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To obtain crystalline thin films of alpha-Quartz represents a challenge due to the tendency for the material towards spherulitic growth. Thus, understanding the mechanisms that give rise to spherulitic growth can help regulate the growth process. Here the spherulitic type of 2D crystal growth in thin amorphous Quartz films was analyzed by electron back-scatter diffraction (EBSD). EBSD was used to measure the size, orientation, and rotation of crystallographic grains in polycrystalline SiO2 and GeO2 thin films with high spatial resolution. Individual spherulitic Quartz crystal colonies contain primary and secondary single crystal fibers, which grow radially from the colony center towards its edge, and fill a near circular crystalline area completely. During their growth, individual fibers form so-called rotational crystals, when some lattice planes are continuously bent. The directions of the lattice rotation axes in the fibers were determined by an enhanced analysis of EBSD data. A possible mechanism, including the generation of the particular type of dislocation(s), is suggested.

[Formula: see text] with the [Formula: see text]-quartz structure is one of the most popular piezoelectrics. It is widely used in crystal oscillators, bulk acoustic wave (BAW) devices, surface acoustic wave (SAW) devices, and so on. [Formula: see text] can also be crystallized into the [Formula: see text]-quartz structure and it has better piezoelectric properties, with higher piezoelectric coefficient and electromechanical coupling coefficients, than [Formula: see text]. Experiments on bulk crystals and theoretical studies have shown that these properties can be tuned by varying the Si/Ge ratio in the [Formula: see text] solid solution. However, to the best of our knowledge, thin films of [Formula: see text] quartz have never been reported. Here we present the successful crystallization of [Formula: see text] thin films in the [Formula: see text]-quartz phase on quartz substrates ([Formula: see text]) with x up to 0.75. Generally, the films grow semi-epitaxially, with the same orientation as the substrates. Interestingly, the [Formula: see text] composition grows fully strained by the quartz substrates and this leads to the formation of circular quartz domains with an ordered Dauphiné twin structure. These studies represent a first step towards the optimization of piezoelectric quartz thin films for high frequency (5 GHz) applications.

Piezoelectric quartz (SiO2) crystals are widely used in industry as oscillators. As a natural mineral, quartz and its relevant silicates are also of interest in geoscience and mineralogy. However, the nucleation and growth of quartz crystals are difficult to control and not fully understood. Here we report successful solid-state crystallization of thin film of amorphous GeO2 into quartz on various substrates, including Al2O3, MgAl2O4, MgO, LaAlO3 and SrTiO3. At relatively low annealing temperatures, the crystallization process is spherulitic: with fibers growing radially from the nucleation centers and the crystal lattice rotating along the growth direction with a linear dependence between the rotation angle and the distance to the core. For increasingly higher annealing temperatures, quartz crystals begin to form. The edges of the sample play an important role in facilitating nucleation followed by growth sweeping inward until the whole film is crystallized. Control of the growth allows single crystalline quartz to be synthesized, with crystal sizes of hundreds of microns achieved on sapphire substrates, which is promising for further piezoelectric applications. Our study reveals the complexity of the nucleation and growth process of quartz and provides insight for further studies.

The growth of α-quartz-based piezoelectric thin films opens the door to higher-frequency electromechanical devices than those available through top-down approaches. We report on the growth of SiO2/GeO2 thin films by pulsed laser deposition and their subsequent crystallization. By introducing a devitrifying agent uniformly within the film, we are able to obtain the α-quartz phase in the form of platelets with lateral sizes above 100 μm at accessible temperatures. Films containing different amounts of devitrifying agent are investigated, and their crystallinity is ascertained with X-ray diffraction and electron back-scatter diffraction. Our work highlights the difficulty in crystallization when competing phases arise that have markedly different crystalline orientation.

Despite its interest for CMOS applications, Atomic Layer Deposition (ALD) of GeO$_{2}$ thin films, by itself or in combination with SiO$_{2}$, has not been widely investigated yet. Here we report the ALD growth of SiO$_{2}$/GeO$_{2}$ multilayers on Silicon substrates using a so far unreported Ge precursor. The characterization of multilayers with various periodicities reveals successful layer-by-layer growth with electron density contrast and absence of chemical intermixing, down to a periodicity of 2 atomic layers., This manuscript has been submitted to Applied Physics Letters

Ferroelectric materials exhibit the largest dielectric permittivities and piezoelectric responses in nature, making them invaluable in applications from supercapacitors or sensors to actuators or electromechanical transducers. The origin of this behavior is their proximity to phase transitions. However, the largest possible responses are most often not utilized due to the impracticality of using temperature as a control parameter and to operate at phase transitions. This has motivated the design of solid solutions with morphotropic phase boundaries between different polar phases that are tuned by composition and that are weakly dependent on temperature. Thus far, the best piezoelectrics have been achieved in materials with intermediate (bridging or adaptive) phases. But so far, complex chemistry or an intricate microstructure has been required to achieve temperature-independent phase-transition boundaries. Here, we report such a temperature-independent bridging state in thin films of chemically simple BaTiO3. A coexistence among tetragonal, orthorhombic, and their bridging low-symmetry phases are shown to induce continuous vertical polarization rotation, which recreates a smear in-transition state and leads to a giant temperature-independent dielectric response. The current material contains a ferroelectric state that is distinct from those at morphotropic phase boundaries and cannot be considered as ferroelectric crystals. We believe that other materials can be engineered in a similar way to contain a ferroelectric state with gradual change of structure, forming a class of transitional ferroelectrics. Similar mechanisms could be utilized in other materials to design low-power ferroelectrics, piezoelectrics, dielectrics, or shape-memory alloys, as well as efficient electro- and magnetocalorics.

