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A Study Of Bifeo₃ And The Hall Effect In Bifeo₃ And Cds, Fred Hoerger Taylor

Masters Theses

"Pure samples of BiFeO₃ were heat treated in oxygen and nitrogen atmospheres in an attempt to reduce the conductivity of the samples. Dielectric constant and dissipation factor measurements, as a function of frequency, were made to determine whether the samples had been altered. A special high temperature Hall effect apparatus was constructed. Using this apparatus an upper limit for the Hall mobility in BiFeO₃ was established. The apparatus was also used for room temperature measurements of Ga-doped CdS samples. Resistivity measurements to be used with the Hall effect results were made on both the BiFeO₃ and the CdS samples. Hot-Point …

A Study Of Bismuth Ferrate And Bismuth Manganate In Solid Solution With Lead Titanate, Harris C. Jones

Masters Theses

"A new sample holder for measuring the high frequency dielectric constant of ferroelectrics at high temperature was constructed. The new sample holder eliminated discontinuities in the slotted line and improved the electrical contact between the ceramic and brass components. Measurements of the high frequency dielectric constant of an aged sample of 90% BiFeO₃ - 10% PbTiO₃ were made as a function of temperature using the slotted line technique. The dissipation function for the aged sample was found to have a more normal behavior near the Curie point than the virgin samples previously measured. Resistivity measurements were made as a function …

Absolute Specification Of X-Ray Spectra By Laplace Transform Analysis Of Attenuation Data, Gerald Robert Lusk

Masters Theses

"A well characterized, variable plate separation ion chamber was utilized as a detector to collect x-ray attenuation data for generating information on the Laplace transform predicted spectrum of a 50 KvCP conventional x-ray tube. The variable plate separation feature allows one to include a wavelength dependent correction to the detector response which is associated with the hardening of the x-ray spectrum as it traverses the attenuating material. With this correction, the conventional two-term Laplace transform was shown to approximate independently the bremsstrahlung and characteristic L radiation from the tungsten target. The detector provides an absolute statement of the target-referenced x-ray …

A Study Of An Electric Method To Excite And Detect Acoustic Waves In Solids, John H. Stevens

Masters Theses

"This experiment has demonstrated that it is possible to generate pulses of acoustic waves in an aluminum single crystal by the direct use of the tensile stress associated with an electric field at the surface of a conductor, and it is possible to detect these waves with a biased, capacitive pickup transducer"--Abstract, page ii.

A Study Of The Molecular Emission And Of The Life Times Of The Metastable States In The Afterglow Spectrum Of A Mercury Discharge, Bruce M. Whitcomb

Masters Theses

"Two methods of studying the spectrum in the early afterglow of a pure mercury sample are discussed. Using a time-sampling technique, information about the intensity of the spectrum as a function of time in the afterglow can be obtained. The intensities of two molecular bands, centered at 3350A and 4850A, are studied. The method of formation of the diatomic mercury molecule and the emission of radiation in the two bands are shown to be density dependent. Mechanisms are presented which explain both the molecular formation and the radiation in the two bands. In an absorption study, the half-lives of the …

A Study Of The Afterglow Of An R-F Excited Mercury Discharge, James A. Aubrecht

Masters Theses

"The short duration afterglow of an r-f discharge in mercury has been examined versus ground state mercury atom density and r-f power. The intensity of the 5771, 5462, 4360, 4079, 4047, 3907, 3651/56, 3342, and 3127/32Å atomic mercury lines were observed to decay as a function of time after the shut off of the active discharge. At temperatures below 333⁰K, all atomic lines decayed exponentially, and no molecular emission was observed. From 333⁰K to 423⁰K, the atomic lines were observed to decay rapidly initially, then exhibit an enhancement effect in intensity which was produced by metastable atom collisions, and finally, …

Absolute Soft X-Ray Dosimetry For Radiation Chemistry Studies, Howard Sajon Joyner

Masters Theses

"A homogeneous, variable plate separation ion chamber consisting of a polyethylene body and employing flowing ethylene as the cavity gas has been designed and tested for the specification soft x-ray (<75kV) energy deposition in typical hydrocarbons. The variable plate separation feature provided primary data on the differential specific ionization originating within the cavity gas occupying the effective collector volume which is independent of inherent chamber inhomogeneities associated with the electrically conducting films comprizing the chamber electrodes. These data demonstrated that charged particle equilibrium is established within the first few ten thousandths of an inch in typical solid hydrocarbons irradiated with this class of sources. Comparison of this type of chamber with a fixed plate separation, static cavity gas mode of operation showed that the latter may predict dose rates with inherent errors exceeding 100%. With the quality of electronic readout accessories presently available, the variable plate separation chamber yielded dose rate data exhibiting a probable error of 3.8 percent (plus the unknown uncertainty in the literature data on the energy required to form an ion pair), and an ultimate limiting error of less than 2 percent appears feasible"--Abstract, page ii.

