-mode (D(k squared negligible) frequencies are independent of the pinning, apart from splitting at corssovers of the guide curves, is a special case of the general result. Two regions of linearity of omega as a function of the magnitude (k sub f) of the wave vector in the plane of the film exist, but have no practical consequences at present. (Author)

The program's objective is to improve the compatibility between substrates and films of epitaxially grown magnetic bubble domain materials. The initial effort has been concerned with gallium-substituted erbium iron garnet films prepared by chemical vapor deposition. The introductory section of this report contains a discussion of the means by which the requirements for the existence of cylindrical magnetic domains may be met in epitaxial films. The experimental section deals with film and substrate matching, garnet substrate crystal composition determinations, improvements in film deposition control and heat treatment of films. Techniques for characterizing magnetic bubble domain films are reviewed and properties of gallium-substituted erbium iron garnet films are discussed. (Author)

In feeding trials with rats, swine, goats and cows the effectiveness of various dietary supplements as countermeasures against 137Cs. 90Sr and 131I were also examined. Ferric ferrocyanide was shown to be effective against 137Cs absorption even when animals were also exposed to whole-body gamma irradiation. Ferrocyanide-anion exchange resins were less effective than ferric ferrocyanide. Sodium alginate derivatives of high L-guluronic acid content were effective against radiostrontium but processing yields were low. A study of the effectiveness of an isotopic exchange resin in reducing levels of radioiodine in milk was initiated. (Author)

An annotated bibliography of sixty one references on the electronic and magnetic properties of lithium ferrite from the Electronic Properties Information Center are provided. Undoped lithium ferrite is attractive for high frequency coincidence limiters and filters because of its narrow linewidth coupled with a 4 pi Ms of 3550 gauss and Curie temperature of 640C. Linewidths as low as 0.90 Oersteds at 5.1 GHz and room temperature have been achieved. Average values range from 1.5 tp 3.0 Oersteds. Lithium ferrite can be prepared with low microwave dielectric losses and high remanence ratios for microwave latching devices. The magnetoelastic coefficient is also low. (Author)

The real and immaginary parts of the dielectric constant of an inhomogeneous 68B2O3-17BaO-15Fe2O3 (mole %) glass have been measured over the temperature range 300K to 77K, together with magnetisation measurements over the same temperature range. The morphology of the precipitate particles produced by heat treating at 618C has been investigated by small angle x-ray scattering and electron microscopy. Two pronounced dielectric dispersions have been found to be associated with a magnetic phase transformation in the glass. The magnetic phase transformation, apparently associated with the Morin transition of the alpha-Fe2O3 precipitates, results in a displaced magnetisation curve along the magnetisation axis on cooling below T(m) in an applied magnetic field. (Author), See also Annual rept. dated Jan 71, AD-718 829.

Magnetically uniaxial rare earth garnets, such as EuEr2Ga(0.7)Fe(4. 3O12 and Y(1.3)GdYb(0.7)Fe(4.1)Ga(0.9)O12, have been grown by quasi steady-state (isothermal) liquid phase epitaxial techniques. The epitaxial layers have been grown on Syton polished (111) Gd3Ga5O12 substrates by the dipping technique in which the substrates, fastened to a platinum holder, are dipped into the supersaturated growth solution. Both PbO-B2O3 and BaO-B2O3-BaF2 solvents have been employed for the crystal growth, since each has certain distinct advantages and disadvantages for this type of growth situation. The BaO-based solvent has been characterized, and a solubility curve for a typical garnet, EuEr2Ga(0.7) Fe(4.3)O12, has been experimentally determined. The magnetic films have been characterized with respect to solvent content and distribution coefficients of the constituent ions for each of the growth solutions, lattice parameter mismatch between epitaxial layer and substrate, and magnetic properties., Sponsored in part by the DARPA.

