Constraints on chondrule generation, disk dynamics, and asteroid accretion from the compositions of carbonaceous meteorites

The elemental and isotopic compositions of meteorites are expected to reflect several key processes that occurred in the early solar system, including the migration of gas and dust throughout the protoplanetary disk, the formation of chondrules, and the accretion of the first planetary bodies. However, the specific origins of the various com positions measured among these rocks are currently poorly constrained, limiting our understanding of these processes. Here, we use previously measured elemental and isotopic compositions of chondrites and iron meteorites to identify that carbonaceous (CC) meteorites are mixtures of non-carbonaceous (NC) material, calcium-aluminum-rich inclusion (CAI) material, and CI (Ivuna-like) material, in varying proportions. These trends indicate that chondrules in CO (Ornans-like), CM (Mighei-like), CV (Vigarano19 like), and TL (Tagish Lake) chondrites share near-identical average proportions of CI material, arguing that they were generated through the remelting of pre-existing NC chondrules all in the same disk environment. Because this proportion likely evolved over space and time throughout the disk, this similarity argues that these chondrules originate from a restricted spatial region and time interval, favoring their generation through a localized event. Moreover, the compositions of CR (Renazzo-like) chondrites indicate that their constituents formed through different mechanisms to those in CO, CM, CV, and TL chondrites. The recovered proportions of CI material in CC iron meteorites and chondrites together also argue for an evolution in either the predominant direction of dust and gas motion in the first ⇠10 AU of the disk or the radial distance of planetesimal accretion throughout the CC reservoir

Disk transport rates from Ti isotopic signatures of refractory inclusions

The early solar system was a dynamic period during which the formation of early solids set into motion the process of planet building. Although both astrophysical observations and theoretical modeling demonstrate the presence of widespread transport of material, we lack concrete quantitative constraints on timings, distances, and mechanisms thereof. To trace these transport processes, one needs objects of known early formation times and these objects would need to be distributed throughout parent bodies with known accretion times and distances. Generally, these criteria are met by “regular” (i.e., non–fractionated and unidentified nuclear and excluding hibonite-rich) Ca-Al-rich inclusions (CAIs) as these objects formed very early and close to the young Sun and contain distinctive nucleosynthetic isotope anomalies that permit provenance tracing. However, nucleosynthetic isotopic signatures of such refractory inclusions have so far primarily been analyzed in chondritic meteorites that formed within ~4 AU from the Sun. Here, we investigate Ti isotopic signatures of four refractory inclusions from the ungrouped carbonaceous chondrite WIS 91600 that was previously suggested to have formed beyond ~10 AU from the Sun. We show that these inclusions exhibit correlated excesses in 50Ti and 46Ti and lack large Ti isotopic anomalies that would otherwise be indicative of more enigmatic refractory materials with unknown formation ages. Instead, these isotope systematics suggest the inclusions to be genetically related to regular CAIs commonly found in other chondrites that have a broadly known formation region and age. Collectively, this implies that a common population of CAIs was distributed over the inner ~10 AU within ~3.5 Myr, yielding an average (minimum) speed for the transport of millimeter-scale material in the early solar system of ~1 cm s−1

Use of Stress to Produce Highly Oriented Tetragonal Lead Zirconate Titanate (PZT 40/60) Thin Films and Resulting Electrical Properties

Thin films of Pb(Zr0.4TiO.6)O3 produced by chemical solution deposition were used to study the effects of stress from different platinized single-crystal substrates on film orientation and resulting electrical properties. Films deposited on MgO preferred a (001) orientation due to compressive stress on the film during cooling through the Curie temperature (TC). Films on Al2O3 were under minimal stress at TC, resulting in a mixture of orientations. Those on Si preferred a (111) orientation due to templating from the bottom electrode. Films oriented in the 〈001〉 direction demonstrated lower dielectric constants and higher Pr and −d31 values than (111) films

Neutron Flux Characterization Techniques for Radiation Effects Studies

In the field of radiation effects in materials, a detailed and precise description of the radiation environment used to damage samples is often required to make sense of subsequent materials analysis. The types of reactions and extent of damage that occur during irradiation strongly depend on the flux spectrum of the particular facility. Different neutron activation techniques for characterizing neutron flux spectra were performed on the University of Texas at Austin TRIGA research reactor\u27s in-core facilities. The results were compared in terms of spectral detail and precision. Activation of Au foils with multiple correction factors, and multiple foil activation employing different deconvolution techniques comprise the methods tested