The Mössbauer Effect In Bismuth Ferrate, Bruce A. Banks

Masters Theses

"The magnetic hyperfine structure of the Fe⁵⁷ nuclei in bismuth ferrate was investigated using the Mössbauer effect. A Mössbauer effect spectrometer was built with consideration given to the elimination of vibration and the optimizing of the source, absorber, and detector geometries to produce the largest fractional Mössbauer effect per fractional standard deviation. The internal magnetic field at the Fe nuclei in BiFeO₃ was determined to (482 ± 9) kilooersteds at room temperature"--Abstract, page ii.

The Faraday Rotation And Dispersive Doppler Effects In The Ionosphere At Oblique Incidence, Charles Roland Baugher Ii

Masters Theses

"Integral equations for the isotropic and anisotropic ray path of a radio wave propagating through the ionosphere are developed. These equations assume a spherically stratisfied ionosphere and are equivalent to a detailed ray-tracing process. A method is devised to utilize these equations in the evaluation of combined Faraday rotation and dispersive Doppler data from earth satellites for subionospheric electron content. The method, which corrects for horizontal ionospheric gradients, is applied to data from the Explorer 22 satellite and some preliminary results are discussed"--Abstract, page ii.

The Construction Of A Multi-Threshold Foil For Fast Flux Measurements, Michael Henry Holkenbrink

Masters Theses

"The construction of a multi-threshold foil for fast neutron flux measurements is investigated. The factors governing the selection of the materials are the energy response of the given reactor, the half-life of the daughter, the prominent gamma ray emitted during decays, the power level of the reactor, the availability of adequate cross section data, and the alloying properties of the composite foil. A ternary system was chosen as a compromise between the difficulty of fabrication and the amount of information gained from one foil. The particular system chosen was In- P- Fe. The threshold reactions of these elements are In¹¹⁵ …

Drop Growth In A Supersaturated Vapor, Roger Buecher

Masters Theses

"Using kinetic theory and the thermodynamics of phase transitions, a method is derived for finding the growth rate and temperature increase of a droplet in water vapor which has been supersaturated by the expansion of a cloud chamber. Calculations are performed for a specific numerical example and compared to other work in this field"--Abstract, page [2].

A Study Of Re-Evaporation Nuclei, Ronald Dawbarn

Masters Theses

"Classical considerations of the evaporation of a homogeneously nucleated droplet in an atmosphere of low humidity, indicates complete evaporation of the drop. Experimental results however, show that there is left behind a residual nucleus that is quite stable. Condensation occurs on these nuclei at comparatively low supersaturations. Using a specially instrumented cloud chamber, experimental procedures are described which attempt to investigate some of the properties of these nuclei. Various possibilities causing this stability are examined and compared to the experimental results obtained"--page [ii].

Operating Characteristics Of A Cloud Chamber Suited For Condensation Measurements, Donald L. Packwood

Masters Theses

"It is the main purpose of this research to investigate the validity of using the adiabatic laws to determine the temperature from the pressure ratio. Some of the effects which might invalidate the use of the adiabatic laws will be studied. Special consideration will be given to the accurate calculation of [gamma]. Carstens' approximate calculation of the heat flow into the chamber due to conduction will be checked. A measurement will be made of how long the chamber remains adiabatic after an expansion when the continuing expansion technique is used. The static temperature gradient throughout the chamber will be measured …

An Instrument For The Measurement Of Anelastic Properties Of Glass, Thomas Frederick Miller

Masters Theses

"An inverted torsion pendulum for measuring the internal friction and dynamic shear modulus of glass fibers over an extended temperature range has been constructed and calibrated. The calibration consists of the determination of the moment of inertia. Extraneous damping losses were investigated and primary sources were found to be (1) the suspension thread, (2) the method of securing the fiber and (3) air damping. Anelastic measurements were made on an annealed vitreous silica fiber and a soda-lime-silica fiber"--Abstract, page ii.