The critical magnetic properties of europium iron garnet (EuIG) have been studied in the vicinity of the Neel temperature. The sample used in this study was a single crystal grown by the flux method. Magnetic measurements were made by utilizing the kink-point method for a spherical specimen in conjunction with a vibrating sample magnetometer. The critical exponents beta, delta, and gamma were determined and compared with the scaling equation, beta(delta-1)=gamma. An analysis was made in order to confirm the scaling prediction that the reduced magnetic field has a functional form which is dependent only upon the reduced magnetization. A test of the validity of the value for the Neel temperature, obtained by plotting applied magnetic field as a function of break-point temperature, has been made by application of the Kouvel-Fisher method. (Author)

The report includes summaries to date of several investigations. The first two sections summarize investigations into the preparation and characterization of perovskite oxides containing mixed transition metal ions. The third section treats continued efforts in characterizing the CrO4(3-) ion as it is found in complex phosphates. The fourth section describes the results of investigations into the influence of structure on the magnetic behavior of transition metal fluorides. In the fifth section a description is given of the advances made in the design of a more efficient facility for recording Mossbauer spectra over the temperature range 4.2K to 300K, and in the final section are presented the results of recently initiated studies which represent extensions of previous work performed under this grant. (Author)

This report describes in detail the technical progress made during the third six months of a three year interdisciplinary research program. One major goal of the program is the growth of yttrium-iron garnet (YIG), single crystals of high quality in both thin film and bulk form. Another is the development of novel techniques for controlling and studying energy propagation characteristics of volume and surface spin waves. One promising technique for accomplishing the former is the use of chemical vapor deposition (CVD) and cumulative progress with this method is recounted fully. The latter goal is being met by a combination of optical and microwave techniques used to probe the dynamics of spin wave propagation. The optical experiments were described in the last semi annual report; microwave propagation studies of magnetostatic surface spin waves in YIG slabs are presented in this report., Includes Master's theses: Growth of Yttrium Iron Garnet (YIG) Single Crystal Films by Chemical Vapor Deposition (CVD), and Propagation of Magnetostatic Surface Spin Waves in YIG Slabs. See also Semi-annual technical rept. no. 2, AD0720386.

The paper discusses the effects of Zn substitution on the switching and hysteresis loop properties of lithium ferrite cores. The Zn reduced the coercive force and thus permitted the use of smaller grains and hence faster switching time (ts). The compositions investigated were: Li(0.5-x/2)Zn(x)Fe(2.5-x/2)04 with x = 0.1, 0.2, and 0.3. Samples were evaluated for grain sizes ranging from 1 to 6 microns. As the grain size was decreased, t sub s decreased and the required drive field (H sub m) increased. Over a substantial range of grain sizes, the decrease in t sub s was faster than the increase in (H sub m). Also discussed are the effects of Zn substitution on the hysteresis loop squareness and temperature stability. (Author)

The properties of magnetoelastic surface waves in a variety of propagating structures are presented. The characteristics of magnetostatic surface waves in a thin magnetic plate are discussed including some new features introduced when a conducting layer is on or near the surface of the plate, and when magnetocrystalline anisotropy is taken into account. Convolution and pulse compression signal processing is possible when the new features are employed. Operating principles are discussed. A demonstration of pulse compression by 325 MHz surface waves in CdS layered LiNb03 is discussed and results are presented. (Author)

The report describes in detail the technical progress made in studies of strong infrared light scattering from coherent spin waves during the second six months of a three year interdisciplinary research program. Coherent light scattering from coherent microwave spin waves in yttrium iron garnet (YIG) is studied theoretically and experimentally. The method is then used, in conjunction with standard microwave techniques, to probe the propagation of spin waves and magnetoelastic waves, in spatially-and/or-temporally-varying magnetic fields. The dispersion of magnetoelastic waves propagating parallel to saturation magnetization when the latter is in an arbitrary crystallographic direction, first presented by Morgenthaler, is rederived. The report discusses the first direct observation of strong Bragg Scattered infrared light (1150 nm wavelength) from coherent microwave spin waves., Report on Steerable Volume and Surface Spin Waves in Ferrimagnetic Films. Doctoral thesis. Also available as Microwave and Quantum Magnetics Group TR-25.