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Octahedral oxide glass network in ambient pressure neodymium titanate.

ABSTRACT: Rare-earth titanates form very fragile liquids that can be made into glasses with useful optical properties. We investigate the atomic structure of 83TiO₂-17Nd₂O₃ glass using pair distribution function (PDF) analysis of X-ray and neutron diffraction with double isotope substitutions for both Ti and Nd. Six total structure factors are analyzed (5 neutron + 1 X-ray) to obtain complementary sensitivities to O and Ti/Nd scattering, and an empirical potential structure refinement (EPSR) provides a structural model consistent with the experimental measurements. Glass density is estimated as 4.72(13) g cm^-3, consistent with direct measurements. The EPSR model indicates nearest neighbor interactions for Ti-O at [Formula: see text] = 1.984(11) Å with coordination of [Formula: see text] = 5.72(6) and for Nd-O at [Formula: see text] = 2.598(22) Å with coordination of [Formula: see text] = 7.70(26), in reasonable agreement with neutron first order difference functions for Ti and Nd. The titanate glass network comprises a mixture of distorted Ti-O₅ and Ti-O₆ polyhedra connected via 71% corner-sharing and 23% edge-sharing. The O-Ti coordination environments include 15% nonbridging O-Ti₁, 51% bridging O-Ti₂, and 32% tricluster O-Ti₃. This structure is highly unusual for oxide glasses melt-quenched at ambient pressure, as it consists of Ti-O_x predominantly in octahedral (with nearly no tetrahedral) coordination.

SUBMITTER: Wilke SK

PROVIDER: S-EPMC9117677 | biostudies-literature | 2022 May

REPOSITORIES: biostudies-literature

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Octahedral oxide glass network in ambient pressure neodymium titanate.

Wilke Stephen K SK Alderman Oliver L G OLG Benmore Chris J CJ Neuefeind Jörg J Weber Richard R

Scientific reports 20220518 1

Rare-earth titanates form very fragile liquids that can be made into glasses with useful optical properties. We investigate the atomic structure of 83TiO2-17Nd2O3 glass using pair distribution function (PDF) analysis of X-ray and neutron diffraction with double isotope substitutions for both Ti and Nd. Six total structure factors are analyzed (5 neutron + 1 X-ray) to obtain complementary sensitivities to O and Ti/Nd scattering, and an empirical potential structur ...[more]

PMID: 35585110

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Project description:Octahedral anatase particles (OAP) with eight exposed and thermodynamically most stable (101) facets were prepared by an ultrasonication-hydrothermal (US-HT) reaction from potassium titanate nanowires (TNW). The precursor (TNW) and the product (OAP) of US-HT reaction were modified with nanoparticles of noble metals (Au, Ag or Pt) by photodeposition. Samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectroscopy (DRS), scanning transmission electron microscopy (STEM) and time-resolved microwave conductivity (TRMC). The photocatalytic activity was investigated in three reaction systems, i.e., anaerobic dehydrogenation of methanol and oxidative decomposition of acetic acid under UV/vis irradiation, and oxidation of 2-propanol under vis irradiation. It was found that hydrogen liberation correlated with work function of metals, and thus the most active were platinum-modified samples. Photocatalytic activities of bare and modified OAP samples were much higher than those of TNW samples, probably due to anatase presence, higher crystallinity and electron mobility in faceted NPs. Interestingly, noble metals showed different influence on the activity depending on the semiconductor support, i.e., gold-modified TNW and platinum-modified OAP exhibited the highest activity for acetic acid decomposition, whereas silver- and gold-modified samples were the most active under vis irradiation, respectively. It is proposed that the form of noble metal (metallic vs. oxidized) as well as the morphology (well-organized vs. uncontrolled) have a critical effect on the overall photocatalytic performance. TRMC analysis confirmed that fast electron transfer to noble metal is a key factor for UV activity. It is proposed that the efficiency of plasmonic photocatalysis (under vis irradiation) depends on the oxidation form of metal (zero-valent preferable), photoabsorption properties (broad localized surface plasmon resonance (LSPR)), kind of metal (silver) and counteraction of "hot" electrons back transfer to noble metal NPs (by controlled morphology and high crystallinity).

Project description:(1) Objective: Rare earth neodymium oxide (Nd2O3) is refined and used extensively around the world, and the occupational and environmental safety of rare piles of the earth has attracted considerable attention. Nd2O3 enters the human body through the respiratory system, reaches various organs through blood circulation, and accumulates to produce toxic effects. At present, little is known about the reproductive toxicity of Nd2O3. Non-coding RNAs participate in a variety of physiological activities and are very important for spermatogenesis. However, it is unknown whether they are involved in Nd2O3-induced reproductive toxicity. Therefore, we conducted a pathological analysis, sperm quality testing, and RNA-seq on the testicular tissue of mice exposed to Nd2O3 to find the key genes and regulatory pathways of male reproductive damage and explore the early biomarkers and mechanisms of reproductive damage caused by Nd2O3. (2) Methods: After exposure of mice to Nd2O3, we carried out a pathological analysis and RNA-seq analysis for miRNAs/lncRNAs/circRNAs/mRNAs on the testicular tissue of mice, and the total RNAs were used to investigate miRNA/lncRNA/circRNA/mRNA expression profiles by strand-specific RNA sequencing at the transcriptome level to help uncover RNA-related mechanisms in Nd2O3-induced toxicity. (3) Results: Nd2O3 damaged testis and sperm morphology, significantly decreased the number of sperm, and deformed the sperm head and tail. RNA-seq analysis showed that the expression level of mRNA/miRNA/circRNA/lncRNA in the testicular tissue of mice exposed to Nd2O3 is abnormal. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis demonstrated that the functional enrichment of differentially expressed genes (DEGs) and their target genes was closely related to the related pathway of spermatogenesis. Furthermore, some miRNAs/lncRNAs/circRNAs that were greatly upregulated or inducibly expressed, implying their potential value as candidate markers for Nd2O3-induced reproductive toxicity, help us to further investigate the mechanisms of key genes, key signaling pathways, and inter-gene regulation for Nd2O3-induced reproductive toxicity. (4) Conclusions: This study provides the first database of a Nd2O3-induced transcriptome. This information is useful for the development of biomarkers of Nd2O3-induced reproductive injury and promotes understanding of the reproductive toxicity mechanism of Nd2O3.

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Octahedral oxide glass network in ambient pressure neodymium titanate.

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Octahedral oxide glass network in ambient pressure neodymium titanate.

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