A Second Study Of Homogeneous Nucleation Of Water Vapor In Helium, Raymond J. Schmitt

Masters Theses

"Absolute homogeneous nucleation rates in a supersaturated mixture of water vapor and helium are measured using a long sensitive time expansion chamber and a method devised by Kassner and Allard. A pulse technique is employed to produce the nucleation in an effort to suppress disturbing influences of vapor depletion and droplet growth. The time-varying nature of the supersaturation during the nucleation pulse is taken into account by an Integration over the pulse. Observed and theoretically predicted droplet concentrations are related by an assumed nucleation rate law which is adjusted until the total droplet populations predicted by integration of the assumed …

A Measurement Of Dead Space And Its Effect On The Homogeneous Nucleation Rate Of Water Vapor In Helium, Michael A. Grayson

Masters Theses

"The existence of a "dead space" surrounding each nucleated water droplet is demonstrated and measurements of its rate of development are made. The effects of this "dead space" are considered to be due to both the removal of vapor from the helium-water vapor mixture and the evolution of heat about the drop due to its growth. The results confirm the usefulness of the concept of a "dead space" and provide a means for its measurement with respect to time. Recommendations for further study and a method of correcting for dead space effects is given"--page [i].

A Study Of The Effect Of The Crystal Orientation On The Internal Friction Of Magnesium Single Crystals., Robert Ray Nothdurft

Masters Theses

"The method of growing, etching, and cutting magnesium single crystals is described in some detail. Ten single crystals of magnesium of different orientations were prepared and studied. The internal friction and relative Young’s modulus were measured for each specimen as a function of applied stress on a quartz composite oscillator. The effect of the orientation on the strain amplitude independent decrement, the strain amplitude dependent decrement and the ratio of the strain amplitude dependent decrement to the relative Young's modulus is compared to the theory of the pinned dislocation model of Granato and Lücke"--Abstract, p. ii

Construction And Test Of Equipment For Use In Ultrasonic Pulse Echo Studies., Charles Joseph Reinheimer

Masters Theses

"An ultrasonic pulse generator was constructed with a variable pulse width ranging from 4 microseconds to 10 milliseconds and a repetition period varying from 15 milliseconds to 5 seconds. The oscillator had an almost continuous range from 500 kilocycles to 18 megacycles per second.

Its applicability in studies of internal friction of metals was demonstrated with a single crystal aluminum sample"-- Abstract, p. vi

The Dielectric Properties Of Thallium Nitrate., Gene E. Gowins

Masters Theses

"The purpose of this research was to investigate the dielectric behavior of thallous nitrate and to determine whether it belongs to space group Pbnm or to Pbn2.

The growing of single crystals of thallous nitrate which are suitable for dielectric measurements is difficult because the crystals are prone to initiate a dendritic growth habit. In the present work single crystals of thallous nitrate were obtained, however, by slow evaporation of an aqueous solution at 55 degrees centigrade. The crystals were plates, not larger than 8 x 8 x 2 mm, whose principal faces were subsequently indentifled as (001) planes. The …

Aging Of The Dielectric Properties Of Some Perovskite Ceramics, Hector Troche-Maldonado

Masters Theses

"The effect of aging upon the dielectric constant and the dissipation factor were investigated for a number of lead titanate zirconate ceramics of varying composition. The ceramics investigated have a perovskite type structure. The materials chosen all have tetragonal symmetry at room temperature but are close in composition to materials of rhombohedral symmetry.

Empirical relations were determined for each specimen giving the rate of aging of the dielectric constant (K) and loss factor in terms of the frequency (f) and the elapsed time (t). The range of frequency was l kcps to l mcps; the range of elapsed time was …

An Investigation Of The Sensitized Fluorescence Of The Mercury-Sodium And The Cesium-Rubidium Systems., Joseph Edward Hueser

Masters Theses

"The experimental apparatus and techniques used for the study of sensitized fluorescence are discussed. In this study both glass and metal absorption cells were employed. Included also is a discussion of the transitions which 11 occur in the mercury-sodium and the cesium-rubidium systems, which were the two systems investigated. Both photographic and photometric techniques were used as means of detecting the sensitized fluorescence. The actual experimental apparatus used are discussed together with conclusions to be drawn and recommendations to be made from the individual experiments. The purpose of the experiments was to better understand the energy exchange processes in a …

Studies Of An Electrical Method For Generating Ultrasonic Waves, Yung-Yien Huang

Masters Theses

“Ultrasonic waves have proved very valuable in the observation of both the velocity and the absorption coefficient of sound in various media. From the velocity measurements of ultrasonic waves in metals, it is possible to obtain elastic constants, such as the compressibility, and the specific heat. Also, the observed attenuation depends greatly on the type and structure of the material. One of the widely used methods for investigation of the internal losses in solid state physics is the pulse-echo technique. This method is being used almost exclusively in internal friction investigation"--Introduction, page 1.