Very sensitive responses to external forces are found near phase transitions. However, transition dynamics and preequilibrium phenomena are difficult to detect and control. We have observed that the equilibrium domain structure following a phase transition in ferroelectric and ferroelastic BaTiO3 is attained by halving of the domain periodicity multiple times. The process is reversible, with periodicity doubling as temperature is increased. This observation is reminiscent of the period-doubling cascades generally observed during bifurcation phenomena, and, thus, it conforms to the “spatial chaos” regime earlier proposed by Jensen and Bak [Phys. Scr. T 9, 64 (1985)] for systems with competing spatial modulations., A. S. E., S. D., and B. N. acknowledge financial support from the alumni organization of the University of Groningen, De Aduarderking (Ubbo Emmius Fonds). Parts of this research were carried out at the light source Petra III at DESY, a member of the Helmholtz Association (HGF). G. C. and N. D. acknowledge Projects No. FIS2015-73932-JIN and No. MAT2016-77100-C2-1-P from the Spanish MINECO and Project No. 2017-SGR-579 from the Generalitat de Catalunya. All work at ICN2 is also supported by the Severo Ochoa Program (Grant No. SEV-2017-0706). The work at Penn State is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, under Award No. FG02-07ER46417 (J. A. Z. and L.-Q. C.) and, partially, by a graduate fellowship from the 3M Company (J. A. Z.).

The Ca-doped Bi-2201 system with nominal composition Bi2Sr2−x Ca x CuO6+δ (x=0.1,0.3,0.5,0.7,0.9) was prepared by sol–gel method and investigated by X-ray diffraction, transmission electron microscopy and resistance measurements. It can be found that the Ca-doped Bi-2201 system was composed of Bi-2201 phase containing Ca (main phase) and a small quantity of Bi16(Sr,Ca)14O38 (impurity). For the main phase, the b ∗ component of the modulation wave vector decreases while the c ∗ component increases with the increase of calcium content. The evolutional mechanism of the modulation wave vector, the correlation between superconductivity and modulation wave vector were also discussed.

Hyperleukocytosis (white blood cell count, >100×109/l), an uncommon presentation of leukemia, is associated with an increased risk of early mortality. It may present with a variety of symptoms secondary to leukostasis, a syndrome caused by the sludging of circulating leukemic blasts in the microvasculature. Adequate measures for managing this medical emergency include hydration, cytoreduction, prevention of tumor lysis and, rarely, leukapheresis in cases complicated by leukostasis and hyperviscosity syndrome. The present study reports a case series of five patients with hyperleukocytic leukemia. In addition, a review of the literature with regard to the incidence, pathophysiology, clinical manifestations and management of this laboratory abnormality is included. This study demonstrated that the central nervous system and lungs are the most common sites for leukostasis, and that emergency cases require aggressive treatment.

To investigate the possible biological function and mechanism of miR-143 in the metastasis of human nasopharyngeal carcinoma (NPC).Using bioinformatics to predict the target gene of miR-143, the 3'UTR and mutant 3'UTR of GLI3 gene was cloned into psiCHECK-2 vector. Dual-luciferase reporter gene assay was employed to examine the repression of the GLI3 gene. miR-143 and GLI3 expression levels in 5-8F cells transfected with miR-143 mimics, inhibitor, or siGLI3 were examined, and the changes in the cell migration ability was assessed by Transwell invasion assay.Bioinformatics prediction indicated the Hh pathway transcription gene GLI3 as a target gene of miR-143, and dual-luciferase reporter assay showed that miR-143 directly combined with the 3'UTR of GLI3. qRT-PCR and Western blotting demonstrated that the expression of miR-143 in 5-8F cells was negatively correlated to GLI3 and suppressed the migration of 5-8F cells.MiR-143 can inhibit the invasion of NPC cells by negative regulation of GLI3 gene, which sheds light on the role of miR-143 and Hh pathway in NPC.

To detect miR-143 expression in human nasopharyngeal carcinoma (NPC) cell lines and explore the role of miR-143 in regulating the adhesion ability of NPC cells.Fluorescence quantitative RT-PCR was used to detect miR-143 expression levels in 5 NPC cell lines (CEN1, CNE2, HONE1, 5-8F, and 6-10B) and an immortalized human nasopharyngeal epithelial cell line (NP69). The retrovirus plasmid pMSCV-puro-miR-143 was constructed and the packaged retroviruses pMSCV-puro and pMSCV-puro-miR-143 were infected in 5-8F cells to establish a cell line with stable miR-143 overexpression, whose adhesion ability was tested with adhesion assay.The expression of miR-143 was down- regulated in the NPC cell lines, and the highly metastatic NPC cell line 5-8F had a expression of only 3.0% of the control level, as compared with the level of 63.59% in the tumorigenic but nonmetastatic NPC cell line 6-10B. The transfected 5-8F cells showed a 1080-fold increase of miR-143 expression (P0.05) with a significantly lowered adhesion ability.miR-143 plays a role in regulating the invasiveness and metastasis of NPC, and overexpression of miR-143 causes a significant reduction of the adhesion ability of the highly metastatic NPC cell line 5-8F.