Determination Of The Fast Flux Of U.M.R. Reactor, Dave Vibhakar Ratilal

Masters Theses

"Measurements of fast flux of University of Missouri at Rolla, Reactor have been made using: (n,p) reactions in Mg²⁷ and Ni⁵⁸ and (n,α) reactions in Al²⁷. The effective activation cross sections at respective threshold energies for various foils have been obtained from AERE and AECL reports and from literature published by various investigators. A RIDL 400 channel analyzer was used for counting"--Abstract, page 1.

Transverse Spin Relaxation Of Optically Pumped Rubidium., Robert Evans Hufft

Masters Theses

The study of the transverse spin relaxation of rubidium vapor is a continuation of the work done by Kenneth Steinbruegge¹ and that in progress by John Martin² at the University of Missouri at Rolla. The purpose of the experiment is to study the change of intensity of the transmitted pumping light at resonance in the longitudinal direction, and the observation of the high frequency modulation of a second "cross" beam of light perpendicular to the first. Under resonant conditions this "cross" beam will exhibit a phase coherence and a loss of phase coherence when parameters of the experiment …

An Investigation Of The Acceleration Of Neutrons, Charles Edward Byvik

Masters Theses

"The acceleration of neutrons via their magnetic dipole moment in an axially symmetric magnetic field is considered. Conditions for bunching are derived and expressions for the off-axis forces are developed. It was found that neutrons off axis are forced back onto the axis and that neutrons slightly depolarized remain in their initial state. A calculation of the acceleration is made using the field of a current loop and the conclusion is that under present laboratory capabilities a neutron accelerator is not feasible"--Abstract, page ii.

The Construction And Analysis Of An Amplifier For Ultrasonic Research, Jerry John Koelling

Masters Theses

“An amplifier to be used for ultrasonic pulse methods was constructed and tested. The frequency range lies between 100 cycles per second and 2 mega-cycles per second and, if tuned circuit plug-in units are used, may be increased to approximately 4 mega-cycles per second. Special demands upon the amplifier are discussed along with basic acoustic attenuation measurements in solid state physics”--Abstract, page ii.

Spin Relaxation Of Optically Pumped Rubidium., Kenneth Brian Steinbruegge

Masters Theses

"This Thesis is intended to be a self-contained guide to the theory and experimental procedures of optical pumping in one of its most usual applications. A particular study is made of optical pumping of rubidium vapor and results are given stating the most efficient temperature range in which to produce large populations of optically oriented rubidium atoms. The thermal relaxation time for optically orientated rubidium for a particular system is given and the effect of trapped resonance radiation is considered in the interpretation of the experimentally obtained curves"--Abstract, p. ii

The Measurement Of The Life-Time Of The 62P3/2 State Of Thallium, Danny Hale Sokolowski

Masters Theses

The measurement of the lifetime of the metastable 6²P_3/2 state of thallium is discussed. Time-sampling equipment techniques and instantaneous methods of display on an oscilloscope for measuring the lifetime are explained. The lifetime is measured as a function of mercury vapor pressure. The decay of the 5350 A thallium line is also measured to give an indication of the effect of the imprisonment of the 3776 A resonance line. This decay of the 5350 A line is also in a mercury atmosphere"--Abstract, page ii.

The Application Of Quantum-Mechanical Concepts To Biological Systems, Andrew A. Cochran

Masters Theses

"The relation between quantum-mechanical concepts and biological systems is explored by studying the relation of both to the concepts of heat capacity and entropy. It is shown that the most important substances in living matter have extremely low heat capacities and entropies at ordinary temperatures. A critical analysis of the two types of quantum-mechanical interactions between particles and the interactions occurring in low-entropy systems shows that the wave properties of matter are strongly predominant in the chemical elements that constitute 99 percent of living matter. It is concluded that the wave aspects of matter are strongly predominant in biological systems. …

Variation Of Sensitized Fluorescence With Penetration Depth Of Incident 2537a Radiation, George Grayson Robinson

Masters Theses

"An investigation of the sensitized fluorescence of a thallium and mercury mixture using a variable depth cell and photomultiplier type of detection is discussed. Data are given to indicate the variation of the intensity of the 3519A thallium line as a function of thallium temperature, as a function of mercury temperature, and as a function of cell depth. Explanations of results require the use of generally accepted ideas concerning energy transfer, emission, and absorption."